ABSTRACT
Objective To investigate the effects of troglitazone on cholesterol homeostasis and secretion of 3T3-L1 cells by sirolimus and the underlying mechanisms. Methods In vitro cultured 3T3-L1 cells were divided into control group,sirolimus (100 nmol/L) group,sirolimus(100nmol/L)+ troglitazone (10 μmol/L) group and troglitazone (10 μmol/L) group.High performance liquid chromatography (HPLC) was used to measure intracellular cholesterol accumulation.ELISA was used to measure leptin excretion.Quantitative real-time PCR and Western blotting were used to examine mRNA and protein expression of PPARγ. Results Free cholesterol of sirolimus +troglitazone group was 1.19 times of sirolimus group (P＜0.05).The leptin secretion levels of control group,sirolimus group,sirolimus+troglitazone group and troglitazone group were (19.02±0.52) μg/L,(15.62±0.47) μg/L,(16.45±0.51) μg/L,(18.07±0.66) μg/L,respectively.And the leptin secretion level of sirolimus+ troglitazone group was 1.05 times of sirolimus group (P＜0.05).The PPARγmRNA expressions of sirolinus group,sirolimus + troglitazone group and troglitazone group were 0.60±0.14,1.12±0.27,1.30±:0.14 folds of control,and the PPARγ mRNA expression of sirolimus + troglitazone group was higher than that of sirolimus group (P＜0.05).PPARγ protein expression had the same tendency. Conclusion Troglitazone reduces the inhibitory effect of sirolimus on PPARγ transactivation and the inhibitory effect of sirolimus on 3T3-L1 cells differentiation and adipogenesis.