Effects of intrathecal nocistatin on the flexor reflex and its interaction with orphanin FQ nociceptin.
We studied the effects of intrathecal (i.t.) nocistatin, a peptide identified from the precursor of orphanin FQ/nociceptin (OFQ) on the spinal nociceptive flexor reflex in decerebrate, spinalized, unanesthetized rats and its interaction with i.t. OFQ. Nocistatin induced a moderate, non-dose-dependent facilitation of the flexor reflex without producing reflex depression whereas i.t. OFQ induced a biphasic dose-dependent facilitatory and inhibitory effect. The facilitatory effect of low dose (0.55 pmol) OFQ was significantly increased by nocistatin. On the other hand, the duration, but not magnitude, of reflex depression induced by a high (550 pmol) dose of OFQ was significantly shortened by 5.5 nmol nocistatin. Thus, nocistatin interacts with OFQ in a complex fashion, increasing excitation and reducing inhibition. No evidence was obtained for an antinociceptive effect of nocistatin in rat spinal cord.
Xu
I S
IS
Department of Medical Laboratory Sciences and Technology, Karolinska Institute, Huddinge University Hospital, Sweden.
Hashemi
M
M
Caló
G
G
Regoli
D
D
Wiesenfeld-Hallin
Z
Z
Xu
X J
XJ
D000818:Animals; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D005260:Female; D007278:Injections, Spinal; D009619:Nociceptors / Q000187:drug effects / Q000502:physiology*; D018847:Opioid Peptides / Q000008:administration & dosage / Q000819:agonists / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D010446:Peptide Fragments / Q000008:administration & dosage / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012018:Reflex / Q000187:drug effects*; D013116:Spinal Cord / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors; D000097629:Nociceptin
D018847:Opioid Peptides; D010446:Peptide Fragments; D000097629:Nociceptin; C111148:nocistatin