Effects of intermittent high glucose on the apoptosis of INS-1 cell and expression of apoptosis-related gene

Objective To investigate the effects of intermittent high glucose on the apoptosis of INS-1 cell and apoptosis-related gene expression,and discuss its potential molecular mechanism.Methods The INS-1 beta cells were cultured and randomly divided into three groups.Normal control group(NG group): containing 5.5 mmol/L glucose;sustained high glucose group(SHG group): containing 33.3 mmol/L glucose;intermittent high glucose group(IHG group): containing 5.5 mmol/L or 33.3 mmol/L glucose,exchanged the culture medium every 24 hours.All the three groups were cultured for three days.Cell viability,percentage of apotosis,insulin secretion,protein expressions of Caspase-3,CytC and Bax and the mRNA levels of gene related to glucose metabolism were detected.Results Compared with the NG group,the apoptosis rate of SHG group and IHG group increased significantly,and the cell viability decreased obviously,the expressions of Bax,CytC and Caspase-3 increased,the insulin secretion well as the mRNA expressions of insulin and PDX-1 gene reduced(all P0.01).Compared with the SHG group,the cell viability and insulin secretion of IHG group decreased significantly,the apoptosis and the protein expression of Caspase-3 increased obviously(all P0.01).There was no statistically significant difference on the expression of CytC and Bax as well as the mRNA levels of insulin and PDX-1 gene.Conclusions Intermittent high glucose can lead to increased apoptosis and dysfunction of islet beta cells,the mechanism may be associated with increase of the expression of Bax,CytC,caspase-3 and decrease of the expressions of insulin and PDX-1 gene.