Nociceptin/orphanin FQ into the rat periaqueductal gray decreases the withdrawal latency to heat and loading, an effect reversed by (Nphe(1))nociceptin(1-13)NH(2).
The present study investigated the effect of intraperiaqueductal grey injection of nociceptin/orphanin FQ (N/OFQ) and an antagonist (Nphe(1))nociceptin(1-13)NH(2) on the hindpaw withdrawal response to thermal and mechanical stimulation in rats. N/OFQ (5 nmol) significantly decreased the nociceptive thresholds in both tests and 1, 5 and 10 nmol of (Nphe(1))nociceptin(1-13)NH(2) significantly reversed this effect in a dose dependent way. Our results demonstrate, that N/OFQ has a nociceptive action, possibly through inhibition of PAG neurons. This effect is blocked by the antagonist (Nphe(1))nociceptin(1-13)NH(2) probably via ORL1 receptors in the periaqueductal grey.
Bytner
B
B
Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden. beata.bytner@fyfa.ki.se
Huang
Y H
YH
Yu
L C
LC
Lundeberg
T
T
Nylander
I
I
Rosen
A
A
D000818:Animals; D006358:Hot Temperature; D008297:Male; D008845:Microinjections; D018847:Opioid Peptides / Q000008:administration & dosage / Q000037:antagonists & inhibitors* / Q000494:pharmacology*; D010147:Pain Measurement / Q000187:drug effects*; D010446:Peptide Fragments / Q000494:pharmacology*; D010487:Periaqueductal Gray / Q000502:physiology*; D010812:Physical Stimulation; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time / Q000187:drug effects; D000097629:Nociceptin
D018847:Opioid Peptides; D010446:Peptide Fragments; D000097629:Nociceptin; C403776:nociceptin-(1-13)-NH2, NPhe(1)-