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CB1 cannabinoid receptor agonist WIN 55, 212-2 decreases intravenous cocaine self-administration in rats

1999; Elsevier BV; Volume: 104; Issue: 1-2 Linguagem: Inglês

10.1016/s0166-4328(99)00059-5

1872-7549

Liana Fattore, M.C. Martellotta, G Cossu, Maria Stefania Mascia, Walter Fratta,

Forensic Toxicology and Drug Analysis

The effect of the CB1 cannabinoid receptor agonist WIN 55, 212-2 on intravenous cocaine self-administration (IVSA) in rats was evaluated. Male Long Evans rats were implanted with silastic catheters through the external jugular vein. The IVSA was conducted in 3-h daily sessions with a fixed ratio (FR1) schedule: the experimental apparatus had a nose-poking response-like operandum. Intravenous pre-treatment with WIN 55, 212-2 (0.25, 0.5 and 1 mg/kg) to rats self-administering cocaine (0.25 or 0.5 mg/kg/inj) at stable baseline, reduces cocaine intake in a dose-dependent manner. The CB1 receptor antagonist SR 141716A (3 mg/kg i.p.) completely reversed the WIN 55, 212-2-induced decrease of cocaine intake. However, pre-treatment of SR 141716A alone (up to dose of 9 mg/kg i.p.) was unable to modify cocaine IVSA. These results indicate that stimulation of CB1 cannabinoid receptors activates rewarding mechanisms which produce reinforcing effects additional to those induced by cocaine.