Fish oil and fenofibrate inhibit pancreatic islet hypertrophy, and improve glucose and lipid metabolic dysfuntions with different ways in diabetic KK mice.

We examined the effects of fish oil and fenofibrate (FF) on the pancreatic islet hypertrophy, and on the modification of glucose and lipid metabolic dysfunctions in KK mice with insulin resistance. The mice were fed one of four diets [25en% lard/safflower oil (LSO), 25en% fish oil (FO), or each of these diets plus 0.1wt% FF (LSO/FF, FO/FF)] for 9 weeks. FO group and both FF groups had significantly lower final body and adipose tissue weights than LSO group. Pancreatic islet hypertrophy was observed only in LSO group but not in the other groups with fish oil or FF. And, it is likely that fish oil has a stronger therapeutic effect on islet hypertrophy. Plasma adiponectin level was significantly higher in FO group but not in both FF groups. Expression of hepatic lipogenic enzyme genes such as fatty acid synthase (FAS) and stearoyl-CoA desaturase-1 (SCD-1) was lower in FO groups with or without FF, whereas fatty acid oxidation-related mRNAs such as acyl-CoA oxidase (AOX) and uncoupling protein-2 (UCP-2) were more abundant in FF groups with or without fish oil. Our results suggest that both fish oil and FF improve pancreatic islet hypertrophy with the amelioration of insulin resistance. Fish oil enhances insulin sensitivity by increasing plasma adiponectin; however, the beneficial effect of FF on insulin resistance seems to be independent of the plasma adiponectin level. These results mean that improvement of glucose and lipid metabolic dysfuctions in diabetic KK mice are independently approached by fish oil and FF.