Vasopressin release from the rat hypothalamo-neurohypophysial system: effects of tachykinin NK-1 and NK-2 receptors agonists and antagonists.
OBJECTIVE
Present experiments were undertaken to study the influence of peptide NK-1 and NK-2 receptor agonists and antagonists as well as substance P and neurokinin A (the natural ligands for these tachykinin receptors) on vasopressin (AVP) secretion from the rat hypothalamo-neurohypophysial (HN) system in vitro.


RESULTS
The results showed that both substance P and highly selective tachykinin NK-1 receptor agonist, i.e., [Sar9,Met(O2)11]-Substance P, enhanced significantly AVP secretion, while the NK-1 receptor antagonist (Tyr6,D-Phe7,D-His9)-Substance P (6-11)--sendide--was found to antagonize the substance P-induced hormone release from isolated rat HN system (all peptides at the concentration of 10(-7) M/L). The NK-2 receptor selective agonist (beta-Ala8)-Neurokinin A (4-10) was essentially inactive in modifying AVP release from the rat HN system in vitro, while neurokinin A (the natural ligand for this tachykinin receptor) was found to stimulate the AVP release; this effect of neurokinin A has been diminished by the NK-2 receptor antagonist (Tyr5,D-Trp(6,8,9),Lys-NH2(10))-Neurokinin A (4-10).


CONCLUSIONS
The present data indicate a role for tachykinin NK-1 (and possibly for NK-2) receptors in tachykinin-mediated stimulation of AVP secretion from the rat HN system in vitro.
Juszczak
Marlena
M
Department of Pathophysiology, Medical University of Lodz, Lodz, Poland. marlenaj@mail.bg.am.lodz.pl
D000818:Animals; D007030:Hypothalamo-Hypophyseal System / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D015288:Neurokinin A / Q000031:analogs & derivatives / Q000494:pharmacology; D064729:Neurokinin-1 Receptor Antagonists; D018377:Neurotransmitter Agents / Q000494:pharmacology; D010446:Peptide Fragments / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D018040:Receptors, Neurokinin-1 / Q000819:agonists / Q000378:metabolism*; D018041:Receptors, Neurokinin-2 / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013373:Substance P / Q000031:analogs & derivatives / Q000494:pharmacology; D014667:Vasopressins / Q000378:metabolism*
D064729:Neurokinin-1 Receptor Antagonists; D018377:Neurotransmitter Agents; D010446:Peptide Fragments; D018040:Receptors, Neurokinin-1; D018041:Receptors, Neurokinin-2; C496429:substance P (6-11), Tyr(6)-D-Phe(7)-D-His(9)-; D014667:Vasopressins; C062618:substance P, Sar(9)-Met(O2)(11)-; C064218:neurokinin A (4-10), beta-Ala(8)-; C069192:neurokinin A(4-10), Tyr(5)-Trp(6,8,9)-Lys(10)-; D013373:Substance P; D015288:Neurokinin A