摘要
目的:①了解游离脂肪酸是否影响大鼠肝细胞胰岛素的结合能力。②脂肪酸影响大鼠肝细胞胰岛素结合的能力的机理是否与细胞内脂肪酸氧化有关。方法:给予离体大鼠细胞高生理和超生理浓度游离脂肪酸—Oleate,或者预先采用细胞内脂肪酸氧化抵制剂及促进剂处理大鼠肝细胞后,再给予 Oleate 处理。胰岛素结合能力采用^(125)Ⅰ胰岛素竞争结合法测定。结果:采用高生理或超生理量的游离脂肪酸处理大鼠离体肝细胞,其胰岛素的结合能力降低,这种降低在高生理浓度Oleate=1.25时最明显,下降36%,与对照组相比,P<0.01。如果预先给予细胞内脂肪酸氧化抑制剂或 PKC 抑制剂(BIM)再用 Oleate 处理,大鼠离体肝细胞对胰岛素的结合能力不降低,与对照组无差异(P<0.05),如果预先给予细胞内脂肪酸氧化促进荆(MP)再用 Oleate 处理大鼠离体肝细胞对胰岛素的结合能力较单用 Oleate 进一步下降,与对照组比较,P<0.05。结论:①Oleate 降低大鼠肝细胞对胰岛素的结合能力,以浓度为125时最大,下降36%。②如果大鼠离体肝细胞预先用细胞内脂肪酸氧化抑制剂/PKC 抑制剂—BIM 处理,则 Oleate 不引起大鼠肝细胞胰岛素结合能力下降。③反之如果预先给予大鼠分离肝细胞细胞内脂肪酸氧化增强剂(MP),则 Oleate 引起大鼠肝细胞胰岛素结合能力下降的作用要进一步增加。提示:Oleate 致大鼠离体肝细胞的胰岛素结合能力降低与细胞内脂肪酸的氧化有关,并可能通过 PKC 通路激活的机制。
Objective:To elucidate the effect of free fatty acid(FFA)on the inhibition of insulin binding in isolated rat hepatocytes.Methods:The rat hepatocytes were infused with oleate(OE)in differ- ent concentrations.Methylpalmoxirate(MP)was added to the incubation media at a concentration of 30mm 30 min before and throughout the incubation period.At the same time,bisindoylmaleimide(BIM)was add- ed to the incubation at a concentration of lum 60min before and throughout the incubation rate together with Oleate 125um.Insulin binding assay was performed by using of method of RIA .Results:Insulin bind- ing was decreased in rat hepatocytes infused with Oleate(OE)of high physiological or super physiological concentration levels with the lowest binding rate at OE 1.25mM.The binding rate decreased by 36% (VS.controlP<0.05).If the hepatocytes were pretreated with BIM throughout the incubation period,the inhibition effect of Oleate on insulin binding was abolished.However,if hepatocytes were pretreated with MP,the decrease in insulin binding including by Oleate was more marked than with Oleate done(P< 0.05).Conclusion:①FFA decreases insulin binding in isolated rat hepatocytes.②Increase of FFA oxi- dation may be involved in the FFA-induced decrease in insulin binding.③The inhibiting effect of Oleate on insulin building of hepatocytes pretreated with PKC inhibitor-BIM was abolished.④The decrease of in- sulin binding induced by oleate was remarkable in hepatocytes pretreated with carnitin palmitoyl trans- ferase inhebitor-MP.These results suggest that Oleate induced insulin binding inhibition of isolated rat hepatocytes may related to intracellular FFA oxidation and the activation of PKC pathway.
