Pentagastrin protects against stress ulceration in rats

Abstract

Stress ulcer formation was examined in the following four groups of 18 rats each: (a) chow fed, (b) fed an isocaloric amount of a liquid diet, (c) fed a liquid diet plus pentagastrin injections (250 μg/kg, 3 times/ day), and (d) fed a liquid diet plus histamine (20 mg/ kg, 3 times/day). The diet regimen lasted 10 days, and injections of saline, pentagastrin, or histamine were given over the last 7 days before water immersion induced stress. Six rats from each group were killed before stress (zero time) and after 4 and 20 hr of stress. Serum gastrin and oxyntic gland mucosal DNA synthesis were significantly lower before stress in all liquid-fed rats compared with chow-fed controls. At this time, the ulcer index was zero in all groups. DNA synthesis decreased, and the ulcer index increased progressively in all groups with exposure to stress. After 4 hr of stress, the ulcer index was 3.8 in the group receiving pentagastrin, compared with 14.1 and 10.7 in the animals receiving liquid diet alone or liquid diet with histamine injections, respectively. During stress, DNA synthesis in the group receiving pentagastrin decreased significantly less than in all other groups. There was significant correlation (r = 0.782; P < 0.01) between ulcer index and the decrease in DNA synthesis. The authors conclude that rats fed liquid diets are more susceptible to restraint-induced stress ulcers because of their lower endogenous gastrin levels and that exogenous pentagastrin increases the resistance of these animals to ulceration. The susceptibility of all groups of animals to stress ulceration was directly correlated with decreases in DNA synthesis.