AJP - Endocrinology and Metabolism, Vol 239, Issue 3 186-E191, Copyright © 1980 by American Physiological Society
Selective inhibition by neuraminidase of insulin action on hexose metabolism of mouse adipocytes
M. Tsuda, S. Taketomi and H. Iwatsuka
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.
