Nociceptin fails to affect heroin self-administration in the rat.
The recently isolated peptide nociceptin has a primary structure similar to that of opioid peptides. Early functional studies suggested that it may act in opposition to opioid systems. To determine whether nociceptin influences the rewarding properties of heroin, nociceptin was given intracerebroventricularly (i.c.v.) to rats trained to self-administer heroin. Rats (n = 8) were given doses of 0.01 microg, 0.1 microg, 1.0 microg and 10.0 microg in a Latin square design. None of the doses significantly affected heroin self-administration rates compared to vehicle. The highest dose of nociceptin used inhibited spontaneous locomotor activity, evidence that the peptide retained its biological activity after i.c.v. infusion. These studies suggest that nociceptin does not affect the rewarding value of heroin.
Department of Neuropharmacology, The Scripps Research Institute, La Jolla, CA 92037, USA.
J R
JR
Walker
M
M
Spina
L
L
Terenius
G F
GF
Koob
D000818:Animals; D004305:Dose-Response Relationship, Drug; D006556:Heroin Dependence / Q000188:drug therapy* / Q000523:psychology*; D066298:In Vitro Techniques; D007275:Injections, Intravenous; D007276:Injections, Intraventricular; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D018847:Opioid Peptides / Q000627:therapeutic use*; D051381:Rats; D017208:Rats, Wistar; D018019:Receptors, Corticotropin-Releasing Hormone / Q000819:agonists / Q000037:antagonists & inhibitors; D011957:Receptors, Opioid / Q000819:agonists*; D012055:Reinforcement Schedule; D012646:Self Administration; D000097629:Nociceptin
D009270:Naloxone; D009292:Narcotic Antagonists; D018847:Opioid Peptides; D018019:Receptors, Corticotropin-Releasing Hormone; D011957:Receptors, Opioid; D000097629:Nociceptin