Cognitive and motor deficits in a rodent model of Parkinson’s disease displaying concurrent dopamine and acetylcholine loss
Ostock CY, Conti MM, Larose T, Meadows S, Bishop C (2015) Cognitive and motor deficits in a rodent model of Parkinson’s disease displaying concurrent dopamine and acetylcholine loss. Neuroscience 2015 Abstracts 676.26/D33. Society for Neuroscience, Chicago IL.
Summary: Dopamine (DA) loss in Parkinson’s disease (PD) is frequently accompanied by degeneration of acetylcholine neurons within the basal forebrain (BF) and the pedunculopontine nucleus (PPN). Recently, Ach neurons in these nuclei have been implicated in both the motor and non-motor symptoms of PD. However, few rodent models of PD actually account for Ach loss in both the BF and PPN. Here, we evaluated the effects of concurrent BF and PPN Ach loss alone and in combination with striatal DA loss on motor and cognitive performance in a rat model of PD. Sprague-Dawley rats (N = 44) received bilateral: striatal 6-OHDA lesions to deplete DA (DA-lesioned; n = 14), BF (192 IgG-Saporin) and PPN (anti-ChAT Saporin) saporin lesions to deplete Ach (Ach-lesioned; n = 10), combined 6-OHDA + saporin lesions (dual-lesioned; n = 6) , or sham lesions (n = 14). Following recovery from surgery, rats underwent a battery of motor and cognitive behavioral tests. Results indicated that Ach-lesioned and dual-lesioned rats displayed spatial memory deficits on the Morris Water Maze and Spontaneous Alternation tests. DA and Ach lesions alone impaired stepping for the forepaw adjusting steps and vibrissae-elicited paw placement tests and this deficit was exacerbated in dual-lesioned rats. However, only rats with Ach or dual lesions showed motor deficits on the rotarod tests. Collectively, these findings demonstrate that Ach loss may exacerbate cognitive and motor symptoms in PD and highlight the importance of including Ach loss in preclinical models of PD.
Kiley BJ, Sengelaub DR (2015) Neuroprotection with androgens following partial motoneuron depletion: A role for microglia. Neuroscience 2015 Abstracts 689.18/K11. Society for Neuroscience, Chicago IL.
Summary: Neurodegenerative disease or nerve injury results in the loss of spinal motoneurons, and remaining motoneurons show a variety of morphological and functional changes. We have previously demonstrated that partial depletion of motoneurons innervating the quadriceps muscles induces dendritic atrophy in remaining motoneurons, with 70% decreases in dendritic length. Treatment with testosterone is neuroprotective, and dendritic atrophy following partial motoneuron depletion is attenuated. In the present study, we explored a potential mechanism for this induced atrophy and the protection by androgen treatment, examining the response of microglia to the partial depletion of motoneurons with and without testosterone treatment. Microglia are activated locally and recruited from other sites in response to injury. Microglia are involved in the removal of synapses and dendrites after injury, and there is evidence that their activation is influenced by steroid hormones. Motoneurons innervating the vastus medialis muscle in adult male rats were selectively killed by intramuscular injection of cholera toxin-conjugated saporin. Simultaneously, saporin-injected rats were given systemic treatments via interscapular implants containing testosterone or left blank. One or three weeks later, microglia were visualized after immunohistochemical staining for Iba1. Microglia surrounding the injured motoneurons were classified as monitoring or activated (primed, reactive, or ameboid) based on morphology and counted stereologically. Compared with intact males, partial motoneuron depletion resulted in increases in the total number of microglia (78% and 24% at 1 and 3 weeks post-saporin, respectively) in the quadriceps motor pool. These changes were driven by increases in the number of activated microglia compared to levels found in intact animals; the number of activated microglia increased by 144% at 1 week post-saporin, and remained elevated at 3 weeks (51%). The increases in the number of activated microglia were attenuated with testosterone treatment; the number of activated forms increased only 34% and 17% at 1 and 3 weeks post-saporin, respectively. These findings suggest that the dendritic atrophy observed in remaining motoneurons after partial motoneuron depletion could be a result of increased microglial activation in the injury site, resulting in collateral damage through synaptic stripping and dendritic loss. The attenuation of both dendritic atrophy and microglial activation with testosterone treatment supports this potential causal effect, and further supports a role for hormones as neurotherapeutic agents in the injured nervous system.
Related Products: CTB-SAP (Cat. #IT-14)
Selective ablation of the intercalated neurons of the amygdala increased the anxiety-like behavior in the Elevated Plus Maze
Palomares E, Hernandez Perez O, Crespo Ramirez M, Aguilar Roblero R, Fuxe K, Perez de la Mora M (2015) Selective ablation of the intercalated neurons of the amygdala increased the anxiety-like behavior in the Elevated Plus Maze. Neuroscience 2015 Abstracts 694.14/N4. Society for Neuroscience, Chicago IL.
Summary: The intercalated (ITC) islands of the amygdala are clusters of inhibitory neurons that surround the basolateral complex (BLA) and contain a dense population of dopamine D1 and μ-opioid receptors. Lateral ITC (lITC) islands provide feed-forward inhibition to the BLA, whereas medial ITC (mITC) islands form an inhibitory interface between the BLA and central nucleus (CeA), the main output region of the amygdala. Previous studies have shown that ITC neurons play a role in fear extinction. However the functional role of the ITC islands in the un-conditioned anxiety has not been studied. To elucidate the involvement of the ITC islands in the anxiety-like behavior in the Elevated Plus Maze, we bilaterally infused the toxin saporin conjugate with the agonist of the μ-opioid receptors, dermorphine, (SAP-DER; 0.75pmol/0.250µl/lado) in closed proximity to the mITC islands to specifically ablate the neurons of the ITC islands. Behaviorally, SAP-DER injections significantly increased the time that the rats spent in the open arm of the maze as compared with their lesion control group. No effects on locomotion in the open-field test were found. These results suggest that ablate of the ITC neurons results in anxiogenic effects and support ITC neurons play an important role in mediate anxiolytic responses.
Related Products: Dermorphin-SAP / MOR-SAP (Cat. #IT-12)
Nam H, Kerman I (2015) A2 noradrenergic neurons regulate forced swim test immobility. Neuroscience 2015 Abstracts 718.10/Y20. Society for Neuroscience, Chicago IL.
Summary: The Wistar-Kyoto rat (WKY) is a well-established animal model of depression- and anxiety-like behavior, characterized by high immobility during the forced swim test (FST) along with a generally inhibited phenotype on related tests of emotional behaviors. Extensive literature indicates that deficits in noradrenergic neurotransmission may contribute to these behavioral traits. Previously, we have reported that the WKY rats are more immobile compared to other rat strains from the beginning of their training phase of the FST, and that they become even more immobile during the testing phase on the next day. We hypothesized that higher immobility during the FST and the greater increase in immobility throughout different phases of the FST are two separate components of rats’ behavior likely mediated by different central mechanisms. We sought to identify the central circuits responsible for these behavioral components by studying activation of neurons within central noradrenergic cell groups during different phases of the FST. The WKY rats along with its parent strain, Wistar rats that experienced either the: 1) 5 minutes training phase (D1), or 2) entire FST (D1 and D2) were compared. Using double-immunocytochemistry for tyrosine hydroxylase and for c-Fos, we determined that within the A2 cell group significantly more noradrenergic neurons were activated in the Wistar than in WKY rats at D1. At D2 WKYs increased their activation of the A2 noradrenergic neurons, and this activation was equivalent to that of the Wistar group. Based on these results, we further investigated the role of A2 cell group during the FST using anti-DBH conjugated saporin (DSAP) to selectively destroy noradrenergic neurons within the area. The Wistar rats treated with DSAP were more immobile during both D1 and D2 of the FST as compared to the rats treated with the vehicle only. Together these data indicate that the A2 noradrenergic cell group regulates FST immobility in rats, and that its activation may contribute to the unique behavioral phenotype of WKY rats. Future experiments aimed at selective activation of A2 noradrenergic neurons will be required to fully elucidate the role of these neurons in mediating behavioral despair and learned helplessness.
Related Products: Anti-DBH-SAP (Cat. #IT-03)
Horner KA, Logan M, Murray RC (2015) Ablation of the patch compartment reduces cocaine-induced stereotypy. Neuroscience 2015 Abstracts 506.23/M12. Society for Neuroscience, Chicago IL.
Summary: Repeated exposure to cocaine (COC) induces stereotypy, which is characterized as inflexible, repetitive behavior. Enhanced relative activation of the patch compartment of the striatum has been shown to positively correlate with the emergence of stereotypy following repeated COC treatment, suggesting that stereotypy may be related to preferential activation of this region. However, the specific contribution of the patch compartment to COC-induced stereotypy following repeated exposure is unknown. To elucidate the involvement of the patch compartment to the development of stereotypy in response to repeated COC exposure, we determined if destruction of this sub-region altered COC-induced behaviors. Animals were bilaterally infused in the striatum with the neurotoxin dermorphin-saporin (DERM-SAP; 17 ng/[[Unsupported Character – Symbol Font ]]l) to ablate the neurons of the patch compartment and allowed to recover for eight days. The animals were given daily injections of COC (25 mg/kg) or saline for one week, followed by a weeklong drug-free period. Animals were then given a challenge dose of COC, placed in activity chambers, observed for 2h and sacrificed. DERM-SAP pretreatment reduced the number of mu-labeled patches in the striatum. DERM-SAP pretreatment significantly reduced the intensity and spatial immobility of COC-induced stereotypy. In support of this observation, increased locomotor activity was seen in DERM-SAP pretreated, COC-treated animals. DERM-SAP pretreatment attenuated COC-induced c-Fos expression in the patch compartment, while enhancing COC-induced c-Fos expression in the matrix compartment. These data indicate that the patch compartment is necessary for repetitive behavior and suggests that alterations in activity in the patch vs matrix compartments may contribute to this phenomenon.
Related Products: Dermorphin-SAP / MOR-SAP (Cat. #IT-12)
Immunolesions of melanopsin receptive neurons attenuates the hormonal reproductive axis in the adult but has no effect on growth in immature Peking ducks
Alenciks E, Frazier K, Porter A, Fraley G (2015) Immunolesions of melanopsin receptive neurons attenuates the hormonal reproductive axis in the adult but has no effect on growth in immature Peking ducks. Neuroscience 2015 Abstracts 613.05/R20. Society for Neuroscience, Chicago IL.
Summary: Several light sensitive receptors have been described in the avian brain that are thought to regulate the reproductive axis independently from the eyes and pineal gland. Recently, our lab has described the presence of 3 photoneuroendocrine systems in the Pekin duck: rhodopsin, opsin 5, & melanopsin. We set out to test the hypothesis that melanopsin receptive neurons are necessary to maintain seasonal reproductive status along with growth and development in the Pekin drake. To accomplish these goals we first investigated 50-week-old Pekin drakes that were housed in the aviary at Hope College under long day length (18 hrs lights on) conditions in floor pens. To specifically lesion melanopsin-receptive neurons, 3 μl of an anti-melanopsin-saporin conjugate (MSAP, 100 ng/ul) was injected into the lateral ventricle (n = 10). Control drakes were injected with 3 ul of equimolar unconjugated anti-melanopsin and saporin (SAP, n = 10). The drakes were returned to the aviary after complete recovery. Reproductive behaviors were analyzed weekly in a test pen with adult hens. After 4 weeks, birds were euthanized and body weights were measured, and brains, pituitaries, and testes collected and stored for analyses. To test melanopsin’s effect on immature ducks the same surgery was performed on a group of 10 day old ducks (n= 10). Ducks were weighed weekly starting at 3 days of age. After a final weight was obtained at 50 days of age, ducks were euthanized and a blood sample was collected and sent out for an avian panel. Mature MSAP-treated drakes had significantly (p< 0.001) reduced relative teste weights compared to SAP controls. qRT-PCR analyses (n= 3 per treatment) of anterior pituitary showed a significant reduction (p< 0.001) in both LH-beta and FSH mRNA’s. Immunoctyochemical analyses (n= 3 per treatment) showed a significant reduction in melanopsin and GnRH-immunoreactivities. Immature drake BW did not differ significantly between MSAP and SAP animals at any of the measured days. The data appeared to drift toward significance near the end of the sampling period (p = 0.297). Blood panel results revealed no significant differences between MSAP and SAP animals in any CBC component. Serum glutamic-oxaloacetic transaminase (SGOT) (p= 0.022) and creatine phosphokinase (CPK) values were significantly elevated (p = 0.006) in MSAP animals compared to controls. Although melanopsin neurons in the PMM appear to have an important role in adult drakes, their importance in the growth of immature ducks is still unclear. However, these data underscore the importance of the photoneuroendocrine system in maintaining the reproductive axis along with growth and development in seasonally breeding birds.
Lack of effects on growth and body weight gain after elimination of the leptin receptor from the brain of immature Pekin drakes
Porter LM, Alenciks E, Frazier K, Porter A, Fraley GS (2015) Lack of effects on growth and body weight gain after elimination of the leptin receptor from the brain of immature Pekin drakes. Neuroscience 2015 Abstracts 613.04/R19. Society for Neuroscience, Chicago IL.
Summary: The presence of the hormone leptin (LEP) is a controversial topic in the field of avian physiology. While LEP is well understood in mammals, the hormone has not been definitively verified in avian species. Although the hormone remains elusive, the leptin receptor (LEPR) has been identified and sequenced in multiple avian species. Its role, however, remains unclear. To attempt to deduce the role of the leptin system in birds, we focused on altering the leptin receptor expression in the brain of immature Pekin ducks. We hypothesized that eliminating the LEPR-expressing neurons of the hypothalamus would elicit an increase in body weight, as is the case for mammals. To test this hypothesis, we injected stereotaxically 3 ul of a solution containing a monoclonal antibody (anti-LEPR) conjugated to saporin (LSAP, 100 ng/ul) was injected into the lateral ventricle of 10 day old Pekin ducks (LSAP, N = 10). Control group animals (SAP) were injected with unconjugated antibody and saporin at equimolar concentrations to the LSAP. Ducks were weighed weekly starting at 3 days of age. After a final weight was obtained at 50 days of age, ducks were euthanized and a blood sample was collected and sent out for an avian panel to assay serum glucose and free fatty acids. We found that the elimination of LEPR had no significant effect on the body weights of the ducks (p>0.05). In addition, The CBC panel did not reveal any significant differences in the overall health of the ducks in each treatment group. Our data indicates LEPR may not play a significant role in the regulation of body weight or growth in juvenile ducks.
Lee J, Jeong D, Chang W, Chang J (2015) Neuroprotective effects of placenta-derived mesenchymal stem cell for rat model of dementia. Neuroscience 2015 Abstracts 626.12/AA3. Society for Neuroscience, Chicago IL.
Summary: Introduction: The neuroprotective effects of mesenchymal stem cell (MSC) in neurodegenerative disease have been recently reported. In contrast of the transplantation effect of MSC derived from bone marrow, adipose tissue and human umbilical cord blood, the study of placenta-derived mesenchymal stem cell (pMSC) is still little known. In this study, we studied the effective method of placenta-derived mesenchymal stem cell (pMSC) transplantation by comparing intracerebroventrical (icv) with intravenous (iv) injection. In addition, we also tried to compare the effect of pMSC transplantation and standard treatment for dementia. Materials and Methods: We used the rat model of dementia by damaging basal forebrain cholinergic neurons using 192 IgG-saporin. 1 week after administration of 192 IgG-saporin, pMSC was injected via intraventricular route (icv, 1.2 x 106 cells/ul) or intravenous route (iv, 5 x 106 cells/200 ul) and Cyclosporine (immunosuppressant drug) were administrated at peritoneal cavity for preventing immune reaction by innate immunity (daily / 5 weeks). To compare the effect of stem cell therapy and standard therapy, some rats were treated with donepezil and 5 weeks after transplantation, all animals were tested visuo-spatial cognitive functions by Morris water maze. Results: The probe test of water maze, performance of pMSC transplantation group and donepezil group increased time spent in target quadrant and in platform zone. Also acetylcholinesterase(AChE) activity was increased in the hippocampus and medial prefrontal cortex(mPFC). Interestingly, iv group showed more improved behavior performance and acetylcholinesterase(AChE) activity than icv group. Immunohistochemistry of stem121 marker of stem cell and iba1 maker of microglia and Western blot of DCX and BDNF were also suggested the beneficial effect of both stem cell therapy and standard donepezil treatment. Conclusions: Our result show that pMSC recover spatial memory of dementia model by increasing acetylcholinesterase(AChE) activity. Intravenous injection of pMSC seemed to be more beneficial route for both risk managing and symptom improvement. And pMSC transplantation also showed similar efficacy of the donepezil for improving cognitive function. For determining the superiority of both treatment, further investigation should be needed. Acknowledgements: This work was supported (YonseiChallenge) by the Yonsei University Future-leading Research Initiative of 2014 and CABMC (Control of Animal Brain using MEMS Chip) funded by Defense Acquisition Program Administration (UD140069ID).
Related Products: 192-IgG-SAP (Cat. #IT-01)
Astrocytic lesions that spare neurons in the nucleus tractus solitarii interfere with cardiorespiratory control
Richerson GB, Dragon DN, Jones S, Wu Y, Talman WT (2015) Astrocytic lesions that spare neurons in the nucleus tractus solitarii interfere with cardiorespiratory control. Neuroscience 2015 Abstracts 297.15/B100. Society for Neuroscience, Chicago IL.
Summary: Conjugates of saporin (SAP) have been widely used to target specific neurons while leaving other neurons undisturbed. We found that killing catecholamine neurons bilaterally in the nucleus tractus solitarii (NTS) by injection of the SAP conjugate containing an antibody to dopamine-_-hydroxylase (anti-DBH-SAP) spared non-catecholamine neurons but led to attenuation of baroreceptor reflexes, lability of arterial pressure, and, in some animals, sudden death. In contrast, selective targeting of catecholamine neurons with 6-hydroxydopamine produced no such cardiovascular events. We hypothesized that SAP conjugates may target non-neuronal cells in the NTS. Indeed, we found that local astrocytes were killed by the conjugates as well as by unconjugated SAP itself. SAP injections into the NTS led to death of astrocytes that expressed glial fibrillary acidic protein (GFAP) but did not affect neuronal structural markers and neuronal biosynthetic enzymes. Our recent studies further suggest that local neurons are physiologically intact. Nonetheless, SAP injections into the NTS significantly reduced cardiovascular responses elicited by glutamate agonists injected into the NTS, and bilateral injections of SAP into the NTS led to attenuation of cardiovascular reflexes whose pathways pass through the NTS, lability of arterial pressure, damage to cardiac myocytes and sudden death resulting from asystole. When asystole and death followed SAP treatment the fatal arrhythmia followed progressive bradycardia. In that treated animals demonstrate altered ventilatory function, we conjecture that it is altered ventilation that leads to cardiac compromise and death.
Related Products: Anti-DBH-SAP (Cat. #IT-03)
Carnes B, DeLacalle S (2015) Compensatory cortical sprouting across the lifespan of the rat. Neuroscience 2015 Abstracts 391.10/C34. Society for Neuroscience, Chicago IL.
Summary: To investigate the plastic capacity of the cholinergic system in a partial animal model of Alzheimer’s disease, adult and aged rats received unilateral lesions of the horizontal diagonal band of Broca (HDB) using the cholinergic-specific toxin 192-IgG-saporin. The rats were sacrificed at 2, 4, 8, 12, or 24 weeks post lesion. Immuno- and histochemical techniques were used to quantify the effects of the lesion. Tissues were stained using an acetylcholinesterase technique. A 230µm by 200µm grid was used to indirectly measure the density of cholinergic fibers in the Entorhinal Cortex (EC). We compared our data to a young (3 month old) control group (Hartonian, 2005) in which the maximal loss of fiber density occurred by 8 weeks post-lesion and recovered to 75% of the intact contralateral EC by 12 weeks. All groups (young adult: 12-15; adult: 18; aged: 24-27 month old rats at the start of the experiment) exhibited a decrease in cortical fiber density after the lesion, which was more pronounced in the young adult group. All groups showed a recovery in fiber density to 60-80% of the intact side by 24 weeks post lesion. Interestingly, the loss occurred faster and more intense in the young adult group (to 25% of the intact side at 8 weeks post-lesion) than in the older ones (to 60% of the intact side by week 12 post lesion). Twenty four weeks after the lesion, the young adult group had recovered fiber density to 70%. The adult group also reached 70%, and the aged group reached 80% of the contralateral intact side. We conclude that following a cholinergic specific lesion, a compensatory mechanism is activated in the basal forebrain such that surviving neurons, projecting to the same target, are able to extend terminals and occupy the denervated area. It remains to be investigated whether the sprouts are able to establish proper synaptic connections and make a functional recovery.
Related Products: 192-IgG-SAP (Cat. #IT-01)
Basal forebrain cholinergic lesions attenuate the reinstatement of cocaine-seeking produced by a discriminative stimulus in goal-trackers but not sign-trackers
Jones JL, Pitchers KK, Robinson TE, Sarter M (2015) Basal forebrain cholinergic lesions attenuate the reinstatement of cocaine-seeking produced by a discriminative stimulus in goal-trackers but not sign-trackers. Neuroscience 2015 Abstracts 411.15/L-15. Society for Neuroscience, Chicago IL.
Summary: Goal-trackers (GTs), compared to sign-trackers (STs), express higher levels of acetylcholine when performing a cue detection and processing task. We hypothesized, therefore, that GTs utilize their basal forebrain cholinergic systems differently and to a greater extent than STs, such that this system may be critical for signal-induced behavior in GTs but not STs. The purpose of this experiment was to investigate individual variation in the reinstatement of drug-seeking behavior produced by a signal indicating cocaine availability (a discriminative stimulus), as well as the influence of the basal forebrain cholinergic system. STs and GTs were trained to self-administer cocaine using an intermittent access (IntA) procedure. The IntA procedure involved allowing animals access to cocaine for discrete 5-min drug available periods indicated by a light signal (DS+) separated by 25-min no drug available periods indicated by a different signal (DS-) in a different location than the DS+. This procedure results in ‘spiking’ brain levels of cocaine. Once stable performance was achieved on this procedure, animals underwent extinction training where the context remained similar to the IntA procedure but was now devoid of both DSs and an active response no longer had any consequence. STs and GTs did not differ in the acquisition or expression of self-administration or extinction training. After behavior was stably extinguished, half of the subjects received bilateral infusions of the cholinotoxic immunotoxin 192 IgG-saporin into the basal forebrain, while the other half received sham surgeries. Animals underwent 5 days of re-extinction. Finally, they underwent a reinstatement test during which the DS+ was presented non-contingently for 2 sec on a variable time schedule. Current results show that the ST-lesion group and both sham groups reinstated responding upon exposure to the DS+, compared to the last day of extinction. In contrast, the GT-lesion group did not reinstate responding, relative to the last day of extinction and, additionally, showed fewer active responses during the reinstatement test than the GT-sham group. Our findings suggest that the basal forebrain cholinergic system is involved in the reinstatement of drug-seeking behavior produced by a signal indicating drug availability in some animals (GTs), but not others (STs), further supporting the notion that drug cues are processed very differently in STs and GTs.
Related Products: 192-IgG-SAP (Cat. #IT-01)
Nociceptive effects of neurotensin(NTS)- and somatostatin(SST)-toxin conjugates applied to the lumbar dorsal horn in rats
Wiley RG (2015) Nociceptive effects of neurotensin(NTS)- and somatostatin(SST)-toxin conjugates applied to the lumbar dorsal horn in rats. Neuroscience 2015 Abstracts 418.11/O12. Society for Neuroscience, Chicago IL.
Summary: Intrathecal injections of NTS or SST have been reported to be anti-nociceptive, and in the case of SST, analgesic in humans. Preliminary experiments in our lab previously showed that lumbar intrathecal injection of the excitatory neuropeptide, NTS, or the inhibitory neuropeptide, SST, conjugated to the ribosome inactivating protein, saporin (sap), produced compulsive scratching/biting of hindquarters resulting in loss of fur and skin. This was thought likely due to pain and/or itching from selective loss of superficial dorsal horn nociceptive inhibitory interneurons expressing NTS receptors. Subsequent experiments using lumbar intrathecal injections of NTS-cholera toxin A chain conjugate resulted in prolonged anti-nociception on hotplate, tail flick and von Frey testing, that was not reversed by naloxone and lasted several days, likely due to sustained activation of the same neurons. The present study sought to determine if the lesions produced by NTS-sap or SST-sap alter nociceptive responses. In the present study, rats, under isoflurane anesthesia, were injected intrathecally using temporarily-placed subarachnoid catheters over the lumbar enlargement with 10 ul of sterile preservative-free normal saline containing either 300-400 ng of NTS-sap, 1 ug of SST-sap or 1 ug blank-sap (control) from Advanced Targeting Systems, San Diego, CA. Catheters were flushed with an additional 10 ul of saline. After post-surgical recovery, the rats were then observed for scratching/biting their hindquarters, nocifensive responses on the hotplate, von Frey mechanical probing of the hindpaws, and on operant thermal escape. 4 of 11 NTS-saporin rats and 5 of 9 SST-saporin rats, but none of 9 blank-saporin rats began scratching within 8-47 days after toxin conjugate injection. Hotplate nocifensive reflex testing at 44.5°C and 47°C showed no significant difference between the groups. Von Frey, operant thermal escape testing and anatomic studies are in progress to further specify the functional effects of the toxin conjugate injections and to identify the dorsal horn neurons being destroyed. The results to date are interpreted as consistent with a possibly unique role for NTS and/or SST receptor-expressing superficial dorsal horn inhibitory interneurons in nociception and/or itch. Excitatory/activating moieties such as cholera toxin A subunit targeted by conjugation to NTS or SST may offer a novel approach to enhance inhibition in nociceptive dorsal horn neurons and to produce analgesia by a non-opioid mechanism.
Zoccal DB, Taxini CL, Gargaglioni LH (2015) Control of sympathetic activity by A5 noradrenergic neurons in the in situ rat preparations. Neuroscience 2015 Abstracts 432.16/X11. Society for Neuroscience, Chicago IL.
Summary: The A5 area represents an important noradrenergic neuronal group located in the ventral pons that receives and sends projections to various medullary areas involved in the cardiorespiratory control. Its involvement in the chemoreflex control was previously studied in anesthetized conditions. In the present study, we explored the contribution of A5 noradrenergic neurons in the processing of sympathetic responses to central and peripheral chemoreceptors stimulation using the in situ working heart-brainstem rat preparation. Juvenile male Holztman rats received bilateral microinjections of either IgG-SAP (50nl, n=7) or toxin anti-dopamine beta-hydroxylase-saporin (anti-DβH-SAP, 4.2 ng/50 nl, n=6) in the A5. One week later, in situ preparations were obtained to record the thoracic sympathetic (tSN) and phrenic nerve (PN) activities; and stimulation of peripheral (KCN, 0.05%, 50nL) and central chemoreceptors (7 and 10% CO2 in the perfusate, 5 min) were performed. Baseline tSN activity (12.5±2.0 vs 12.6±2.4 μV), PN burst amplitude (40.7±9.7 vs 44.8 ±19.9 μV) and frequency (13±1 vs 15±2 bpm) and the respiratory-sympathetic coupling pattern were similar between control and A5-lesioned rats. The sympathetic ([[unable to display character: ∆]]tSN: 110±12 vs 58±8 %, P<0.05), but not the phrenic response to peripheral chemoreflex stimulation was marked attenuated in animals with lesion of A5 noradrenergic neurons. As to the central chemoreflex, the tSN response to 7% CO2 tSN: 9.5±1.4 vs 3.9±1.7%, P<0.05), but not to 10% CO2 (16.4±2.9 vs 10.9±1.6%) was lower in A5-lesioned rats in comparison to controls. On the other hand, the PN response to 7 and 10% CO2 were similar between control and A5-lesioned rats. Our data show that the A5 noradrenergic neurons are critical for the full expression of the sympathetic chemoreflex responses, possibly by providing an excitatory drive to the neurons generating sympathetic activity.
Yegla B, Francesconi JA, Forde JC, Parikh V (2015) Cholinergic contributions to PASA and functional compensation in rats. Neuroscience 2015 Abstracts 253.11/V29. Society for Neuroscience, Chicago IL.
Summary: Neuroimaging studies have indicated increased recruitment of prefrontal regions coupled to reduced activation of posterior regions in task-performing older adults. This shift of activity in cortical networks is described as posterior-anterior shift in aging (PASA). What cellular mechanisms contribute to PASA and how it provides functional compensation for age-related decline in cognitive capacities remains unknown? Cortically-projecting forebrain cholinergic neurons modulate cortical networks and facilitate attentional processes. Here we examined whether cortical cholinergic inputs contribute to PASA expression and maintenance of attentional capacities in aging. Young (3 months) and aged (24 months) Wistar rats were trained in a sustained attention task (SAT) that requires them to distinguish between signal and non-signal events. After attaining criterion performance (_70% correct responses for 3 consecutive sessions), rats received bilateral infusions of cholinoselective immunotoxin 192-IgG SAP either into the prefrontal cortex (PFC) or posterior parietal cortex (PPC) to produce partial cholinergic deafferentation. Control animals were infused with saline. Following behavioral testing 4 weeks post-surgery, animals were perfused 45-min after the last session to examine changes in neuronal activity in the PFC and PPC using c-fos immunohistochemistry. Partial prefrontal cholinergic deafferentation in aged rats produced robust deficits in response accuracy on signal trials as compared to aged sham (p=0.04) and young lesion (p=0.03) rats. In general, c-fos expressing neurons were higher in the PFC of aged rats as compared to young rats. Although prefrontal neuronal activity did not differ between the aged sham and PFC lesion group, there was a trend for a higher neuronal activity in the PPC of the latter. Surprisingly, attentional performance displayed a negative correlation with the prefrontal activity. Neuronal activity in the PPC did not correlate with performance. PPC-infused aged rats displayed no lesion effect on SAT and performed better than aged rats infused with 192 IgG-SAP into the PFC (p=0.04). Moreover, partial loss of cholinergic inputs into the PPC reduced PFC recruitment as compared to PFC lesioned aged rats. Collectively, these data suggest that reduced cortical activity in young rats compared to aged rats may represent better neural capacity, or the efficient utilization of normal brain regions, for task performance. Moreover, PASA is not triggered by prefrontal cholinergic inputs, but these inputs may regulate the reciprocal interactions between the PFC and PPC networks to maintain optimal performance in aging.
Related Products: 192-IgG-SAP (Cat. #IT-01)
Postpartum lesions targeting serotonergic neurons in the dorsal raphe alter various aspects of maternal behavior
Holschbach MA, Vitale EM, Lonstein JS (2015) Postpartum lesions targeting serotonergic neurons in the dorsal raphe alter various aspects of maternal behavior. Neuroscience 2015 Abstracts 247.17/R3. Society for Neuroscience, Chicago IL.
Summary: The survival and wellbeing of mothers and their young require high levels of maternal care, aggression toward conspecifics, and low anxiety. These behaviors are affected by pharmacological manipulation of serotonin signaling, but no experiments have analyzed in detail the effects of serotonin-specific lesions of the midbrain on all of these postpartum behaviors. We performed serotonin-specific lesions of the dorsal raphe using a saporin-conjugated toxin targeting the serotonin transporter. After dorsal raphe infusion of the toxin or an inactive control conjugate on postpartum day 2, undisturbed maternal behavior was observed daily and retrieval of scattered pups observed every other day for one week after surgery. Anxiety-like behavior was measured in an elevated plus maze and light dark box on postpartum days 8 and 9, respectively, followed by tests of aggression toward a male intruder in the home cage. Serotonergic lesions of the dorsal raphe altered numerous postpartum behaviors. During undisturbed observations, lesioned animals groomed themselves less and showed more crouching over and less licking of pups. Lesions did not greatly affect pup retrieval or anxiety-like behavior, but did reduce the average duration of attack bouts during aggression testing. This experiment indicates new roles for DR serotonin in the suite of behavioral changes occurring during the postpartum period.
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Direct impact of dopaminergic and noradrenergic systems on adult-hippocampal neurogenesis in adult rats and the relevance to dementia in Parkinson’s disease
Ermine C, Wright JL, Parish CL, Thompson LH (2015) Direct impact of dopaminergic and noradrenergic systems on adult-hippocampal neurogenesis in adult rats and the relevance to dementia in Parkinson’s disease. Neuroscience 2015 Abstracts 217.06/C66. Society for Neuroscience, Chicago IL.
Summary: A key pathological feature of Parkinson’s disease (PD) is the progressive degeneration of midbrain dopaminergic neurons, causing motor dysfunction. However there are a range of ‘non-movement’ related features (including cognitive dysfunction, dementia and sleep disorder), which are not alleviated by dopamine replacement therapy. We are currently investigating the hypothesis that reduced hippocampal neurogenesis contributes to cognitive dysfunction in PD. We aim to characterise the effect of the dopaminergic and noradrenergic system on the adult-hippocampal neurogenesis in order to identify potential targets for the treatment cognitive impairments related to neurogenesis. We induced lesions of the different systems in adult rats using stereotaxic injections of toxins: 6-hydroxydopamine (dopaminergic system) and anti-dopa-β-hydroxylase-saporin (noradrenergic system). Four weeks later, the new cells were marked by pulses of bromodeoxyuridine (Brd-U) twice daily for 1 week. The animals were then sacrificed 4 weeks later for tissue collection. A high-performance liquid chromatography has confirmed that both lesions were successful: dopamine level in the striatum dropped to 20% and noradrenaline level in the hippocampus dropped to 8.3%. Surprisingly there was no difference in the number of Brd-U positive cells or in the number of double positive Brd-U/NeuN cells between our groups. The results show that while both noradrenergic and dopaminergic systems are implicated in the onsets of non-motor symptoms, they may not act through the regulation of adult-hippocampal neurogenesis like it was previously thought. Importantly our project has allowed reconsideration of how neurogenesis is involved in PD and redirected the therapies to better potential targets for treatment.
Related Products: Anti-DBH-SAP (Cat. #IT-03)
Preliminary investigation on the antidepressive effect of chronic oxotremorine treatment in a rodent model of Alzheimer’s disease
Nair DV, Al-Badri MM, Peng H, Pachego-Quinto J, Eckman CB, Iacono D, Eckman EA (2015) Preliminary investigation on the antidepressive effect of chronic oxotremorine treatment in a rodent model of Alzheimer’s disease. Neuroscience 2015 Abstracts 40.29/C34. Society for Neuroscience, Chicago IL.
Summary: Alzheimer’s disease (AD) is a progressive neurodegenerative disease and the rate of progression varies from individual to individual. A great deal of evidence supports the idea that depression and other neuropsychiatric conditions co-exist with cognitive decline. However, the neurobiological basis of these symptoms and their influence on the clinical course of AD remain unclear. Our lab has shown previously that the 192-IgG saporin rat model of AD-like basal forebrain cholinergic cell loss exhibits a depression-like phenotype that develops months after the well-described impairment in spatial working memory. Furthermore, we have shown that chronic intracerebroventricular administration of the muscarinic agonist oxotremorine reverses both spatial working memory deficits and the depression-like behavior triggered by cholinergic denervation, and induces hippocampal neurogenesis. Current experiments are focused on determining additional pathological correlates of depression in this model and how they may be modulated by muscarinic agonists. To induce AD-like basal forebrain cholinergic cell loss, adult female Sprague Dawley rats were injected intracerebroventricularly (icv) with the immunotoxin 192-IgG-saporin (SAP) or saline as control (SHAM). After a 5 week recovery period, the rats received either 2 or 6 weeks of icv infusion of either oxotremorine or vehicle (saline) via osmotic minipump. Behavioral testing to assess the depressive phenotype was carried out using the sucrose consumption test every 2 weeks during oxotremorine treatment. The phenotype was further confirmed by forced swim test. The levels of ChAT, tryptophan hydroxylase (TPH), muscarinic receptors and FosB and ΔFosB were assessed in the hippocampus, basal forebrain, and orbitofrontal cortex by western blot and immunohistochemistry. Our preliminary results show increases in TPH, M1 receptors and FosB in the hippocampus, basal forebrain, and orbitofrontal cortex of a subset of treated animals, but no changes ChAT or ΔFosB. Further experiments are in progress to determine if there are changes in the expression of these and additional proteins in other brain regions including the nucleus accumbens, an area involved in activational aspects of motivation which also contributes to behavioral disorders such as to depression. The results of these studies may provide new insight in understanding the molecular basis of depression and antidepressant action of oxotremorine thereby defining new targets for possible therapeutic intervention for depressive symptoms in AD.
Related Products: 192-IgG-SAP (Cat. #IT-01)
Pittenger CJ (2015) Modeling Tourette syndrome pathophysiology through targeted manipulation of striatal interneurons. Neuroscience 2015 Abstracts 6.07. Society for Neuroscience, Chicago IL.
Summary: Postmortem studies of Tourette syndrome patients has revealed a reduction in the number of specific striatal interneurons. The authors explored the hypothesis that this neuronal deficit is enough to produce the symptoms of Tourette syndrome in mice. Animals received 90-ng injections of Anti-ChAT-SAP (Cat. #IT-42) into the striatum. Rabbit IgG-SAP (Cat. #IT-35) was used as a control. The data suggest that loss of the striatal interneurons is enough to produce some, but not all, of the symptoms caused by Tourette syndrome.