Diacylglycerols Modulate Insulin Action in Rat Adipocytes

Summary

Effect of 1,2-diacylglycerols on the insulin receptor function and insulin action in rat adipocytes was studied. 1,2-dioctanoylglycerol (100 μg/ml) did not alter insulin binding but it did stimulate phosphorylation of the β-subunit of the insulin receptor as well as its tyrosine kinase activity. However, dioctanoylglycerol inhibited insulin-stimulated receptor autophosphorylation. This concentration of dioctanoylglycerol inhibited insulin-stimulated CO₂ metabolism, lipogenesis and 3-O-methyl-glucose Transport in a dose-dependent manner but did not alter any of these bioeffects in absence of insulin. While there was no direct link between diacylglycerol effect on tyrosine kinase activity of the insulin receptor and insulin action in rat adipocytes, the parallel inhibition of insulin-stimulated receptor autophosphorylation and insulin bioeffects by dioctanoylglycerol suggests its direct or indirect role in insulin signalling in rat fat cells.

Key words

Insulin Action - Insulin Receptor - Diacylglycerol - Protein Tyrosine Kinase