A neuropeptide FF agonist blocks the acquisition of conditioned place preference to morphine in C57Bl/6J mice.
Neuropeptide FF behaves as an opioid-modulating peptide that seems to be involved in morphine tolerance and physical dependence. Nevertheless, the effects of neuropeptide FF agonists on the rewarding properties of morphine remain unknown. C57BL6 mice were conditioned in an unbiased balanced paradigm of conditioned place preference to study the effect of i.c.v. injections of 1DMe (D-Tyr1(NMe)Phe3]NPFF), a stable agonist of the neuropeptide FF system, on the acquisition of place conditioning by morphine or alcohol (ethanol). Morphine (10 mg/kg, i.p.) or ethanol (2 g/kg, i.p.) induced a significant place preference. Injection of 1DMe (1-20 nmol), given 10 min before the i.p. injection of the reinforcing drug during conditioning, inhibited the rewarding effect of morphine but had no effect on the rewarding effect of ethanol. However, a single injection of 1DMe given just before place preference testing was unable to inhibit the rewarding effects of morphine. By itself, 1DMe was inactive but an aversive effect of this agonist could be evidenced if the experimental procedure was biased. These results suggest that neuropeptide FF, injected during conditioning, should influence the development of rewarding effects of morphine and reinforce the hypothesis of strong inhibitory interactions between neuropeptide FF and opioids.
Centre de Recherches sur la Cognition Animale, CNRS UMR 5169, Bât 4R3 b3, Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex 4, France.
Stéphane
S
Marchand
Alexandre
A
Betourne
Virginie
V
Marty
Stéphanie
S
Daumas
Hélène
H
Halley
Jean-Michel
JM
Lassalle
Jean-Marie
JM
Zajac
Bernard
B
Frances
D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects; D003213:Conditioning, Psychological / Q000187:drug effects*; D000431:Ethanol / Q000494:pharmacology; D005260:Female; D007276:Injections, Intraventricular; D051379:Mice; D008810:Mice, Inbred C57BL; D009020:Morphine / Q000494:pharmacology*; D009842:Oligopeptides / Q000819:agonists* / Q000494:pharmacology*; D018013:Receptors, Neuropeptide / Q000819:agonists; D012201:Reward
D009842:Oligopeptides; D018013:Receptors, Neuropeptide; C083929:neuropeptide FF receptor; C105455:neuropeptide FF, Tyr(1)-N-methyl-Phe(3)-; D000431:Ethanol; D009020:Morphine; C053651:phenylalanyl-leucyl-phenylalanyl-glutaminyl-prolyl-glutaminyl-arginyl-phenylalaninamide