Topiramate treatment causes skeletal muscle insulin sensitization and increased Acrp30 secretion in high-fat-fed male Wistar rats

Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego; and The Whittier Diabetes Institute, La Jolla, California Submitted 18 April 2005 ; accepted in final form 18 July 2005 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 glucose tolerance tests and caused increased insulin sensitization in adipose and muscle tissues as assessed by euglycemic clamp studies. The insulin-stimulated glucose disposal rate increased twofold (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 a three- to fourfold increase in circulating levels of total and high-molecular-weight (HMW) adiponectin (Acrp30). Western blot analysis revealed normal AMPK (Thr 172 ) phosphorylation in liver with a twofold 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; and 3 ) the tissue "specific" effects are associated with increased serum levels of adiponectin, particularly the HMW component. high fat; insulin sensitization; adenosine monophosphate-activated protein kinase; adiponectin Address for reprint requests and other correspondence: J. Wilkes, Dept. of Medicine (0673), UCSD, 9500 Gilman Dr., La Jolla, CA 92093 (e-mail: jwilkes{at}gnf.org )