Substance p in the dorsal vagal complex inhibits medullary trh
-induced gastric acid secretion in rats.
Yang, Hong, and Yvette Tach[acute]e.
CURE: Digestive Diseases Research Center, VA Medical Center West
Los Angeles, Department of Medicine and Brain Research Institute,
University of California, Los Angeles, California, 90073
APStracts 3:0276G, 1996.
Substance P (SP) and thyrotropin-releasing hormone (TRH) containing
neurons in medullary midline raphe nuclei project to the dorsal vagal
complex (DVC). The modulatory role of SP on basal and TRH in the DVC
-induced stimulation of gastric acid secretion (GAS) was studied in
urethane-anesthetized rats. The stable SP agonist, DiMe-C7 ([pGlu5,
MePhe8, MeGly9]-SP5-11, 50 and 100 pmol) injected unilaterally into
the DVC reduced the GAS response (47 +/- 12 [mu]mol/60 min) to co
-injected TRH analog, RX 77368 (25 pmol) by 53% and 85% respectively
while DiMe-C7 (100 pmol) alone had no effect on basal and
pentagastrin-stimulated GAS. DiMe-C7 (100 pmol/site) inhibited the
GAS response to kainic acid injected into the raphe pallidus (Rpa)
when injected bilaterally into the DVC but not the hypoglossal
nuclei. The SP (NK1) receptor antagonist, CP-96,345, injected
bilaterally into the DVC (1 nmol/site) increased basal GAS (33 +/- 8
[mu]mol/90 min) and potentiated the GAS response to kainic acid into
the Rpa by 40%. These results suggest that SP acts on NK1 receptors
in the DVC to reduce medullary TRH-induced stimulation of GAS in
rats.
Received 5 August 1996; accepted in final form 16 December 1996.
APS Manuscript Number G320-6.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 31 December 1996