Lipid lowering effect of omega-3 fatty acids in genetically obese zucker rats

Abstract

Omega-3 fatty acids (n-3 FA) are known to reduce blood lipid levels. Recent data, however, suggested that n-3 FA supplementation may worsen glycemic control in diabetic humans. This study was designed to explore the effects of n-3 FA feeding on lipid metabolism and glycemic control in a strain of genetically obese, hyperlipidemic rats. Lean and obese Zucker rats were fed a semi-purified diet made with either n-3 FA or corn oil (n-6, 10% w/w for both diets). After 16 weeks feeding, lean and obese rats fed the n-3 FA diet showed a significant reduction in blood triglyceride (TG) levels. Obese rats had significantly elevated TG levels in comparison with lean rats. Lean n-3 FA fed rats had elevated lipoprotein lipase activity in adipose tissue while hepatic triglyceride lipase activity was lowered by n-3 FA feeding in both lean and obese rats. Hepatic lipogenic enzyme activities were suppressed by fish oil feeding. However, fish oil feeding significantly increased hepatic gluconeogenic enzyme activity in lean rats. Therefore, n-3 FA feeding may exert different effects on blood lipid and glucose levels in lean and obese subjects.