Active and passive avoidance behaviour in rats produced by IV infusions of ethanol

The ability of ethanol to motivate avoidance responding was used as a measure of the drug's aversive stimulus properties. In Experiment I, four groups of rats were infused with either ethanol (200, 400, 800 mg/kg IV) or saline if they failed to jump a high hurdle. The ethanol groups acquired the jumping response (active avoidance), while the saline group only showed a tendency not to jump. In Experiment II, the hypothesis was tested that the same infusions might be self-administered if the contingency were reversed so that responses produced rather than avoided the drug. Four groups of rats were given the same doses of ethanol or saline if they traversed a runway and entered a goal box. Initially, all animals made the response, however the drug-treated groups eventually showed a dose-dependent tendency to refrain from entering the goal box (passive avoidance). Thus ethanol can maintain behavioral control similar to that produced by commonly used aversive stimuli (e.g. foot shock) and can do so at lower doses than those found to be effective in previous reports of ethanol-mediated aversions. It is suggested that the mechanism by which ethanol comes to be a reinforcing agent must take into account the pervasive negative properties of the drug.