Effects of the Chinese medicine Jiang-Tang-Ke-Li on insulin resistance in fructose-fed rats

The aim of this study was to determine the effect of Jiang-Tang-Ke-Li (JTKL ), a Chinese medicine used to treat diabetes mellitus, on insulin resistanc e and hypertension in fructose-fed rats (FFR). Six-week-old male Sprague-Da wley rats were fed either normal rat chow (control) or a fructose-rich chow (FFR) for 6 weeks. For the last 2 weeks of the 6-week period of either die t, the rats were treated by gavage with gum arabic solution as a vehicle (c ontrol or FFR) or JTKL (3.24 g/kg/day; FFR+JT), and then an euglycemic hype rinsulinemic glucose clamp technique was performed to estimate insulin sens itivity. Systolic blood pressure was measured each week of the 6-week perio d. At the end of the glucose clamp, the soleus and extensor digitorum longu s (EDL) muscles were dissected out for determination of the role of tumor n ecrosis factor (TNF)-alpha by an ELISA assay, Systolic blood pressures in t he FFR groups were significantly higher than that in the control group, alt hough there was no effect on systolic blood pressure for the last 2 weeks o f treatment with JTKL, The average rate of glucose infusion during the gluc ose clamp, as an index of insulin sensitivity (M value), was significantly lower in the FFR than in the control rats, and treatment with JTKL for 2 we eks significantly increased the M value to that of control. TNF-alpha level s were significantly higher in the soleus and EDL muscles of the FFR (480 /- 46 and 570 +/- 45 pg/g wet tissue in the soleus and EDL muscles, respect ively) than in those of the control rats (177 +/- 34 and 206 +/- 33 pg/g we t tissue in the soleus and EDL muscles, respectively; p <0.01). Treatment w ith JTKL for 2 weeks significantly lowered TNF-alpha levels to the control levels (189 +/- 22 and 239 +/- 92 pg/g wet tissue in the soleus and EDL mus cles, respectively). The results suggest that the Chinese medicine JTKL imp roves insulin resistance and modulates TNF-alpha in the soleus and EDL musc les in hypertensive and insulin-resistant fructose-fed rats.