sfn2001

Janni G, Jasmin L, Ohara PT (2001) Schwann cells can enter the demyelinated spinal cord from dorsal roots via scar tissue. Neuroscience 2001 Abstracts 157.4. Society for Neuroscience, San Diego, CA.

Summary: We have studied the routes of entry of Schwann cells into the demyelinated spinal cord. Following application of the toxin CTB-Sap (B fragment of Cholera toxin conjugated to Saporin) into the intrathecal space of adult rats there occurs massive loss of oligodendrocytes with secondary demyelination of the lumbar spinal cord with sparing of axons. Concurrent with the demyelination, an arachnoiditis develops that results in dorsal roots becoming adherent to the lateral spinal cord. Light and electron microscopy showed that Schwann cells in the dorsal roots were always separated from the demyelinated axons by a mesenchymal interface part of which was formed by the dorsal root perineurium. Within 15 days of the demyelination, Schwann cell precursors (p75 immunopositive) migrated from the dorsal roots into the spinal cord via the adhesions and were found to divide within the cord. Schwann cell myelination of demyelinated central axons was consistently observed by day 30. Therefore the Schwann precursors were able to migrate into demyelinated spinal cord through non-neuronal cellular barriers without being in direct contact with demyelinated axons. These findings suggest that, under appropriate conditions, Schwann cells might be introduced therapeutically into the demyelinated spinal cord via intrathecal application and avoid direct spinal injection.

Related Products: CTB-SAP (Cat. #IT-14)

Burk JA, Herzog CD, Porter MC, Mahoney J, Bruno JP, Sarter M (2001) Interactions between partial cortical cholinergic deafferentation and aging on sustained attention performance in rats. Neuroscience 2001 Abstracts 202.5. Society for Neuroscience, San Diego, CA.

Summary: Previous studies have provided only limited support for the idea that aging alone impairs the functions of basal forebrain corticopetal cholinergic neurons. Conversely, aging has been hypothesized to exacerbate the functional consequences of prior insult to, or degenerative processes in, the basal forebrain cholinergic system. The present study assessed the effects of aging on the sustained attention performance of rats with moderate lesion-induced loss of cortical cholinergic inputs. Previous studies on the effects of extensive (> 70 %) cortical cholinergic deafferentation indicated that the integrity of this system is necessary for the animals’ ability to detect rare and unpredictable visual signals. In the present longitudinal experiment, moderate (< 50 %) 192 IgG-saporin-induced loss of cortical cholinergic inputs, produced in well-trained, 16 month-old rats, did not – as was intended - immediately affect their attentional performance. Animals continued to undergo attentional performance training for the remainder of their lives. At the age of 31 months, impairments in performance began to emerge in lesioned animals. Compared to their sham-lesioned counterparts, lesioned animals exhibited a steeper decrement in their ability to detect hits in the course of a test session. At this age, the performance of sham-lesioned animals did not differ from their earlier performance prior to and immediately after the lesion. These results support the general hypothesis that aging serves to exacerbate the effects of pre-existing degeneration of the basal forebrain cholinergic system.

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

Rinaman L, Wonders CP (2001) Targeted destruction of A2/C2 catecholamine neurons alters hypothalamic responses to vagal stimulation. Neuroscience 2001 Abstracts 131.4. Society for Neuroscience, San Diego, CA.

Summary: Central catecholamine (CA) pathways participate in viscerosensory modulation of hypothalamic neuroendocrine function. Different brainstem CA cell groups may relay different types of viscerosensory signals to different classes of hypothalamic effectors. The present study sought to determine the role of dorsal medullary A2/C2 neurons in hypothalamic responses to exogenous cholecystokinin (CCK), which activates gastrointestinal vagal sensory inputs to the caudal brainstem. Saporin toxin conjugated to dopamine-beta-hydroxylase antibody (anti-DbH-sap; 10 ng in 100 nl) or control toxin was microinjected unilaterally or bilaterally into the A2/C2 region of the dorsal vagal complex in adult male rats. After 10-14 days, rats were injected i.p. with CCK (10 ug/kg) and perfused with fixative 1 hr later. Brainstem and forebrain sections were processed for dual immunocytochemical detection of cFos (a marker of neural activation) and DbH (to define the lesion). Additional forebrain sections were processed for cFos and either oxytocin (OT), vasopressin (AVP), or corticotropin-releasing factor (CRF) to identify hypothalamic neurons activated by CCK. Anti-DbH-sap destroyed the majority of A2/C2 neurons within the microinjection site(s), with minimal non-specific damage. A2/C2 lesions markedly attenuated CCK-induced activation of OT neurons and, to a lesser extent, attentuated CRF activation. Conversely, CCK-induced cFos expression was significantly increased in AVP neurons. The latter effect was observed only after bilateral lesions. These results indicate that A2/C2 neurons participate in vagal sensory-mediated stimulation of OT neurons and CRF neurons, and inhibition of AVP neurons.

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

Luger NM, Sabino MC, Schwei MJ, Rogers SD, Pomonis JD, Keyser CP, Mach DB, Salak-Johnson J, Clohisy DR, Mantyh PW (2001) Intrathecal infusion of substance P-saporin ablates substance p receptor expressing neurons in the dorsal horn of the spinal cord and attenuates bone cancer pain. Neuroscience 2001 Abstracts 55.4. Society for Neuroscience, San Diego, CA.

Summary: Over 75% of advanced cancer patients must cope with chronic cancer pain. Interestingly, bone cancer pain is the most common and difficult to control. While current therapies are effective in alleviating many aspects of bone cancer pain, they are often accompanied by significant unwanted side effects. To better understand the population of spinal cord neurons that are involved in conveying bone cancer pain and to determine the efficacy of a novel therapeutic modality, we ablated substance P receptor (SPR)+ neurons in the spinal cord using intrathecal infusion of substance P-Saporin (SP-SAP). SP-SAP is a suicide ligand which consists of the ribosomal inactivating factor saporin conjugated to substance P, a peptidergic neurotransmitter involved in nociception. SP-SAP selectively ablates SPR+ neurons located in lamina I and III-V of the spinal cord. C3H male mice received intrathecal SP-SAP treatment 30 days prior to injection of 2472 osteosarcoma cells into the intramedulary space of a femur. Following injection, osteolytic sarcoma cells were confined within the femur by an amalgam plug. Mice were behaviorally tested 17 days post-tumor implantation and both ongoing and movement-evoked pain assessed. Ablation of SPR+ neurons in the dorsal spinal cord coincided with attenuation of both spontaneous and movement-evoked pain behaviors. These results suggest that SPR expressing neurons are involved in the development and progression of the bone cancer pain state and SP-SAP may serve as a useful therapy to treat this debilitating condition. Supported by NIH & VA.

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

Gadd CA, Murtra P, Hall CN, Gana M, Webber MJ, De Felipe C, Hunt SP (2001) NK1-expressing neurons critical for morphine reward behaviors in mice: C-fos expression and ablation of NK1-expressing neurons. Neuroscience 2001 Abstracts 224.13. Society for Neuroscience, San Diego, CA.

Summary: We have previously shown using conditioned place preference (CPP) that mice lacking the preferred receptor for substance P (NK1) show an absence of the rewarding response to morphine as well as reduced conditioned place aversion and physical withdrawal signs following chronic opiate treatment (Nature 405, 180-183). To locate those regions of the brain in which NK1-expressing neurons are crucial for opiate-mediated reward behavior, we examined the expression of c-Fos following acute (10 mg/kg IP) and chronic (increasing doses from 10 to 100 mg/kg IP) morphine administration, and following CPP to morphine (7.5 mg/kg) in wild-type and NK1 knockout mice. The expression of c-Fos in the brains of mice treated with chronic or acute morphine treatment was similar in both genotypes. Moreover, NK1-expressing neurons in the striatum and nucleus accumbens (NAc) were never seen to co-express c-Fos immunoreactivity. In contrast, the expression of c-Fos following the CPP protocol was significantly different between genotypes with a reduced number of c-Fos positive neurons in NK1 knockout mice in the amygdala and hippocampus but not in the NAc or dorsomedial striatum (DMS). We next investigated the effects of selective ablation of NK1 expressing neurons by injecting substance P-saporin into these regions. Our results suggest that destruction of these cells in the amygdala but not in the NAc or DMS causes a reduction in CPP to morphine without affecting anxiety levels or locomotor activity.

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

Camara AL, Pereira EF, Alkondon M, Randall WR, Castro NG, Cintra WM, Albuquerque EX (2001) Septal innervation of the hippocampus regulates expression α7 nicotinic receptors in CA1 and CA3 pyramidal neurons. Neuroscience 2001 Abstracts 145.1. Society for Neuroscience, San Diego, CA.

Summary: To investigate the effects of septal innervation on expression of α7 nicotinic receptors (nAChRs) in CA1 and CA3 pyramidal neurons in the hippocampus, the patch-clamp technique and confocal microscopy were applied to organotypic hippocampal cultures and septal-hippocampal co-cultures. In the co-cultures, septal fibers labeled with DiI were visualized in the hippocampus. Field stimulation of septal fibers also resulted in postsynaptic currents that could be recorded from CA1 and CA3 pyramidal neurons in the hippocampus. These currents had glutamatergic, GABAergic and cholinergic components. The latter originated most likely from the septal cholinergic neurons that were labeled in situ with the cholinergic marker Cy3-192 IgG. α7 nAChRs in the somatodendritic region of CA1 and CA3 pyramidal neurons in the hippocampus in cultures and co-cultures were activated by the α7 nAChR agonist choline, which elicited type IA currents, and were visualized by labeling with rhodamine-conjugated α-bungarotoxin (Rho-α-BGT). After 21 days in vitro, the amplitude of type IA currents was substantially smaller in pyramidal neurons in septal-hippocampal co-cultures than in hippocampal oragnotypic cultures. Labeling of the somatodendritic region of hippocampal pyramidal neurons with Rho-α-BGT was also less intense in the organotypic co-cultures than in cultures. These results suggest that functional septal innervation of the hippocampus regulates the expression of α7 nAChRs in hippocampal pyramidal neurons.

Related Products: 192-IgG Mouse Monoclonal, Cy3-labeled (Cat. #AB-N43FL3)

Yan J, Price DL, Koliatsos VE (2001) Nestin expression in neurons of the medial septum/diagonal band in the adult rat. Neuroscience 2001 Abstracts 25.9. Society for Neuroscience, San Diego, CA.

Summary: Nestin is a marker for neuronal precursor cells in normal animals. In adult animals, nestin (+) cells are limited to the ventricular wall, hippocampus and the rostral migratory stream, where neurogenesis is known to persist throughout life. We are now reporting the existence of nestin (+) cells in the medial septum/diagonal band area based on immunocytochemical staining with different nestin antibodies. Many of these cells colocalize ChAT and nestin. In addition, some nestin (+) cells can be traced with the carbocyanin dye SP-DiI injected into the lateral ventricle to label cell lineages originating in the ependymal layer. Medial septal/diagonal band lesions by complete fimbria-fornix transections or 192-IgG-saporin conjugate injections into the ventricle cause an increase in BrdU (+) and nestin (+) cells in medial septum/diagonal band especially in anterior planes. We are currently double labeling the sections with BrdU and nestin or TUJ1. Our working hypothesis is that there may be ongoing neurogenesis in the medial septum/diagonal band in the adult brain, especially after injury or under pathological conditions and this may have implications for pathogenesis and treatment of Alzheimer’s disease.

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

Gu JG, Nakatsuka T, Tanaka E, Takeda D, Jennifer LX (2001) Capsaicin-sensitive inhibitory pathway in rat spinal cord dorsal horn. Neuroscience 2001 Abstracts 158.13. Society for Neuroscience, San Diego, CA.

Summary: The inhibitory system in the spinal cord plays an important role in regulating nociceptive sensory inputs. Here we examined inhibitory synaptic activity in lamina V neurons of the spinal dorsal horn following the activation of capsaicin VR1 receptors. Experiments were performed with spinal cord slice preparations and inhibitory postsynaptic currents (IPSCs) were recorded using patch-clamp technique. Bath application of capsaicin (2 μM) increased the amplitude and frequency of GABAergic and glycinergic spontaneous IPSCs in the majority of lamina V neurons tested. The effects of capsaicin were completely antagonized by capsazepine (10 μM), and were also blocked in the presence of tetrodotoxin (0.5 μM). However, when CNQX (20 μM) and APV (100 μM) were used to block glutamatergic synaptic transmission, the effects of capsaicin were not abolished. Furthermore, after the injection of IB4-saporin into sciatic nerve to remove IB4-positive C-primary afferent terminals, capsaicin still increased sIPSC frequency in the presence of CNQX and APV. These results suggest that inhibitory pathway could be recruited in the absence of glutamatergic inputs from primary afferents. The release of neuropeptides from capsaicin-sensitive C-primary afferents may activate GABAergic and glycinergic interneurons in superficial laminae, and the inhibitory activity may be further forwarded to lamina V neurons. The capsaicin-sensitive inhibitory pathway may play an important role in the control of nociceptive transmission in the spinal cord.

Related Products: IB4-SAP (Cat. #IT-10)

Power AE, Thal LJ, McGaugh JL (2001) Memory enhancement induced by post-training norepinephrine in the basolateral amygdala is blocked by 192-IgG saporin lesions of the nucleus basalis magnocellularis. Neuroscience 2001 Abstracts 84.13. Society for Neuroscience, San Diego, CA.

Summary: Drugs and stress hormones act in the basolateral amygdala (BLA) to modulate memory storage. The BLA projects to the nucleus basalis magnocellaris (NBM), which sends broad cholinergic projections to the neocortex. These NBM-cortex projections have been implicated in learning, memory storage and cortical plasticity. The current study was designed to test whether the cholingeric NBM-cortex projections are involved in BLA-mediated memory modulation. Rats were given bilateral cholinergic lesions of the NBM with 192-IgG saporin (0.1 μg/ 0.5 μl per side) or sham infusions, and implanted with bilateral cannulae aimed at the BLA. One week after surgery the rats were trained in the inhibitory avoidance task. Immediately after training, the rats were given bilateral infusions of norepinephrine (0.3μg, 1.0 μg, or 3.0 μg) or vehicle (0.2 μl PBS) into the BLA. On a 48-h retention test, the norepinephrine infusions produced a dose-dependent enhancement of retention (0.3μg and 1.0 μg doses) in sham-operated controls. NBM-lesioned rats that received these memory-enhancing doses of norepinephrine had retention latencies that did not differ from vehicle infused controls. Thus memory enhancement induced by post-training intra-BLA infusion of norepinephrine was blocked in 192-IgG saporin NBM-lesioned rats. ChAT assays of frontal and occipital cortices confirmed the lesions. These findings indicate that the cholinergic NBM-cortex projections are involved in BLA-mediated modulation of memory.

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

Nakatsuka T, Takeda D, Gu JG (2001) α,β-methylene ATP sensitive P2X receptor mediated enhancement of glutamate release from the central terminals of Aδ primary afferents onto lamina V neurons in rat spinal cord. Neuroscience 2001 Abstracts 158.16. Society for Neuroscience, San Diego, CA.

Summary: We examined the role of αβmATP-sensitive P2X receptors in modulating glutamate release from sensory synapses of the spinal cord by using whole-cell patch-clamp recordings from dorsal horn neurons in lamina V region. The majority of lamina V neurons synapsed with terminals expressing αβmATP-sensitive P2X receptors. Application of P2X receptor agonist 100 μM αβmATP resulted in a large increase in mEPSC frequency. The increases in mEPSC frequency by αβmATP were completely abolished by the P2X receptor antagonist 10 μM PPADS, but were not blocked by Ca2+ channel blocker 30 μM La3+. αβmATP remained to be effective in increasing mEPSC frequency after the removal of superficial dorsal horn (lamina I-III) or after the injection of IB4-saporin into sciatic nerve to remove P2X3 expressing afferent terminals. Furthermore, we found that αβmATP-sensitive synapses of lamina V neurons were associated with central terminals derived from Aδ primary afferents. The EPSCs evoked by dorsal root stimulation at Aδ-fiber intensity were potentiated by 1 μM αβmATP as well as by the ecto-ATPase inhibitor 10 μM ARL67156, and depressed in the presence of 10 μM PPADS and 5 μM suramin. These results suggest that αβmATP-sensitive P2X receptors play a significant role in modulating excitatory synaptic transmission in the spinal cord.

Related Products: IB4-SAP (Cat. #IT-10)