Effect of cyproheptadine on thyrotrophin and prolactin secretion in normal man.

In order to investigate the effect of cyproheptadine, a compound with antiserotoninergic activity, on the secretion of thyrotrophin (TSH) and prolactin (PRL), the nocturnal secretory patterns of these hormones have been studied in 4 normal men in the basal state and after an oral treatment with the drug. In addition, the TSH and PRL responses to TRH of 6 women were compared in the basal conditions and after cyproheptadine treatment. The TSH nocturnal secretion was slightly modified by drug treatment. The response to TRH as well as the basal levels were comparable in the treated and non-treated subjects. In contrast, the PRL secretion measured through the nocturnal investigation was significantly inhibited by cyproheptadine administration as were the PRL basal levels in the TRH test. The PRL response to TRH was comparable in both situations.