Thyrotropin-releasing hormone receptors in gut tissues resemble pituitary receptors

The relative order of activity of thyrotropin-releasing hormone (TRH) and various analogs in contracting the isolated guinea pig antrum and duodenum correlated with their potencies in activating thyroid-stimulating hormone (TSH) release. The action of TRH in both tissues was selectively antagonized by the putative pituitary TRH receptor antagonist, chlordiazepoxide (10 microM). The data indicate that the contractions produced by TRH in these gut tissues are mediated by TRH receptors with similar characteristics as the pituitary TRH receptors responsible for TSH release.