Melatonin, pinealectomy, and release of neurohypophysial hormones: in vitro studies.
The effect of melatonin as well as pinealectomy on the basal and K(+)-evoked release of vasopressin and oxytocin from the neurointermediate lobes in vitro was determined. Pineal removal resulted in a diminution of vasopressin and oxytocin release from the neurointermediate lobes in vitro. Melatonin (10(-3) or 10(-6) M/l) increased vasopressin and oxytocin release from neurointermediate lobes of sham-operated rats. Nevertheless, when pinealectomized rats served as donors of the neurointermediate lobes, melatonin (10(-3) or 10(-6) M/l) increased vasopressin release under basal conditions. For the same tissue, melatonin did not affect the oxytocin release either under basal conditions or during depolarization due to excess potassium. When 10(-7) M/l melatonin was used, no changes in either vasopressin or oxytocin release were observed in vitro.
Juszczak
M
M
Department of Pathophysiology, School of Medicine, Lodz, Poland.
Stempniak
B
B
Guzek
J W
JW
D000818:Animals; D008297:Male; D008550:Melatonin / Q000494:pharmacology*; D010121:Oxytocin / Q000378:metabolism*; D010870:Pineal Gland / Q000502:physiology / Q000601:surgery*; D010904:Pituitary Gland, Posterior / Q000187:drug effects*; D051381:Rats; D014667:Vasopressins / Q000378:metabolism*
D014667:Vasopressins; D010121:Oxytocin; D008550:Melatonin