Comparison of Serum Hormone Titers in Golden Hamsters During Testicular Growth Induced by Pinealectomy and Photoperiodic Stimulation1

Abstract

Testicular growth and changes in levels of circulating follicle-stimulating hormone (FSH; follitropin), luteinizing hormone (LH; lutropin), prolactin (PRL) and androgens, were compared in intact and pinealectomized hamsters exposed to short (6L:18D) [6 h of light:18 h of dark] or long (14L:10D) days. Testicular growth induced by long days and/or pinealectomy proceeded at the same rate. In all groups an increase in serum FSH preceded testicular growth by 2 wk, while increased serum PRL titers occurred simultaneously with testicular growth. Serum LH and androgens were also increased during testicular growth; androgen levels in animals exposed to long days were consistently greater than in males exposed to short days.