Dietary cod protein decreases triacylglycerol accumulation and fatty acid desaturase indices in the liver of obese type-2 diabetic KK-Ay mice

This study investigated the effects of cod protein (CP) on the serum, liver, fecal lipid contents and fatty acid (FA) composition in the liver of obese type-2 diabetic KK-Ay mice. Male KK-Ay mice were fed a casein-based semi-purified diet (Control) or a diet with substitution of part of the dietary protein (50%) by CP for 4 weeks. The CP diet significantly decreased the contents of serum triacylglycerol (TAG), serum non-esterified FAs, serum alanine aminotransferase, and liver TAG compared with the Control diet. In addition, dietary CP decreased saturated FA, monounsaturated FA, and the FA desaturase indices (C16:1/C16:0 and C18:1/C18:0) in the liver. The changes in FA desaturase indices induced by the FP diet could be inhibited by stearoyl-CoA desaturase (SCD)-1 activity due to suppression of the SCD-1 mRNA expression level. These results suggest that the intake of CP has a beneficial effect on the liver in the presence of obesity and diabetes.