Abstract: 【Abstract】 Objective To study the impact of elevated glucose on the expression of insulin gene and insulin transcript facor MafA，and to clarify the mechanism of the protection of α-lipoic acid for β cell under oxidative stress. Methods βTc6 cells were cultured in DMEM, and then cultured for 48 h in media containing 5mmol/L glucose (NG group)，16.7 mmol/L glucose (HG group)，or 16.7mmol/L glucose and 200μmol/L α-lipoic acid (HG+ALA group) espectively. The insulin concentration in supernatant of cells cultured in different glucose medium was assayed by RIA. The mRNA expression levels of insulin and MafA was determined by RT-PCR. Results In HG group，insulin mRNA levels were decreased by 66.2％(P<0.05)，and MafA mRNA levels decreased by 69.5％(P<0.05)，as compared with NG group．In HG+ALA group，insulin mRNA levels were increased by 5.45 fold(P<0.05)，and MafA mRNA levels by 4.49 fold(P<0.05) respectively，as compared with HG group. There was no significant difference in insulin and MafA mRNA levels between NG and HG + ALA group (P>0.05). Conclusions These data suggested that elevation in glucose concentrations led to a decrease in insulin and insulin transcript factor MafA mRNA levels in βTc6 cells . α-lipoic acid could attenuate this impact of elevated glucose through increasing the expression level of MafA.

Key words: glucotoxicity, oxidative stress, MafA, α-lipoic acid