The inhibition by somatostatin of the thyrotropin response to thyrotropin-releasing hormone in normal subjects.

The influence of somatostatin on the TRH-induced TSH secretion was studied in 6 normal subjects. A consistent inhibitory effect of somatostatin was observed. The inhibitory effect occurred with a time lag of more than 5 minutes. In 4 of the subjects a secondary rise in serum TSH was observed after the cessation of somatostatin infusion, suggesting mechanisms other than simple competition at receptor sites.