Department of Physiology, Monash University, Clayton 3800, Victoria, Australia.
Endocrinology. 2013 Jan;154(1):65-76. doi: 10.1210/en.2012-1847. Epub 2012 Nov 26.
FTY720 is a sphingosine-1-phosphate analog that has been shown to inhibit ceramide synthesis in vitro. Because ceramide accumulation in muscle is associated with insulin resistance, we aimed to examine whether FTY720 would prevent muscle ceramide accumulation in high fat-fed mice and subsequently improve glucose homeostasis. Male C57Bl/6 mice were fed either a chow or high fat-diet (HFD) for 6 wk, after which they were treated with vehicle or FTY720 (5 mg/kg) daily for a further 6 wk. The ceramide content of muscle was examined and insulin action was assessed. Whereas the HFD increased muscle ceramide, this was prevented by FTY720 treatment. This was not associated with alterations in the expression of genes involved in sphingolipid metabolism. Interestingly, the effects of FTY720 on lipid metabolism were not limited to ceramide because FTY720 also prevented the HFD-induced increase in diacylglycerol and triacylglycerol in muscle. Furthermore, the increase in CD36 mRNA expression induced by fat feeding was prevented in muscle of FTY720-treated mice. This was associated with an attenuation of the HFD-induced increase in palmitate uptake and esterification. In addition, FTY720 improved glucose homeostasis as demonstrated by a reduction in plasma insulin, an improvement in whole-body glucose tolerance, an increase in insulin-stimulated glucose uptake, and Akt phosphorylation in muscle. In conclusion, FTY720 exerts beneficial effects on muscle lipid metabolism that prevent lipid accumulation and improve glucose tolerance in high fat-fed mice. Thus, FTY720 and other compounds that target sphingosine-1-phosphate signaling may have therapeutic potential in treating insulin resistance.
FTY720 是一种鞘氨醇-1-磷酸类似物,已被证明可在体外抑制神经酰胺合成。由于肌肉中神经酰胺的积累与胰岛素抵抗有关,我们旨在研究 FTY720 是否可以防止高脂肪喂养的小鼠肌肉中神经酰胺的积累,并随后改善葡萄糖稳态。雄性 C57Bl/6 小鼠分别用标准饮食(chow)或高脂肪饮食(HFD)喂养 6 周,然后用载体或 FTY720(5mg/kg)每天处理进一步 6 周。检查肌肉中的神经酰胺含量,并评估胰岛素作用。尽管 HFD 增加了肌肉中的神经酰胺,但 FTY720 治疗可预防这种情况。这与鞘脂代谢相关基因表达的改变无关。有趣的是,FTY720 对脂质代谢的影响不仅限于神经酰胺,因为 FTY720 还可防止 HFD 诱导的肌肉中二酰基甘油和三酰基甘油的增加。此外,FTY720 还可预防高脂肪喂养引起的肌肉中 CD36 mRNA 表达增加。这与脂肪摄取和酯化增加引起的 HFD 诱导的增加减弱有关。此外,FTY720 通过降低血浆胰岛素、改善全身葡萄糖耐量、增加胰岛素刺激的葡萄糖摄取以及肌肉中 Akt 磷酸化来改善葡萄糖稳态。总之,FTY720 对肌肉脂质代谢产生有益影响,可防止高脂肪喂养小鼠的脂质积累并改善葡萄糖耐量。因此,FTY720 和其他靶向鞘氨醇-1-磷酸信号的化合物可能具有治疗胰岛素抵抗的治疗潜力。