Lauric acid (LA), which is the primary fatty acid in coconut oil, was reported to have many metabolic benefits. TLR4 is a common receptor of lipopolysaccharides and involved mainly in inflammation responses. Here, we focused on the effects of LA on skeletal muscle fiber types and metabolism. We found that 200 μM LA treatment in C2C12 or dietary supplementation of 1% LA increased MHCIIb protein expression and the proportion of type IIb muscle fibers from 0.452 ± 0.0165 to 0.572 ± 0.0153, increasing the mRNA expression of genes involved in glycolysis, such as HK2 and LDH2 (from 1.00 ± 0.110 to 1.35 ± 0.0843 and from 1.00 ± 0.123 to 1.71 ± 0.302 in vivo, respectively), decreasing the catalytic activity of lactate dehydrogenase (LDH), and transforming lactic acid to pyruvic acid. Furthermore, LA activated TLR4 signaling, and TLR4 knockdown reversed the effect of LA on muscle fiber type and glycolysis. Thus, we inferred that LA promoted glycolytic fiber formation through TLR4 signaling.

中文翻译：

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月桂酸通过TLR4信号加速糖酵解肌纤维形成

据报道，月桂酸（LA）是椰子油中的主要脂肪酸，具有许多代谢益处。TLR4是脂多糖的常见受体，主要参与炎症反应。在这里，我们重点研究了LA对骨骼肌纤维类型和代谢的影响。我们发现，在C2C12中进行200μMLA处理或通过膳食补充1％LA可以使MHCIIb蛋白表达和IIb型肌纤维的比例从0.452±0.0165增至0.572±0.0153，从而增加糖酵解相关基因（如HK2）的mRNA表达和LDH2（体内1.00±0.110至1.35±0.0843和1.00±0.123至1.71±0.302，分别降低了乳酸脱氢酶（LDH）的催化活性，并将乳酸转化为丙酮酸。此外，LA激活了TLR4信号传导，而TLR4敲低则逆转了LA对肌纤维类型和糖酵解的作用。因此，我们推断LA通过TLR4信号传导促进了糖酵解纤维的形成。