Mediation of thyrotropin-releasing hormone induced gastric motility increases in developing rats.
Centrally administered thyrotropin-releasing hormone (TRH) induces vagally mediated gastrointestinal effects which may be cholinergic, serotonergic or a combination. This study investigated mediation of TRH-stimulated gastric motility in developing rats. A serotonin (5-HT) antagonist (5-HT2, ketanserin or xylamidine; 5-HT3, MDL 72222) or an acetylcholine receptor blocker (atropine) was administered intraperitoneally 30 min prior to intracisternal TRH (5-10 micrograms). The 5-HT-depleting para-chlorophenylalanine (p-CPA) was administered 48 or 72 h prior to TRH. Gastric motility, monitored via extraluminal strain gauge, was not increased with TRH in atropine-pretreated rats. MDL 72222 had a significant age-related effect on TRH-induced gastric motility increases while 5-HT2 antagonists and p-CPA treatment did not. Thus, acetylcholine receptor blockade inhibits TRH-stimulated gastric motility in young and adult rats while 5-HT3 antagonism eliminates the motility response in young (7 and 10 days) rats.
Bond
E F
EF
Department of Physiological Nursing, University of Washington, Seattle 98195.
Heitkemper
M M
MM
Gruver
M K
MK
D000375:Aging / Q000378:metabolism; D000704:Analysis of Variance; D000818:Animals; D001285:Atropine / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D005260:Female; D010134:Fenclonine / Q000494:pharmacology*; D005769:Gastrointestinal Motility / Q000187:drug effects*; D007274:Injections, Intraperitoneal; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects; D011247:Pregnancy; D051381:Rats; D012702:Serotonin Antagonists / Q000494:pharmacology*; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology*
D012702:Serotonin Antagonists; D013973:Thyrotropin-Releasing Hormone; D001285:Atropine; D010134:Fenclonine