Effects of dietary whey proteins, their peptides or amino-acids on the ileal mucosa of normally fed and starved rats

Abstract

The effects of three liquid diets, differing only in the molecular form of the nitrogen source (whole whey proteins, WP; trypsic whey protein hydrolysate, WPH, and amino-acid mixture, AAM) were studied on the mucosa morphology and brush border hydrolase (BBH) activities (disaccharidases, peptidases) of the ileum of normally fed male Wistar rats (controls) and during refeeding of rats starved for 72h. All three diets produced repair of the fasting induced mucosal atrophy; the AAM diet gave the most rapid response and highest villus height (p < 0.01). This was correlated with an increase in crypt mitoses (p < 0.01). Similar results were obtained in controls with AAM. The sucrase (S) and acid amino peptidase (AAP) specific activities of controls were higher (p < 0.01) on the WPH diet; neutral amino peptidase (NAP) was unaffected. Dipeptidyl peptidase IV (DDP) was lowest on AAM while glucoamylase (G) highest on WP. Fasting increased S and DDP activity, and produced no change in the other BBH. Large variations in BBH occurred during refeeding except for NAP which remained stable. Control values were restored at 96h, except for AAP. The results show that BBH and mucosa morphology of the ileum in the rat can be modified by the molecular form of the nitrogen source and that the nutritional status interferes with this adaptation. These data could have implications for the therapy of small bowel disease.