Effects of restraint stress on voluntary ethanol intake and ulcer proliferation in rats

The present study examined the effect of exposure to a schedule of predictable restraint stress on voluntary ethanol consumption and ulcer proliferation in rats. Following ethanol screening rats were divided into high, medium and low ethanol consuming groups on the basis of daily ethanol intake (g/kg/day) and exposed to daily 1 hr restraint stress for 10 consecutive days. Voluntary ethanol consumption was monitored both during the stress period and for an additional 25 days post-stress. Stomach pathology was assessed on days 1, 5 and 10 of the stress period as well as at the conclusion of the post-stress period. Results indicated a differential effect of stress on ethanol intake in that high ethanol preferring rats consumed less ethanol in the first 5 days of the post-stress period as compared to non-stressed controls. In contrast, the medium ethanol preferring group drank more ethanol than controls during days 1-5 of the post-stress period. Ethanol consumption for the low ethanol groups did not change during the entire experiment. Stomach pathology data revealed no ulcer formation in the stressed groups during the stress period. At the end of the post-stress period, however, stressed animals exhibited a significantly greater ulcer severity (mean cumulative ulcer length) and ulcer frequency (mean number of ulcers per rat) than non-stressed groups. Stomach pathology for ethanol consuming groups did not differ from controls, indicating that ethanol did not, by itself, affect ulcer development.