Melatonin inhibits the substance P-induced secretion of vasopressin and oxytocin from the rat hypothalamo-neurohypophysial system: in vitro studies.
The aim of the present investigations was to study the influence of substance P (a member of a family of peptides known as tachykinins) on basal and K(+)-evoked vasopressin (AVP) and oxytocin (OT) release from rat hypothalamo-neurohypophysial system in vitro as well as to determine whether this effect of substance P is sensitive to melatonin. The present results show that substance P stimulates basal AVP and OT release from isolated hypothalamo-neurohypophysial system, when used at the concentrations of 10(-6) and 10(-7)M/l. At the concentration of 10(-9)M/l, however, substance P was found to stimulate the in vitro secretion of AVP, but not that of OT. Melatonin diminished basal release of AVP; it also significantly inhibited the substance P-stimulated secretion of AVP and OT. K(+)-evoked release of the neurohypophysial hormones was not further modified by either substance P or melatonin. The present results show that the stimulatory effect of substance P on basal release of AVP and OT from rat hypothalamo-neurohypophysial system in vitro is sensitive to inhibitory influence of melatonin.
Juszczak
Marlena
M
Department of Pathophysiology, Medical University of Lodz, Lodz, Poland. lena@bg.am.lodz.pl
Stempniak
Bozena
B
D000818:Animals; D004305:Dose-Response Relationship, Drug; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects* / Q000378:metabolism*; D008297:Male; D008550:Melatonin / Q000494:pharmacology*; D009924:Organ Culture Techniques; D010121:Oxytocin / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013373:Substance P / Q000008:administration & dosage / Q000494:pharmacology*; D014667:Vasopressins / Q000378:metabolism
D014667:Vasopressins; D013373:Substance P; D010121:Oxytocin; D008550:Melatonin