L-carnitine administration effects on AMPK, APPL1 and PPARγ genes expression in the liver and serum adiponectin levels and HOMA-IR in type 2 diabetes rat model induced by STZ and nicotinamide

Abstract

Diabetes is a chronic disease and a public health problem globally. L-Carnitine is synthesized in the liver, promotes fatty acids oxidation and currently is used as a supplement against weight gain. Carnitine level is found to be reduced in diabetic patients and to be beneficial as a supplement at diabetes, but the mechanisms­ of this effect is not fully understood. Therefore, we evaluated the oral L-carnitine supplementation on expression of AMP-activated protein kinase (AMPK), peroxisome proliferator-activated receptor gamma (PPARγ), adaptor protein APPL1 genes in the liver and insulin and adiponectin levels in the serum of diabetic rats. Rats were randomly divided into three groups (n = 8) as follow: group 1 – control without any treatment, group 2 – diabetic control rats which received STZ (45 mg/kg) and nicotinamide (200 mg/kg) by i.p. injection, group 3 – diabetic rats which received 600 mg/kg/day carnitine orally for 35 days. It was found that L-carnitine supplementation reduced the level of fasting glucose compared to that in control and diabetic groups (P = 0.001, P = 0.0001 respectively) and increased adiponectin level compared to diabetic nontreated rats (P = 0.0001). Homeostasis model assessment of insulin resistance (HOMA-IR) was significantly increased in the diabetic group and reduced in the group that received L-carnitine. These promising beneficial effect of L-carnitine on the type 2 diabetes in rats’ model was shown to be conducted through the up-regulation of AMPK, PPARγ and APPL1 genes expression in the liver and elevation of serum adiponectin level.

Keywords

• l-carnitine
• diabetes
• nicotinamide
• homa-ir
• ampk
• pparγ
• appl1