sfn2006

Shiromani PJ, Blanco-Centurion C, Xu M, Murillo-Rodriguez E, Gerashchenko D, Hof PR (2006) Adenosine and sleep debt in the basal forebrain. Neuroscience 2006 Abstracts 458.13. Society for Neuroscience, Atlanta, GA.

Summary: The waxing and waning of the sleep drive is hypothesized to be regulated by endogenous sleep factors acting on specific neurons in the brain. One such factor, adenosine (AD), accumulates during wake and begins to inhibit neural activity in wake-promoting brain regions. The current version of the AD hypothesis (Strecker et al., Sleep, 2006) postulates that the adenosine A1 receptor activation on cholinergic neurons in the basal forebrain (BF) is key to sleep debt. Here we directly test this by administering 192-IgG-saporin to lesion the BF cholinergic neurons and then measuring AD levels in the BF via microdialysis. 46 Sprague-Dawley rats were administered either saline (n=21) or 192-IgG-SAP (n=25) (under anesthesia) and two weeks later when it is known that the cholinergic neurons have died, experiments were started. Rats were maintained on 12:12 light-dark schedule and given food and water ad-libitum. In rats with 95% lesion of the BF cholinergic neurons (n=7) AD levels in the BF did not increase with 6 h of prolonged waking but consistent with established findings it increased in non-lesioned rats (n=6). The lesioned rats had intact sleep drive after 6 and 12 h of prolonged waking, including a robust increase in delta power, indicating that the AD accumulation in the BF is not necessary for sleep drive. Next we determined that in the absence of the BF cholinergic neurons the selective adenosine A1 receptor agonist, CHA, administered to the BF continued to be effective in inducing sleep in a concentration-dependent manner, indicating that the BF cholinergic neurons are not essential to sleep induction. Basal sleep-wake levels and the amplitude of the diurnal rhythm of sleep-wake were not different between lesioned and non-lesioned rats. Thus, the hypothesis that basal forebrain cholinergic neurons are central to the AD regulation of sleep debt is rejected since neither the activity of the BF cholinergic neurons nor the accumulation of AD in the BF during wake is necessary for accumulating sleep debt.

Related Products: 192-IgG-SAP (Cat. #IT-01)

Li A, Ritter S (2006) Glucoprivation enhances dopamine-beta-hydroxylase gene expression in hindbrain catecholamine cells. Neuroscience 2006 Abstracts 359.12. Society for Neuroscience, Atlanta, GA.

Summary: Hindbrain catecholaminergic neurons are key participants in systemic glucoregulation. Using in situ hybridization, we investigated the effects of glucoprivation on gene expression of dopamine-beta-hydroxylase (DBH), a key enzyme for catecholamines synthesis, to further define the catecholamine subpopulation activated by glucoprivation. Glucoprivation induced by systemic injection of the glycolytic inhibitor, 2-deoxy-D-glucose (2DG, 250 mg/kg body weight) increased total DBH mRNA expression in caudal ventrolateral medullary cell groups (namely, A1, the A1/C1 overlap, and middle C1) from 6 – 49 times control levels. In retrofacial C1, A5 and A7 no enhancement was observed. In the dorsomedial medulla, DBH mRNA hybridization signal was modestly increased (tripled) in cell group A2, but not in the area postrema. Furthermore, a previous hypothalamic microinjection of the retrogradely transported immunotoxin, anti-DBH-saporin, profoundly reduced DBH-positive cells in hindbrain, and abolished the 2DG-stimulated increases of DBH mRNA expression in the caudal ventrolateral medulla and A2 regions. The strong glucoprivation-induced enhancement of DBH gene expression in particular cell populations is consistent with the demonstrated importance of catecholaminergic neurons for glucoregulation and provides further evidence for functional specialization within the catecholamine cell population.

Related Products: Anti-DBH-SAP (Cat. #IT-03)

Blanco-Centurion CA, Shiromani PJ (2006) Hypocretin-1 stimulates wake and decreases sleep in the basal forebrain of rats with 192-IgG-sap induced lesion of the cholinergic neurons. Neuroscience 2006 Abstracts 458.7. Society for Neuroscience, Atlanta, GA.

Summary: Hypocretin (orexin) containing neurons are located in the lateral hypothalamus (LH) from where they project to major arousal centers in the brain including the basal forebrain (BF). Waking, in part, may be driven by the action of HCRT on BF neurons. However, the BF contains various phenotypes of neurons and to test whether HCRT stimulates wake via the cholinergic neurons we utilize 192-IgG-saporin (192-IgG-SAP) to lesion the BF cholinergic neurons and then determine the potency of HCRT-1 in stimulating wake. Sprague-Dawley rats were administered (under anesthesia) saline (n=5) or 192IgG-SAP (4-6 ug/6ul, n=7). Three weeks later microinjections of aCSF or HCRT (0.06, 0.125, 0.25 nmol/250ul) were administered to the BF via a cannula in a random order. Sleep was recorded for 6h. In lesioned rats 95% of the BF cholinergic neurons were destroyed. However, in these rats, HCRT-1 in a dose-dependent manner significantly increased the time to onset of NREM and REM sleep and this was not different compared to non-lesioned rats. Percent wake was also not different compared to non-lesioned rats. Four hours after microinjection, wake-sleep levels were back to normal. Two studies (Espana et al., 2001) (Thakkar et al., 2001) have infused HCRT-1 into the BF and monitored changes in sleep-wake. However, because the BF contains a heterogenous population of neurons, HCRT-1 is likely to act on all of the BF neurons that contain the HCRT receptor. Here, we found that in the absence of the BF cholinergic neurons HCRT-1 increased wake and decreased sleep to the same degree as in non-lesioned rats, suggesting that non-cholinergic BF neurons are able to mediate unabated HCRT’s arousal signal.

Related Products: 192-IgG-SAP (Cat. #IT-01)

Farias P, Valdes J, Riveros M, Torrealba F (2006) The tuberomammillary nucleus is a key component of the arousal system for the appetitive phase of feeding. Neuroscience 2006 Abstracts 361.24. Society for Neuroscience, Atlanta, GA.

Summary: The histaminergic neurons from the tuberomammilary nucleus (TMN) are important in maintaining a high level of arousal or increased sensory alertness. We have seen TMN activation (assessed by Fos-ir) in three different motivated behaviors: feeding, drinking and sexual. The aim of this work is to prove that TMN neurons are essential to promote the arousal during the appetitive phase of feeding. We evaluated the effect of TMN lesion performed with the neurotoxin-saporin coupled to orexin-B on locomotor activity and on thermal responses during food presentation to hungry rats as well as changes in Fos-ir of arousal nuclei and subcortical regions involved in thermal responses. Rats were implanted with telemetric transponders to measure locomotor activity and body core temperature. The brains were processed for Fos-ir, and counterstained with appropriate antibodies to identify ascending arousal system (AAS) nuclei. Histaminergic neurons in the TMN were identified by adenosine deaminase (ADA)-ir. The lesions significantly decreased the number of ADA ir/mm2. The larger lesion (<54% surviving neurons) produced a significant decreased in locomotion and temperature responses to food enticing, compared to intact rats or rats with smaller lesion. Larger lesion abolished the increase in Fos-ir of the AAS nuclei (except the locus coeruleus), and the increase in Fos-ir in thermoregulatory nuclei observed in intact rats. The activation of the orexin neurons of the lateral hypothalamic area and the increase in locomotor activity during food presentation were correlated with the activation of the dorsal TMN. The increased Fos-ir in locus coeruleus and dorsal raphe, and the increase in body core temperature were correlated with the activation of the ventral TMN. In conclusion the TMN neurons seems to act as a “master switch” since they are necessary to initiate the increased arousal that characterizes motivated behaviors, and they likely engage other arousal nuclei as well as thermoregulatory nuclei during the appetitive phase of feeding.

Related Products: Orexin-B-SAP (Cat. #IT-20)

Cortez AM, Amodeo D, Chavez C, Flesher M, Balbous M, Butt AE (2006) Selective 192 IgG-saporin lesions of the cholinergic basal forebrain impair negative patterning discrimination learning in rats. Neuroscience 2006 Abstracts 162.7. Society for Neuroscience, Atlanta, GA.

Summary: We have previously argued that the cholinergic nucleus basalis magnocellularis (NBM) is necessary for complex or “configural” association learning, but is not necessary for simple association learning. The current experiment further tests the hypothesis that the cholinergic basal forebrain is involved in configural association learning by examining the respective contributions of the NBM projections to neocortex and the medial septal (MS) projections to hippocampus in separate groups of rats. Rats with bilateral 192 IgG-saporin lesions of either the NBM or MS were tested in a negative patterning operant discrimination task. Rats were food-reinforced (+) for responding in the presence of a light (L+) or a tone (T+), but were not reinforced (-) for responding in the presence of the configural stimulus comprised of the light and tone presented simultaneously (LT-). We have previously shown that NBM lesions cause a transient but significant impairment in negative patterning discrimination learning. Consequently, we hypothesized a similar NBM lesion-induced impairment in the current experiment. Because hippocampus lesions cause dramatic disruptions in the acquisition of the negative patterning task, it was hypothesized that lesions of the cholinergic neurons of the MS would cause a greater degree of impairment than NBM lesions. Consistent with our hypotheses, NBM lesions retarded but did not prevent acquisition. MS lesions, in contrast, caused significantly greater impairments than NBM lesions. Rats in both lesion groups responded normally to L+ and T+ but responded more often to LT-. These findings demonstrate intact simple association learning but disrupted configural association following damage to the cholinergic neurons of the NBM or MS. Results suggest that cholinergic basal forebrain modulation of neocortex and hippocampus contributes to configural association learning.

Related Products: 192-IgG-SAP (Cat. #IT-01)

Abitoye PA, Li P, Gibbs RB, Johnson DA (2006) Steroid sulfatase inhibitor (p-O-sulfamoyl) – tetradecanoyl tyramine (du-14) enhances memory retention in rats with cholinergic lesion. Neuroscience 2006 Abstracts 163.15. Society for Neuroscience, Atlanta, GA.

Summary: Previous studies have shown that altering the metabolism of neurosteroids via inhibition of steroid sulfatase (SSI) would reverse scopolamine induced amnesia. In this study we tested whether the SSI, DU-14 could enhance memory retention of foot shock in rats with a selective lesion of cholinergic neurons projecting from the medial septum to the hippocampus using a passive avoidance paradigm. Male Sprague-Dawley rats were infused with either 0.2 μg of 192 IgG-saporin (SAP), a selective cholinergic immunotoxin, or artificial cerebrospinal fluid (CSF) into the medial septum. One week later, the animals were placed into a passive avoidance apparatus and administered footshock trials (1 mA / 1 sec) until criterion (2 consecutive trials with a crossover latency of at least 5 min). On the next day, rats from SAP and CSF groups were then randomly assigned to receive DU-14 (30mg / kg) or corn oil (vehicle) daily for 6 days. Rats were tested for memory retention three hours after the last day dosing. DU-14 increased crossover latency by 74.5% in the CSF control group and 54.8% in SAP treated animals. In order to determine whether DU-14 or SAP treatment inhibited locomotor activity independent of memory, other animals were dosed with vehicle or DU-14 and crossover latency was tested before acquisition of footshock. There were no significant differences between treatment groups. These results suggest that steroid sulfatase inhibition may enhance memory retention in rats with hippocampal cholinergic lesion.

Related Products: 192-IgG-SAP (Cat. #IT-01)

Rivat C, Vera-Portocarrero LP, Ibrahim MM, Mata HP, Stagg NJ, De Felice M, Porreca F, Malan TP (2006) Ascending and descending pathways support fentanyl-induced pain hypersensitivity with and without a surgical incision. Neuroscience 2006 Abstracts 248.10. Society for Neuroscience, Atlanta, GA.

Summary: Acutely administered the analgesic opioid fentanyl has been shown to enhance mechanical hypersensitivity in a model of surgical pain induced by hindpaw incision in the rat. Recent evidence showed the importance of descending pathways originating from the rostral ventromedial medulla (RVM) in opioid-induced hyperalgesia after sustained morphine administration. Such hyperalgesia is also associated with numerous neurochemical changes in primary afferent fibers and spinal dorsal horn, such as increased spinal dynorphin expression. These changes may activate ascending pathways, mediated in part by NK-1 neurotransmission. Here, we examined the roles of ascending and descending pathways in sensory hypersensitivity after acute fentanyl administration. Male Sprague-Dawley rats received 4 fentanyl (4×100 μg/kg, s.c.) or saline injections administered at 15 min intervals. Some animals also received an incision in the plantar hindpaw. Thermal hyperalgesia and tactile allodynia were measured daily. In control rats, fentanyl induced analgesia followed by an immediate and long-lasting hyperalgesia, as previously described. Fentanyl also enhanced pain sensitivity induced by plantar incision. In SP-saporin pretreated rats, fentanyl induced analgesia and a moderate long-lasting hyperalgesia. The SP-saporin pretreatment slightly reduced both hyperalgesia and allodynia in postoperative rats and, to a larger extent, in fentanyl treated rats. Lidocaine injection in the RVM completely reversed fentanyl-induced sensory hypersensitivity and fentanyl enhancement of incision-induced hyperalgesia and allodynia. A slight reduction of incision-induced sensory hypersensitivity was observed after lidocaine injection in rats without fentanyl pretreatment. Spinal dynorphin content increased by 30 ± 7% and 71 ± 33% in fentanyl and fentanyl/incision treated rats, respectively. These data support the crucial role of the descending pathways from the RVM in the fentanyl-induced hyperalgesia and the partial implication of the NK-1 receptor containing ascending pathways.

Related Products: SP-SAP (Cat. #IT-07)

Hayashida K, Clayton B, Ma W, Eisenach J (2006) Brain-derived neurotrophic growth factor from p75-expressing sensory afferents drives spinal noradrenergic fiber sprouting following nerve injury in rats. Neuroscience 2006 Abstracts 248.19. Society for Neuroscience, Atlanta, GA.

Summary: We previously showed that peripheral nerve injury in mice results in sprouting of noradrenergic (NA) fibers in the spinal cord, possibly reflecting a substrate for increased efficacy of α2-adrenoceptor agonists such as clonidine. Here we tested whether spinal NA fiber sprouting also occurs in rats after peripheral nerve injury and examined the role of brain derived neurotrophic factor (BDNF) for such sprouting. Ligation of L5 and L6 spinal nerves unilaterally in rats resulted in mechanical hypersensitivity of the paw ipsilateral to injury and sprouting of NA fibers in the dorsal horn of the lumbar spinal cord. BDNF content increased in L4-L6 dorsal root ganglia (DRG) ipsilateral to injury and in lumbar spinal cord following nerve injury and intrathecal infusion of BDNF antiserum prevented spinal NA sprouting. Pro-BDNF immunoreactivity increased in L4-L6 DRG neurons ipsilateral to injury, especially in large-size neurons, and was highly co-localized with the low affinity neurotrophin receptor, p75NTR. Intrathecal injection of anti-p75NTR linked to saporin destroyed p75NTR expressing afferents and reversed NA sprouting after nerve injury. Manipulations which blocked NA sprouting (BDNF antiserum, anti-p-75NTR saporin) also prevented the increased analgesic efficacy of intrathecal clonidine observed after nerve injury. These results suggest that increased BDNF synthesis and release from p75NTR expressing injured and uninjured sensory afferents drives spinal NA sprouting following nerve injury and this sprouting increase the capacity for analgesia from drugs which utilize the NA pathway.

Related Products: 192-IgG-SAP (Cat. #IT-01)

Tait DS, Brown VJ, Farovik A, Theobald DE, Dalley JW, Robbins TW (2006) Lesions of the dorsal noradrenergic bundle impair attentional set-shifting in the rat. Neuroscience 2006 Abstracts 264.4. Society for Neuroscience, Atlanta, GA.

Summary: Rats with medial prefrontal cortex (mPFC) lesions are impaired in attentional set shifting (Birrell and Brown, 2000, J Nsci, 20:4320-4324). The mPFC receives multiple projections, but norepinephrine (NE) has previously been reported to modulate attention by its action in the mPFC (for review see Dalley et al., 2004, Nsci Biobeh Rev, 28:771-784), including shifting attentional set. Indeed, there is recent evidence that increasing NE in the mPFC by autoreceptor antagonism improves set-shifting performance in rats (Lapiz and Morilak, 2006, Nsci, 137:1039-1049). Furthermore, reduction of prefrontal NE by infusion of anti-DBH-saporin into PFC has been shown to impair attentional set-shifting in rats (Eichenbaum et al., 2003, SfN Abstract 940.7). The main source of noradrenergic input to the mPFC is from locus coerulus via the dorsal noradrenergic bundle (DNAB). This study examined the effect of lesions of the DNAB on the acquisition, maintenance and shifting of attentional set. Eleven male Lister-hooded rats received bilateral DNAB lesions by infusion of 6-hydroxydopamine (4μg in 2μl each side) at (nosebar -2.4mm) AP -6.0mm, ML ±1.0mm, DV -5.0mm (from dura). Twelve control rats received injections of vehicle. Rats learned to dig for bait in bowls then learned two simple discriminations – based on the bowls odor or the digging substrate – to a criterion of six consecutive correct trials. The next day, a series of discriminations tested acquisition of novel discriminations (both intra (ID) and extradimensional (ED)) and reversal learning. Trials to criterion, incorrect trials and dig-latencies were recorded and analysed. At conclusion of testing, brain tissue samples were analysed for NE content by HPLC-ECD. All rats required more trials to reverse previously learned associations, and to learn new discriminations when attentional refocusing was required (ED shift). Rats with DNAB lesions were unimpaired at reversal stages, but were impaired at the ED acquisition stage. Lesioned rats showed reductions of NE levels in mPFC (up to 95% in the infralimbic region, 89% in the prelimbic region and 93% in cingulate area Cg1). These data provide further evidence for the role of NE in attentional set-shifting, and combine with previous data to elucidate the mechanisms by which mPFC mediates attentional set-shifting in the rat.

Related Products: Anti-DBH-SAP (Cat. #IT-03)

Chauhan NB (2006) Cholinergic immunolesioning produced tangle-like inclusions in TgCRND8 brain. Neuroscience 2006 Abstracts 271.8. Society for Neuroscience, Atlanta, GA.

Summary: Today’s Alzheimer’s disease (AD) research lacks a “complete” model that would represent both plaque and tangle pathology together with correlative memory deficits. Although currently developed transgenic model including APP/PS1/tau mutations do not “truly” represent AD because tangles observed in AD brain are independent of tau mutations. Subtly increased β-amyloid (Aβ) levels either due to familial mutations or sporadic causes, primarily targets pre-tangle cytopathology and degeneration of basal forebrain cholinergic neurons (BFCN) via deranged signaling of glygogen synthase kinase 3-beta (GSK3β)-, protein kinase A (PKA)-, and extracellular signal-regulated kinase (ERK2) of ERK-mitogen-activated protein kinase (MAPK) cascade, leading to reduced phosphorylation of cAMP responsive element binding protein (CREB) that results in synaptic and memory deficits much earlier than the emergence of classic AD-pathology. Thus, subtly elevated Aβ, together with BFCN deficits resulting from Aβ-induced deranged signaling, set up a vicious feedback loop to produce characteristic plaque- and tangle-pathology observed in AD. Based on these facts, we wished to test if selective lesioning of basal fore brain cholinergic neurons during the early stages of amyloid build-up will exacerbate tau phosphorylation and produce tangle-like inclusions in transgenic mice with APP mutations. We produced selective immunotoxic lesions of BFCN by injecting the BFCN-specific cholinergic immunotoxin, which is known to specifically target p75-expressing BFCN and spare p75-expressing cerebellar neurons (Mu-p75-Saporin, Advanced Targeting Systems, #IT-16), intracerebroventricularly (ICV) in TgCRND8 mice harboring Swedish (KM670/671NL) and Indiana (V717F) mutations. This model exhibited tangle-like inclusions, provoked already existing plaque pathology, and worsened already impaired behavioral deficits.

Related Products: mu p75-SAP (Cat. #IT-16)

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