烟酰胺单核苷酸对酒精诱导大鼠肝细胞胰岛素抵抗的影响

Nicotinamide mononucleotide alleviates ethanol-induced hepatic insulin resistance

目的 探讨烟酰胺单核苷酸(nicotinamide mononucleotide,NMN)对酒精诱导肝脏胰岛素抵抗的影响及作用机制。方法原代大鼠肝细胞分为不同浓度(0、0.1、0.25、0.5、1 mmol·L^(-1)),CCK-8实验检测NMN对细胞活性的影响;酒精暴露(25 mmol·L^(-1))诱导肝细胞胰岛素抵抗模型,并在此基础上添加不同浓度NMN(0.1、0.5 mmol·L^(-1))或联合沉默信息调节因子-1(silent information regulator 1,SIRT1)的抑制剂Ex527(10μmol·L^(-1))进行干预,酶法和蒽酮法分别检测肝细胞葡萄糖利用率和糖原含量;Western blot检测p-PI3K/PI3K、p-Akt/Akt比值及SIRT1表达水平;荧光试剂盒检测肝细胞内NAD^(+)含量。结果与酒精模型组相比,高、低浓度的NMN均增加了肝细胞的葡萄糖利用率及糖原含量,并上调了p-PI3K/PI3K和p-Akt/Akt水平;同时,高、低浓度的NMN有效恢复了细胞内NAD^(+)水平及SIRT1蛋白表达。此外,Ex527明显阻断了NMN的改善作用。结论NMN对酒精诱导的肝脏胰岛素抵抗存在一定保护作用,作用机制可能与其上调细胞NAD^(+)/SIRT1通路,并进一步恢复PI3K/Akt胰岛素信号通路活化相关。

Aim To explore the potential protective effects of nicotinamide mononucleotide(NMN)on ethanol-induced hepatic insulin resistance.Methods Primary rat hepatocytes were divided into groups of different concentrations(0,0.1,0.25,0.5,1 mmol·L^(-1)).The effects on cell viability of hepatocytes by different concentrations of NMN were assessed by CCK-8 method.Next,the hepatocytes were incubated with ethanol(25 mmol·L^(-1))to establish insulin resistance model,and incubated with different concentrations of NMN(0.1,0.5 mmol·L^(-1))with or without Ex527(an inhibitor of SIRT1,10μmol·L^(-1)).Glucose oxidase and anthrone methods were used to measure the glucose utilization and glycogen content respectively.Western blot was used to detect the ratios of p-PI3K/PI3K and p-Akt/Akt and the expression of SIRT1.Fluorimetric NAD^(+)Assay Kit was used to measure the NAD^(+)level in hepatocytes.Moreover,the effects of NMN on the ethanol-induced hepatic insulin resistance were explored.Results Compared with ethanol group,NMN treatment not only increased the glucose utilization and glycogen content,but also up-regulated the ratios of p-PI3K/PI3K and p-Akt/Akt at both concentrations.Meanwhile,NMN effectively recovered the NAD^(+)level and SIRT1 expression in hepatocytes.Furthermore,the protective effects of NMN on ethanol-induced hepatic insulin resistance was blocked by Ex527.Conclusions NMN could alleviate ethanol-induced hepatic insulin resistance by up-regulating NAD^(+)/SIRT1 pathway and further recovering PI3K/Akt insulin signaling pathway.