| dc.description | Two hypotheses, tension reduction and relief, have been proposed to explain the mechanism by which ethanol consumption is reinforcing. According to tension reduction, ethanol reduces the tension, fear or anxiety associated with the expected occurrence of an unpleasant event and because this is negatively reinforcing organisms learn to consume ethanol to obtain its tension reducing effects. By contrast, the relief hypothesis suggests that ethanol is reinforcing because it can counteract deficiencies in receptor stimulation which occur after the cessation of aversive events, during periods of relief. In these experiments adult male Sprague Dawley rats had restricted access to ethanol in order to maximize its consumption in temporal proximity to the shock session. When access was restricted to a brief period away from the home cage immediately after (Experiment 1) or before shock sessions (Experiments 2--6) or during extinction (Experiments 7 and 8) consumption data failed to support either hypothesis whether comparisons were made within or between groups. Ethanol consumption did not differ between groups that had access to ethanol contiguous with shock or at the same time on no-shock days (Experiments 1 and 2). Consumption by Ethanol groups was lower than consumption by Sucrose and Water groups before shock sessions (Experiments 3 and 4). Thirst partially accounted for ethanol consumption in Experiment 5. In Experiment 6 there was no evidence for differential consumption of ethanol between periods with and without signals for aversive events. In Experiments 7 and 8, there were no differences between the ethanol and sucrose consumption of Shock and No Shock groups. Because ethanol could have had tension reducing effects (even if these effects were not eliciting consumption) freezing and bolus production were recorded as measures of conditioned fear (in Experiments 5, 7 and 8). Non-specific effects of ethanol could adequately account for differences between groups in these measures. | en_US |
