黄秋葵醇提物中2种成分对肝细胞糖异生及AMPKα磷酸化的影响

目的观察黄秋葵醇提物中槲皮素和异槲皮苷对肝细胞糖异生及磷酸烯醇式丙酮酸羧激酶(PEPCK)、葡萄糖-6-磷酸脱氢酶(G6Pase)的影响,并探讨其机制。方法体外培养小鼠原代肝细胞,以乳酸和丙酮酸为糖异生底物。予不同浓度槲皮素、异槲皮苷干预24 h后,葡萄糖氧化酶法测定培养液上清葡萄糖浓度,RT-PCR法检测PEPCK、G6Pase、AMPKαmRNA表达,Western blot法检测总AMPKα、AMPKαThr172磷酸化水平。结果与空白组比较,糖异生诱导组上清葡萄糖浓度显著升高(P<0.01);槲皮素和异槲皮苷干预后,80μmol/L槲皮素组、异槲皮苷组显著低于糖异生诱导组(P<0.01);糖异生诱导组PEPCK、G6Pase AMPKαmRNA相对表达显著升高(P<0.01);80μmol/L槲皮素组、异槲皮苷组PEPCK、G6Pase表达显著低于糖异生诱导组(P<0.05)。Western blot显示,80μmol/L槲皮素组、异槲皮苷组AMPKαThr172磷酸化水平均较糖异生诱导组增加。结论黄秋葵醇提物中槲皮素和异槲皮苷呈剂量依赖性地抑制体外培养原代肝细胞糖异生及其关键酶基因转录,AMPKαThr172磷酸化可能与两者抑制糖异生机制有关。

Inhibition of phosphoenolpyruvate carboxykinase gene expression by metformin in cultured hepatocytes

Objective To investigate the effect and mechanism of the antihyperglycemic agent metformin on the expression of phosphoenolpyruvate carboxykinase (PEPCK) gene in hepatocytes and to determine whether the effects of metformin in hepatocytes are transmitted throughout the known insulin signaling pathways Methods Confluent H4IIE rat heptoma cells were cultured for 16 h with 0 1 mmol/L metformin either in absence or presence of 0 1 nmol/L insulin, and then stimulated with various agents The expression of PEPCK gene was examined by Northern blot analysis Results Therapeutic concentrations of metformin significantly inhibited basal PEPCK mRNA expression and also decreased cAMP and dexamethasone induced PEPCK gene expression through interaction with insulin In the presence of insulin signaling pathway inhibitors wortmannin and UO126, metformin reduced PEPCK mRNA levels, but wortmannin blocked inhibitory regulation of insulin on PEPCK gene expression Conclusion Metformin inhibits PEPCK gene expression via either an insulin independent or an interacting with insulin manner The results suggest that a possible mechanism by which metformin reduces gluconeogenesis could be associated with the inhibition of PEPCK gene expression