Serotonin in the dorsal vagal complex: disparate effects on trh
analogue-stimulated gastric acid secretion, motility and
cytoprotection.
Chi, Jinhan, Jennifer Kemerer, and Robert L. Stephens, Jr.
Department of Physiology, The Ohio State University, Columbus, Ohio
43210
APStracts 3:0090R, 1996.
Convergent evidence suggests that TRH is a principal regulator of
several vagally-mediated gastric responses. Serotonin (5-HT)
interacts with TRH in the dorsal vagal complex (DVC) to augment
gastric acid secretory responses. This study investigated the ability
of 5-HT to alter other gastric responses mediated by TRH
administration into the DVC. Co-injection of 5-HT (7.9 pmoles) and
the TRH analogue RX 77368 (0.66 pmoles) produced a 117% enhancement
in one-hour gastric acid output as compared to rats treated with RX
77368 (0.66 pmoles) alone into the DVC. In contrast, co
-administration of RX 77368 (4 pmoles) with various doses of 5-HT
(0.0048-480 pmoles) was ineffective to significantly alter
stimulation of gastric antral motility produced by RX 77368 (4
pmoles) alone. The effect of a lower dose of DVC RX 77368 (0.66
pmoles) on gastric motility was also not changed by 5-HT co
-administration. Moreover, the cytoprotective effect of DVC RX 77368
(1.5 pmoles) on oral ethanol-induced gastric mucosal lesions was
reversed by 5-HT co-administration (54 or 18 pmoles). The results
suggest that activation of 5-HT receptors in the DVC can augment, not
affect and attenuate DVC TRH-analogue stimulated gastric acid
secretion, antral motility and cytoprotection, respectively.
Received 10 October 1995; accepted in final form 21 February
1996.
APS Manuscript Number R635-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 20 March 96