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 antioxidant defense system, in stratified squamous and oxyntic mucosae in pigs fed diets with differing propensity to promote gastric lesions. Barrows (n = 24; 48.7+/-1.0 kg BW) housed in individual pens were used in the experiment. 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 microm), and half were fed the diet as a finely ground pelleted (FGP; average particle size = 528 microm) feed. Initiation and termination of the experiment were staggered over a 3-wk period. Diets were fed for 6 wk. Visual evaluation of the stratified squamous mucosa of the proximal stomach showed increased (P<.001) damage in animals fed the FGP diet. These results were supported by histological evaluation. Thiobarbituric acid-reacting substances (TBARS), indicative of peroxide generation, relative to amount of protein were higher (P<.001) in stratified squamous than in oxyntic mucosa, and, per unit of tissue, TBARS were highest in stratified squamous mucosa of animals fed the FGP diet. Glutathione peroxidase activity followed a pattern similar to that of peroxides. Prostaglandin E2 was higher (P<.004) in stratified squamous than in oxyntic mucosa. In contrast, the activity of catalase was higher (P<.001) in oxyntic mucosa and was not affected by diet. The data show differences in the production of peroxides, the antioxidant defense system, and PGE2 between stratified squamous and oxyntic mucosae. Generation of prooxidants and the antioxidant defense system may play a role in the predilection of ulcers for the stratified squamous mucosal region of the pig stomach.