Conditioned saccharin aversion induced by self-administered cocaine negatively correlates with the rate of cocaine self-administration in rats

Abstract

Previous studies showed that the degree of saccharin aversion induced by a self-administered drug correlated with the amount of drug taken. The present paradigm evaluated the relationship between conditioned saccharin (0.15% w/w) aversion and cocaine self-administration (0.15 mg/kg per injection) when drug intake was limited to 1 mg/kg per session over five taste–drug pairings. The low dose of self-administered cocaine induced a significant decrease in saccharin intake as a result of the conditioning pairings. In addition, conditioned saccharin intake was significantly correlated with the rate of cocaine self-administration ( r=−0.54; P<0.05). A second experiment was designed to control for the effect of cocaine concentration in blood per unit of time. Saccharin was paired with one of three doses of non-contingent IV cocaine (0, 1, 3, 5 mg/kg) over five taste–drug pairings. Although, 3 or 5 mg/kg of non-contingent IV cocaine induced a dose-dependent decrease in saccharin intake after five taste–drug pairings, the low dose of 1 mg/kg was not effective in inducing the effect. Taken together, these results suggest that 1 mg/kg per session of cocaine was effective in inducing saccharin aversion only in rats that self-administered the drug at a high rate. It is suggested that a Pavlovian effect such as conditioned saccharin aversion induced by a self-administered drug may be an alternative tool to investigate the anticipation of addictive drugs.