Nitric oxide mediation of morphine-induced place preference in the nucleus accumbens of rat.
In the present study, the effects of intra-nucleus accumbens injection of L-arginine, a nitric oxide (NO) precursor, and N(G)-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthase (NOS) inhibitor, on morphine-induced conditioned place preference in male Wistar rats were investigated. Our data showed that subcutaneous (s.c.) injection of morphine sulphate (0.5-10 mg/kg) significantly increased the time spent in the drug-paired compartment in a dose-dependent manner. Intra-accumbens administration of L-arginine (0.03 and 0.05 microg/rat) with an ineffective dose of morphine (0.5 mg/kg) elicited significant conditioned place preference, while intra-accumbens administration of L-NAME (0.3, 0.1 and 1 microg/rat) decreased the acquisition of conditioned place preference induced by morphine (7.5 mg/kg). The response to different doses of L-arginine was decreased by L-NAME (0.03 microg/rat). L-Arginine and L-NAME by themselves did not elicit any effect on place conditioning. Intra-accumbens administration of L-arginine but not L-NAME significantly decreased the expression of morphine (7.5 mg/kg)-induced place preference. The attenuation of already established morphine-induced place preference on the test day by L-arginine was inhibited by L-NAME. The results indicate that NO may be involved in the acquisition and expression of morphine-induced place preference.
Gholami
Azam
A
Department of Biology, Faculty of Science, Tehran University, Tehran, Iran.
Haeri-Rohani
Ali
A
Sahraie
Hedayat
H
Zarrindast
Mohammad-Reza
MR
D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D001120:Arginine / Q000494:pharmacology; D001522:Behavior, Animal / Q000187:drug effects*; D003216:Conditioning, Operant / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000008:administration & dosage / Q000494:pharmacology; D008297:Male; D008845:Microinjections; D009020:Morphine / Q000494:pharmacology*; D019331:NG-Nitroarginine Methyl Ester / Q000008:administration & dosage / Q000494:pharmacology; D009569:Nitric Oxide / Q000096:biosynthesis / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D052248:Nitric Oxide Synthase Type I; D009714:Nucleus Accumbens / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar
D000701:Analgesics, Opioid; D004791:Enzyme Inhibitors; D009569:Nitric Oxide; D009020:Morphine; D001120:Arginine; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; C496322:Nos1 protein, rat; D019331:NG-Nitroarginine Methyl Ester