Serum from Jiao-Tai-Wan treated rats increases glucose consumption by 3T3-L1 adipocytes through AMPK pathway signaling.

Type 2 diabetes (T2DM) is characterized by hyperglycemia resulting from insulin resistance. Jiao-Tai-Wan (JTW), a traditional Chinese medicine consisting of a 10:1 formulation of Rhizoma Coptidis (RC) and Cortex Cinnamomi (cinnamon) was shown to have hypoglycemic efficacy in a type 2 diabetic mouse model. Here we investigated whether glucose consumption by insulin-resistant adipocytes could be modulated by serum from JTW-treated rats, and if so, through what mechanism. JTW-medicated serum was prepared from rats following oral administration of JTW decoction twice a day for 4 days. Fully differentiated 3T3-L1 adipocytes - rendered insulin resistance by dexamethasone treatment - were cultured in medium containing JTW-medicated rat serum. JTW-medicated serum treatment increased glucose uptake, up-regulated levels of phosphorylated adenosine 5'-monophoshate-activated protein kinase (p-AMPK), and stimulated expression and translocation of glucose transporter 4 (GLUT4). JTW-medicated serum induced significantly greater up-regulation of p-AMPK and GLUT4 than either RC or cinnamon-medicated serum. JTW-medicated serum induced effects on 3T3-L1 adipocytes could be partially inhibited by treatment with the AMPK inhibitor compound C. In conclusion, JTW-medicated serum increased glucose consumption by IR adipocytes partially through the activation of the AMPK pathway, and JTW was more effective on glucose consumption than either RC or cinnamon alone.

Anti-Diabetic Activities of Jiaotaiwan in db/db Mice by Augmentation of AMPK Protein Activity and Upregulation of GLUT4 Expression.

Jiaotaiwan (JTW), which is composed of Coptis chinensis (CC) and cinnamon (CIN), is one of the most well-known traditional Chinese medicines. In this study, we investigated the antidiabetic effects and mechanism of JTW in db/db mice. Results showed that JTW significantly decreased the level of fasting blood glucose and improved glucose and insulin tolerance better than CC or CIN alone. JTW also effectively protected the pancreatic islet shape, augmented the activation of AMP-activated protein kinase (AMPK) in the liver, and increased the expression of glucose transporter 4 (GLUT4) protein in skeletal muscle and white fat. AMPK and GLUT4 contributed to glucose metabolism regulation and had an essential function in the development of diabetes mellitus (DM). Therefore, the mechanisms of JTW may be related to suppressing gluconeogenesis by activating AMPK in the liver and affecting glucose uptake in surrounding tissues through the upregulation of GLUT4 protein expression. These findings provided a new insight into the antidiabetic clinical applications of JTW and demonstrated the potential of JTW as a new drug candidate for DM treatment.