sfn2002

Gallegos RA, Lee RS, Crawford E, Wills DN, Carr JR, Zhukov VI, Slaght KE, Huitron-Resendiz S, Criado JR, Henriksen SJ (2002) Selective lesion of ventral tegmental area neurons expressing mu-opioid receptors alters EEG power spectrum across sleep/wake cycle. Neuroscience 2002 Abstracts 276.14. Society for Neuroscience, Orlando, FL.

Summary: The ventral tegmental area (VTA) has long been implicated in motivated behaviors. Our previous study (Lee et al, J Neurosci 2001) also suggests a role for VTA GABAergic neurotransmission in REM sleep. In the current study the potential role of the VTA in modulating electroencephalogram (EEG) activation was explored by selectively deactivating mu-opioid receptor expressing cells in the VTA. Under sodium pentobarbital anesthesia, rats received either (1) a sham operation (2) a single bilateral VTA injection of NMDA (3) a saporin injection or (4) an injection of a dermorphin-saporin (DERM-SAP) conjugate (Advanced Targeting Systems, San Diego). Animals were also fitted with skull electrodes for recording the EEG. The filtered EEG was recorded continuously for 24 hours beginning 21 to 28 days after surgery. Frequency analysis of the EEG in 15-sec epochs revealed differences in the distribution of relative power in the DERM-SAP animals, compared to controls. Low frequency components (0.5-3.0 Hz and 3.0-8.0 Hz) were enhanced in dual lesioned animals during the dark phase but only during sleep. These results indicate that a selective inactivation of cells in the VTA has specific effects on arousal mechanisms in the intact animal.

Related Products: Dermorphin-SAP / MOR-SAP (Cat. #IT-12)

Burgess SE, Gardell LR, Xie Y, Ossipov MH, Vanderah TW, Malan TP, Porreca F, Lai J (2002) Dermorphin-saporin targets descending facilitation in the rostral ventromedial medulla (rvm) to block CCK-induced abnormal pain. Neuroscience 2002 Abstracts 351.11. Society for Neuroscience, Orlando, FL.

Summary: Abnormal pain from L5/L6 spinal nerve ligation (SNL) has been shown to require a time-dependent activation of descending facilitatory pathways arising in the RVM. Additionally, RVM microinjection of L365,260, a cholecystokinin (CCKB) receptor antagonist, reverses SNL-induced tactile and thermal hyperalgesia. These observations suggest the possibility that RVM CCK might “drive” such facilitation from the RVM by activating the endogenous descending facilitation system. Rats were treated with a single RVM injection of dermorphin (DERM) (μ opioid agonist), unconjugated saporin (SAP), or dermorphin-saporin (DERM-SAP) and responses to non-noxious tactile (von Frey filaments) or noxious radiant heat stimuli applied to the hindpaw were measured before and after RVM microinjection of CCK to uninjured rats. RVM DERM-SAP, DERM or SAP did not significantly alter baseline sensory thresholds over 28 days post-injection. At day 28, the rats received bilateral microinjections of CCK (30ng) in the RVM. Rats pretreated with DERM or SAP showed a time-related and revsersible CCK-induced tactile and thermal hypersensitivity. In contrast, RVM CCK failed to produce changes in sensory threshold in animals pretreated with DERM-SAP. The RVM pretreatments did not alter responses in control rats challenged with CCK vehicle. Additionally, lesions of the dorsolateral funiculus also blocked RVM CCK-induced tactile and thermal hypersensitivity. These data support the possibility of CCK-mediated activation of descending facilitation from the RVM as a mechanism of neuropathic pain.

Related Products: Dermorphin-SAP / MOR-SAP (Cat. #IT-12)

Guyenet PG, Stornetta RL, Rosin DL, Wang H, Sevigny CP, Weston MC (2002) Somatostatin immunoreactivity is a diagnostic marker of the pre-Boetzinger complex. Neuroscience 2002 Abstracts 362.4. Society for Neuroscience, Orlando, FL.

Summary: Selective ablation of the neurokinin-1 receptor-ir (NK1R-ir) neurons of the ventral respiratory group (VRG) causes major respiratory deficits. Since this population of NK1R-ir neurons is heterogeneous, additional markers are needed to identify which subgroup is most critical to respiratory rhythmogenesis. In the present study, the pre-Boetzinger complex (pre-BoetC) was defined as a 500 μ-long segment of the ventral respiratory group (VRG) located rostral to the spinally projecting inspiratory premotor neurons. This region of the ventral medulla was the only one that contained somatostatin-immunoreactive (SST-ir) neuronal somata. These cells were small (108 μ²), generally fusiform and they expressed very high levels of preprosomatostatin (PPSST) mRNA. All SST-ir neurons were strongly NK1R-ir and were destroyed by saporin conjugated with an NK1R agonist. Most SST-ir neurons (>90%) contained vesicular glutamate transporter 2 (VGLUT2) mRNA whereas <1% contained GAD-67 mRNA and few (6%) contained preproenkephalin mRNA. The results of retrograde labeling experiments with Fluoro-Gold demonstrated that SST-ir neurons do not project to the spinal cord but that over 75% project to the contralateral pre-BoetC. In conclusion, somatic SST immunoreactivity can be used as a diagnostic marker of the pre-BoetC. The SST-ir cells of the pre-BoetC are small glutamatergic interneurons with contralateral projections and they express high levels of NK1 receptors. The homogeneous features of this group of interneurons and their exclusive location in the pre-BoetC suggest that they could be the NK1R-ir neurons whose destruction disrupts respiratory rhythm. (HL 28785 & 60003).

Related Products: SSP-SAP (Cat. #IT-11)

Dinh TT, Duffy P, Ritter S (2002) Immunotoxin lesion of spinally projecting catecholamine neurons impairs the adrenal medullary response to glucoprivation and the sympathetic response to forced swim. Neuroscience 2002 Abstracts 76.5. Society for Neuroscience, Orlando, FL.

Summary: Distinct populations of hindbrain catecholamine neurons project spinally to innervate sympathetic and adrenal medullary preganglionic neurons. Previously we injected the immunotoxin, saporin conjugated to anti-dopamine beta hydroxylase (DSAP), into the spinal cord to selectively lesion these neurons. DSAP lesions abolished adrenal medullary Fos expression following insulin-induced hypoglycemia or 2-deoxy-D-glucose (2DG) and eliminated the hyperglycemic response to 2DG, which is mediated by adrenal medullary epinephrine (E) secretion. Here we examine the plasma E and norepinephrine (NE) responses to 2DG (250 mg/kg, s.c.) and to 5 min of forced swim in rats injected at T2-T4 with DSAP or unconjugated saporin (SAP) control solution. Blood was sampled remotely via jugular catheters between 0 and 240 min after 2DG or swim. Immunohistochemistry confirmed loss of dopamine B-hydroxylase throughout the spinal cord of DSAP rats. In DSAPs, both plasma E and hyperglycemic responses to 2DG were abolished or severely impaired compared to SAPs. 2DG did not elevate plasma NE in either group. Swim stress increased NE in both SAPs and DSAPs, but the DSAP response was only 60% of the SAP response. Results show for the first time that the selective activation of the adrenal medulla by glucoprivation, described previously, is mediated by spinally projecting catecholamine neurons. Results also demonstrate that spinal catecholamine terminals, presumeably arising from different hindbrain neurons, contribute to, but are not entirely responsible for, sympathetic neuronal responses to swim stress.

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

Varga C, Grosche J, Brauer K, Seeger J, Harkany T, Hartig W (2002) Cholinergic neurons in the rabbit forebrain: Chemoarchitecture, in vivo labeling, immunolesions. Neuroscience 2002 Abstracts 35.3. Society for Neuroscience, Orlando, FL.

Summary: While the rabbit basal forebrain and its cholinergic components became useful targets for modeling of neuropathological changes associated with Alzheimer’s disease, their neuroanatomical organization is still largely elusive. Hence, we focused on (i) the number of cholinergic basal forebrain neurons (CBFN)in the major nuclei based on choline acetyltransferase (ChAT) immunoperoxidase labeling, (ii) the density of ChAT-immunoreactive fibers in distinct neocortical and hippocampal areas, (iii) mapping of projecting CBFN by low-affinity neurotrophin receptor p75 (p75NTR ) staining and (iv) the double fluorescence labeling of ChAT and the neuronal markers p75NTR, nitric oxide synthase (NOS), calbindin, calretinin, parvalbumin, tyrosine hydroxylase and substance P. While cholinergic interneurons were found in the hippocampus, they were not detectable in the neocortex. CBFN were shown to abundantly co-express p75NTR, except in the substantia innominata and ventral pallidum. Whereas cholinergic neurons were devoid of most investigated markers, a subset also contained calbindin or NOS. The selective in vivo labeling of CBFN was achieved with intracerebroventricularly (i.c.v.) injected carbocyanine 3-conjugated ME20.4IgG that recognizes an extracellular epitope of p75NTR. Parallel experiments revealed that the i.c.v. injection of ME20.4IgG-saporin conjugates led to the specific immunolesion of cholinergic cells in about one week, whereas long-term effects of the immunotoxin remain to be further elucidated.

Related Products: ME20.4-SAP (Cat. #IT-15)

Turchi JN, Saunders RC, Mishkin M (2002) Effects of cholinergic deafferentation of rhinal cortex on visual recognition in monkeys. Neuroscience 2002 Abstracts 82.5. Society for Neuroscience, Orlando, FL.

Summary: Excitotoxic lesions of the rhinal (perirhinal/entorhinal) cortices yield substantial deficits in visual recognition (Baxter and Murray, 2001; Malkova et al., 2001). To evaluate the mnemonic role of cholinergic inputs to this region, we compared the visual recognition performance of untreated monkeys with that of monkeys given rhinal cortex infusions of the selective cholinergic immunotoxin ME20.4-SAP. This toxin binds to the p75 receptor, borne by corticopetal cholinergic neurons of the basal forebrain, and is retrogradely transported to the cell body where it permanently destroys ribosomal function. Both groups were first trained to criterion in the rule for delayed nonmatching-to-sample (DNMS) with trial-unique stimuli at a 10-s delay in a Wisconsin General Testing Apparatus. This was followed by treatment and recovery for the experimental group (n=3) and an equivalent rest period for the control group (n=4), after which both groups were retrained on the DNMS rule and then given a memory performance test with increasing delays (30, 60, and 120 s) and list lengths (3, 5, 10, and 20 stimuli). The experimental group relearned the DNMS rule without significant impairment but then demonstrated robust deficits when tested with increasing delays (a mean of 83% vs 95% for controls) and list lengths (67% vs 86% for controls). The findings complement results obtained in a study of muscarinic receptor blockade in the perirhinal cortex (Tang et al., 1997) and indicate that cholinergic integrity of the rhinal cortex is critical for visual recognition memory.

Related Products: ME20.4-SAP (Cat. #IT-15)

Mohapel P, Leanza G, Lindvall O (2002) Alterations in forebrain acetylcholine influence hippocampal neurogenesis in the adult rodent. Neuroscience 2002 Abstracts 23.9. Society for Neuroscience, Orlando, FL.

Summary: Little is known about how various experiential, environmental and pathological factors regulate neurogenesis in the adult hippocampus. Since the hippocampus receives abundant cholinergic innervation and contains some of the densest distributions of acetylcholine (ACh) fibers, we investigated its potential role in adult neurogenesis. Adult rats received multiple bromodeoxyuridine (BrdU) injections 3 weeks following lesions of the adult rodent forebrain cholinergic projections by intracerebroventricular infusions of 192 IgG-saporin. The day following BrdU administration we observed a significant 20% to 30 % decrease in proliferation in the subgranular cell layer of the dentate gyrus with ACh lesioning. This decrease persisted through to 4 weeks after BrdU administration, when most proliferated cells co-expressed neuronal markers. Conversely, in a separate experiment, naive rats receiving simultaneous injections of the ACh agonist physostigmine and BrdU demonstrated a 30 % increase in proliferated cells (1 day later) and neurons (4 weeks later) in the subgranular cell layer. Our data indicate that cholinergic mechanisms in the forebrain are involved in the regulation of neurogenesis and that this effect may be indirect or direct in the hippocampus.

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

Zambon NJ, Liberatore MA, Nagle RA, Pokala VN, Li P, Johnson DA (2002) Steroid sulfatse inhibition potentiates working memory deficit induced by 192 IgG-saporin. Neuroscience 2002 Abstracts 82.6. Society for Neuroscience, Orlando, FL.

Summary: Infusion of 192 IgG-saporin (SAP) into the medial septum (MS) of rats selectively lesions cholinergic neurons and impairs acquisition of a delayed matching to position T-maze task. Since steroid sulfatase inhibitors allosterically inhibit the GABA-A receptor and enhance cognition, the present study investigated the cognitive effects of sulfatase inhibition on SAP lesioned animals. Male Sprague-Dawley rats received intraseptal infusions of either cerebrospinal fluid (CSF) or 0.22 μg/μl SAP. Eight days after the infusion, the rats were given an IP injection of either the steroid sulfatase inhibitor DU-14 (30mg/ml) or vehicle daily for 14 days, then every other day during the testing period. In the acquisition phase of testing, each rat completed 8 trial pairs per day until reaching criterion (15 of 16 correct choices). The rats were then tested for retention of the task by inserting delays of 10, 20, and 30 seconds after the first trial of a pair. DU-14 potentiated the impairment in acquisition produced by SAP. The introduction of a delay resulted in deceased performance in all treatment groups except rats administered DU-14 without SAP lesioning. These results suggest that DU-14 may enhance cognition in cholinergically intact animals, but the combination of DU-14, with cholinergic lesioning of MS, impairs working memory by inhibition of both cholinergic and GABAergic neurotransmission.

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

Pokala VN, Libertore MA, Zambon NJ, Nagle RA, Li PK, Witt-Enderby PA, Johnson DA (2002) Effect of 192 IgG-saporin medial-septum lesion on hippocampal receptor density in rats. Neuroscience 2002 Abstracts 82.7. Society for Neuroscience, Orlando, FL.

Summary: The aim of the study was to quantify the effect of selective cholinergic neurotoxin192 IgG-saporin (SAP) medial septal (MS), lesions on hippocampal muscarinic, GABAA and NMDA receptor density. Rats were injected with SAP (0.22 and 0.45 μg/μl) into the MS. After 6 weeks, hippocampal tissue was collected and saturation radioligand binding assays were performed to determine the receptor density. 3H-QNB was a muscarinic antagonist, 3H-muscimol a GABAergic agonist and 3H-MK-801 an NMDA antagonist were utilized. The results demonstrated a dose dependent increase in muscarinic receptor density (B-max) of 226 and 355% respectively. These results suggest changes in receptor density in response to hippocampal cholinergic denervation.

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

Chang Q, Gold PE (2002) Residual hippocampal cholinergic functions after 192 IgG-saporin lesions of the medial septum/ventral diagonal band (MS/VDB). Neuroscience 2002 Abstracts 82.8. Society for Neuroscience, Orlando, FL.

Summary: 192 IgG-saporin (SAP) injections into the MS/VDB reportedly destroy acetylcholine (ACh) neurons projecting to hippocampus (HC) without associated impairments of learning and memory on HC-dependent tasks. These findings contrast sharply with those obtained with many other methods showing close associations between ACh functions in the HC and learning and memory. The present experiment addressed this conflict. SAP was injected into MS/VDB 1 week before the start of neural and behavioral measures. We found: 1) Using in vivo microdialysis, release of ACh in the HC was not abolished but was ~30% of control values. The percent increase in ACh release during spontaneous alternation testing was greater in SAP-treated than in control rats. 2) SAP-treated rats had significant impairments on the HC-dependent alternation task. Moreover, intra-HC injections of physostigmine (20 ng in 1 µl), an indirect ACh agonist, enhanced alternation scores. 3) Physostigmine (0.6 mg/kg, IP) induced more intense tremors in SAP-treated than in control rats. 4) While SAP-treated rats had near-total depletion of cells in MS/VDB stained using immunocytochemistry for choline acetyltransferase (ChAT), quantitative densitometry showed no depletion of ChAT staining in either CA1 or the dentate gyrus in the SAP group. These findings suggest that there are residual and even heightened ACh functions which can compensate for the insult of MS/VDB SAP lesions, complicating the use of this lesion to evaluate the role of septohippocampal cholinergic projections in learning, memory or other functions.

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