Voluntary ethanol intake of individually- or pair-housed rats: effect of ACTH or dexamethasone treatment

The effect of ACTH or dexamethasone treatment on ingestion of 10% ethanol, 0.5 M NaCl and water was studied in individually- and pair-housed rats. Crowding or decreasing the amount of space per rat by increasing the number of rats per cage from 1 to 2, together with the associated increase in social interactions caused a large increase in ethanol intake. In pair-housed rats and in rats housed alone, ACTH treatment caused a large increase in Na intake but no change in ethanol intake. In pair-housed rats and in rats housed alone, dexamethasone treatment caused no change in either ethanol or Na intake. Thus, it would appear that the induction or maintenance of a high ethanol intake of rats during crowding, a presumed social stressor, can not be attributed entirely to either an increase in blood ACTH levels with the subsequent increase in glucocorticoid hormones or to a decrease in blood ACTH and natural glucocorticoid hormone levels. However, the possibility that ACTH and/or adrenocorticoid hormones, combined with other physiological or environmental factors, causes stressor-induced ethanol intake cannot be excluded.