Melatonin-Pineal Relationships in Female Golden Hamsters

Light deprivation by blinding in female hamsters was followed by a regression of the reproductive organs, an elevation of pituitary LH concentration and a depression of pituitary prolactin levels. Pinealectomy negated almost completely the effects of light deprivation on the neuro-endocrine-reproductive axis. Weekly subcutaneous implants of a melatonin: beeswax pellet completely prevented the pineal gland from inhibiting reproductive physiology in blinded hamsters. The findings suggest that melatonin is not the pineal antigonado-trophic factor in female golden hamsters. Melatonin implanted hamsters also had higher than normal levels of plasma prolactin.