PHARMACOLOGICAL EVIDENCE FOR THE RELEASE OF GALANIN FROM RAT STOMACH

The neuropeptide galanin has been shown to occur in nerve fibres in th e circular muscle layer of the rat stomach. The present experiments ai med at demonstrating a functional correlate for this observation by te sting the motor effects of galanin on circular strips of the rat gastr ic corpus in vitro. Exogenous galanin elicited only small contractions of the smooth muscle which were dose-related but did not show a clear sigmoid dose-response relationship. These responses were resistant to atropine plus guanethidine or TTX. When the muscle strips were electr ically stimulated, they showed pronounced rebound contractions after t he end of the stimulus. These rebound contractions were significantly reduced by either desensitizing the strips to galanin or by addition o f spantide. It is concluded that galanin is released from the myenteri c plexus in the stomach and acts to modulate gastric contractions eith er postsynaptically or by modifying the release of tachykinins.