Involvement of Nitric Oxide within the Ventral Tegmental Area on the ?Acquisition and Expression of Morphine-Induced Conditioned Place ?Preference in Morphine-Sensitized Rats
Trauma Monthly: 12 (2); 107-115 Article Type: Research Article
January 1, 2007
January 1, 2007
H. Involvement of Nitric Oxide within the Ventral Tegmental Area on the ?Acquisition and Expression of Morphine-Induced Conditioned Place ?Preference in Morphine-Sensitized Rats,
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Objective. In the present study, the effects of intra-ventral tegmental area administration of L-arginine, a nitric oxide precursor, and N G-nitro-L-arginine methyl-ester (L?NAME), a nitric oxide synthase inhibitor, on the acquisition and expression of morphine-induced place conditioning in morphine-sensitized rats were studied. Material and Methods. Subcutaneous (s.c.) administration of morphine (5 mg/kg) induced conditioned place preference. Repeated pretreatment of morphine (5 mg/kg, s.c.) followed by 5 days no drug treatment, increased conditioning response induced by morphine (0.5 mg/kg, s.c.). Results. Intra-ventral tegmental area administration of L-arginine (0.01, 0.1 and 0.3 µg/rat) has no effect on the acquisition and/or expression of morphine place conditioning in non-sensitized and sensitized rats. Intra-ventral tegmental area injections of L-NAME (0.1 µg/rat) reduced the expression but not the acquisition of morphine place conditioning in the sensitized animals. Conclusion. The results indicate that nitric oxide (NO) within the ventral tegmental area is not involved in the acquisition and expression of morphine place conditioning in morphine-sensitized rats.
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