Reserpine Inhibits Rat Anterior Pituitary Hormone Secretion in Vitro: Effects on GH,TSH,and LH

Abstract

We have extended our observations on the ability of reserpine to inhibit secretion of anterior pituitary hormones in vitro. The release of newly synthesized [³H]GH and radioimmunoassayable TSH and LH from female rat anterior hemipituitary glands was measured after 5 hr incubation in [³H]leucine in the presence or absence of reserpine. Reserpine, 9 μM, blocked the release of each hormone stimulated by 50 mM K⁺ but not basal hormone secretion. Stimulation of [³H]GH release by 10 μM PGE₁, or 5 mM dbcAMP was not affected by 5 μM reserpine, while stimulation of TSH release by 70 nM TRH was significantly blunted with 5 μM reserpine. The influence of reserpine on pituitary hormone secretion may define a pattern suggesting that the drug interferes with utilization of the extracellular but not the intracellular calcium mobilized during the secretory process.