Effect of L-carnitine administration on serum insulin and adiponectin levels, and AMPK, APPL1 and PPARγ gene expression in STZ-induced diabetic rat liver

Diabetes is considered as a metabolic disease in which insulin secretion and functions are disturbed and characterized by hyperglycemia. L-carnitine is synthesized in most mammals and plays critical role in fatty acid oxidation and energy production. Data about the L-carnitine hypoglycemic effects are controversial. We evaluated long-term oral L-carnitine administration effects on blood glucose, insulin and adiponectin levels, as well as expression of AMPK, APPL1 and PPARγ genes in liver of STZ-induced diabetic rats. Group 1 (control), did not receive any treatment, group 2 received 50 mg/kg STZ by i.p injection, group 3 received single dose of 50 mg/kg STZ by i.p injection and also 600 mg/kg/day L-carnitine orally for 5 weeks. Our results showed that L-carnitine long-term oral supplementation significantly reduced blood glucose and normalized insulin levels in diabetic rats. Also, we found that L-carnitine significantly increased AMPK and APPL1 expression, and showed a mild elevation of PPARγ expression. In sum, we suggest that long-term L-carnitine supplementation has beneficial effects on diabetic rats which showed hypoglycemic effects. Probably the beneficial effects of L-carnitine are contributed to the upregulation of insulin sensitizers such as AMPK and adiponectin