EFFECT OF CHRONIC ETHANOL ADMINISTRATION ON INTESTINAL MICROVILLUS MEMBRANE GLYCOSYLATION IN RATS FED RAT PELLET DIET AND PROTEIN-RICH DIET

Effect of chronic ethanol administration daily for 40 days together wi th 30% protein (HP) diet on microvillus membrane (MVM) glycosylation i n rat intestine was studied. Ethanol administration to rats on a norma l diet enhanced the hexose and sialic acid contents of brush borders b ut significantly reduced (p<0.05) membrane fucose levels. Feeding of t he HP diet induced a generalized increase in MVM glycosylation. Ethano l feeding of rats maintained on the HP diet differently affected membr ane glycosylation. Hexosamine content was enhanced, fucose and hexose contents were reduced, and sialic acid levels were unaltered under the se conditions. The binding of I-125-wheat-germ agglutinin and I-125-pe anut agglutinin to MVM was compatible with the chemical analysis of su gars in the various experimental groups. Incorporation of [C-14]mannos e or [C-14]glucosamine into MVM from different groups of rats revealed an increase in mannosylation but a decrease in glucosamine incorporat ion into MVM from ethanol- or HP-fed animals. Ethanol feeding along wi th HP diet enhanced the incorporation of labelled sugars into MVM comp ared with that of the HP-fed controls. Electrophoretic distribution of radiolabelled membrane glycoproteins from the different groups reveal ed that glycoproteins of M(r) 60,000 were highly labelled. These resul ts suggest that ethanol ingestion along with control or HP diet marked ly modifies the intestinal MVM glycosylation but that these effects va ry under different dietary regimens.