Age-dependent alterations of insulin binding to hepatic plasma membranes, erythrocytes and adipocytes in rat.
The insulin binding to hepatic plasma membranes, erythrocytes and adipocytes of 1-, 2-, and 9-month-old rats was measured by using [125I]insulin. When rats were fed a fat-free diet, the capacities of the insulin bindings significantly decreased with aging, whereas the dissociation constants were not altered. The capacities of 9-month-old rats were decreased to about half those of 1-month-old rats for plasma membranes, and about one-third for erythrocytes and adipocytes. On the other hand, the plasma insulin levels tended to be high with increasing age at 9-10 a.m., while the levels were even more elevated at 8-9 p.m. and not altered by aging. The insulin binding capacities were increased by feeding the fat-free diet to rats adapted to a stock diet and the increases were reduced with aging. The insulin binding capacities correlated well with the magnitudes of induction of lipogenic enzymes as reported previously [Iritani, N., Fukuda, H., & Fukuda, E. (1981) Biochim. Biophys. Acta 665, 636]. Therefore, it is suggested that insulin binding is implicated in age-dependent alterations of lipogenic enzyme induction.
D000273:Adipose Tissue / Q000378:metabolism*; D000375:Aging; D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D004032:Diet; D004912:Erythrocytes / Q000378:metabolism*; D007328:Insulin / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000378:metabolism*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains
D007328:Insulin