George P. Vincent

Effects of cimetidine on stress ulcer and gastric acid secretion in the rat

Cimetidine at 25, 50, and 100 mg/kg significantly inhibited gastric acid secretion in rats with chronic gastric cannulas. Rats receiving either 50 or 100 mg/kg of cimetidine secreted significantly less gastric acid 3 hr after injection. Cimetidine failed to reduce the number or size of gastric lesions in rats exposed to the activity-stress procedure, but cimetidine at 100 mg/kg significantly reduced the number and size of gastric lesions in rats subjected to a supine restraint procedure.

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.

Sex Differences and Incidence of Activity-Stress Ulcers in the Rat

Female rats housed in running-wheel activity cages and fed 1 hr. daily ran significantly more than similarly housed and fed male rats. Male rats survived an average of 10 days, whereas mean survival time for female rats was 7.3 days. Experimental activity rats developed glandular stomach ulcers. Pair fed controls housed in cages without activity wheels were ulcer-free. Among experimental activity rats, there were no sex differences with respect to the number or severity of ulcers.

Activity-stress ulcer in the rat, hamster, gerbil and guinea pig ☆ ☆☆

Abstract Rats, hamsters, gerbils and guinea pigs were housed in activity cages and fed 1 hr each day. By the end of the 21-day experimental period, 86, 100, 70 and 70% of rats, hamsters, gerbils and guinea pigs had developed lesions in the glandular stomach. This procedure was thus capable of producing lesions in species other than the rat, thereby increasing the value of the procedure as an ulcerogenic technique.

Daily feeding schedule and housing on incidence of activity-stress ulcer

In Experiment 1 the number and size of ulcers resulting from exposure to an activity-stress procedure were inversely related to the length of the pre-stress experience with either 1 hr or 2 hr daily feeding schedules. In Experiment 2, rats housed in group cages during the pre-stress period were more vulnerable to the ulcerogenic effects of the activity-stress procedure. A pellet food or powdered food treatment condition failed to provide significant group differences. Vulnerability to stress-ulcer is discussed in terms of the disparity of the environmental conditions between the acclimation period and the activity-stress period.

A clinical evaluation of rats dying in the activity-stress ulcer paradigm

Abstract Rats fed 1 hr daily and housed in running-wheel activity cages exhibited excessive running and developed stomach ulcers as compared to food control, body weight control and home cage control rats. In addition to the observed gastric disease, experimental animals had increased bilirubins, decreased glycogen and decreased serum proteins suggesting that hepatic disease played a role in the lethal consequence of exposing rats to the activity-stress procedure. The decreases in liver glycogen and serum glucose suggested that the terminal problem was related to incipient exhaustion of metabolic substrates.

Age differences and stress ulcer in the rat

Rats 2-, 7- and 12-mo. old were exposed to supine body restraint plus cold (5 degrees C) for 3 hr. The mean cumulative length of lesions for the 2-, 7-, and 12 mo. old rats was 22.0, 43.0 and 16.0 mm. respectively. The same experimental design was used in a second study, but the pylorus was ligated prior to restraint. Total acid output/hr. was 134.6, 178.2, and 64.7 muEq/60 min. respectively for the three age groups. Older rats were not more susceptible to stress-ulcer and gastric acid was not significantly related to degree of ulceration.

Post-stress development and healing of supine-restraint induced stomach lesions in the rat

In Experiment 1, rats were subjected to 3 hr of supine restraint and sacrificed either immediately, 30, 60, 90, 120 or 180 min following restraint. Rats sacrificed 90 min after restraint revealed significantly more stomach lesions as compared to other treatment conditions. The healing rate for supine-restraint ulcers was observed in Experiment 2 and comparisons with conventional restraint procedures, as reported in other publications, would suggest a slower healing rate for lesions induced with supine restraint. Experiment 3 indicated that cimetidine significantly accelerated the rate of healing for supine-restraint lesions.

The effects of food deprivation on restraint induced gastric lesions in the rat

Abstract The effects of pre-restraint fasting on subsequent development of stomach lesions was examined in each of two experiments. In Experiment 1, rats were food deprived for 0, 12, 24, 48 or 72 hours prior to 3 hours of supine cold-restraint. The extent of glandular lesion induction was significantly greater for animals fasted for 12 hours as compared to the stomach conditions of rats assigned to the other pre-restraint treatment conditions. The effects of extended fasting intervals and restraint induction of rumenal stomach lesions was investigated in Experiment 2. Rats were food deprived for 48, 72 or 96 hours and immobilized. Restraint-stress was found to potentiate the severity of rumenal lesions for animals receiving 96 hours of prior fasting when compared to control rats similarly food deprived but not restrained. These findings suggest that the rat stomach is differentially susceptible to restraint-induced lesion formation. Shorter fasting intervals are related to lesions in the corpus of the stomach, while protracted periods of fasting will intensify rumenal pathology.

Vendor differences in starvation-induced gastric ulceration ☆

The incidence of starvation-induced gastric lesions was observed in Sprague-Dawley rats obtained from four different vendors (ARS/Sprague-Dawley, Hilltop, Holtzman, and Charles River). Food was withheld for 5 days from rats weighing 150, 200, 260 or 330 g. Glandular lesions occurred in 150 g rats; rumenal lesions occurred in 200+ rats. ARS/Sprague-Dawley rats developed more glandular lesions, whereas Hilltop rats developed more rumenal lesions.