ABSTRACT
Objective: To observe the effect of Schisandra Chinensis polysaccharide (SCP) on the serum inflammatory factors in the rats with type 2 diabetes mellitus (T2DM) induced by high-fat diet and low dose of streptozotocin (STZ), and to explore its underlying mechanism in the treatment of T2DM. Methods: The male Wistar rats were given high-fat diet and introperieoneally injected with low dose of STZ (30 mg · kg-1) in one time to establish the rat T2DM models. The successful model rats were randomly divided into model group, low dose (25 mg · kg-1)of SCP group, middle dose (50 mg · kg-1) of SCP group and high dose (100 mg · kg-1) of SCP group; there were 10 rats in each group. Another 10 healthy rats were used as normal control group. Eight weeks after the intragastric administration of SCP, oral glucose tolerance test (OGTT) was performed in the rats of various groups. The fasting blood glucose (FBG) and insulin (INS) levels were detected by glucose oxidase method and radioimmunoassay method, respectively, and the insulin sensitivity index (ISI) was calculated. The levels of interleukin-6 (IL-6), C-reactive protein (CRP), interleukin-lβ (IL-lβ), tumor necrosis factor-α (TNF-α) and nuclear factor-κB (NF-κB) in serum of the rats were measured by enzyme linked immunosorbent assay (ELISA) method. HE staining was used to observe the pathomorphology of pancreas tissue of the rats. Results: Compared with normal control group, the serum FBG level of the rats in model group was significantly increased (P<0.01), and the area under the curve (AUC) of blood glucose of the rats was significantly increased, the serum INS level and the ISI were significantly decreased (P<0.05 or P<0.01); the levels of IL-6, CRP, IL-1β, TNF-α, and NF-κB in serum were all significantly increased (P<0.05 or P<0.01). Compared with model group, the serum FBG levels of the rats in different doses of SCP groups were markedly decreased (P<0.05), the AUC of blood glucose of the rats were significantly decreased, the INS and the ISI levels were significantly elevated (P<0.05); the levels of IL-6, CRP, IL-1β, TNF-α and NF-κB in serum were significantly decreased (P<0.05 or P<0.01). Compared with low dose of SCP group, the FBG levels of the rats in middle and high doses of SCP groups were significantly decreased (P<0.05), the serum INS level of the rats in high dose of SCP group was significantly increased (P<0.05). The HE staining results showed that compared with normal control group, the islets were atrophied, the number of cells in islets was decreased and the boundary was irregular in model group; compared with model group, the islet boundary in different doses of SCP groups became clear, the areas were increased, and the number cells was increased significantly. Conclusion: SCP can decrease the FBG level, increase the INS level and improve insulin resistance (IR) in the T2DM rats induced by high-fat diet combined with low dose of STZ, and its mechanism might be related to its inhibiting inflammation response.
ABSTRACT
Objective To prepare recombinant human epidermal growth factor (rhEGF) sustained-release microspheres and evaluate their morphology, rhEGF releasing activities and cell proliferation activity in vitro and compare difference of rhEGF sustained-release microspheres and rhEGF in facilitaring ulcer healing in diabetic rats. Methods (1) rhEGF sustained-release microspheres were prepared by the modified double emulsion method. Morphology of the microspheres was detected by transmission electron microscope and size distribution measured by laser granularity meter/Zeta electric potential meter. ELISA assays were applied to determine rhEGF releasing. (2)Proliferation of mouse fibroblasts was analyzed by MTr method. (3) Diabetic rat models were prepared and divided into four groups, ie, rhEGF sustained-release mierospheres group (Group A), rhEGF stock solution group (Group B), blank sustainedrelease mierospheres group (Group C) and PBS meustruum control group (Group D), which were given drug once a day. The wound healing rate was calculated by taking photographs at days 3,7,14 and 21. Skin specimens from the wound edge were harvested partially for observation of hydroxyproline (HYP) contents. Immunohistochemistry was employed to detect integrin 131 and keratin-19 and measure their positive staining area ratio. Results (1) The particle diameter of rhEGF sustained-release microspheres was 193.5 nm, with relative uniform particle diameter distribution. There showed no conglutination among rhEGF susrained-release microspheres, with good dispersibility. Releasing drug lasted for 24 hours and accorded with Higuchi release kinetic model. (2) Different concentrations of rhEGF sustained-release microspheres could promote the proliferation of mouse fibroblast, especially the concentration of 10 μg/L (P <0.05, compared with the control). (3) From the 7th day after treatment, Group A had the fastest wound healing rate, with statistical difference compared with other three groups (P < 0.05). Group A had higher HYP contents and positive area ratio of integrin β1 and keratin-19 than Group B. Conclusions rhEGF sustained-release microspheres prepared by the modified double emulsion method have uniform particle size and can last release for 24 hours. Compared with rhEGF stock solution, rhEGF sustained-release microspheres have faster and better ulcer healing and higher healing quality in diabetic rats.