Selective inhibition by neuraminidase of insulin action on hexose metabolism of mouse adipocytes

Abstract

Mouse adipocytes treated with neuraminidase showed a decreased response of glucose oxidation to insulin although insulin binding to the cells was normal. The decreased response was associated with the release of sialic acids from the cells by enzyme digestion. The hormone action on 2-deoxyglucose uptake was also decreased. However, the hormone action on glyceride-glycerol synthesis or lipogenesis from glucose was unaltered when enzyme-treated cells were incubated with higher glucose concentration (greater than or equal to 5 mM). However, at lower glucose concentrations (< 5 mM), in which glucose transport was a rate-limiting step, the hormone action was markedly decreased. When fructose was used as a substrate, the enzyme-treated cells showed an impaired response to insulin in fructose oxidation but not in glyceride-glycerol synthesis and lipogenesis from fructose. These results suggest that the postreceptor systems of insulin action on glyceride-glycerol synthesis and lipogenesis from hexose are different from those of the hormone action on hexose transport and oxidation. Furthermore, alteration in insulin-sensitive metabolic profiles may be caused, in part, by changes in glycoproteins and/or glycoplipids on the cell surface.