Effects of ethanol on locomotor depression and corticosterone release induced by restraint-stress: support for a stress-ethanol interaction.

The interaction between restraint-stress and ethanol was investigated in the rat. The effects of ethanol pretreatment (0.0, 1.0, 1.5, 2.0 g/kg, 20% v/v) on locomotor depression and corticosterone release induced by restraint-stress (15, 60 min) were measured. Restraint durations of 15, 30, 90 and 120 min were found to decrease locomotor activity while animals restrained for 60 min did not differ from home cage controls. All restraint durations induced a significant increase in plasma levels of corticosterone. Locomotor activity counts of ethanol-pretreated (1.0, 1.5, 2.0 g/kg; 20% v/v) animals restrained for 15 min were not found to be lower than those of ethanol-pretreated animals remaining in home cages. Ethanol pretreatment did not differentially affect the locomotor activity of restrained or home cage animals in the 60-min condition. Plasma corticosterone levels of ethanol-pretreated animals restrained for 15 min were identical to those of ethanol-pretreated home cage controls. However, ethanol-pretreated animals restrained for 60 min demonstrated plasma corticosterone levels higher than those obtained by ethanol pretreatment or 60-min restraint alone. Blood ethanol levels were not found to be different between ethanol-control and ethanol-stress animals. These results provide support for a stress-ethanol interaction. They also suggest a differential interaction of ethanol with different intensities of stress.