A shift in microvillus membrane fucosylation to sialylation by ethanol ingestion in rat intestine.

The luminal surface of enterocytes is covered with glycocalyx which is rich in glycoproteins. Ethanol ingestion is shown to induce morphological and biochemical changes in the intestine. In this study, the effect of ethanol ingestion on membrane glycoproteins has been investigated. Chemical analysis of microvillus membranes revealed an increase in hexose and sialic acid contents, but a reduction in fucose levels in ethanol-fed rats compared with controls. The observed changes were apparent in animals fed with ethanol for 35-56 days compared with controls. Lectin-binding assay indicated an increase in Wheat germ agglutinin (affinity for GlcNAc/sialic acid) and a decrease in Aleuria aurantia (affinity for alpha-L: -fucose) reactivity of brush borders in ethanol-fed animals for 4-8 weeks. Western blot analysis using biotin-labeled Wheat germ agglutinin revealed increased binding to proteins of M(r) 66-205 kDa in ethanol-fed rats compared with controls. The binding of Aleuria aurantia to membrane proteins of M(r) 97-185 kDa was reduced in ethanol-fed animals. These findings suggest that long-term ethanol feeding modulates the sialylation and fucosylation processes of microvillus membrane proteins in rat intestine. This could affect the intestinal digestive and absorptive functions in chronic alcoholism.