title: Oxytocin release induced by melatonin in the ewe.
abstract: The pineal gland indolamine melatonin now appears to be a primary mediator of the timing of estrus in mammals. Because the neurohypophyseal nonapeptides arginine vasotocin and oxytocin have recently been identified in the pineal glands of several species, we sought to assess the possibility of an interaction between melatonin and the neurohypophyseal hormones. An acute melatonin infusion (216 mumol) was administered to pregnant and nonpregnant ewes. Although plasma arginine vasopressin and arginine vasotocin levels did not change, melatonin produced a significant increase in plasma oxytocin in the nonpregnant though not the pregnant ewe. These data suggest a possible interaction between melatonin and oxytocin in the integration of mammalian reproduction cycles.
mesh_terms: D000818:Animals; D001127:Arginine Vasopressin / Q000378:metabolism; D004971:Estrus; D005260:Female; D008550:Melatonin / Q000494:pharmacology* / Q000502:physiology; D010121:Oxytocin / Q000378:metabolism*; D010870:Pineal Gland / Q000187:drug effects / Q000378:metabolism; D011247:Pregnancy; D012756:Sheep; D014668:Vasotocin / Q000378:metabolism
chemical_list: D001127:Arginine Vasopressin; D010121:Oxytocin; D008550:Melatonin; D014668:Vasotocin