Mechanism Investigation of the Improvement of Chang Run Tong on the Colonic Remodeling in Streptozotocin-Induced Diabetic Rats

Abstract

Previous study demonstrated that Chang Run Tong (CRT) could partly restore the colon remodeling in streptozotocin- (STZ-) induced diabetic rats. Here we investigated the mechanisms of such effects of CRT. Diabetes was induced by a single injection of 40 mg/kg of STZ. CRT was poured into the stomach by gastric lavage once daily for 60 days. The remodeling parameters were obtained from diabetic (DM), CRT treated diabetic (T1, 50 g/kg; T2, 25 g/kg), and normal (Con) rats. Expressions of advanced glycation end product (AGE), AGE receptor, transforming growth factor-β1 (TGF-β1), and TGF-β1 receptor in the colon wall were immunochemically detected and quantitatively analyzed. The association between the expressions of those proteins and the remodeling parameters was analyzed. The expressions of those proteins were significantly higher in different colon layers in the DM group (P < 0.05, P < 0.01) and highly correlated to the remodeling parameters. Furthermore, the expressions of those proteins were significantly decreased in the T1 group (P < 0.05, P < 0.01) but not in the T2 group (P > 0.05). The corrective effect on the expressions of those proteins is likely to be one molecular pathway for the improvement of CRT on the diabetes-induced colon remodeling.

Figure 1

The representative samples of immunohistochemical staining for AGE, RAGE, TGF-β1, and TGF-β1 receptor in different groups. The brown color indicated positive staining and the arrows were to point the examples where the immunostaining is positive. The staining of all proteins was stronger in the muscle layer than other layers. The staining of AGE, RAGE, TGF-β1, and TGF-β1 receptor in different layers was stronger in the DM group than in Con group. Treatment with a high dosage of CRT (T1 group) partially reversed the abnormal expressions of different proteins in the different layers of the colon wall; however they did not significantly change in the T2 group. Bar = 1 mm.