Effect of exposure to dietary nivalenol on activity of enzymes involved in glutamine catabolism in the epithelium along the gastrointestinal tract of growing pigs.

ABSTRACT

Changes in the activity of enzymes involved in oxidative metabolism of glutamine, and in protein content, in the epithelial tissue along the gastrointestinal (GI) tract of growing pigs exposed to nivalenol (NIV) in the diet were investigated. The epithelial tissue was taken from the stomach, small intestine and colon of three groups of animals fed diets without NIV (control), with inclusion of 2.5 mg NIV/kg diet (low dose) and with inclusion of 5.0 mg NIV/kg diet (high dose). The activities of glutaminase, glutamate dehydrogenase, oxoglutarate dehydrogenase, isocitrate dehydrogenase and alanine aminotransferase were determined. In the control pigs the activities of oxoglutarate dehydrogenase and alanine aminotransferase were higher (P < 0.05) in the epithelium of the small intestine as compared with the stomach and colon, while there were no differences in the activities of glutaminase, glutamate dehydrogenase and isocitrate dehydrogenase. With increasing inclusion of NIV in the diet the activity of oxoglutarate dehydrogenase decreased (P < 0.05) in the epithelium of the small intestine and colon, and the activity of alanine aminotransferase tended (P = 0.07) to increase in the epithelium of the small intestine. The activities of glutaminase, glutamate dehydrogenase and isocitrate dehydrogenase remained unaffected by the inclusion of NIV in the diet. In the control pigs the protein content in the epithelium of the small intestine was higher (P < 0.05) than in the stomach and colon, while there were no effects of NIV inclusion in the diet on the protein content. It can be concluded from the present study that the epithelial tissue of the small intestine and colon of pigs exposed to a diet containing NIV will have a reduced enzymatic capacity to utilise alpha-ketoglutarate in the tricarboxylic acid cycle (TCA-cycle), suggesting an impaired energy supply to these organs.