Background: Thiazolidinediones exert anti-inflammatory and anti-oxidative roles and attenuate atherosclerosis by mechanisms partially independent of their metabolizing actions. High doses of angiotensin type 1 receptor (AT1R) blocker losartan (LST) seem to promote fat cell formation by preserving PPARgamma activity.
Methods: C57BL/6J diet-induced atherosclerotic susceptible mice randomly received a normal or a high-fat high-cholesterol (HFHC) diet and were treated with rosiglitazone (RG), LST or a vehicle for 12 weeks.
Results: HFHC was associated with increased PPARgamma gene expression without an over regulation of PPARgamma responsive genes, whereas RG and LST treatments were found to maintain PPARgamma activity without resulting in increased PPARgamma gene expression. A better anti-inflammatory and antioxidant profile in mice treated with RG regarding LST was observed in spite of a similar PPARgamma preserved activity. Chromatin immunoprecipitation (ChIP) assays revealed that animals under HFHC diet treated with RG showed a significant nuclear factor erythroid 2-like 2 (Nrf2)-dependent down-regulation of the expression of the CD36 gene.
Conclusion: The PPARgamma agonist RG exerts antioxidant properties that significantly reduced Nrf-2-dependent CD-36 up-regulation in mice under HFHC diet. Because LST treatment was also associated with a preserved PPARgamma activity, our data suggests that these RG antioxidant effects are partially independent of its PPARgamma metabolizing properties.