Thiazolidinediones inhibit lipoprotein lipase activity in adipocytes.

Evidence from laboratory and animal studies provides groundwork for understanding mechanisms and potential before human studies continue.

• Level A · Stronger Clinical Evidence
• Level B · Emerging clinical evidence with positive signals
• Level C · Early human research exploring benefits
• Level D · Scientific groundwork from lab and animal studies
• Emerging · Emerging topic under active research

Abstract (original English)

The thiazolidinediones troglitazone and BRL 49653 improve insulin sensitivity in humans and animals with insulin resistance. Adipose tissue lipoprotein lipase is an insulin-sensitive enzyme. We examined the effects of thiazolidinediones on lipoprotein lipase expression in adipocytes. When added to 3T3-F442A, 3T3-L1, and rat adipocytes in culture, troglitazone and BRL 49653 inhibited lipoprotein lipase activity. This inhibition was observed at concentrations as low as 0.1 microM and within 2 h after addition of the drug. Lipoprotein lipase activity was inhibited in differentiated adipocytes as well as the differentiating cells. Despite this decrease in enzyme activity, these drugs increased mRNA levels in undifferentiated 3T3-F442A and 3T3-L1 cells and had no effect on mRNA expression or synthesis of lipoprotein lipase in differentiated cells. Western blot analysis showed that these drugs did not affect the mass of the enzyme protein. Lipoprotein lipase activity in cultured Chinese hamster ovary cells was not inhibited by troglitazone. Glucose transport, biosynthesis of lipids from glucose or the biosynthesis of proteins were unaffected by thiazolidinediones in differentiated cells, whereas glucose transport and lipid biosynthesis were increased when these drugs were added during differentiation. These results show that troglitazone and BRL 49653 have a specific, post-translatio

Evidence level

Evidence from laboratory and animal studies provides groundwork for understanding mechanisms and potential before human studies continue.

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