The Ewha Medical Journal
Ewha Womans University School of Medicine
Original Article

Blockade by Naloxone and Naltrexone of the TRH-induced Stimulation of Colonic Transit in the Rabbit

Young Sook Pae
Corresponding author: Young Sook Pae. Department of Pharmacology, College of Medicine, Ewha Womans University, Korea.

Copyright ⓒ 1984. Ewha Womans University School of Medicine. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Published Online: Jul 24, 2015


Thyrotropin releasing hormore(TRH) administered intracerebroventricularly (i.c.v) in microgram quantities to anesthetized rabbits, produces marked stimulation of colonic motility, transit and fluid accumulation. These effects depend on an intact vagal system. Atropine blocks hypermotility but not the increased intestinal transit and fluid accumulation. The latter effects are antagonized by antiserotonin compounds. In this study, we found that pretreatment of rabbits with naloxone(2.5 mg/kg) or naltrexone(1.0 mg/kg) attenuated or blocked the TRH-induced colonic transit and increase in luminal fluid, but not the hypermotility. In this respect the narcotic antagonist effects resemble those produce by the antiserotonine compounds or opiate agonists.