Inhibition by Somatostatin on the Release of TSH Induced in Man by Thyrotropin-Releasing Factor

Abstract

Concomitant administration of somatostatin and thyrotropin-releasing factor (TRF) significantly inhibited the release of TSH induced by TRF without affecting the simultaneous secretion of prolactin (PRL) in normal adult subjects. However, within our experimental design (iv bolus of 250 μg TRF plus 500 μg somatostatin followed by constant infusion of 500 μg somatostatin over 45 min) the inhibition of TSH release by somatostatin was incomplete. The present study demonstrates that somatostatin in humans not only exerts an inhibitory effect on growth hormone secretion but also on TSH release in response to TRF. These findings suggest an interrelationship between the regulation of growth hormone and TSH secretion.