Reena Gupta

Intestinal Epithelial Cell Surface Glycosylation in Mice

The effects of variation in dietary protein content have been investigated on brush border glycosylation and enzyme activities in mice small intestine. The comparison of different parameters was made between the mice fed 30% (high protein, HP) and 18% protein (pair-fed, PF, and ad libitum-fed) for 21 days. The activities of brush border sucrase, lactase, p-nitrophenyl (PNP)-beta-D-glucosidase and PNP-beta-D-galactosidase were reduced in the HP diet-fed mice compared to PF and ad libitum-fed controls. Alkaline phosphatase and leucine amino-peptidase activities were significantly enhanced while gamma-glutamyl transpeptidase activity was unaltered under these conditions. Total hexoses and sialic acid content in the brush borders were reduced significantly in the test group compared to the controls while hexosamine and fucose contents remained essentially similar in different groups. The results on the binding of wheat germ agglutinin and Ulex europaeus agglutininI to microvillus membranes corroborated the chemical analysis data on sialic acid and fucose contents of the membranes. Peanut agglutinin binding was enhanced in mice from the HP group. Incorporation of (14C)-mannose into membranes was significantly less in HP diet-fed mice. These results indicate that the feeding of HP diet to mice brings about marked alterations in small intestinal epithelial cell surface glycosylation and enzyme functions.

Ethanol-Induced Changes in Lipid Composition of Intestinal Microvillus Membrane in Rats Fed Different Dietary Fats

Background/Method: The effect of feeding ethanol for 5 weeks on the lipid composition of the intestinal microvillus membrane (MVM) was studied in rats fed a commercial rat pellet (RP) diet or purified diets containing 10% coconut oil (CCO), corn oil (CO) or fish oil (FO). Results: A low cholesterol/phospholipid ratio and increased saturated fatty acid level were observed in MVM from the CCO or FO groups. Chronic administration of ethanol to RP- or CO-fed animals increased phospholipids, total and free cholesterol, and the triglyceride and ganglioside content of MVM. The free cholesterol and phospholipid content was reduced while the triglyceride level remained unaffected by ethanol treatment in the CCO or FO groups. Ethanol ingestion decreased 10:2 and 20:4 (n–6 fatty acids) but increased the saturated fatty acid content of MVM in all the dietary groups except in CCO-fed animals where the 18:2 level was not affected. An elevated 18:1, but decreased 22:6 percentage was observed in the ethanol-fed FO group. The fatty acid composition of MVM from the CCO-fed group was least affected by ethanol treatment. Conclusion: These observations suggest that the type of dietary fat modifies ethanol-mediated alterations in MVM lipid composition.

Intestinal Absorption of Macromolecules and Epithelial Cell Surface Glycosylation in Suckling Rats Nursed on Mothers Fed Low-Protein Diet-I

The effect of feeding 8% protein (low-protein; LP) diet to lactating rats has been studied on the absorption of macromolecules and the glycosylation of enterocytes in suckling animals. The absorption of 125I-labelled bovine serum albumin, gamma-globulin and alpha-lactalbumin was 24-314% more in pups nursed on mothers fed LP diet compared to the pair-fed controls. The observed enhancement in protein absorption was associated with a significant increase in the binding of these proteins to microvillus membranes (MVM). The sialic acid content of brush borders was unaltered but the fucose level was augmented (p less than 0.01) in pups nursed on rats fed LP diet. The binding of 125I-labelled wheat germ agglutinin and Ulex europeus agglutinin I to MVM was in agreement to the data on sialic acid and fucose levels of the membranes. The binding of peanut agglutinin to MVM was 30% low in pups from LP-diet-fed animals. The incorporation of (14C) D-mannose into MVM was essentially unaffected but that of (14C) N-acetylglucosamine was reduced in pups reared on mothers given LP diet. These findings suggest that the quality of maternal nutrition affects the absorption of macromolecules and the glycosylation in developing rat intestine.