Dietary Conjugated Linoleic Acid Alleviates Nonalcoholic Fatty Liver Disease in Zucker (fa/fa) Rats

Abstract

Nonalcoholic fatty liver disease (NAFLD) is the preferred term to describe the spectrum of liver damage ranging from hepatic steatosis to steatohepatitis, liver fibrosis, and cirrhosis, and it is emerging as the most common liver disease in industrialized countries. Thus, the discovery of food components that would ameliorate NAFLD is of interest. Conjugated linoleic acid (CLA), a mixture of positional and geometric isomers of linoleic acid, has attracted considerable attention because of its potentially beneficial biological effects both in vitro and in vivo. We tested whether dietary CLA protects Zucker (fa/fa) rats from hepatic injury. After 8 wk of feeding, hepatomegaly, hepatic triglyceride (TG) accumulation, and elevated hepatic injury markers in plasma were markedly alleviated in CLA-fed Zucker rats compared with linoleic acid-fed (control) rats. These effects were attributed in part to the enhanced hepatic activities of carnitine palmitoyltransferase, a key enzyme of fatty acid beta-oxidation, and microsomal TG transfer protein, an important factor for lipoprotein secretion due to the CLA diet. We previously reported that the severe hyperinsulinemia in control Zucker rats was attenuated in CLA-fed rats due to an enhanced level of plasma adiponectin, which improves insulin sensitivity. In the present study, the adiponectin concentration was increased and the mRNA expression of tumor necrosis factor-alpha, an inflammatory cytokine, was markedly suppressed in the liver of CLA-fed Zucker rats. We speculate that the enhanced level of liver adiponectin may prevent the development and progression of NAFLD in CLA-fed Zucker rats.

Maintenance of adiponectin attenuates insulin resistance induced by dietary conjugated linoleic acid in mice

“…Although it is unclear why the combination of CLA with ROSI has additional effects in liver and muscle, it may be attributable to increased adiponectin levels with ROSI administration. It is possible that in the presence of adequate adiponectin, CLA increases lipid utilization and decreases lipid accumulation in tissues, similar to observations from rat studies (33)(34)(35).…”

Anti‐obesity effects of conjugated linoleic acid, docosahexaenoic acid, and eicosapentaenoic acid

“…The adverse effects to induce fat liver and/hepatic steatosis have been also observed by other groups, and increasing studies indicate that t10, c12 isomer is the major player [9,22,97,133]. However, dietary CLA was reported to alleviate nonalcoholic fatty liver disease or hepatic steatosis in ZDF rats [134,135]. The discrepancy illustrated a relationship between the state of insulin resistance and liver-lipid metabolism, and suggested that CLA might act to favorably modify lipid metabolism in ZDF rats.…”

Physiological Functions of iso-type Short-Chain Fatty Acid and Omega 3 Polyunsaturated Fatty Acids Containing Oil in Obese OLETF Rats

“…Previous study indicates that adiponectin has protective effects against fatty liver disease 49 . Additionally, we previously suggested that the enhanced levels of serum and liver adiponectin contribute to the alleviation of fatty liver diseases through the enhancement of lipoprotein synthesis and secretion in Zucker fa/fa rats 50 . In the present study, serum adiponectin level was signifi cantly increased by porpoise oil feeding.…”