Through the central V2, not V1 receptors influencing the endogenous opiate peptide system, arginine vasopressin, not oxytocin in the hypothalamic paraventricular nucleus involves in the antinociception in the rat.
Our previous study has proven that hypothalamic paraventricular nucleus (PVN) played a role in the antinociception. The central bioactive substances involving in the PVN regulating antinociception were investigated in the rat. The results showed that electrical stimulation of the PVN increased the pain threshold, and L-glutamate sodium injection into the PVN elevated the pain threshold, but the PVN cauterization decreased the pain threshold; pain stimulation raised the arginine vasopressin (AVP), not oxytocin (OXT), leucine-enkephalin (L-Ek), beta-endorphin (beta-Ep) and DynorphinA1-13 (DynA1-13) concentrations in the PVN tissue using micropunch method, heightened AVP, L-Ek, beta-Ep and DynA1-13, not OXT concentrations in the PVN perfuse liquid, and reduced the number of AVP-, not OXT, L-Ek, beta-Ep and DynA1-13-immunoreactive neurons in the PVN especially in the posterior magnocellular part of the PVN using immunocytochemistry. There was a negative relationship between the PVN AVP concentration and the pain threshold; pain stimulation enhanced the AVP, not OXT mRNA expression in the PVN using in situ hybridization and RT-PCR; intraventricular injection of anti-AVP serum completely reversed L-glutamate sodium injection into the PVN-induced antinociception, and administration of naloxone - the opiate peptide antagonist, partly blocked this L-glutamate sodium effect, but anti-OXT serum pretreatment did not influence this L-glutamate sodium effect; L-glutamate sodium injection into the PVN-induced analgesia was inhibited by V2 receptor antagonist - d(CH2)5[D-Ile2, Ile4, Ala-NH2(9)]AVP, not V1 receptor antagonist - d(CH2)5Tyr(Me)AVP. The data suggested that the PVN was limited to the central AVP, not OXT, which was through V2, not V1 receptors influencing the endogenous opiate peptide system, to regulate antinociception.
Yang
Jun
J
Institute for Pharmaceutical and Medicinal Science, Guangdong Bangmin Pharmaceutical Co. Ltd., Jianghai District, Jiangmen, Guangdong 529000 China. yj6676@yahoo.com
Chen
Jian-min
JM
Song
Cao-You
CY
Liu
Wen-Yan
WY
Wang
Gen
G
Wang
Cheng-hai
CH
Lin
Bao-Chen
BC
D000704:Analysis of Variance; D000818:Animals; D001127:Arginine Vasopressin / Q000378:metabolism* / Q000494:pharmacology; D015152:Blotting, Northern; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D004558:Electric Stimulation / Q000379:methods; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D018698:Glutamic Acid / Q000494:pharmacology; D007150:Immunohistochemistry / Q000379:methods; D017403:In Situ Hybridization / Q000379:methods; D008297:Male; D008845:Microinjections / Q000379:methods; D018847:Opioid Peptides / Q000502:physiology*; D010121:Oxytocin / Q000378:metabolism; D010147:Pain Measurement / Q000379:methods; D017288:Pain Threshold / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D010286:Paraventricular Hypothalamic Nucleus / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D012333:RNA, Messenger / Q000096:biosynthesis; D011863:Radioimmunoassay / Q000379:methods; D051381:Rats; D017207:Rats, Sprague-Dawley; D017483:Receptors, Vasopressin / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013997:Time Factors
D018847:Opioid Peptides; D012333:RNA, Messenger; D017483:Receptors, Vasopressin; D001127:Arginine Vasopressin; D018698:Glutamic Acid; D010121:Oxytocin