Effects of TRH on the activity of gastric inflation-related neurons in the solitary nucleus in the rat.

Thyrotropin-releasing hormone (TRH) has been identified as a potent central regulator of gastrointestinal function. It has been hypothesized that TRH influences gastric function by modulating the effectiveness of gastric vago-vagal reflexes. To test this hypothesis, we studied the effects of TRH on neurons of the nucleus of the solitary tract (NTS) that respond to gastric inflation. Of the 23 inflation-sensitive neurons studied, 11 or 48% had reduced spontaneous activity after TRH injection; none were excited. These results provide evidence that a part of the TRH effect on the regulation of gastric function involves suppressing the NTS response to gastric afferent input from the vagus nerve.