Regulatory Effects of Skate Skin-Derived Collagen Peptides with Different Molecular Weights on Lipid Metabolism in the Liver and Adipose Tissue

This study investigated the effects of skate skin collagen peptide (SSCP) with different molecular weights (MWs) on the lipid metabolism in the liver and adipose tissue. Male db/db mice were orally administered with water (control group) or low SSCP (LCP group) or high SSCP (HCP group) MW for 8 weeks whereas male m/m mice were used for comparison (normal group) (n = 10 each group). Compared to the control group, the LCP and HCP groups had lower adipose tissue mass, plasma and hepatic lipid concentrations, and plasma leptin levels (p < 0.05). Protein expression levels of lipogenesis-related protein were reduced in both liver and adipose tissues of SSCP-fed groups whereas those for lipolysis were elevated (p < 0.05). In particular, the LCP had the higher effects relative to the HCP. The above results were supported by histological analysis, revealing that SSCP administration decreased the size of adipose droplets and suppressed hepatic lipid accumulation. Our results showed that SSCP has potential antiobesity properties through the improvement of lipid metabolism in the liver and adipose tissue; in particular, the lower MW of collagen peptide had the greater effects.