|
|
||||||||
Nerve-Gut Research Laboratory, Department of Gastroenterology, Hepatology and General Medicine, Royal Adelaide Hospital, Adelaide, South Australia 5000, Australia
To investigate GABAB receptors along vagal afferent pathways, we recorded from vagal afferents, medullary neurons, and vagal efferents in ferrets. Baclofen (7-14 µmol/kg iv) reduced gastric tension receptor and nucleus tractus solitarii neuronal responses to gastric distension but not gastroduodenal mucosal receptor responses to cholecystokinin (CCK). GABAB antagonists CGP-35348 or CGP-62349 reversed effects of baclofen. Vagal efferents showed excitatory and inhibitory responses to distension and CCK. Baclofen (3 nmol icv or 7-14 µmol/kg iv) reduced both distension response types but reduced only inhibitory responses to CCK. CGP-35348 (100 nmol icv or 100 µmol/kg iv) reversed baclofen's effect on distension responses, but inhibitory responses to CCK remained attenuated. They were, however, reversed by CGP-62349 (0.4 nmol icv). In conclusion, GABAB receptors inhibit mechanosensitivity, not chemosensitivity, of vagal afferents peripherally. Mechanosensory input to brain stem neurons is also reduced centrally by GABAB receptors, but excitatory chemosensory input is unaffected. Inhibitory mechano- and chemosensory inputs to brain stem neurons (via inhibitory interneurons) are both reduced, but the pathway taken by chemosensory input involves GABAB receptors that are insensitive to CGP-35348.
-aminobutyric acid B receptors; ferret; mechanoreceptors; vagal
reflexes; cholecystokinin; nucleus tractus solitarii
This article has been cited by other articles:
![]() |
R. L. Young, A. J. Page, T. A. O'Donnell, N. J. Cooper, and L. A. Blackshaw Peripheral versus central modulation of gastric vagal pathways by metabotropic glutamate receptor 5 Am J Physiol Gastrointest Liver Physiol, February 1, 2007; 292(2): G501 - G511. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. A. Slattery, A. J. Page, C. L. Dorian, S. M. Brierley, and L. A. Blackshaw Potentiation of mouse vagal afferent mechanosensitivity by ionotropic and metabotropic glutamate receptors J. Physiol., November 15, 2006; 577(1): 295 - 306. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. Liu, J. L. Puckett, T. Takeda, H.-Y. Jung, and R. K. Mittal Crural diaphragm inhibition during esophageal distension correlates with contraction of the esophageal longitudinal muscle in cats Am J Physiol Gastrointest Liver Physiol, May 1, 2005; 288(5): G927 - G932. [Abstract] [Full Text] [PDF] |
||||
![]() |
A F Ciccaglione and L Marzio Effect of acute and chronic administration of the GABAB agonist baclofen on 24 hour pH metry and symptoms in control subjects and in patients with gastro-oesophageal reflux disease Gut, April 1, 2003; 52(4): 464 - 470. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. Liu, N. Pehlivanov, and R. K. Mittal Baclofen blocks LES relaxation and crural diaphragm inhibition by esophageal and gastric distension in cats Am J Physiol Gastrointest Liver Physiol, December 1, 2002; 283(6): G1276 - G1281. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. N. Sengupta, B. K. Medda, and R. Shaker Effect of GABAB receptor agonist on distension-sensitive pelvic nerve afferent fibers innervating rat colon Am J Physiol Gastrointest Liver Physiol, December 1, 2002; 283(6): G1343 - G1351. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. A. Jensen, J. Mosbacher, S. Elg, K. Lingenhoehl, T. Lohmann, T. N. Johansen, B. Abrahamsen, J. P. Mattsson, A. Lehmann, B. Bettler, et al. The Anticonvulsant Gabapentin (Neurontin) Does Not Act through gamma -Aminobutyric Acid-B Receptors Mol. Pharmacol., June 1, 2002; 61(6): 1377 - 1384. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. D. Smid, R. L. Young, N. J. Cooper, and L. A. Blackshaw GABABR expressed on vagal afferent neurones inhibit gastric mechanosensitivity in ferret proximal stomach Am J Physiol Gastrointest Liver Physiol, December 1, 2001; 281(6): G1494 - G1501. [Abstract] [Full Text] [PDF] |
||||
![]() |
L. A. Blackshaw Receptors and Transmission in the Brain-Gut Axis: Potential for Novel Therapies: IV. GABAB receptors in the brain-gastroesophageal axis Am J Physiol Gastrointest Liver Physiol, August 1, 2001; 281(2): G311 - G315. [Abstract] [Full Text] [PDF] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |