Dietary Camphene Attenuates Hepatic Steatosis and Insulin Resistance in Mice

Objective: The aim of this study was to investigate the protective effects of camphene on high-fat diet (HFD)-induced hepatic steatosis and insulin resistance in mice and to elucidate its mechanism of action. Design and Methods: Male C57BL/6N mice were fed with a normal diet, HFD (20% fat and 1% cholesterol of total diet), or HFD supplemented with 0.2% camphene (CPND) for 10 weeks. Results: Camphene alleviated the HFD-induced increases in liver weight and hepatic lipid levels in mice. Camphene also increased circulating adiponectin levels. To examine the direct effects of camphene on adiponectin secretion, 3T3-L1 adipocytes were incubated with camphene. Consistent with in vivo result, camphene increased adiponectin expression and secretion in 3T3-L1 adipocytes. In HFD-fed mice, camphene increased hepatic adiponectin receptor expression and AMP-activated protein kinase (AMPK) activation. Concordant with the activation of adiponectin-AMPK signaling, camphene increased hepatic expression of fatty acid oxidation-related genes and decreased those of lipogenesis-related genes in HFD-fed mice. Moreover, camphene increased insulin-signaling molecules activation and stimulated glucose transporter-2translocation to the plasma membrane in the liver. Conclusions: These results suggest camphene prevents HFD-induced hepatic steatosis and insulin resistance in mice; furthermore, these protective effects are mediated via the activation of adiponectin-AMPK signaling.