The modulation of hepatic adenosine triphosphate and inflammation by eicosapentaenoic acid during severe fibrotic progression in the SHRSP5/Dmcr rat model

Abstract

Aims: Eicosapentaenoic acid (EPA) can ameliorate certain liver lesions involved in non-alcoholic steatohepatitis (NASH). A previous study has found that stroke-prone spontaneously hypertensive 5/Dmcr (SHRSP5/Dmcr) rats fed a high fat-cholesterol (HFC) diet developed fibrotic steatohepatitis with histological similarities to NASH. This study evaluated the potential effects and mechanisms of action of EPA supplementation using this rodent model.

Main methods: Male rats were randomly assigned to groups that were fed with either the stroke-prone (SP) diet or HFC diet with or without EPA for 2, 8 and 14 weeks, respectively. The liver histopathology, biochemical features, mRNA and protein levels, and nuclear factor-κB (NF-κB) DNA binding activity were determined.

Key findings: The SP diet-fed rats presented normal livers. Conversely, the HFC diet-fed rats developed microvesicular/macrovesicular steatosis, inflammation, ballooning degeneration and severe fibrosis. At 2 weeks, the administration of EPA inhibited hepatic inflammatory recruitment by blocking the phosphorylation of inhibitor of κB-α (IκBα), which antagonizes the NF-κB activation pathway. The dietary supplementation of EPA for 8 weeks ameliorated hepatic triglyceride accumulation and macrovesicular steatosis by inhibiting the HFC diet-induced decrease in the protein levels of enzymes involved in fatty acid β-oxidation including carnitine palmitoyltransferase 1, very long chain acyl-CoA dehydrogenase and peroxisomal bifunctional protein. Although the administration of EPA elicited no histologically detectable effects on severe fibrosis at 14 weeks, it restored an HFC diet-induced decline in hepatic adenosine triphosphate (ATP) levels and suppressed ballooning degeneration, suggesting that EPA may inhibit HFC diet-induced ATP loss and cell death.

Significance: Initial amelioration of the inflammation and steatosis in the rats after EPA supplementation indicates a possibility to treat steatohepatitis. Additionally, this study provides new insights into the roles of EPA in hepatic ATP depletion and subsequent hepatocellular injury during severe fibrosis.