Actions of thyrotropin-releasing hormone on gastrointestinal functions in man. III. Inhibition of gastric motility in response to distension.

The intragastric pressure/volume relationship has been measured in six healthy volunteers. Increased gastric motility was achieved by gastric distension, by stepwise increasing the volume from 0--600 ml. When thyrotropin-releasing hormone (TRH), 0.04 mg/h, was infused concomitantly in the individuals, gastric motility was significantly inhibited (p less than 0.05) and, with 1 mh/h of TRH, nearly abolished compared with the saline control test. The basal pressure was unaffected at 0.04 mg/h, whereas a significant rise was seen after 1 mg/h of TRH (p less than 0.05) compared with the control test. In three of the subjects the effect of rapid injection of TRH (0.2 mg), followed by infusion of TRH (0.6 mg/h), on the stimulated gastric motility was analysed. After the injection of TRH, almost no motor activity was observed during the 15-min observation period. It is concluded that TRH has a potent inhibiting effect on gastric motility, and the possible physiological role of TRH in the gastric regulation in man is discussed.