Effects of Cholecystokinin-8s in the Nucleus Tractus Solitarius of Vagally Deafferented Rats.
From: Department of Neuroscience, Pennington Biomedical Research Center, Louisiana State University System, 6400 Perkins Road, Baton Rouge, LA 70808, USA.
American journal of physiology. Regulatory, integrative and comparative physiology
- Publish Date: Mar 2007
- ISSN: 0363-6119
- Volume: 292
- Issue: 3
- Pages: R1092-100
- Medium: Print
- Language: English
- Citation (JAMA): Baptista V, Browning K N, Travagli R A, et al. Effects of Cholecystokinin-8s in the Nucleus Tractus Solitarius of Vagally Deafferented Rats.. Am. J. Physiol. Regul. Integr. Comp. Physiol. Mar 2007;292:R1092-100
Abstract
We have shown recently that cholecystokinin octapeptide (CCK-8s) increases glutamate release from nerve terminals onto neurons of the nucleus tractus solitarius pars centralis (cNTS). The effects of CCK on gastrointestinal-related functions have, however, been attributed almost exclusively to its paracrine action on vagal afferent fibers. Because it has been reported that systemic or perivagal capsaicin pretreatment abolishes the effects of CCK, the aim of the present work was to investigate the response of cNTS neurons to CCK-8s in vagally deafferented rats. In surgically deafferented rats, intraperitoneal administration of 1 or 3 mug/kg CCK-8s increased c-Fos expression in cNTS neurons (139 and 251% of control, respectively), suggesting that CCK-8s’ effects are partially independent of vagal afferent fibers. Using whole cell patch-clamp techniques in thin brain stem slices, we observed that CCK-8s increased the frequency of spontaneous and miniature excitatory postsynaptic currents in 43% of the cNTS neurons via a presynaptic mechanism. In slices from deafferented rats, the percentage of cNTS neurons receiving glutamatergic inputs responding to CCK-8s decreased by approximately 50%, further suggesting that central terminals of vagal afferent fibers are not the sole site for the action of CCK-8s in the brain stem. Taken together, our data suggest that the sites of action of CCK-8s include the brain stem, and in cNTS, the actions of CCK-8s are not restricted to vagal central terminals but that nonvagal synapses are also involved.
Mesh Headings (Keywords): Analgesics, Non-Narcotic, Animals, Brain Stem, Capsaicin, Dose-Response Relationship, Drug, Electrophysiology, Female, Injections, Intraperitoneal, Male, Neurons, Patch-Clamp Techniques, Proto-Oncogene Proteins c-fos, Rats, Rats, Sprague-Dawley, Sincalide, Solitary Nucleus, Synaptic Transmission, Vagus Nerve
Check for Full Text / PubMed Unique Identifier (PMID): 17122331
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