29 entries found for : sfn2012
Spatial memory facilitation by electrical stimulation of the medial septum in rats.
Jeong D, Lee J, Lee S, Kim S, Chang J (2012) Spatial memory facilitation by electrical stimulation of the medial septum in rats. Neuroscience 2012 Abstracts 851.01. Society for Neuroscience, New Orleans, LA.
Summary: Recently, deep brain stimulation has been used to treat various neurological disorders. Some studies support that DBS can be a strategy to treat Alzheimer’s disease. The aim of this study was to evaluate the effect of electrical stimulation in the medial septum using rat model mimicking basal forebrain cholinergic deficits of Alzheimer’s disease. Four experimental groups were composed of normal, lesion, lesion + implantation and lesion + stimulation. 192 IgG-saporin (Selective cholinergic toxin, 8ul of 0.63ug/ul) were bilaterally injected into the lateral ventricle. Electrode was stereotactically implanted into the left medial septum (AP +0.6, ML 0.16, DV -6). Stimulation parameters are 50Hz, 120us pulse width and 1 volt. One week after implantation, Stimulation started for 2 weeks. Two weeks after surgery, water maze was performed for 1 week and rats were sacrificed immediately after behavioral test. Features were verified by immunochemistry and AChE assay. During the training trials, latencies of lesion and implantation significantly increased in day3 and day4. In contrast, latency of stimulation group had no differences as compared to normal group but it decreased significantly when compared to lesion group in day4. In the probe test, lesion group had decreases in time in target quadrant, time in platform zone and the number of platform crossing. Although they did not perform as normal group, stimulation group showed tendency of recovery. IHC and AChE assay are ongoing. Spatial memory is associated with hippocampus. We had expected activation of hippocampus by stimulation of the medial septum. We confirmed that stimulation of the medial septum facilitates acquisition and recall of spatial memory. Currently we are studying the effects of medial septal stimulation on the hippocampus.
Related Products: 192-IgG-SAP (Cat. #IT-01)
Evidence that focal hippocampal interneuron loss disrupts theta- and gamma- band activity.
Rossi CA, Lehmkuhle MJ, Dudek FE (2012) Evidence that focal hippocampal interneuron loss disrupts theta- and gamma- band activity. Neuroscience 2012 Abstracts 918.06. Society for Neuroscience, New Orleans, LA.
Summary: Hippocampal theta (6-12 Hz) and gamma (40-100 Hz) activity are oscillatory local field potentials (LFPs) that are thought to play a critical role in the encoding and storage of new information. GABA-ergic interneurons are hypothetically involved in the generation and pacing of these oscillatory patterns of activity. The current study aimed to directly test the hypothesis that interneurons are responsible for local gamma and theta generation in the dorsal CA1 region of the hippocampus in mice. Selective focal interneuron lesions were made by intrahippocampal injection of the targeted neurotoxin SSP-Saporin into dorsal CA1 in the hippocampus of GAD67-GFP transgenic mice. Chronic recording electrodes were also implanted in the lesion area. LFPs were monitored continuously, along with video recordings of the subjects, for a period of several weeks. LFP recordings were analyzed over 24-hour periods for the occurrence of theta- and gamma-band activity. Analysis of LFP data revealed attenuation of both local theta and gamma activity in SSP-saporin-injected animals compared to controls. These results suggest a direct role of GABA-ergic interneurons in the generation of local rhythmic activity in these two frequency bands, and, by extension, an important role in learning and memory processes.
Related Products: SSP-SAP (Cat. #IT-11)
Cholinergic contributions to learned attentional suppression in the rat with touchscreens.
Ljubojevic V, Botly L, De Rosa E (2012) Cholinergic contributions to learned attentional suppression in the rat with touchscreens. Neuroscience 2012 Abstracts 729.13. Society for Neuroscience, New Orleans, LA.
Summary: One of the tasks of the attentional system is to filter environmental input according to its behavioral relevance. The neuromodulator acetylcholine (ACh) is thought to play a role in this process because of its ability to boost the signal-to-noise ratio of incoming sensory information. Cholinergic innervation of the attentional system has been shown to be necessary for successful selection of behaviorally-relevant stimuli (signal). However, it is not yet clear if ACh also plays a part in the attentional suppression of behaviorally-irrelevant information (noise). Thus, we examined the effect of cortical cholinergic deafferentation on attentional suppression in rats. To measure attentional suppression, we used a rat analog of the learning-to-ignore (LI) task originally designed for human participants (Dixon et al., 2009). The paradigm consisted of three stages of training (Prime1, Prime2, Probe; 10 sessions per stage), each of which involved stages of visual simultaneous discriminations between two stimuli. In both Prime conditions, individuals learned to respond to target stimuli (A+ and then C+ respectively), while ignoring the same distractor stimulus (B-). During Probe, the previously ignored stimulus became the target (B+) and a novel stimulus (D-) was introduced as a distractor. Eighteen male Long-Evans rats were trained to perform the touchscreen-based LI task. Like the human data, a behavioral decrement (lower accuracy) was observed during the Probe phase of the LI task when compared to Prime 1 and 2, which suggests that the ignored distractor stimulus was suppressed during Prime. We hypothesized that administration of the ACh-specific immunotoxin, 192 IgG-saporin, into the nucleus basalis magnocellularis (NBM) would lead to better performance during Probe condition relative to controls. Accordingly, the rats were subjected to either cholinergic immunotoxic (SAP, N=10) or sham lesion surgery (SHAM, N=8). After 2 weeks of post-surgical recovery, the rats were tested on the LI task with a new stimulus set. The two groups performed comparably during Prime1 and 2, with both SAP and SHAM rats successfully learning the discriminations. As predicted, during Probe SAP rats exhibited significantly less behavioral decrement than controls. Histological analysis revealed that the lesion was chemically and anatomically specific to cholinergic cells in the NBM. This counterintuitive finding suggests that the improved performance during Probe, due to reduced ACh input to the neocortex, was due to inefficient attentional suppression of the behaviorally-irrelevant stimulus.
Related Products: 192-IgG-SAP (Cat. #IT-01)
Ortiz-Barajas O, Ramos-Rodriguez J, Berrocoso E, Garcia Alloza M (2012) Limited effect of serotonergic denervation on beta-amyloid and cognitive impairment in APPswe/PS1dE9 mice. Neuroscience 2012 Abstracts 751.12. Society for Neuroscience, New Orleans, LA.
Summary: Alzheimer’s Disease (AD) is a neurodegenerative disease characterized by progressive cognitive and memory impairment. Amyloid-beta (Aβ) deposition, as senile plaques (SP), seems to play a key role in the development and progression of the illness. Moreover SP tend to accumulate in cortex and hippocampus, relevant areas in learning and memory. On the other hand neuronal loss is the pathological feature that best correlates with duration and severity of the illness and at present animal available animal models hardly reproduce the complexity of the disease. We have previously seen that selective cortical and hipocampal cholinergic denervation, using murine p-75 saporin, may worsen cognitive abilities in APPswe/PS1dE9 mice as well as increase SP deposition in denervated areas. In the present work we lesioned 7 months old APPswe/PS1dE9 mice with 1 µl of 5,7-dyhidroxytiptamine (0.16 µg/µl) injected in the raphe nucleus (RN). In order to guarantee selective removal of cortical and hipocampal serotonergic inervation, and protect noardernergic and dopaminergic neurons, animals were i.p. injected with desipramine and nomifensine before surgery. We observed a clear reduction of tryptophan hydroxilase staining in the RN. In the Morris water maze test we observed learning and memory impairment in APPswe/Ps1dE9 mice, without a synergistic effect of the serotonergic lesion. When we assessed SP deposition we did not observe a significant increase of SP in cortex or hipocampus 14 days after the lesion, as we observed after selective cholinergic denervation. Altogether our data suggest that cognitive impairment and induced SP depositioin observed after cholinergic denervation is not achieved when serotonergic system is affected, supporting a selective effect mediated by different neurotransmitter systems. Acknowledgements: MG-A: RYC-2008-02333, ISCIII-Subdirección General de Evaluación y Fomento de la Investigación (PS09/00969), Fundación Dr. Eugenio Rodriguez Pascual, Junta Andalucia Excelencia (CTS-7847).
Related Products: mu p75-SAP (Cat. #IT-16)
Ostock CY, Lindenbach D, Jaunarajs KL, Dupre KB, Goldenberg A, Bhide NS, Bishop C (2012) Noradrenergic denervation by DBH saporin reduces behavioral responsivity to L-DOPA in the hemi-parkinsonian rat. Neuroscience 2012 Abstracts 758.06. Society for Neuroscience, New Orleans, LA.
Summary: Dopamine (DA) replacement therapy with L-DOPA remains the most effective treatment for Parkinson’s disease (PD), but prolonged use frequently leads to deleterious side effects including involuntary choreic and dystonic movements known as L-DOPA induced dyskinesias (LID). It has been well established that DA loss in PD is accompanied by concomitant noradrenergic (NE) denervation of the locus coeruleus (LC); however, the contribution of NE loss to LID remains controversial and is often overlooked in traditional animal models of PD. Previous work from our lab demonstrated that rats with NE depletion induced by the selective NE neurotoxin DA beta hydroxylase saporin (DBH saporin) display reduced behavioral sensitivity to L-DOPA. The current investigation sought to further characterize the utility of DBH saporin lesions in a rodent model of PD by employing immunohistological techniques to correlate NE cell loss with behavioral outcome. Male Spraque-Dawley rats received unilateral 6-OHDA lesions of the medial forebrain bundle with intraventricular injections of either vehicle or DBH saporin. A number of well characterized behavioral tests were employed to determine lesion effects and L-DOPA responsiveness including: the abnormal involuntary movements scale for rodent dyskinesia, the forepaw adjusting steps (FAS) test as a metric of L-DOPA’s anti-parkinsonian efficacy, and locomotor chambers to observe motor performance. Sensitivity of primed animals to different doses of L-DOPA (0-12 mg/kg) and DA agonists SKF81297 (0., 0.08, 0.8 mg/kg) and Quinpirole (0, 0.05, 0.5 mg/kg) was assessed. Reduced behavioral responsiveness was associated with reductions in tyrosine hydroxylase positive cells within the LC of DBH saporin lesioned animals. Results indicate that NE denervation reduced anti-parkinsonian efficacy of L-DOPA on the FAS test. In primed rats, LC NE loss attenuated dyskinetic responses to L-DOPA and the DA agonist SKF81297. Taken together, these results indicate that DBH saporin lesions not only mimick the NE loss seen in idiopathic PD, but also reveal an underexplored contribution of the NE system to the manifestation of PD symptoms and LID.
Related Products: Anti-DBH-SAP (Cat. #IT-03)
Intercalated nucleus modulates chemosensory processing in medial amygdala.
Biggs LM, Simonton AR, Meredith M (2012) Intercalated nucleus modulates chemosensory processing in medial amygdala. Neuroscience 2012 Abstracts 781.07. Society for Neuroscience, New Orleans, LA.
Summary: The vomeronasal organ is necessary for interpretation by naive rodents (hamsters, mice) of many chemosensory signals. Information is relayed to medial amygdala (Me) via the accessory olfactory bulbs. FRA (Fos related antigen) responses in Me to chemosensory cues suggest this area is important for categorization of cues based on biological relevance to the animal. Anterior Me (MeA) is activated by all chemosensory cues (conspecific and heterospecific). Posterior Me (MeP) activates for conspecific and biologically relevant heterospecific stimuli only. Other heterospecific stimuli suppress MeP, apparently via GABA inhibition, while the adjacent medial-caudal intercalated nucleus (m-ICNc) is activated. Intercalated nuclei (ICNs) are groups of GABAergic cells between amygdala main-divisions. Those adjacent to basolateral and central amygdala (BLA, CeA) are known to mediate BLA, CeA responses via GABA inhibition, modulated by inhibitory DA-D1 receptors on ICN cells. We hypothesize that m-ICNc modulates MeP in a similar manner, as suggested by FRAs data, but this has not yet been tested directly. In hamsters, we show a hyperpolarization of MeP cells and suppression of ongoing spiking in whole-cell slice electrophysiology using in-slice stimulation of m-ICNc. The effect of dopamine and other modulators on this functional relationship is under study with agonists and antagonists. ICN, but not Me, cells carry mu-opioid receptors (MORs). In mice, we use Dermorphin-Saporin, a toxin that selectively destroys MOR+ neurons, to lesion m-ICNc to assess its role in chemosensory responses in MeP. Also in mice, a specific MUP protein in male urine (mMU) facilitates learning of a male’s chemosensory signature by females. We have quantified Me response to high and low molecular weight (HMW, LMW) fractions (LMW lacks protein) and whole mMU using FRAs immediate early gene expression. Preliminary results show no significant difference between HMW, LMW, or whole mMU in Me, however within the BLA (involved in volatile odor learning), there are significant differences in activity between stimuli in females without post-weaning exposure to male urine and no prior exposure to adult male urine.
Related Products: Dermorphin-SAP / MOR-SAP (Cat. #IT-12)
Carr F, Géranton SM, Hunt SP (2012) Descending facilitation contributes to changes in dorsal horn gene expression in a rat model of inflammatory joint pain. Neuroscience 2012 Abstracts 785.07. Society for Neuroscience, New Orleans, LA.
Summary: Chronic pain is associated with increased excitability and changes in gene expression within the dorsal horn. Descending facilitation from the rostral ventromedial medulla (RVM) is known to contribute to this excitability and behavioural hypersensitivity in a number of pain states. This would suggest that some of the gene changes associated with chronic pain could be driven by descending pathways terminating in the dorsal horn. We have previously demonstrated that ablation of a subset of RVM neurons expressing the mu opioid receptor (MOR) attenuates behavioural hypersensitivity following joint inflammation. The aim of the present study was to combine lesion of the RVM with microarray analysis of the dorsal horn to identify genes regulated by descending facilitation in this pain model. Selective lesion of MOR expressing cells of the RVM was carried out in rats by microinjection of the selective toxin dermorphin-saporin. Non-lesioned controls received vehicle microinjection. 4 weeks after the lesion procedure when depletion of the MOR+ cells was complete, both groups received an injection of 10μl Complete Freund's Adjuvant to the left ankle joint. 7 days later the animals were sacrificed and the ipsilateral quadrant of the dorsal horn of the spinal cord lumbar region (L4-L6) removed. RNA was extracted and microarray analysis carried out using Affymetrix GeneChip Rat Gene 1.0 ST Arrays. Raw data was analysed in R using Bioconductor open source software. Limma testing was applied and a list of genes differentially regulated in animals with prior RVM lesion compared to non-lesioned controls was generated. The majority of differentially regulated genes (73%) were downregulated in the lesioned group. We used the DAVID bioinformatics resource to cluster the genes into groups with similar functional annotations (Huang et al., 2009). This analysis identified 16 gene clusters with significantly enriched functional annotations. Among these enriched functions were ribosomal function and biogenesis, inflammatory response (including the chemokine CXCL10), GPCR signalling (including the serotonin receptor 5HTR1D) and transcriptional regulation (including the transcriptional repressor RCOR2). Following on from identification of functional categories, validation of genes of interest was carried out using RT-qPCR. Our findings suggest that descending facilitation contributes to gene expression changes within the dorsal horn and that this may correlate with behavioural hypersensitivity observed in chronic pain.
Related Products: Dermorphin-SAP / MOR-SAP (Cat. #IT-12)
Wang F, Eisenach JC, Peters CM (2012) Depletion of spinal norepinephrine increases the duration of postoperative pain related behaviors following acute plantar incision and partial nerve injury in the rat. Neuroscience 2012 Abstracts 785.11. Society for Neuroscience, New Orleans, LA.
Summary: Background and Objective: The percentage of patients that develop chronic postsurgical pain can range from 10-50% depending on the type of surgery. The underlying mechanisms responsible for the transition from an acute to chronic postoperative pain state are unknown. Recent clinical studies suggest that the integrity of endogenous pain inhibitory circuits may be important for preventing this transition. The descending noradrenergic transmission has well-known inhibitory effects on spinal synaptic transmission and norepinephrine has anti-inflammatory effects on spinal glial activation. We hypothesized that disrupting spinal noradrenergic fibers in rats prior to peripheral tissue injury would enhance spinal glial activity and impair resolution of postoperative pain. Methods: To test this hypothesis, we used a model of acute pain (Brennan incision model) and a model of nerve injury involving partial L5 spinal nerve ligation. We intrathecally injected dopamine β hydroxylase conjugated to the ribosomal toxin saporin (DβH-sap, 5 μg) or control (IgG-sap) to Sprague-Dawley rats 14 days prior to surgery to deplete noradrenergic fibers. Sensitivity to mechanical stimuli (von Frey) and spontaneous guarding were assessed for several weeks. We used immunohistochemistry to assess microglial (IBA1) and astrocyte (GFAP) activation in spinal cord tissue. Results: Depletion of noradrenergic fibers resulted in a significant increase in the duration of mechanical hypersensitivity in the ipsilateral paw of rats with plantar incision (6 days in IgG-sap treated rats vs. at least 21 days in DβH-sap treated rats) and partial L5 spinal nerve ligation (42 days in IgG-sap treated rats vs. at least 70 days in DβH-sap treated rats). Depletion of noradrenergic fibers did not affect mechanical withdrawal thresholds in normal rats suggesting both tissue injury and spinal noradrenergic depletion were required for prolonged mechanical hypersensitivity. The duration of spontaneous guarding following plantar incision was not affected by DβH-sap treatment. Additionally, microglia and astrocyte activation was increased in the spinal cord 21 days following incision and 70 days after nerve injury in DβH-sap treated rats compared to IgG-sap treated rats. Conclusions: These findings highlight the crucial role of spinally projecting noradrenergic pathway in the resolution of incision and nerve injury induced hypersensitivity which may be due in part to inhibitory effect of norepinephrine on spinal glial activation. Future studies will focus on the adrenergic receptor subtypes and mechanisms responsible for the transition from acute to chronic postoperative pain in these models.
Related Products: Anti-DBH-SAP (Cat. #IT-03)
Effects of a dual hypocretin receptor antagonist on sleep and wakefulness in rats.
Schwartz MD, Dittrich L, Fisher SP, Lincoln W, Liu H, Miller MA, Warrier DR, Wilk AJ, Morairty SR, Kilduff TS (2012) Effects of a dual hypocretin receptor antagonist on sleep and wakefulness in rats. Neuroscience 2012 Abstracts 799.23. Society for Neuroscience, New Orleans, LA.
Summary: Benzodiazepine receptor agonists promote sleep by activating GABAA receptors, leading to generalized reduction in cortical activity. They are widely used as hypnotic medications, but have side effects including risk for tolerance and/or dependence, as well as cognitive impairment while under their influence. The excitatory hypocretin (HCRT) neuropeptides promote wakefulness by activating multiple subcortical wake-promoting neurotransmitter systems which, in turn, project to and regulate cortical activity. Blocking HCRT signaling should therefore promote sleep by acting specifically on subcortical brain areas regulating sleep and wake without adversely impacting cortical function. Here, we assessed the ability of the dual HCRT receptor antagonist almorexant (ALM) to promote sleep in rats following ablation of a major sleep-wake regulatory region, the cholinergic basal forebrain (BF). We predicted that ALM would be less effective at inducing sleep in BF-lesioned rats compared to neurologically-intact rats, whereas benzodiazepine-based compounds should be equally as effective in lesioned and intact rats. Male rats received bilateral stereotaxic injections of saline or the selective cholinergic neurotoxin192-IgG-saporin (SAP) directed at the BF and were implanted with telemetry for recording sleep EEG. Following recovery, animals were given increasing doses of ALM, the GABA-A receptor agonist zolpidem (ZOL), or vehicle. Spontaneous sleep/wake regulation and homeostatic recovery from sleep deprivation was also assessed. At baseline, NREM sleep in the dark (active) phase was reduced in SAP rats compared to intact rats; SAP rats also exhibited decreased NREM recovery sleep following 6 h sleep deprivation in the dark phase. Sleep in the light (rest) phase was unaffected by SAP. Analysis of ALM and ZOL administration in these animals is currently in progress.
Related Products: 192-IgG-SAP (Cat. #IT-01)
Neural plasticity in injured spinal cord.
Gulisano M, Parenti R, Gulino R (2012) Neural plasticity in injured spinal cord. Neuroscience 2012 Abstracts 846.09. Society for Neuroscience, New Orleans, LA.
Summary: Sonic hedgehog and Noggin are morphogenetic factors involved in neural induction and ventralization of the neural tube, but recent findings suggest that they could participate in regeneration and functional recovery after injury. Here, in order to verify if these mechanisms could occur in the spinal cord and involve synaptic plasticity, we measured the expression levels of Sonic hedgehog, Noggin, Choline acetyltransferase, Synapsin-I, and Glutamate receptor subunits (GluR1, GluR2, GluR4), in a motoneuron-depleted mouse spinal lesion model obtained by intramuscular injection of Cholera toxin-B saporin. The lesion caused differential expression changes of the analyzed proteins. Moreover, motor performance was found correlated with Sonic hedgehog and Noggin expression in lesioned animals. The results also suggest that Sonic hedgehog could collaborate in modulating synaptic plasticity. Together, these findings confirm that the injured mammalian spinal cord has intrinsic potential for repair and that some proteins classically involved in development, such as Sonic hedgehog and Noggin could have important roles in regeneration and functional restoration, by mechanisms including synaptic plasticity.
Related Products: CTB-SAP (Cat. #IT-14)
Krajewski-Hall SJ, Mittelman-Smith MA, Williams H, Lafrance KJ, Mcmullen NT, Rance NE (2012) A role for kisspeptin/neurokinin B/dynorphin (KNDy) neurons in the regulation of estrous cycles and the estrogen modulation of body temperature. Neuroscience 2012 Abstracts 585.02. Society for Neuroscience, New Orleans, LA.
Summary: We have recently described a method to selectively ablate kisspeptin/neurokinin B/dynorphin (KNDy) neurons using stereotaxic injections of NK3-SAP, a neurokinin 3 receptor agonist conjugated to saporin (Mittelman-Smith, Endocrinology, 2012). These studies revealed a critical role for arcuate KNDy neurons in tonic gonadotropin secretion, the rise in serum LH after ovariectomy and estrogen modulation of body weight. Here we determine the effects of KNDy neuron ablation on estrous cycles and the estradiol modulation of body temperature. In the first study, stereotaxic injections of NK3-SAP or Blank-SAP were made in the arcuate nucleus of ovary-intact, adult female rats. Rats with nearly complete KNDy-neuron ablation (verified by NKB immunohistochemistry) exhibited constant diestrus and ovarian atrophy, confirming the importance of these neurons in reproductive regulation. In a second experiment, we evaluated the effects of KNDy neuron ablation on the thermoregulatory axis in rats that were ovariectomized (OVX) and then treated with 17β-estradiol (E2). Tail skin temperatures (TSKIN) and core temperatures (TCORE) were recorded in rats throughout the light/dark cycle and during exposure to different ambient temperatures (TAMBIENT) in an environmental chamber. Notably, the average TSKIN of KNDy-ablated rats was consistently lower than control rats, indicative of lower levels of cutaneous vasodilatation. Moreover, KNDy neuron ablation blocked the reduction of TSKIN by E2 that occurred during the light phase in the environmental chamber, but did not affect the E2 suppression of TSKIN during the dark phase. At a high TAMBIENT of 33 C, the mean TCORE of OVX control rats increased to 39.0 C, and was reduced by E2 replacement. In contrast, at this high TAMBIENT, the average TCORE of OVX, KNDy-ablated rats was lower than OVX control rats, and TCORE was not altered by E2 replacement. Because KNDy neurons exhibit dramatic changes in morphology and gene expression in postmenopausal women, we have hypothesized these neurons contribute to the generation of hot flushes. These studies support this hypothesis by providing the first evidence that KNDy neurons participate in the E2 modulation of body temperature and promote cutaneous vasodilatation, one of the cardinal signs of a hot flush.
Related Products: NKB-SAP (Cat. #IT-63), Blank-SAP (Cat. #IT-21)
Acetylcholine and Learning: Are they related and does it matter for associating events across time?
Anderson ML, Govindaraju KP, Shors TJ (2012) Acetylcholine and Learning: Are they related and does it matter for associating events across time?. Neuroscience 2012 Abstracts 600.12. Society for Neuroscience, New Orleans, LA.
Summary: Decades ago, acetylcholine was considered intrinsic to processes related to attention and/or learning and memory. Much of this was based on its presumed role in dementia associated with Alzheimer’s disease. However, in the last decade or so, this relationship has been questioned and with good reason (Parent & Baxter, 2004). That said, only a few studies have addressed the involvement of acetylcholine in tasks that require an animal to associate stimuli separated in time, such as trace eyeblink conditioning. This type of task is dependent on the hippocampus and is severely disrupted in both patients with Alzheimer’s disease and animal models of the disorder (Kishimoto, 2012; Waddell et al., 2008; Woodruff-Pak & Papka, 1996). In the present study, we hypothesized that animals with minimal Ach input to both hippocampi would not learn whereas those with input into one hippocampus could. The immunotoxin 192 IgG-Saporin was infused into the MSDB to selectively kill cholinergic neurons in Sprague-Dawley rats and then trained with either delay or trace eyeblink conditioning. Delay conditioning requires that the stimuli during training are contiguous in time and is not dependent on the hippocampus. Animals were given 200 trials for four days for 800 trials in total. A complete bilateral MSDB-cholinergic lesion was considered complete if the number of neurons that express choline acetyltransferase was reduced by 75 %. A bilateral lesion of this magnitude prevented early acquisition of the trace response (p<.05). Indeed, none of the animals so far trained reached a learning criterion of 60 % CRs during any session of training. In contrast, animals with a loss of ACh in just one hemisphere were able to learn the CR. Furthermore, preliminary data suggest delay conditioning was unaffected by the loss of ACh from the septum. Finally, animals with half the number of cholinergic neurons were still able to learn trace eyeblink conditioning regardless of whether the damage was bilateral or unilateral. Thus, it would appear that the progressive loss of ACh coincides with the loss of learning potential, especially when that learning requires associations across time. This approach and the experimental results may model the progressive nature of Alzheimer’s disease, in which the loss of neuronal function is slow but cumulative.
Related Products: 192-IgG-SAP (Cat. #IT-01)
Grupe M, Paolone G, Jensen AA, Nielsen KS, Christensen JK, Grunnet M, Sarter M (2012) Positive allosteric modulation of 4 2* nicotinic acetylcholine receptors augments the amplitudes of prefrontal nicotine-evoked glutamatergic transients. Neuroscience 2012 Abstracts 696.15. Society for Neuroscience, New Orleans, LA.
Summary: α4β2* nicotinic acetylcholine receptors (nAChR) are a promising target for cognition enhancement. These receptors have been demonstrated to mediate the modulatory effects of the tonic component of cholinergic neurotransmission on fast prefrontal glutamatergic-cholinergic interactions. Specifically, α4β2* nAChR are expressed by thalamic glutamatergic afferents and amplify cue-evoked glutamatergic release events, thereby initiating a chain of neuronal events required for the detection of cues in attention tasks (Hasselmo & Sarter, 2011). In this study we investigated the effect of NS9283, a potent and selective positive allosteric modulator of low-sensitivity α4β2 nAChR (Timmermann et al., 2012), on nicotine-evoked glutamatergic release events in the mPFC of anaesthetized rats. Glutamatergic transients were recorded using amperometric measures of currents generated by the oxidation of glutamate and, subsequently, peroxide, on Platinum electrodes equipped with immobilized glutamate oxidase (see Parikh et al., 2010). Nicotine was pressure-ejected (0.040-2 nmol in 40-100 nL, respectively) into the vicinity of the recording electrode situated in the thalamic input layer of the prelimbic cortex. Systemic (i.p.) administration of NS9283 (3.0 mg/kg; administered 30 min prior to nicotine) enhanced the amplitude of glutamatergic transients evoked by the lowest dose of nicotine (40 pmol) by 72%. The modulator did not increase the efficacy of nicotine. Local pressure-ejections of NS9283 (400 pmol in 40 nL) per se were capable of evoking glutamatergic release events, presumably reflecting modulation of the effects of endogenous acetylcholine at these nAChRs. Accordingly, 192 IgG saporin-induced removal of cholinergic projections to the recording region abolished NS9283-evoked glutamatergic transients. Collectively, this evidence substantiates the identification of NS9283 as a positive modulator of nAChRs and its potency in vivo to modulate evoked glutamatergic release events. These results are consistent with the hypothesis that such compounds facilitate cue detection processes and thereby enhance attentional performance. Supported by NIH grant MH080332 and The Ministry of Science, Innovation and Higher Education, Denmark, PhD grant 10-084289.
Related Products: 192-IgG-SAP (Cat. #IT-01)
Selective damage to glia in the nucleus tractus solitarii attenuates cardiovascular reflexes.
Talman WT, Jones S, Nitschke Dragon D, Lin L-H (2012) Selective damage to glia in the nucleus tractus solitarii attenuates cardiovascular reflexes. Neuroscience 2012 Abstracts 524.05. Society for Neuroscience, New Orleans, LA.
Summary: Lesions of the nucleus tractus solitarii (NTS) are known to attenuate or abolish cardiovascular reflex responses. We have previously reported that lesions produced by saporin (SAP) conjugates and focused on neurons that express the neurokinin-1 (NK1) receptor or on other neurons that express both tyrosine hydroxylase (TH) and dopamine-β-hydroxylase (DBH), also attenuate baroreflex function in rats. We found that lesions of both types of neurons also led to loss of glia that stained with glial fibrillary acidic protein (GFAP). Further, we found that injection of SAP alone into the NTS led to loss of GFAP staining while leaving neurons in the region unaffected. Because both of the lesions directed at neurons were made by a toxic conjugate containing SAP, we sought to determine if SAP alone produced changes in cardiovascular reflex function. We found that injection of SAP (3 ng in 100 nl) into the NTS led to loss of the glial marker GFAP as well as connexin 43 (Cx43) immunofluorescent labeling in the NTS but did not affect the neuronal markers NMDAR1 (NMDA receptor subunit 1), GluR2 (AMPA receptor subunit 2), neuronal nitric oxide synthase (nNOS), TH, DBH, vesicular glutamate transporters (VGluTs), choline acetyl transferase (ChAT), NK1, and protein gene product 9.5 (PGP 9.5). In animals treated with bilateral injections of SAP into the NTS, reflex responses were decreased during testing of the baroreflex, the chemoreflex, or the von Bezold Jarisch reflex. Comparable decreases in baroreflex responses were seen in animals treated with SAP alone when compared with other animals treated with SAP conjugates that targeted and concentrated damage to TH/DBH neurons or NK1 neurons in NTS. In contrast, when TH/DBH neurons were targeted by the toxin 6-hydroxydopamine (6-OHDA) lability of arterial pressure did not occur as it did in the other SAP and SAP conjugate studies and reflex responses to the activation of the baroreflex, the chemoreflex, and the von Bezold Jarisch reflex did not differ from control. Furthermore, injections containing SAP or a SAP conjugate, but not those containing 6-OHDA, led to lability of arterial pressure as well as cardiac arrhythmias and cardiac myocytolysis. Our studies cannot exclude a physiological effect of SAP on neurons nor can it exclude an indirect effect of glial damage on NTS neurons. However, the similarity of responses when glia seem to have been targeted alone in contrast to those responses when select neuronal types seem to have been targeted suggests that each of the cardiovascular reflexes relies on intact glia in the NTS for full reflex expression.
Related Products: Anti-DBH-SAP (Cat. #IT-03), SSP-SAP (Cat. #IT-11)
Mallory CS, Paolone G, Koshy Cherian A, Blakely RD, Sarter M (2012) Paying attention with a compromised cholinergic system: Attenuated activation of cholinergic neurotransmission in attentional task-performing CHT+/- mice. Neuroscience 2012 Abstracts 536.08. Society for Neuroscience, New Orleans, LA.
Summary: Prefrontal cholinergic neurotransmission is necessary for sustained attentional performance. In rats, prefrontal acetylcholine (ACh) release reaches 140% over baseline during the performance of a sustained attention task (SAT; St. Peters et al., 2011a). SAT performance also increases the density of choline transporters (CHT) in synaptic plasma membranes (Apparsundaram et al., 2005), which we hypothesize is needed to sustain elevations of cholinergic activity and behavioral responses. Here we employed the SAT recently adapted for use in mice (St. Peters et al., 2011b) and developed new techniques that permit monitoring of ACh release via microdialysis of mice performing the SAT in order to determine the impact of genetically manipulated levels of choline transporter capacity. First, reverse dialysis of atropine (50 µM) increased ACh release levels in naive WT mice. In contrast, CHT+/- mice could not sustain these increases, consistent with changes observed in levels of muscarinic receptors in the CHT +/- mice (Bazalakova et al., 2007). However, SAT performance did not differ significantly between WT controls and CHT+/- mice. Furthermore, basal (absolute) levels of ACh release were comparable between strains. However, performance-associated increases in ACh release were strikingly attenuated in CHT+/- mice, reaching 40% over basal levels versus 130% in WT. Performance-associated increases in ACh release in CHT+/- mice were TTX-sensitive, similar to release monitored in WT mice (1 µM via reversed dialysis). To determine whether cholinergic activity was necessary for SAT performance in CHT+/- mice we then removed basal forebrain cholinergic neurons by infusing murine-p75NTR-saporin obtaining similar impairment on SAT performance in both strains. Finally, and because cholinergic activity modulates cortical circuitry primarily via nAChR, mecamylamine (MEC; 50 µM) was reverse dialyzed during SAT performance. WT mice were only moderately impaired in the SAT task, whereas the performance of CHT+/- mice rapidly declined and the performance-associated ACh levels rapidly returned to the pre-task levels. In summary CHT+/- mice are able to perform the basic SAT, despite attenuated levels of cholinergic neurotransmission, likely as a result of compensatory postsynaptic mechanisms. However, their attentional performance and underlying cholinergic signaling exhibit heightened sensitivity to behavioral and pharmacological challenges. Together, these findings suggest that CHT+/- mice are an important model for the impaired cognitive control of attentional performance that is a common symptom of ADHD, schizophrenia and other cognitive disorders.
Related Products: mu p75-SAP (Cat. #IT-16)
The effects of basal forebrain cholinergic neuron of recognition tests.
Lee J, Jeong D, Chang J (2012) The effects of basal forebrain cholinergic neuron of recognition tests. Neuroscience 2012 Abstracts 345.10. Society for Neuroscience, New Orleans, LA.
Summary: The cholinergic neurons of the Medial septum and the basal nucleus areas of the basal forebrain project to the frontal cortex and the Hippocampus, and degeneration of the cholinergic basal forebrain neuron is a common feature of Alzheimer's disease(AD) and vascular dementia and it has been correlated with cognitive decline. This research studied to verify the effects of cholinergic neuron in basal forebrain and the role of hippocampus and frontal cortex on recognition through recognition test and immunohistochemistry after damaging cholinergic neuron of the basal forebrain by intraventricular injection of 192 IgG-saporin. 192 IgG-saporin of 8ul (0.63ug/ul) was injected to the bilateral lateral ventricle of rats. After 2 weeks, Novel object recognition (NOR) test and Object in place (OIP) test was conducted to elucidate damage of cholinergic neuron. After completing the behavioral test, the ChAT cholinergic neuron in the brain was ascertained to confirm with immunohistochemistry if cholinergic neuron was damaged. In NOR test, the lesion group with 192 IgG-saporin showed 10% lower novel object preference than normal group. In OIP test, the normal group showed 50% novel object preference and the lesion group with 192 IgG-saporin showed 30% novel object preference in an hour delay test. On the other hand, the normal group and the lesion group with 192 IgG-saporin shoed 33% and 35% novel object preference respectively in a day delay test. However, this rate is not that significant value enough to elucidate behavioral difference between normal group and lesion group. In immunohistochemistry, the number of cholinergic neuron was remarkably decreased in basal forebrain. According to both of the behavioral tests, lesion group seem to less remember novel object than normal group. Also, they searched less the novel object that changed its location than normal group in the short term condition. However, there was no significant difference in the long term condition. These results suggest that the lesion with 192 IgG-saporin can damage spatial working memory.In the Immunohistochemistry result of the lesion condition, cholinergic input to hippocampus in basal forebrain affects recognition. However, the effect is not so essential.
Related Products: 192-IgG-SAP (Cat. #IT-01)
Lee S-Y, Ma J, Chung C, Han J-S (2012) Effects of chronic stress on alterations of GR-PKA-NF-kappa B signaling and spatial learning in rats with cholinergic deafferentation. Neuroscience 2012 Abstracts 345.20. Society for Neuroscience, New Orleans, LA.
Summary: Aging and Alzheimer’s disease (AD) is associated with diminished integrity of the cholinergic innervations of the hippocampus and cortex. Previously, we demonstrated that removal of the cholinergic innervations impaired regulation of the HPA axis with response to acute stress and induced changes in the interaction among glucocorticoid receptor (GR), nuclear factor-κB (NF- κB) p65, and the cytoplasmic catalytic subunit of protein kinase A (PKAc) in the hippocampus. The current research examined effects of chronic stress on the altered signaling induced by cholinergic deafferentation. Young adult rats received immunotoxic lesions of basal forebrain cholinergic neurons by intracranial injections of 192 IgG-saporin into the medial septum/vertical limb of the diagonal band and substantia innominata/nucleus basalis. After 2 weeks recovery from surgery, rats with cholinergic lesions and vehicle-injected control rats were subjected to 1 hr restraint stress per day for 2 weeks. Rats with only cholinergic deafferentation or sham-operated rats with chronic stress showed intact spatial learning. Rats with cholinergic deafferentation that received chronic stress showed impairments of spatial learning. And we examined that cholinergic deafferentation induced alterations in GR and NF- κB p65 expression in hippocampus and prefrontal cortex. Thus the loss of cholinergic integrity during aging and in AD may increase proneness to chronic stress.
Related Products: 192-IgG-SAP (Cat. #IT-01)
Fricks-Gleason AN, Keefe KA (2012) Poster: Evaluating the role of neuronal nitric oxide synthase-containing striatal interneurons in methamphetamine-induced dopamine neurotoxicity. Neuroscience 2012 Abstracts 360.06. Society for Neuroscience, New Orleans, LA.
Summary: It is well established that exposure to multiple high doses of methamphetamine (METH) produces damage to central monoamine systems. A number of factors, including the production of nitric oxide (NO), have been implicated in this neurotoxicity. While it is relatively clear that NO contributes to METH-induced neurotoxicity to the dopamine (DA) nerve terminal, the source of this NO has not been clearly delineated. There is considerable evidence suggesting that the generation of NO arises a consequence of the activation of neuronal nitric oxide synthase (nNOS). In striatum, nNOS is located post-synaptic to the DA nerve terminal in a subpopulation of striatal interneurons. Thus, we have hypothesized that DA-mediated activation of the nNOS-containing striatal interneurons is necessary for METH-induced neurotoxicity. These interneurons, along with the cholinergic neurons of striatum, selectively express the neurokinin-1 (NK-1) receptor, which is activated by the neuropeptide Substance P. Consequently, toxins targeted to NK-1 receptor-containing neurons can be used to lesion this population of striatal interneurons. One such toxin, a conjugate of Substance P to the ribosome inactivating protein saporin (SSP-SAP), has been shown to be effective in selectively destroying neurons expressing the NK-1 receptor in striatum. Therefore, using targeted deletion of the nNOS-containing interneurons via SSP-SAP, we examined the extent to which impairing post-synaptic production of NO attenuates METH-induced neurotoxicity. The SSP-SAP lesions resulted in a significant and selective loss of nNOS-containing interneurons throughout the striatum, although it was not possible to completely eliminate all of the neurons. Surprisingly, however, this marked deletion of nNOS-containing interneurons did not confer resistance to METH-induced DA neurotoxicity, even in areas completely devoid of nNOS-positive cell bodies and histochemical detection of NOS activity with NADPH diaphorase histochemical staining. Furthermore, these lesions did not attenuate NO production, as assessed via nitrotyrosine immunohistochemistry, even in areas devoid of nNOS. Taken together, these data suggest that nNOS-containing interneurons either are not necessary for METH-induced DA neurotoxicity, leaving open the potential contribution of other sources of NO, such as endothelial NOS (eNOS), or produce NO/RNS that can diffuse extensively through striatal tissue and thereby still mediate the neurotoxicity.
Related Products: SSP-SAP (Cat. #IT-11)
Koppen JR, Stuebing SS, Winter SS, Cheatwood JL, Wallace DG (2012) Infusion of GAT1-Saporin into the medial septum spares mnemonic function and impairs self-movement cue processing. Neuroscience 2012 Abstracts 394.25. Society for Neuroscience, New Orleans, LA.
Summary: Spatial orientation depends on multiple neural systems processing environmental and self-movement cues. Previous research has demonstrated a relationship between cholinergic function in the medial septum and processing of self-movement cues. The medial septum also sends GABAergic projections to the hippocampus that synapse on interneurons, thereby producing a strong dis-inhibitory effect on hippocampal pyramidal neurons. Initial studies using non-selective lesion techniques have supported the involvement of this system in spatial orientation; however, the development of an immunotoxin (i.e., GAT1-Saporin) that selectively targets GABAergic neurons, allows for a novel technique in which to study this relationship. The current study examined the effect of infusing GAT1-Saporin or saline into the medial septum on performance during multiple spatial tasks. Environmental and self-movement cue processing was evaluated using the food hoarding paradigm, whereas mnemonic function was evaluated using several water maze tasks. Although GAT1-Saporin spared performance on water maze tasks, impaired performance was observed when rats were restricted to using self-movement cues (i.e., testing under dark conditions) during food hoarding. The current study adds to the growing literature that supports a role for components of the septohippocampal system in self-movement cue processing during spatial navigation.
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Emerging roles of pathogens in alzheimer’s and moderate magnetic field therapy: dc emf 0.5 tesla
Nichols TW (2012) Emerging roles of pathogens in alzheimer’s and moderate magnetic field therapy: dc emf 0.5 tesla. Neuroscience 2012 Abstracts 438.10. Society for Neuroscience, New Orleans, LA.
Summary: Chronic spirochetal infection can cause slowly progressive dementia, cortical atrophy and amyloid deposition in the atrophic form of general paresis. There is a significant association between Alzheimer disease (AD) and various types of spirochete (including the periodontal pathogen Treponemas and Borrelia burgdorferi), and other pathogens such as Chlamydophyla pneumoniae and herpes simplex virus type-1 (HSV-1). (Miklossy 2011 Exp Rev Mol Med) Miklossy’s lab exposed mammalian glia & neuronal cells in vitro to Borrelia burgdorferi spirochetes and bacterial lipopolysaccharides (LPS). Morphological changes analogous to amyloid deposits were observed at 2-8 wks exposure. Increased levels of ß-amyloid precursor protein and hyperphosphorylated tau were detected by WB.The frequency of spirochetes is significantly higher in the brains of Alzheimer patients compared to controls.The statistical analysis is based on the cumulative data of the literature. (P=1.5x10-17,OR=20, 95%CI=8-60! Seven out of ten brains from the Harvard McLean Brain bank were positive for Borrelia DNA. Alan Mac Donald MD. “Borrelia Infection is the root cause of at least 70% of Alzheimer's disease, based on the detection of positive In situ DNA hybridization results in the cytoplasic GVB sites of hippocampal neurons ( with no positive signals detected in the nucleus) for flagellin B DNA sequences of Borrelia burgdorferi.” Antibiotics in Alzheimer’s disease: A randomized controlled trial of doxycycline and rifampin for patients with Alzheimer’s disease 2004. Cognitive decline was statically improved in treatment over placebo. Minocycline protects basal forebrain cholinergic neurons from mu p 75-saporin immunotoxic lesioning 2004 in animal model. Minocycline attenuates neuronal cell death and improves cognitive impairment in Alzheimer’s disease models 2007. Minocycline does not affect amyloid ß phagocytosis by human microglia cells. (Minocycline attenuates the release of TNF-α by human microglia upon exposure to Abeta, SAP and C1q) 2007. Moderate Magnetic Field Therapy (0.5 Tesla) in 15 Alzheimer’s patients. Results; Cognition Improved: group average hours = 184.Mechanism hypothesis: Overview of crosstalk between SMF & IL-6.Wang, Z, Sarje A, Che PL, Yarema K. Moderate strength (0.23-0.28T) static magnetic fields (SMF) modulate signaling and differentiation in human embryonic cells. BMC Genomic 2009;10:356
Related Products: mu p75-SAP (Cat. #IT-16)
Neuromedin B serves a role in nociceptive signaling.
Mishra SK, Holzman S, Hoon MA (2012) Neuromedin B serves a role in nociceptive signaling. Neuroscience 2012 Abstracts 471.22. Society for Neuroscience, New Orleans, LA.
Summary: We are interested in identifying new somatosensory signaling molecules and used an array based differential screen. In order to subtract genes not involved in signaling processes, we compared expression profiles in trigeminal ganglia (TG) with those of the geniculate ganglia (GG); a ganglia similar in structure but with different function. One gene we uncovered was neuromedin B (NMB), as expected from the differential expression, neuropeptide NMB is expressed in TG and dorsal root ganglia (DRG), but not in GG. Double labeling experiments, revealed NMB is expressed in a subset of sensory neurons that co[[unable to display character: ‐]]label with CGRP and TRPV1, suggestive of a role for NMB in nociception. Indeed, administration of NMB[[unable to display character: ‐]]antagonist greatly attenuates edema and nerve sensitization following stimulation of peripheral nerves with mustard oil, demonstrating that NMB contributes to neurogenic inflammation. Moreover, direct injection of NMB causes local swelling and nociceptive sensitization. Interestingly, we also found the receptor for NMB is expressed in interneurons in the superficial layers of the dorsal horn. We used NMB[[unable to display character: ‐]]saporin to specifically eliminate NMB-receptor expressing spinal cord cells and determined that they are required for responses to noxious heat, but not for reactions to mechanical and pruritic stimuli. Thus, NMB may be a neurotransmitter that is selectively involved in the perception of thermal stimuli, and has a role in neurogenic inflammation.
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Kalinchuk AV, Kim S, Mccarley RW, Basheer R (2012) Cholinergic basal forebrain neurons contribute to the biochemical and electrophysiological changes in the cortex during sleep deprivation. Neuroscience 2012 Abstracts 486.24. Society for Neuroscience, New Orleans, LA.
Summary: Short term sleep deprivation (SD) (2-3h) increases the levels of inducible nitric oxide (NO) synthase (iNOS)-mediated NO and adenosine (AD) in the basal forebrain (BF) (Basheer et al., 1999; Kalinchuk et al., 2006). We showed recently that the prolongation of SD for 5h triggers similar biochemical changes in the prefrontal/frontal cortex (PFC/FC), the area which receives projections from the BF (Kalinchuk et al., 2010). Lesion of the BF cholinergic cells using immunotoxin 192-IgG saporin attenuates SD-induced AD increase in the BF and recovery non-rapid eye movement (NREM) sleep response (Kalinchuk et al., 2008). However, it is not known whether the cholinergic cells play a role in SD-induced biochemical changes in the cortex. In the current study we lesioned BF cholinergic cells, and compared SD-induced biochemical changes simultaneously in the PFC and BF in the same animals before and after the lesion. We correlated the changes in the biochemical markers, NO and adenosine, with the changes in electrophysiological markers of homeostatic sleep pressure, encephalogram (EEG) theta power during SD and delta power during recovery NREM sleep after SD. Male rats were implanted with electrodes for EEG/electromyogram (EMG) recording and 2 guide cannulae for microdialysis probes targeting BF and PFC. Microdialysis samples were collected simultaneously from both areas every 30 min during 8h SD. Dialysates were analyzed for AD using high performance liquid chromatography (HPLC)/fluorescent detection and for NO metabolites nitrate and nitrite (NOx) using Fluorimetric Assay Kit (Cayman). The lesion of the BF cholinergic cells was performed using the local injections of 192-IgG saporin into the BF, and similar experiment was repeated 2 weeks after the injection. Histochemical analysis confirmed the localization of the probes in the BF and PFC and the quality of the lesion procedure. Before saporin injection, SD induced increases in the levels of NOx and AD, which became significant after 1h (NOx) and 2h (AD) of SD in the BF and after 4h (NOx) and 5h (AD) of SD in the FC. EEG recording detected increases in the intensity of theta power during SD and delta power during following recovery NREM sleep. 2 weeks after saporin injection, SD-induced changes in NOx and AD were significantly attenuated both in the BF and the PFC. Also the increases in theta and delta power were significantly attenuated. We conclude that cholinergic neurons of the BF, which provide strong activating input to the PFC, contribute to the generation of homeostatic sleep pressure during SD, including its biochemical and electrophysiological correlates.
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The GRP peptide and the GRPR-positive interneurons control fear acquisition and extinction.
Zushida K, Light K, Uchida S, Hevi C, Shumyatsky GP (2012) The GRP peptide and the GRPR-positive interneurons control fear acquisition and extinction. Neuroscience 2012 Abstracts 496.03. Society for Neuroscience, New Orleans, LA.
Summary: The gastrin releasing peptide (GRP) is the marker of the neural circuits relaying fear-related conditioned stimulus (CS) information to the amygdala. The GRP is expressed by principal cells and the GRP-receptor (GRPR) is expressed by interneurons. The GRPR is expressed in the amygdala and hippocampus. To examine the role of the GRPR-positive interneurons in these two brain areas, we performed local injections of the bombesin-saporin (SAP)-toxin, which selectively eliminates the GRPR-expressing cells. The intra-BLA [lateral (LA) and basal nuclei (BA) of amygdala] injection of bombesin-SAP before fear conditioning significantly enhanced cued, but not contextual fear memory. We did not observe any significant effect of post-training intra-BLA injections of bombesin-SAP on fear memory recall. Also, there were no significant effects of bombesin-SAP on acquisition of contextual and cued fear memory in mice injected bombesin-SAP into LA, BA and central amygdala (CeA), respectively. Also, we examined cued fear memory in the GRP knockout mice and found significant enhancement in their cued fear memory. These results support the idea that GRPR-expressing interneurons play an inhibitory role in acquisition of fear memory and suggested inhibitory effect by the GRPR-expressing GABA interneurons on fear memory requires both LA and BA but not CeA.
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Hayward LF (2012) Neurotoxic lesion of CRF-R1 neurons in the amygdala selectively attenuates the heart rate response to acute stress in the spontaneously hypertensive rat. Neuroscience 2012 Abstracts 281.28. Society for Neuroscience, New Orleans, LA.
Summary: The magnitude of a person’s autonomic response to mental stress is predictive of one’s risk for the development of cardiovascular disease and has been linked to indicators of exaggerated neuronal activity in the amygdala. Recent evidence from our lab identified a link between changes in the expression of the neuropeptide corticotrophin-releasing factor (CRF) within the central nucleus of the amygdala (CEA) to exaggerated cardiovascular responses to acute stress in the spontaneously hypertensive rat (SHR). The present study was undertaken to evaluate the impact of selective lesion of CRF-R1 neurons in the amygdala on the cardiovascular response to acute air jet stress (AJS) in the SHR. Male SHR rats underwent local bilateral microinjections of 10 nanograms/200 nl per side of blank-saporin (n=4) or CRF-receptor (R1) targeting saporin (n=4) into the region of the CEA. Following 7-10 days of recovery and two days following arterial catheter instrumentation, animals underwent AJS testing. CRH-R1 lesion in the amygdala produced a small reduction in resting systolic blood pressure (160±6 vs 173±4 mmHg, p<0.1) but not change in heart rate (354±16 vs 352±+4 bpm). CRH-R1 lesion also significantly attenuated the mean rise heart rate in response to AJS (72±21 vs 130±13 bpm) and facilitated a more rapid heart rate recovery independent of any effect on the blood pressure response to AJS. The findings demonstrate for the first time that CRF-R1 activation in the amygdala selectively contributes to the elevated heart rate response to stress in individuals with hypertension, thus providing a link between the exaggerated activity in the amygdala and a specific cardiovascular response to stress.
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Knockdown of noradrenergic locus coeruleus (LC) neurons alleviates chronic orofacial pain
Kaushal R, Ma F, Zhang L, Bright CR, Taylor BK, Westlund KN (2012) Knockdown of noradrenergic locus coeruleus (LC) neurons alleviates chronic orofacial pain. Neuroscience 2012 Abstracts 164.19. Society for Neuroscience, New Orleans, LA.
Summary: Trigeminal neuralgia (TN) is an excruciating and debilitating form of clinical orofacial pain. Noradrenergic locus coeruleus (LC, pontine A6 neurons) is involved in bidirectional modulation of pain. Multiple studies indicate that LC activity is increased during noxious stimulation and following inflammation or nerve damage. Predominantly known for its role in the feedback inhibition of pain, emerging studies also indicate a contribution of the LC in pain facilitation. For example, lesions of the LC significantly reduce tonic behavioral responses to intraplantar formalin injection, prevent autotomy, and reduce hypersensitivity associated with peripheral nerve injury. In this study we hypothesized that noradrenergic (LC) neurons contribute to the facilitation of chronic pain in TN. We used a rat model of TN involving infraorbital nerve chronic constriction injury (ION-CCI) which produces mechanical hypersensitivity as assessed by a reduction in von Frey threshold. Administration of anti-dopamine-β-hydroxylase saporin (anti-DβH-saporin) toxin was performed for selective elimination of noradrenergic LC neurons or IgG saporin (nonspecific) as the control either by intracerebroventricular (i.c.v space 2) or by bilateral spinal trigeminal nucleus (STN) injections. Under minimal restraint, rats received either no stimulation or repeated stimulation with either a 2 or 15-gm von Frey hair applied directly to the maxillary branch. Withdrawal threshold (tactile allodynia) from von Frey fiber stimulation to the face was not changed as compared to baseline in animals subjected to sham surgery; this was true in both saporin and anti-DβH-saporin groups. However, i.c.v. anti-DβH-saporin significantly increased withdrawal threshold animals with ION-CCI as compared to IgG saporin controls. More selective destruction of the LC-trigeminal pathway with bilateral STN anti-DβH-saporin injection also alleviated behavioral signs of chronic orofacial hyperalgesia. Elimination of noradrenergic LC neurons was confirmed by complete loss of tyrosine hydroxylase (TH) immunoreactivity in anti-DβH-saporin injected animals. Compared to unstimulated controls, mechanical stimulation increased immunoreactive phosphorylated extracellular cell-regulated protein kinase (pERK), a marker of neuronal activity, in the LC and STN. Nerve injury also increased expression of a neuronal injury and stress marker, activating transcription factor 3 (ATF3), in trigeminal ganglia neurons. Together, these results indicate that noradrenergic locus coeruleus neurons facilitate chronic orofacial neuropathic pain.
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Mathis C, Moreau P-H, Zerbinatti C, Goutagny R, Cosquer B, Geiger K, Kelche C, Cassel J-C (2012) Combined loss of entorhinal and basal forebrain cholinergic hippocampal inputs deeply impairs spatial navigation memory in C57BL/6J and hAPPxapoE mice. Neuroscience 2012 Abstracts 203.28. Society for Neuroscience, New Orleans, LA.
Summary: The hippocampus plays a key role in spatial learning and memory. Major inputs provided by the cholinergic basal forebrain (CBF) and the entorhinal cortex (EC) neurons are expected to modulate hippocampal functions. Surprisingly, the selective lesion of one or the other produces only moderate performance degradation in spatial navigation tasks, suggesting possible compensation provided by other hippocampal inputs. We therefore assessed the effects of single versus combined lesions of the EC (NMDA excitotoxin) and the CBF (mu-p75 saporin immunotoxin) on several forms of memory in C57BL/6 mice. Single lesions had moderate or no effects, while the combined lesions completely abolished long-term spatial memory retention in the water-maze and the Barnes-maze navigation tasks. Object recognition memory was selectively and profoundly affected by the loss of cholinergic neurons, whereas object location memory was only marginally affected by the lesions. These results suggest that the integrity of both the CBF and the EC is critical to establish an enduring spatial navigation memory. The synergistic interaction between the two lesions is particularly relevant to Alzheimer’s disease (AD) since both structures undergo severe degeneration in parallel to dramatic impairments in spatial navigation tasks. The apolipoprotein E4 (apoE4) allele, a major genetic risk factor for AD, has been proposed as a cholinergic deficit predictor and has been associated with larger EC atrophy in AD patients. Thus, the effects of single and combined EC and CBF lesions were evaluated on Barnes maze navigation performance in hAPPxapoE mice knocked-in for the human apoE3 or apoE4 gene allele on a (normal) human APP YAC transgenic background. Long-term spatial memory performances of hAPPxapoE3 and hAPPxapoE4 mice were dramatically affected by the CBF lesion and the combined lesions, but not by the EC lesion. A similar pattern of deficit was observed on learning performances in apoE4 not in apoE3 mice; the latter were only affected by the combined lesions. In conclusion, the apoE4 genotype had no effect on the consequences of EC and combined lesions, but it worsened the outcome of CBF lesions compared to the apoE3 genotype. Since the mice of the two genotypes showed similar loss of cholinergic neurons, our data may reflect a deleterious impact of apoE4 on the activity of the few surviving neurons (about 20%). Alternatively, our findings would also be consistent with impaired compensatory mechanisms following cholinergic loss which could depend on other hippocampal inputs such as the entorhinal cortex. Further analyses are underway to clarify this issue.
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IB4 (+) neurons contribute to force-induced cancer pain but not cancer proliferation
Ye Y, Viet CT, Dang D, Schmidt BL (2012) IB4 (+) neurons contribute to force-induced cancer pain but not cancer proliferation. Neuroscience 2012 Abstracts 67.10. Society for Neuroscience, New Orleans, LA.
Summary: The primary treatment for cancer pain is μ-opiates; however, often μ-opiates are not effective and they produce multiple debilitating side effects. Recent studies show that μ- and δ-opioid receptors are separately expressed on IB4 (-) and IB4 (+) neurons, which mediate thermal and mechanical pain, respectively. We investigated the contribution of IB4 (+) and IB4 (-) neurons to cancer-induced mechanical and thermal hypersensitivity and investigated the role of these fibers to cancer proliferation. We used two separate mouse cancer pain models: 1) a cancer supernatant injection model, and 2) an orthotopic cancer model. The former model isolated the effect of the cancer secretome while the latter examined the effect of the following constituents within the cancer microenvironment: the cancer, the cancer secretome and the host tissue. Using the cancer supernatant model, along with injection of a selective δ-opioid receptor agonist and a P2X3 antagonist to target IB4 (+) neurons, we showed that IB4 (+) neurons played arole in cancer-supernatant-induced mechanical allodynia, but not thermal hyperalgesia. Selective ablation of IB4 (+) neurons in the spinal cord using IB4-saporin affected cancer-supernatant-induced mechanical but not thermal hypersensitivity. In the orthotopic cancer model, mice with paw cancer exhibited both mechanical and thermal hypersensitivity. Selective ablation of IB4(+) neurons decreased mechanical hypersensitivity; however thermal hypersensitivity was increased. We hypothesized that increased thermal hyperalgesia was associated with a compensatory elevation of TRPV1 expression in the spinal cord. Thermal latency in the mouse cancer paw was increased by intrathecal TRPV1 antagonist and selective removal of TRPV1 terminals by capsaicin in the IB4-saporin treated mice compared to saporin treated mice. Mechanical threshold was not affected by either the TRPV1 antagonist or capsaicin treatment. In the spinal cord, TRPV1 protein levels were increased in cancer mice compared to naïve mice, and TRPV1 was likely to be increased in the IB4-saporin treated cancer mice compared to saporin treated cancer mice. We investigated cancer proliferation by measuring tumor volume. Tumor volume was not affected by selective ablation of IB4 (+) neurons. Our findings suggest that peripherally administered pharmacological agents targeting IB4 (+) neurons, such as a selective δ-opioid receptor agonist or P2X3 antagonist, might be effective for treating cancer pain in patients. Acknowledgements: Supported by NIH/NIDCR R21 DE018561
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Jokiaho A, Donovan C, Watts A (2012) Catecholaminergic neurons in the ventrolateral medulla are differentially activated by the rate of fall in blood glucose during hypoglycemia, and are required for the rate-dependent hypoglycemic activation of sympathoadrenal responses. Neuroscience 2012 Abstracts 93.05. Society for Neuroscience, New Orleans, LA.
Summary: Hypoglycemic counterregulation is mediated by glucosensors located in the hypothalamus, hindbrain, and portal-mesenteric veins (PV). We have previously shown that when hypoglycemia develops slowly PV glucose sensing is critical for both the sympathoadrenal response and hindbrain Fos activation. Hindbrain catecholaminergic (CA) neurons provide extensive inputs to the hypothalamus and are key participants in the control of energy homeostasis and in the responses to glycemic challenges. However, the role of the various CA cell groups together with the organization of the circuitry between peripheral and central glucose sensing units and the effectors that mediate counterregulatory response to hypoglycemia are unknown. To investigate the role of CA neurons in this network we use hyperinsulinemic-hypoglycemic clamps to induce fast (20mins)- or slow (75min)-onset hypoglycemia in male Wistar rats with saporin/anti-dopamine β-hydroxylase (DBH) DSAP immunotoxin lesions. The hypothalamic paraventricular nucleus (PVH) was injected bilaterally with DSAP or saporin conjugated to mouse IgG (SAP) as controls. PVH DSAP lesions remove about 80% of the DBH-ir and PNMT-ir cell bodies in the ventrolateral medulla. We found that hypothalamic CA afferents are required for sympathoadrenal (epinephrine and nor-epinephrine) responses to slow- but not fast-onset hypoglycemia. We also found robust Fos activation in CA neurons in the ventrolateral (A1, C1) and the dorsomedial medulla, particularly in the nucleus of the solitary tract (NTS; A2, C2). In rats with intact forebrain CA innervations, fast-onset hypoglycemia led to significantly greater DBH/Fos colocalization in the A1, A1/C1 and C1 regions compared to slow-onset hypoglycemia. We further identified substantial numbers of Fos-positive nuclei colocalized in adrenergic neurons (phenylethanolamine-N-methyltransferase (PNMT)) in the A1/C1 and C1 regions, and again these numbers were greater in fast-onset compared to slow-onset hypoglycemia. In SAP and DSAP animals, slow- and fast -onset hypoglycemia led to robust Fos expression in the area postrema and medial parts of the NTS. However, in these two regions there was virtually no Fos and DBH/PNMT-ir colocalization showing that AP and NTS neurons activated following hypoglycemia are not CA. The mechanisms that process the sensory information responsible for sympathoadrenal counterregulatory responses to fast- and slow-onset hypoglycemia are clearly different. We now show that different rates of hypoglycemia onset engage distinct CA cell groups, which in turn differentially participate in rate-dependent counterregulatory responses.
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Li A-J, Wang Q, Smith BR, Ritter S (2012) Lateral and fourth ventricular phloridzin injections stimulate feeding but do not produce hyperglycemia. Neuroscience 2012 Abstracts 93.18. Society for Neuroscience, New Orleans, LA.
Summary: Sodium-coupled glucose transporters (SGLTs) are a family of glucose transporter found in small intestine, kidney, brain capillaries and some neurons. Because SGLTs are membrane receptors, they interact with extracellular glucose in a metabolism-independent manner. Early work using the SGLT inhibitor, phlorizin, suggested that fourth ventricular phlorizin injection increased feeding, but not blood glucose (Flynn FW and Grill HJ, 1985). To further examine this finding, we injected phloridzin, a competitive inhibitor for SGLT-1 and SGLT-2 into the lateral ventricle (LV) or the 4th ventricle (4V) in rats, and the effects of the injections on food intake and blood glucose were examined. We found that both LV and 4V injections of phloridzin enhanced food intake in rats and that LV and 4V injections were of similar potency. In contrast, neither injection elevated blood glucose levels in the present experiments. We also found that enhancement of feeding by 4V phloridzin was abolished by medial hypothalamic injections of anti-dopamine beta hydroxylase saporin, a retrogradely transported catecholamine immunotoxin that selectively lesions norepinephrine and epinephrine neurons that innervate the injection site. Taken together, these results suggest that SGLT receptors in the brain constitute a novel, nonmetabolic, glucose sensing mechanism that contribute to control of food intake.
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