Impacts of fish oil on the gut microbiota of rats with alcoholic liver damage.

The purpose of this study was to clarify the effects of fish oil on the gut microbiota of rats with alcoholic liver damage. Thirty-six male Wistar rats (8 weeks old) were divided into six groups: C (control), CF25 (control diet with 25% fish oil substitution), CF57 (control diet with 57% fish oil substitution), E (ethanol-containing diet), EF25 (ethanol-containing diet with 25% fish oil substitution), and EF57 (ethanol-containing diet with 57% fish oil substitution) groups. All groups were pair-fed an isoenergetic diet based on the E group. Rats were sacrificed after 8 weeks. Rats in the E group showed significant hepatic injuries including high plasma aspartate transaminase and alanine transaminase activities, hepatic cytokine levels, plasma endotoxin level, and protein expression of the toll-like receptor-4 signaling pathway; moreover, lipid accumulation and inflammation based on histological examinations were also observed. In contrast, these phenomena was ameliorated in rats of the EF25 and EF57 groups. Although the intestinal structure did not change among the groups, alterations in the gut microbiotic composition were observed due to chronic ethanol intake and fish oil replacement such as the Firmicutes-to-Bacteroidetes ratio, Chao-1 index, ACE index, a principal component analysis and linear discriminant analysis of effect size. In terms of the gut-liver axis, this study confirmed that fish oil replacement exerted ameliorative effects on ethanol-induced liver injuries in rats by acting through alterations in the microbiotic composition.

Fish oil up-regulates hepatic autophagy in rats with chronic ethanol consumption.

In this study, we examined the regulation of autophagy by fish oil in rats under ethanol-containing diets. Thirty male Wistar rats (8-week-old) were divided into six groups and fed a control diet or an ethanol-containing diet, which was adjusted with fish oil to replace 25% or 57% of the olive oil. After 8 weeks, rats in the E (ethanol diet) group showed the significantly higher plasma aspartate transaminase (AST) and alanine transaminase (ALT) activities, protein expression of cytochrome P450 2E1 (CYP2E1), and levels of hepatic inflammatory cytokines. However, all of those items had significantly decreased in the EF25 (ethanol with 25% fish oil) and EF57 (ethanol with 57% fish oil) groups. As to autophagic indicators, protein expressions of mammalian target of rapamycin (mTOR), Unc-51-like autophagy activating kinase 1 (ULK1) and p62 were significantly increased in the E group. Conversely, the protein expressions of light chain 3II (LC3II)/LC3I and Beclin1 were significantly decreased in the E group. On the other hand, protein expressions of phosphorylated Akt, mTOR, ULK1, and p62 were down-regulated, protein expressions of LC3II/LC3I and Beclin1 were conversely up-regulated in the EF25 and EF57 groups. Fish oil activated hepatic autophagy via inhibiting the Akt signaling pathway, which exerted protective effects against ethanol-induced liver injury in rats.

Effects of Fish Oil on Lipid Metabolism and Its Molecular Biological Regulators in Chronic Ethanol-Fed Rats.

The purpose of this study was to clarify the hepatoprotective mechanisms of fish oil in ethanol-fed rats based on lipid metabolism. Thirty eight-week-old male Wistar rats were divided into six groups: C (control), CF25 (control diet with 25% fish oil substitution), CF57 (control diet with 57% fish oil substitution), E (ethanol-containing diet) group, EF25 (ethanol-containing diet with 25% fish oil substitution), and EF57 (ethanol-containing diet with 57% fish oil substitution) groups. All of the groups were pair-fed an isoenergetic diet based on E group. Rats were sacrificed after eight weeks. When compared with C group, the plasma aspartate transaminase (AST) activity and hepatic steatosis and inflammatory cell infiltration were significantly higher, while plasma adiponectin level and hepatic AMP-activated protein kinase α (AMPKα) protein expression was significantly lower in the E group. However, the hepatic damage, including steatosis and inflammation were ameliorated in the EF25 and EF57 groups. Moreover, mRNA levels of fatty acid-oxidative enzymes, such as medium-chain acyl-coenzyme A dehydrogenase (MCAD) and carnitine palmitoyltransferase I (CPT-1) were significantly elevated in the EF57 group than those in E group. Partial replacement with fish oil might improve the fatty acid oxidation by raising mRNA levels of downstream transcription factors, finally inhibit the ethanol-induced hepatic steatosis in rats.