Impact of L-Carnitine and Cinnamon on Insulin-Like Growth Factor-1 and Inducible Nitric Oxide Synthase Gene Expression in Heart and Brain of Insulin Resistant Rats

Problem statement: Evaluate the effects of daily administration of L-carnitine and cinnamon extract for two weeks on the expression of Insulin-like Growth Factor-1 (IGF-1) and inducible Nitric Oxide Synthase (iNOS) genes in cardiac and brain tissues of rats with Insulin Resistance (IR). Approach: Rats were divided into 4 groups (8 animals each): Group (1) rats fed control diet (60% starch) as control while groups (2, 3 and 4) fed high fructose diet (60% fructose). At the beginning of the 3rd week of feeding, rats of group (3) were treated with L-carnitine (300 mg kg^-1 body weight/day, i.p.) and animals of group (4) received a daily oral dose of cinnamon aqueous extract (0.5 mL rat^-1). The animals were maintained in their respective groups for 4 weeks. Results: Feeding high fructose diet causes significant reduction in Insulin Receptor Substrate-1 (IRS-1) (amounted 30.65%) and elevation in iNOS expression (reached 51%) in the cardiac tissues as compared to control. In brain tissues, the IGF-1 mRNA was reduced in fructose loaded groups (28.81%). Administration of either L-carnitine or cinnamon extract significantly improves the expression of the cardiac studied genes but with no effects on the brain tissues. Conclusion: The present study illustrated that CE was more potent than L-carnitine in improving the IR.