Through V2, not V1 receptor relating to endogenous opiate peptides, arginine vasopressin in periaqueductal gray regulates antinociception in the rat.
Our previous study has proven that central arginine vasopressin (AVP) plays an important role in antinociception, and pain stimulation raises AVP concentration in the periaqueductal gray (PAG). The nociceptive effect of AVP in PAG was investigated in the rat. The results showed that microinjection of AVP into PAG increased pain threshold, whereas microinjection of V2 receptor antagonist-d(CH2)5[d-Ile2, Ile4, Ala9-NH2]AVP into PAG decreased pain threshold in a dose-dependent manner, but local administration of V1 receptor antagonist-d(CH2)5Tyr(Me)AVP did not change pain threshold; Pain stimulation elevated AVP, Leucine-enkephalin (L-Ek), Methionine-enkephalin (M-Ek) and beta-endorphin (beta-Ep), not dynorphinA(1-13) (DynA(1-13)) concentrations in PAG perfuse liquid; PAG pre-treatment with naloxone, an opiate receptor antagonist or V2 receptor antagonist completely reversed AVP-induced increase in pain threshold, however, PAG pre-treatment with V1 receptor antagonist did not influence this effect of AVP administration. The data suggest that AVP in the PAG, through V2 rather than V1 receptor, regulates antinociception, which progress relates to enkephalin and endorphin.
Yang
Jun
J
Institute for Pharmaceutical and Medical Science, Guangdong Bangmin Pharmaceutical Co. Ltd., Jianghai District, Jiangmen, Guangdong 529000, China. yj6676@yahoo.com
Chen
Jian-Min
JM
Liu
Wen-Yan
WY
Song
Chao-You
CY
Lin
Bao-Cheng
BC
D000700:Analgesics / Q000494:pharmacology; D000818:Animals; D065092:Antidiuretic Hormone Receptor Antagonists; D001127:Arginine Vasopressin / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000494:pharmacology*; D008297:Male; D008845:Microinjections; D009270:Naloxone / Q000494:pharmacology; D009619:Nociceptors / Q000187:drug effects / Q000502:physiology; D018847:Opioid Peptides / Q000502:physiology; D017288:Pain Threshold / Q000187:drug effects / Q000502:physiology; D010487:Periaqueductal Gray / Q000187:drug effects* / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017483:Receptors, Vasopressin / Q000187:drug effects* / Q000502:physiology*
D000700:Analgesics; D065092:Antidiuretic Hormone Receptor Antagonists; D018847:Opioid Peptides; D017483:Receptors, Vasopressin; C070737:argipressin, beta mercapto(beta,beta)-cyclopentamethylenepropionic acid(1)-Ile(2,4)-Ala-NH2(9)-; D001127:Arginine Vasopressin; D009270:Naloxone