Effects of pioglitazone on free fatty acid–induced change of GPR40 expression and insulin secretion in βTC–3 cell

Abstract

Objective To investigate the effects of free fatty acids (FFAs) on gene expression of G protein coupled receptor 40 (GPR40) and the insulin secreting function in βTC–3 cell, and the intervening influence of pioglitazone (Piog) on FFA–induced these impairment of βTC–3 cell. Methods βTC–3 cells were cultured in vitro and divided into control group, FFAs group, Piog group and Piog+ FFAs group, then the mRNA of GPR40 was detected by nested semi–quantitative reverse transcription polymerase chain reaction (RT–PCR). The protein concentration was determined with BCA kit, and insulin secretion was examined in every group by radioimmunoassay. Data analysis was assessed by using one–way ANOVA and Bivariate Correlation. Results (1)The cell morphology and gene expression of GPR40 were not varied in each level FFAs groups for 12 h, but the cells were transformed and gene expression of GPR40 was decreased with the prolongation of intervening duration in different groups (F24 h=5.475, F48 h=25.923, all P<0.05). (2)BIS and GSIS in βTC–3 cells were not changed after the treatment of FFAs in the range of 0.25 to 1.0 mmol/L for 12 h, but with the prolongation of duration (24 or 48 h), the cells which were exposed to FFAs showed a decreased in BIS and GSIS (F24 h BIS=6.876, F48 h BIS=12.421, F24 h GSIS=27.767, F48 h GSIS=36.382, all P<0.05). (3)When the cells were cultured with 1.0 mmol/L FFAs in the presence of 0.1 to 10 μmol/L Piog, a dose–dependent increase of gene expression of GPR40 and insulin secretion were induced in the co–treated groups (FGPR40=14.303, FINS=56.618, all P<0.05). Conclusions Elevated FFAs may inhibit the gene expression of GPR40, and impair insulin secretion function of βTC–3 cells. Piog may be able to resist this impairment of FFAs. Key words: Fatty acids, nonesterified; Insulin; βTC–3 cells; G protein coupled receptor 40; Pioglitazone