title: Effects of melatonin on reproductive and accessory reproductive organs in male rats.
abstract: Effects of daily injections of melatonin on male rat reproductive and accessory reproductive organs were studied. The weight of the prostate was decreased by treatment with a high dose of melatonin (8.0 mg/kg, s.c., injection time; 17:00) once daily for 30 d. The weights of the other accessory reproductive organs and testes were not influenced by melatonin. Lower doses (0.8, 2.4, 4.8 mg/kg), had no effect. After the successive treatment with melatonin (8.0 mg/kg), the testosterone levels in testes and in serum and the conversion rate of [3H]testosterone to [3H]dihydrotestosterone in the prostate were not influenced. The activity of acid phosphatase and the uptake of [3H]testosterone by the prostate, in contrast, were significantly decreased after the successive treatment with melatonin. These data suggest that melatonin may have a direct inhibitory action on male rat prostate, though only at a high dose.
authors.affiliation: Laboratory for Pharmaceutical Education, Tokyo College of Pharmacy, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Yamada
mesh_terms: D000818:Animals; D005837:Genitalia, Male / Q000187:drug effects*; D008297:Male; D008550:Melatonin / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D008550:Melatonin