The influence of melatonin on the content of vasopressin and oxytocin in the hypothalamus and neurohypophysis in euhydrated and dehydrated male rats.
Melatonin injected in a single intraperitoneal dose of 100 micrograms/100 g b.w. to euhydrated rats resulted in a decrease of neurohypophysial oxytocin content but the hypothalamic oxytocin storage as well as the hypothalamo-neurohypophysial storage of vasopressin were not changed. Following 8 d of once-daily melatonin treatment the hypothalamic and neurohypophysial oxytocin and vasopressin content was decreased. It might be therefore suggested that melatonin increases the release of neurohypophysial hormones and/or decreases their synthesis. Melatonin did not significantly modify the neurohypophysial vasopressin depletion rate in animals deprived of water up to 8 days. No consistent effects of melatonin on the decrease of hypothalamo-neurohypophysial content of oxytocin were noted under conditions of dehydration and simultaneous administration of melatonin up to 8 d.
D000818:Animals; D007031:Hypothalamus / Q000032:analysis*; D008297:Male; D008550:Melatonin / Q000494:pharmacology*; D010121:Oxytocin / Q000032:analysis*; D010904:Pituitary Gland, Posterior / Q000032:analysis*; D051381:Rats; D011919:Rats, Inbred Strains; D014882:Water-Electrolyte Balance
D010121:Oxytocin; D008550:Melatonin