Effects of acute administration of nicotine, amphetamine, diazepam, morphine, and ethanol on risky decision-making in rats

Rationale: Most individuals can accurately assess the risks and rewards associated with choice alternatives and decide accordingly; however, drug users often display maladaptive decision-making, such that choices are biased toward excessively risky options. Objective: The purpose of this study was to investigate the effects of a range of drugs of abuse on risky decision-making. Methods: Male Long-Evans rats were trained in the Risky Decision-Making Task, in which they chose between two levers, one which produced a small, safe food reward and the other which produced a large, risky food reward. The large reward was accompanied by the risk of a mild footshock, the probability of which increased over the course of each test session (0%, 25%, 50%, 75%, and 100%). Results: Nicotine (0.6 mg/kg) and amphetamine (1.5 mg/kg) caused a significant decrease in choice of the large risky reward (decreased risk taking). Diazepam (1.0 mg/kg) caused a significant increase in choice of the large risky reward (increased risk taking), whereas morphine (3.0 mg/kg) caused only a trend toward increased choice of the large risky reward. Ethanol had no effect on choice behavior. Conclusions: These results show that acute administration of drugs of abuse can modulate risk taking in a drug-specific manner, either increasing or decreasing preference for highly rewarding, but risky, options. © 2011 Springer-Verlag