High-fat diet reduces levels of type I tropocollagen and hyaluronan in rat skin.

Although it is known that nutritional conditions affect the skin function, little information is available on the effect of a high-fat (HF) diet on skin. In this study, Sprague-Dawley rats were fed HF diets for 28 days, and we investigated the effect of this diet on type I tropocollagen and hyaluronan in rat skin. The HF diets reduced the levels of type I tropocollagen, COL1A1 mRNA, hyaluronan, and rat hyaluronan synthase (rhas)2 mRNA, which play a primary role in hyaluronan synthase in the dermis. However, rhas3 mRNA level in the skin was increased. The HF diets also decreased the skin mRNA expression of transforming growth factor (TGF)-beta1, which enhances the expression of COL1A1 and rhas2 mRNA and decreases rhas3 mRNA expression, and decreased the hepatic mRNA expression of insulin-like growth factor (IGF)-I, which enhances COL1A1, rhas2, and TGF-beta1 mRNA expression. The serum level of adiponectin, which promotes the syntheses of type I collagen and hyaluronan, was decreased in the HF diet groups. These findings suggest that an HF diet reduces the levels of type I tropocollagen and hyaluronan in the skin by suppressing the action of TGF-beta1, IGF-I and adiponectin, and these effects are deleterious for skin function.