Insensitivity of the reproductive system of pinealectomized superior cervical ganglionectomized male Syrian hamsters to twice daily injections of melatonin

The reproductive responses to twice daily melatonin injections were studied in intact, pinealectomized (PINX), superior cervical ganglionectomized (SCGX), and in PINX + SCGX male hamsters. A significant drop in testicular and accessory organ weights, plasma testosterone (T) and thyroxine (T4) ensued in the intact, PINX and SCGX animals. In PINX + SCGX hamsters, although the testicular weights were slightly reduced, the accessory organ weights, plasma T and T4 levels remained unchanged. The results suggest that both pineal and the superior cervical ganglia may mediate melatonin-induced reproductive collapse. Both the pineal and the ganglia could be target organs for melatonin.