%0 Journal Article %A J De Vry %A I Donselaar %A J M Van Ree %T Food deprivation and acquisition of intravenous cocaine self-administration in rats: effect of naltrexone and haloperidol. %D 1989 %J Journal of Pharmacology and Experimental Therapeutics %P 735-740 %V 251 %N 2 %X In order to create optimal conditions for the acquisition of i.v. cocaine self-administration in the rat, three groups of rats were deprived of food to different extents in order to obtain body weight reductions of 5 to 15, 15 to 25 and 25 to 35% of the pre-experimental body weights, and were tested for five consecutive 6-hr sessions in a continuous reinforcement procedure for self-administration of cocaine (0.12 mg/ml) or saline. Self-administration interacted with weight loss and indicated that: 1) a minimum level of 15 to 25% weight loss was required to obtain cocaine self-administration; 2) weight loss-induced potentiation of cocaine self-administration resulted from an interaction of increased nonspecific lever pressing activity and increased reinforcing effects of the compound; and 3) optimal differentiation between cocaine- and saline-induced responding was obtained at 15 to 25% weight loss. Daily pretreatment during the five test sessions, with 0.1 to 1.0 mg/kg of naltrexone or 43 to 375 micrograms/kg of haloperidol, dose-dependently decreased the number of cocaine (0.12 mg/ml) self-injections. Naltrexone pretreatment, and to a lesser extent haloperidol pretreatment, appeared to affect cocaine self-administration in a specific manner; both treatments affected responding on the reinforced lever, but not responding on the nonreinforced lever. Self-administration of 0.06 mg/ml of cocaine tended to be decreased by naltrexone (1 mg/kg) and haloperidol (375 micrograms/kg); whereas self-administration induced by 0.25 mg/ml of cocaine was not significantly affected by naltrexone or haloperidol. Both treatments failed to affect self-administration of saline.(ABSTRACT TRUNCATED AT 250 WORDS) %U https://jpet.aspetjournals.org/content/jpet/251/2/735.full.pdf