The effects of food deprivation, nutritive and non-nutritive feeding and wheel running on gastric stress ulcers in rats.

Feeding and housing conditions that induce gastric lesions were investigated. Rats were housed in activity wheels or in hanging cages and exposed to food deprivation, ad lib cellulose or 6 g of cellulose per day for 5 days. Food-deprived rats in both housing conditions had ulcers in the rumen but many rats also had mucosal ulcers. Cellulose prevented rumenal ulcers but produced a tendency toward more severe mucosal ulcers. Ulcers in wheel-housed rats were somewhat larger but the difference was not significant. In a second experiment, rats were fed 6 g/day laboratory chow or 6 g/day chow + ad lib cellulose until b.wt. reached a preset criterion. On the average, about 10 days on the feeding regimen were required to induce ulcers in these groups. None of the rats had rumenal ulcers. Mucosal ulcers were reliably larger in rats that received cellulose in addition to 6 g of chow. There was no difference in ulcer area between wheel-housed and cage-housed rats. The results indicate that solid bulk, regardless of its caloric value or amount, protects the nonglandular stomach whereas noncaloric bulk tends to aggravate ulcers in the glandular stomach. A small amount of chow delays the rate of b.wt. loss and consequently ulcer formation. Furthermore, wheel running is not necessary to produce mucosal ulcers when food intake is insufficient to maintain b.wt. and b.wt. at sacrifice seems to be a good predictor of ulcer formation.