COMBINED EFFECTS OF BUPRENORPHINE AND A NONDRUG ALTERNATIVE REINFORCER ON IV COCAINE SELF-ADMINISTRATION IN RATS MAINTAINED UNDER FR SCHEDULES

Although previous studies have shown that pharmacological agents, such as buprenorphine, and alternative nondrug reinforcers, such as money or sweetened solutions, reduce cocaine self-administration, few studie s have examined the combined effects of these two approaches. The purp ose of the present study was to evaluate the effects of the opioid par tial agonist buprenorphine (0.1 mg/kg) and concurrent access to either water or a glucose plus saccharin solution (G+S, 3% and 0.125% wt/vol ) in rats self-administering intravenous (IV) cocaine (0.4 mg/kg per i nfusion) under fixed-ratio schedules (FR2, 8 or 32). One group had con current access to water and another group had concurrent access to G+S . After 3 consecutive days of stable cocaine self-administration, a si ngle buprenorphine injection (0.1 mg/kg IV) was administered 30 min be fore the start of the experimental session for 3 consecutive days. To summarize the results, (1) the presence of an alternative non-drug rei nforcer significantly reduced cocaine self-administration; (2) bupreno rphine selectively decreased cocaine, but not water or G+S, self-admin istration; (3) the decrease in cocaine infusions by buprenorphine was greatest on the first day of buprenorphine administration; and (4) exp ressed as a percentage of baseline conditions, the combination of bupr enorphine and G+S produced a greater decrease in cocaine self-administ ration than either buprenorphine or G+S alone. These results indicate that combined treatment with buprenorphine and concurrent access to a sweetened solution is a more effective strategy for reducing cocaine s elf-administration than either strategy alone.