Aim: 

Lipoic acid, a natural antioxidant compound, has shown several beneficial effects in obesity and diabetes. The aim of this study was to determine the effects of dietary supplementation with lipoic acid on leptin and adiponectin, two adipokines involved in the control of body weight and insulin sensitivity.

Methods: 

Control and high fat-fed male Wistar rats were assigned into two subgroups; in one of them the diet was supplemented with a-lipoic acid (0.25wt/100wt of diet) during 8 weeks. Two Pair-Fed groups, which received the same amount of food eaten by the groups treated with lipoic acid, but without adding this antioxidant, were also included in order to evaluate if the effects of lipoic acid are only secondary to its effects on food intake.

Results: 

Lipoic acid significantly decreased plasma leptin levels in both lean (P<0.001) and obese (P<0.01) rats, which appears to be secondary to the lipoic acid reduction of fat depots. In contrast, lipoic acid caused a significant increase in adiponectin circulating levels mainly in lean rats (P<0.001). In addition, lipoic acid supplementation induced a significant increase in the adiponectin/total white adipose tissue (WAT) ratio (P<0.05) in obese rats, which was not observed in its corresponding pair fed group, suggesting a direct stimulatory action of lipoic acid on adiponectin production by adipose tissue. Furthermore, a significant negative correlation between the HOMA index and serum adiponectin/total WAT ratio was also observed. (r= -0.548, P<0.01).

Conclusion: 

These data suggest that the lipoic acid beneficial effects on insulin resistance could be secondary, at least in part, to its effects on adiponectin levels.