Effect of antioxidant capacity on blood lipid metabolism and lipoprotein lipase activity of rats fed a high-fat diet.

Objective: The present study explored the effect of antioxidant capacity on blood lipid metabolism and lipoprotein lipase (LPL) activity of rats fed with a high-fat diet (HFD). Furthermore, the relation of the atherosclerotic index (AI) and LPL activity to total antioxidant capacity (TAC) was studied.

Methods: Thirty-two Sprague-Dawley rats were randomly assigned to one of four groups (n = 8). The control group consumed an ordinary diet (5.1% fat, w/w). The other three experimental groups were fed with an HFD (14.1% fat, w/w), an HFD plus 0.1% lipoic acid (LA), or an HFD plus 0.1% N-acetylcysteine (NAC). After 4 wk, serum levels of triacylglycerol, total cholesterol, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol and LPL activity were examined. To evaluate rats' antioxidant status, TAC and superoxide dismutase activities and malondialdehyde level were measured.

Results: The HFD induced abnormal increases in lipid peroxidation, serum concentrations of total cholesterol, triacylglycerol, and low-density lipoprotein cholesterol, and a decrease in high-density lipoprotein cholesterol concentration. Decreased activity of LPL, accompanied by a depressed antioxidant defense system, was observed in HFD-fed rats. These changes were partially restored in the NAC- and LA-treated groups. There was a negative correlation between AI and TAC (r = -0.969, P < 0.05). In addition, a significant positive correlation between LPL activity and TAC was found (r = 0.979, P < 0.05).

Conclusion: Oxidative injury and lipid abnormalities were induced by an HFD. Administration of LA and NAC can improve the antioxidant capacity and activity of LPL and reduce blood lipid significantly. Antioxidant capacity is correlated with AI and LPL activity.