Equol interferes with palmitic acid-induced muscle tube atrophy in L6 cells by regulating autophagy

To observe the effect of equol（Eq）intervention on palmitic acid（PA）-induced myoblast atrophy in rat myoblast cell line L6 and to explore its underlying mechanism.

L6 cells were divided into control group, model group（0.25 mmol/L PA）, intervention group（0.25 mmol/L PA+1 μmol/L Eq）and autophagy inhibitor（3-methyladenine, 3-MA）group（0.25 mmol/L PA+1 μmol/L Eq+1 mmol/L 3-MA）. After 24 h of intervention, glucose uptake capacity of cells was detected, muscle tube growth was observed by HE staining, autophagosome number was observed with transmission electron microscopy, and mitochondrial morphology labeled by fluorescent probe was observed by laser confocal microscopy. The expression levels of MyHC, p62, LC3, MFN2 and DRP1 were detected by Western blotting.

Compared with the control group, 24 h of PA treatment resulted in significantly decreased glucose consumption（P<0.05）, decreased muscle tube diameter（P<0.05）, reduced number of autophagosomes, increased mitochondrial fission, and reduced expression levels of MyHC and MFN2（P<0.05）, and elevated DRP1, p62 level and LC3-Ⅰ/LC3-Ⅱ ratio（P<0.05）. While Eq intervention reserved above changes induced by PA treatment（P<0.05）. However, the effects of Eq on PA-induced glucose consumption, myotube diameter, autophagosome number, mitochondrial fission, protein levels of MyHC, p62, MFN2, DRP1 and LC3-Ⅰ/LC3-Ⅱ ratio in L6 cells could be effectively inhibited by 3-MA treatment.

Eq effectively ameliorates PA-induced muscle tube atrophy in L6 cells, which may partially be related to Eq alleviating mitochondrial fission by promoting autophagy.