ABSTRACT
Butyrate is a short-chain fatty acid produced during fermentation of fibers and other substrates in the gastrointestinal tract. A recent study has shown that elevation of butyrate availability by dietary supplementation exerts favorable effects on glucose metabolism. However, it remains unclear whether butyrate intake affects insulin-sensitive glucose transporter (GLUT-4) protein content in skeletal muscle, which has been shown to be closely related to muscle glucose transport capacity and whole-body insulin sensitivity. The purpose of this study was therefore to examine the effects of dietary intake of butyrate on muscle GLUT-4 protein content and whole-body insulin sensitivity in rats. Seven-week-old male Sprague-Dawley rats were placed on a sodium butyrate diet (SB) or standard chow diet (CON) for 2 wks. Sodium butyrate was incorporated into the standard chow diet at 5 % wt/wt. After the 2-wk dietary intervention, insulin tolerance test (ITT) was performed to evaluate whole-body insulin sensitivity. GLUT-4 protein contents in soleus and epitrochlearis muscles were determined by western blot analysis. There were no significant differences in body weight, food intake and intra-abdominal fat weight between the SB and CON groups. GLUT-4 protein contents in soleus and epitrochlearis muscle were significantly lower in the SB than CON group. The SB group had less reduction in glycemia than did the CON group during ITT. These results suggest that dietary intake of sodium butyrate may decrease muscle GLUT-4 protein content and impair whole-body insulin sensitivity in rats.