胰岛素抵抗PKC作用与AA对IR防治研究

目的探讨高浓度软脂酸（palmitate，PA）诱导HepG2细胞胰岛素抵抗（insulin resistance，IR．）的蛋白激酶C（protein kinase C，PKC）信号通道分子机制及花生四烯酸（arachidonic acid，AA）对IR的防治作用。方法建立具有IR的细胞模型，加PKC抑制剂（chelerythrine chloride，CC）作用1h后，用蒽酮法测定细胞内糖原含量，Western blot检测胞内糖原合酶（glycogen synthase，GS）和蛋白激B（PKB）蛋白水平以探讨其对胰岛素信号通路的影响；探讨从对PA引起IR的防治机制。结果分组用与不用CC作用HepG2细胞1h，再加胰岛素刺激，PA组与本组未加CC时相比，磷酸化的GS（P-Ser641 GS）蛋白水平显著减少（P〈0．05），而PA组磷酸化的PKB（P-Ser473 PKB）蛋白水平和糖原含量与control组比较都有显著增加（P〈0．05）；PA＋从组加与不加cc相比，糖原含量减少，Western blot结果显示P-Set641 GS蛋白水平略有增加但无统计学意义（P〉0．05），P—Ser473 PKB蛋白水平没有明显变化（P〉0．05）。结论在PA诱导的肝细胞IR方面PKC起着重要作用，它能抑制PKB和GS的活性而减少糖原合成；从能改善PA引起的IR，其分子机制之一可能是减少了PKC的过度激活。而减少对PKB抑制、增加GS的活性使糖原合成增加所致。

Role of PKC in insulin resistance and study on prevention effect of Arachidonic acid

ObjectiveTo study on the mechanism of insulin resistance(IR) for HepG2 cells induced by high concentrations of palmitate (PA) and the prevention effect of Arachidonic acid (AA). Methods The model of hepatic insulin resistance was established. After activated by chelerythrine chloride(CC) of protein kinase C inhibitor for 1h, hepatic glycogen contents were measured, then protein levels of phosphate- glycogen synthase(P- Ser641 GS) and phosphate- PKB (P- Ser473 PKB) were determined in total cell lysates by Western- immunoblot. The prevention effect of AA on PA- induced IR was observed.ResultsProtein levels of P- Ser641 GS in PA group were reduced while cultured at CC contrast to PA group of no CC, protein levels of P- Ser473 PKB and hepatic glycogen contents in PA group were elevated; the glucose contents in PA with AA group were decreased, protein levels of P- Ser641 GS in PA group were increased, but the protein levels of P- Ser473 PKB had no change.ConclusionPKC had an important role in hepatic insulin resistance by PA, it could inhibit activation of PKB and GS, also reduce glycogen synthesis; AA can significantly improve IR, the possible mechanism results in that it could deduce the overactivation of PKC and increase the glycogen synthesis.