Omega-3 polyunsaturated fatty acids ameliorate ethanol-induced adipose hyperlipolysis: A mechanism for hepatoprotective effect against alcoholic liver disease.

Alcohol exposure induces adipose hyperlipolysis and causes excess fatty acid influx into the liver, leading to alcoholic steatosis. The impacts of omega-3 polyunsaturated fatty acids (n-3 PUFA) on ethanol-induced fatty liver are well documented. However, the role of n-3 PUFA in ethanol-induced adipose lipolysis has not been sufficiently addressed. In this study, the fat-1 transgenic mice that synthesizes endogenous n-3 from n-6 PUFA and their wild type littermates with an exogenous n-3 PUFA enriched diet were subjected to a chronic ethanol feeding plus a single binge as model to induce liver injury with adipose lipolysis. Additionally, the differentiated adipocytes from 3T3-L1 cells were treated with docosahexaenoic acid or eicosapentaenoic acid for mechanism studies. Our results demonstrated that endogenous and exogenous n-3 PUFA enrichment ameliorates ethanol-stimulated adipose lipolysis by increasing PDE3B activity and reducing cAMP accumulation in adipocyte, which was associated with activation of GPR120 and regulation of Ca2+/CaMKKβ/AMPK signaling, resultantly blocking fatty acid trafficking from adipose tissue to the liver, which contributing to ameliorating ethanol-induced adipose dysfunction and liver injury. Our findings identify that endogenous and exogenous n-3 PUFA enrichment ameliorated alcoholic liver injury by activation of GPR120 to suppress ethanol-stimulated adipose lipolysis, which provides the new insight to the hepatoprotective effect of n-3 PUFA against alcoholic liver disease.