Acute chlordiazepoxide increases risky choice in rats and repeated administration attenuates this effect

Risky choice is a defining feature of many psychological disorders and maladaptive behavior. There is evidence that benzodiazepines, a class of drugs that act on the GABA system, may increase risky choice. Long-term use of these medications is common, but relatively little is known about how repeated/chronic use of benzodiazepines affects risky decision making. The present study examined effects of acute and repeated chlordiazepoxide, a prototypic benzodiazepine, on probability discounting in eight male Sprague-Dawley rats. The probability-discounting task involved choices between a single food pellet with guaranteed delivery and three food pellets with decreasing probabilities of delivery across each experimental session. Risky choice was operationally defined as choice for the larger, uncertain reinforcer over the smaller, certain reinforcer. During baseline, responding was sensitive to the programmed contingencies, and larger-reinforcer choice decreased as the probability of delivery decreased. Acute administration of chlordiazepoxide (1.0-30.0 mg/kg) dose-dependently increased risky choice and trial omissions. Tolerance to chlordiazepoxide's effects on these outcomes was observed after repeated 10.0 mg/kg administration. The results of the present study indicate that acute chlordiazepoxide can increase risky choice in a probability-discounting task and that tolerance to this effect develops after chronic exposure to the drug. Limitations of the present study are discussed, as are directions for future research on benzodiazepines and risky choice.