Effects of diets differing in propensity to promote gastric lesions on defense systems in gastric mucosae

The objectives were to characterize biochemical changes, focusing on the an tioxidant defense system, in stratified squamous and oxyntic mucosae in pig s fed diets with differing propensity to promote gastric lesions. Barrows ( n = 24; 48.7 +/- 1.0 kg EW) housed in individual pens were used in the expe riment. Barrows were fed a corn-soybean meal diet. Half of the animals were fed the diet as a coarsely ground meal (CGM; average particle size = 886 m u m), and half were fed the diet as a finely ground pelleted (FGP; average particle size = 528 mu m) feed. Initiation and termination of the experimen t were staggered over a 3-wk period. Diets were fed for 6 wk. Visual evalua tion of the stratified squamous mucosa of the proximal stomach showed incre ased (P < .001) damage in animals fed the FGP diet. These results were supp orted by histological evaluation. Thiobarbituric acid-reacting substances ( TBARS), indicative of peroxide generation, relative to amount of protein we re higher (P < .001) in stratified squamous than in oxyntic mucosa, and, pe r unit of tissue, TEARS were highest in stratified squamous mucosa of anima ls fed the FGP diet. Glutathione peroxidase activity followed a pattern sim ilar to that of peroxides. Prostaglandin E-2 was higher (P < .004) in strat ified squamous than in oxyntic mucosa. In contrast, the activity of catalas e was higher (P < .001) in oxyntic mucosa and was not affected by diet. The data show differences in the production of peroxides, the antioxidant defe nse system, and PGE(2) between stratified squamous and oxyntic mucosae. Gen eration of prooxidants and the antioxidant defense system may play a role i n the predilection of ulcers for the stratified squamous mucosal region of the pig stomach.