ACTION OF PINEAL INDOLEAMINES ON THE REPRODUCTIVE SYSTEMS OF THE MALE C-57 MOUSE AND GOLDEN-HAMSTER

Intraperitoneal administration of melatonin, methoxytryptamine and methoxytryptophol in the late afternoon to mice exposed to a 14 L:10 D photoperiod induced appearance of necrotic cells in seminiferious tubules and an increase in incidence of aspermic tubules. The histological appearances of the seminal vesicles and coagulating glands were, however, unaffected by the treatments. Treatment of mice with methoxyindoleacetic acid did not produce discernible changes in the testes and accessory sex organs. Subcutaneous injections of the aforementioned pineal indoles at a dose of 250 mug/injection for 3 months to mature male hamsters kept under a 14 L:10 D photoperiod did not evoke changes in the testes, seminal vesicles and coagulating glands, suggesting a down-regulation of melatonin receptors by administration of a high dose of pineal indole over a prolonged period.