Angiotensin type 1 receptor blockers telmisartan and irbesartan activate PPARα

Abstract

Objective To investigate the effect of telmisartan and irbesartan on PPARα transcriptional activity, and to clarify their molecular mechanisms in improving glucose and lipid metabolism. Methods The structural expression vectors, including pCMV-PPARα, pGL3-PPRE and the internal control vector pRL-TK, were transiently eo-transfected into COS-7 cells using SuperFect, the cells were eontinously cultured with various concentrations of telmisartan and irbesartan, and then the PPRE controlled luciferase activity was determined by using a dual-luciferase reporter gene assay system. PPARα mRNA and protein expression levels were detected by RT-PCR and Western blot after 3T3-L1 adipoeytes were treated with various concentrations of telmisartan or irbesartan. Results (1) Both telmisartan and irbesartan stimulated PPARα transcriptional activity in concentration-and time-dependent manners in cultured COS-7 cells with the maximal effect at 60 h, with the results increased by 3.8 and 2.6 folds respectively at the concentration of 100 μmol/L compared with control group (both P<0.01). (2) The PPARγ antagonist GW9662 did not inhibit fenofibrate, telmisartan and irbesartan-stimulated PPARα transcriptional activities. (3) Both telmisartan and irbesartan increased PPARα mRNA and protein expression levels in a dose-dependent manner in 3T3-L1 adipocytes. Conclusion Angiotensin type 1 receptor blockers, telmisartan and irbesartan, can both increase PPARα transcriptional activity, which may contribute to their metabolic effects. Key words: PPARα; Telmisartan; Irbesartan