Gary B. Glavin

Aggression, body temperature and stress ulcer

Female rats which were exposed to supine restraint plus cold for 3 hr and were able to bite a passing nylon brush, developed fewer gastric lesions as compared to control rats which were similarly restrained but did not have access to the aggressive biting response. A second study, wherein rats were exposed to two restraint sessions, replicated the results obtained from the first experiment. Core body temperature measures revealed that rats with access to the biting response were more successful in maintaining body temperature. The protective effect of aggression may thus be due to the reduction in restraint hypothermia and not necessarily the affective qualities of the aggressive response per se.

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.

Activity stress effects on voluntary ethanol consumption, mortality and ulcer development in rats.

The present study was designed to investigate the relationship between activity stress, alcohol consumption and ulcer proliferation. Ethanol consuming rats were initially divided into low, medium or high ethanol preferring groups on the basis of daily ethanol intake (g/kg/day). Following a habituation period in activity cages, animals were fed for 1 hr per day. Access to both water and ethanol remained ad lib. Yoked control home cage animals were fed the same amount of food consumed by their wheel-housed partners. This procedure continued until wheel-housed animals died, at which time they and their yoked home cage control partners were examined for ulcers. Results indicated that in contrast to the yoked controls, only the high ethanol-preferring rats reduced their ethanol consumption. Although no differences were apparent in ulcer frequency (mean number of ulcers per rat) or severity (mean cumulative ulcer length in millimeters), animals exposed to ethanol had a lower ulcer incidence (number of rats per group developing ulcers) and mortality rate than non-ethanol exposed animals.

Prenatal maternal stress: Differential effects upon male and female offspring responses to restraint stress as adults

Pregnant primiparous rats were subjected to four days of light restraint stress on postconception days 7 through 10, inclusive, coincident with the development of the fetal gastrointestinal system. Twenty male and twenty female offspring from prenatally stressed and nonstressed rats were then subjected to two hours of supine cold-restraint as adults. Eighty percent of nonprenatally stressed offspring developed gastric lesions, while 47.5% of offspring of prenatally stressed mothers displayed lesions. A significant sex-stress interaction was detected, indicating that male offspring from prenatally stressed mothers display less severe gastric lesions in response to restraint stress as adults than do male offspring from nonprenatally stressed mothers. Female offspring from both prenatal stress conditions showed similar levels of stress-induced lesions.

Ethanol-stress interaction: Differences among ethanol-preferring rats' responses to restraint

Rats were screened in an alcohol-water free-choice paradigm and divided into low-ethanol preferring (1.5-2.5 g/kg/day), medium-ethanol-preferring (2.5-4.5 g/kg/day) and high-ethanol-preferring (4.5-6.0 g/kg/day) groups. In addition, a non-ethanol-exposed group was included. Each of these groups was again subdivided with half the animals in a group being food deprived for 16 hr, and the other half having ad lib access to food. All rats were then subjected to restraint in the supine position in a cold (4-6 degrees C) environment for 3 hr. Significant differences in ulcer incidence and severity (cumulative length of the ulcers expressed in millimeters) occurred, suggesting that higher intake of alcohol is associated with greater ulcer severity. This pattern occurred for both food-deprived and non-deprived animals.