Tangshen Formula Attenuates Colonic Structure Remodeling in Type 2 Diabetic Rats

Effect of Tangshen formula on the remodeling of small intestine and colon in Zucker diabetic fatty rats

Background and aim

Previous study have demonstrated that Tangshen Formula (TSF) could attenuate colonic histomorphological remodeling in the diabetic rat model induced by high fat diet plus low dosage streptozotocin (STZ). However, it is not clear whether TSF has same effect on small intestine and the effect on biomechanical properties of bowel. The aim of this study is to investigate the effect of TSF on histomorphological and biomechanical remodeling of small intestine and colon by using Zucker Diabetic Fatty (ZDF) Rat model.

Materials and methods

ZDF rats (obese fa/fa) with blood glucose higher than 11.7 mmol/L were divided into ZDF group (diabetic control group) and ZDF + TSF group (TSF treatment group), the later were intragastrically administered TSF. The ZDF rats (lean fa/+) were served as normal control (ZL) group. The rats in the ZL and ZDF groups were administered with saline. The experimental period covered from 8 weeks to 24 weeks. At the end of experiment, the ileal and colonic segments were studied in vitro. The histomorphometry and biomechanical parameters were measured.

Results

Compared with ZL group histomorphologically, the wet weight per unit length, wall thickness, wall area and fractions of total and type I and type III collagen in different layers for both ileum and colon increased in ZDF group. Those increasing parameters were partially inhibited in ZDF + TSF group. Compared with ZL group biomechanically, ZDF and ZDF + TSF groups had smaller opening angle and residual strain in ileum, and bigger opening angle and residual strain in colon. Whereas the wall became softer in circumferential direction and stiffer in longitudinal direction for both ileum and colon. However, no difference of biomechanical parameters was found between ZDF and ZDF + TSF groups.

Conclusion

The histomorphological and biomechanical remodeling of ileum and colon were happened in ZDF rats （obese fa/fa）. TSF could partly attenuate ileal and colonic histomorphological remodeling rather than biomechanical remodeling.

Protective Effect of Tangshen Formula () on Interstitial Cells of Cajal in Colon of Diabetic Rats

OBJECTIVE

To explore the effect of Tangshen Formula (, TSF), a Chinese herbal medicine, on interstitial cells of Cajal (ICC) in the colon of diabetic rats.

METHODS

Fifty-four male Wistar rats were randomly divided into normal control (NC, n=14) and high-fat diet (HFD) groups (n=40). After 6 weeks, the rats in the HFD group were injected intraperitoneally streptozotocin once (30 mg/kg). Thirty rats with fasting blood glucose higher than 11.7 mmol/L were randomly divided into diabetes (DM) and TSF groups, 15 rats in each group. Rats in the NC and DM groups were intragastrically administered with saline, and those in the TSF group were given with TSF (2.4 g/kg) once daily for 20 weeks. Expression levels of Bax, Bcl-2, and caspase-3 in colonic smooth muscle layer were measured by Western blotting and immunohistochemical staining. The number of ICC was determined by immunohistochemical staining. Immunofluorescence was used for analyzing the ratio of classically activated macrophages (M1) and alternatively activated macrophages (M2) to total macrophages. Electron microscopy was used to observe the epithelial ultrastructure and junctions.

RESULTS

TSF appeared to partially prevented loss of ICC in DM rats (P<0.05). Compared with the NC group, expression levels of Bcl-2, Bax, caspase-3, and TNF-α as well as the ratio of M1 to total macrophages increased in DM rats (all P<0.05), and the ratio of M2 to total macrophages decreased (P<0.05 or P<0.01). Compared with the DM group, TSF decreased the expression levels of abovementioned proteins and restore M2 to total macrophages ratio (P<0.05 or P<0.01). TSF appeared to attenuate the ultrastructural changes of epithelia and improve the tight and desmosome junctions between epithelia reduced in the DM rats.

CONCLUSION

Reduced number of ICC in DM rats may be associated with damage of the intestinal barrier. The protective effects of TSF on ICC may be through repair of the epithelial junctions, which attenuates inflammation and inflammation-initiated apoptosis in colon of DM rats.