Effects of acetylcholine on the release of thyrotropin-releasing hormone from the rat retina in vitro.

Abstract

Effects of acetylcholine on the release of thyrotropin-releasing hormone (TRH) from the rat retina were studied in vitro. The retina was incubated in medium 199 (pH 7.4) with 1.0 mg/ml of bacitracin and 100 micrograms/ml of ascorbic acid (medium) for 20 min. The amount of TRH release into the medium was measured by radioimmunoassay. The TRH release from the rat retina was enhanced significantly in a dose-related manner with the addition of acetylcholine and inhibited with addition of atropine. The stimulatory effect of acetylcholine on TRH release from the retina was blocked with the addition of atropine. The elution profile of methanol-extract of the rat retina was identical to that of synthetic TRH. The findings suggest that the cholinergic system stimulates TRH release from the rat stomach in vitro.