Submitted on April 18, 2005
Accepted on July 18, 2005
Topiramate Treatment Causes Skeletal Muscle Insulin Sensitization And Increased Acrp30 Secretion In High-Fa--Fed Male Wistar Rats
Jason J Wilkes1*, M.T. Audrey Nguyen1, Gautam K Bandyopadhyay1, Elizabeth Nelson1, and Jerrold M Olefsky1
1 Department of Medicine, University of California, San Diego, La Jolla, USA
* To whom correspondence should be addressed. E-mail: wilkesjason{at}hotmail.com.
We show that Topiramate (TPM) treatment normalizes whole body insulin sensitivity in high-fat-diet (HFD) fed male Wistar rats. Thus, drug treatment markedly lowered glucose and insulin levels during GTTs and caused increased insulin sensitization in adipose and muscle tissues as assessed by euglycemic clamp studies. The insulin stimulated glucose disposal rate (GDR) increased by 2-fold (indicating enhanced muscle insulin sensitivity) and suppression of circulating FFAs increased by 200 to 300% consistent with increased adipose tissue insulin sensitivity. There were no effects of TPM on hepatic insulin sensitivity in these TPM treated HFD fed rats. In addition, TPM administration resulted in 3-4 fold increase in circulating levels of total and high molecular weight (HMW) adiponectin (Acrp30). Western blot analysis revealed normal AMPK (Thr172) phosphorylation in liver with a 2-fold increased phospho AMPK in skeletal muscle in TPM treated rats. In conclusion: 1) TPM treatment prevents overall insulin resistance in HFD male Wistar rats. 2) Drug treatment improved insulin sensitivity in skeletal muscle and adipose tissue associated with enhanced AMPK phosphorylation. 3) The tissue "specific" effects are associated with increased serum levels of adiponectin, particularly the HMW component.
