Metformin influences cardiomyocyte cell death by pathways that are dependent and independent of caspase-3
Metformin influences cardiomyocyte cell death by pathways that are dependent and independent of caspase-3
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DOI：
10.1007/s00125-006-0338-9
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发表时间：
2006-09-01
期刊：
影响因子：
8.2
通讯作者：
Rodrigues, B.
中科院分区：
文献类型：
--
作者：
An, D.;Kewalramani, G.;Rodrigues, B.
AIMS/假说二甲双胍已被证明可以增加脂肪酸氧化，这种作用是由AMP激活的蛋白激酶(AMPK)介导的。材料与方法用1 mmol/L棕榈酸孵育心肌细胞，不加或不加二甲双胍(1~5 mm o l/L)。培养1~16h后，通过测定培养液中乳酸脱氢酶释放量和Hoechst染色评价细胞损伤程度。为了探讨二甲双胍对心肌细胞的作用机制，测定了AMPK和乙酰辅酶A羧基酶的底物利用率和磷酸化程度。结果心肌细胞与棕榈酸孵育16h后，细胞凋亡率增加，1和2 mmol/L的二甲双胍可部分拮抗此作用。二甲双胍的这种有益作用与增加AMPK磷酸化、棕榈酸氧化和抑制高脂肪诱导的(1)长链碱基生物合成蛋白1水平、(2)神经酰胺水平和(3)caspase-3活性增加有关。意外的是，5 mmoL/L二甲双胍显著增加了高脂孵育的心肌细胞的凋亡率。这种作用与糖酵解、乳酸积累和心肌细胞孵育液中pH的显著下降有关。结论/解释我们的研究表明，二甲双胍减少了高脂诱导的心肌细胞死亡，可能是通过抑制神经酰胺的合成。然而，在高浓度的情况下，二甲双胍会导致质子和乳酸积累，导致细胞损伤，而这种损伤不依赖于caspase-3。
Aims/hypothesis Metformin has been shown to increase fatty acid oxidation, an effect mediated by AMP activated protein kinase (AMPK). We hypothesised that metformin could prevent both caspase-3 activation and apoptosis when induced by palmitic acid.Materials and methods Cardiomyocytes were incubated with 1 mmol/l palmitic acid, in the absence or presence of metformin (1-5 mmol/l). Following 1 to 16 h, cell damage was evaluated by measuring lactate dehydrogenase released into the incubation medium, and Hoechst staining. To investigate the mechanism of metformin's effect on cardiomyocytes, substrate utilisation and phosphorylation of AMPK and acetyl-CoA carboxylase were measured. Intracellular mediators of apoptosis were also evaluated.Results Incubation of myocytes with palmitic acid for 16 h increased apoptosis, an effect that was partly blunted by 1 and 2 mmol/l metformin. This beneficial effect of metformin was associated with increased AMPK phosphorylation, palmitic acid oxidation and suppression of high-fat-induced increases in (1) long chain base biosynthesis protein 1 levels, (2) ceramide levels, and (3) caspase-3 activity. Unexpectedly, 5 mmol/l metformin dramatically increased apoptosis in myocytes incubated with high fat. This effect was associated with a robust increase in glycolysis, lactate accumulation, and a significant drop of pH in the myocyte incubation medium.Concluaions/interpretation Our study demonstrates that metformin reduces high-fat-induced cardiac cell death, probably through inhibition of ceramide synthesis. However, at high concentrations, metformin causes proton and lactate accumulation, leading to cell damage that is independent of caspase-3.