Food aversion learning based on voluntary running in non-deprived rats: a technique for establishing aversive conditioning with minimized discomfort

This article presents an experimental preparation for establishing conditioned food aversion (CFA) by voluntary wheel running in rats with laboratory chow and water freely available. In Experiment 1, unfamiliar food (raisins) was avoided by rats when they first encountered it. This neophobic food avoidance was habituated by repeated tests; the rats gradually increased their raisin consumption. However, the consumption remained suppressed in rats that accessed the raisins after wheel running. This finding implies that running yielded CFA, which suppressed consumption of the unfamiliar food rather than increasing it. Because running generated kaolin clay ingestion, which is a behavioral marker of nausea, it is suggested that the running-based CFA was mediated by weak gastrointestinal discomfort. Experiment 2 supported the claim that the suppressed consumption is due to running-based CFA by showing the specificity of food suppression. Demonstration of CFA based on voluntary activity in non-deprived rats will contribute to basic research on learning and memory as an alternative technique for studying aversive conditioning with minimized discomfort in animals.