牛磺熊脱氧胆酸在棕榈酸诱导的INS-1细胞凋亡中的作用（Effects of Tauroursodeoxycholic Acid on the Apoptosis of INS-1 Cells Cultured by Palmitate）

为观察牛磺熊脱氧胆酸(Tauroursodeoxycholic acid,TUDCA)对棕榈酸(Palmitate)诱导的INS-1细胞凋亡的影响,分别用不同浓度棕榈酸(0.25mmol·L-1、0.5mmol·L-1、1.0mmol·L-1),棕榈酸(0.5mmol·L-1)+不同浓度TUDCA(25μmol·L-1、50μmol·L-1、100μmol·L-1)培养INS-1细胞12h,用MTT法检测细胞毒性作用,流式细胞术检测细胞凋亡,RT-PCR技术检测凋亡相关基因Bax/Bcl-2的表达.结果表明,与空白对照组比较,棕榈酸组(浓度≥0.5mmol·L-1)INS-1细胞凋亡率显著上升(p<0.05);加TUDCA培养组,当浓度≥50μmol·L-1时,与棕榈酸组相比,INS-1细胞凋亡率显著下降(p<0.05),呈剂量-效应关系.此外,棕榈酸组(浓度≥0.5mmol·L-1)INS-1细胞凋亡相关基因Bax表达显著上升(p<0.05),Bcl-2则明显下降;加TUDCA后,Bax基因表达显著下降(p<0.05),而Bcl-2则明显上升(p<0.05),并呈剂量-效应关系.以上结果表明,TUDCA能够减少游离脂肪酸引起的INS-1细胞凋亡,对INS-1细胞发挥保护作用.而凋亡促进基因Bax的表达下调,凋亡抑制基因Bcl-2的表达上调可能是其作用机制之一.

Effects of Tauroursodeoxycholic Acid on the Apoptosis of INS-1 Cells Cultured by Palmitate

In order to study the effects of Tauroursodeoxycholic acid(TUDCA) on the apoptosis of INS-1 cells cultured by palmitate in vitro,INS-1 cells were divided into two kinds of groups,one was cultured in the presence of palmitate(0.25mmol·L-1,0.5mmol·L-1,1.0mmol·L-1)for 12h,another was pretreated with TUDCA(25μmol·L-1,50μmol·L-1,100μmol·L-1)before cultured in palmitate(0.5mmol·L-1).The proliferation was measured with thiozolyl blue(MTT)method.The cell apoptosis was detected by flowcytometry(FCM).The expressions of Bax/Bcl-2 genes were assessed by semi-quantitative RT-PCR.Results showed that proliferation of INS-1 cells were inhibited,and the apoptosis was induced significantly by palmitate(concentration: ≥0.5mmol·L-1).The survival rate was significantly increased,and the apoptosis rate was significantly decreased,when INS-1 cells were co-cultured with TUDCA.Moreover,the expression of Bax gene was promoted,while expression of Bcl-2 gene was depressed by palmitate.The expression of Bax gene was remarkably reduced and the expression of Bcl-2 gene was efficiently enhanced when INS-1 cells were co-cultured with TUDCA in a dose dependent manner.Above results indicate that TUDCA can protect INS-1 cells from toxin-induced apoptotic cell death by palmitate,the mechanism by which TUDCA exerts its protection effects is probably related to downregulation of Bax gene and upregulation of Bcl-2 gene.