| Objective To provide the promoting effect of astragalus polysaccharides (APS) on nerve regeneration and the dose-effect relationship. To explore the effect of astragalus polysaccharides on the cellular immune function and macrophage function of Wallerian degeneration sciatic nerves in rats. To investigate the effect of supernatants of macrophages on Schwann cell proliferate capability and status of Schwann cell cycle.Methods In vivo: Sciatic nerve injury model was set up in 60 female Wistar rats and then they were randomly divided into four groups: the high dose APS group A (40mg/kg/d), the moderate dose APS group B (20mg/kg/d), the low dose APS group C (10mg/kg/d) and the control group D. Differential dosages of APS were peritoneal injected every postoperative day in each experimental group, the same volume of saline was administrated in the control group, keeping on 28days. Electrophysiological, histological& TEM, immunohistochemistry examinations and functional evaluation were used to assess status of nerve regeneration on 4th, 8th and 12th weeks of operative intervals respectively followed by gross observation.In vitro: (1)10 female Wistar rats were established sciatic nerve injury model, randomly divided into APS group and control group. Then 20mg/kg/d of astragalus polysaccharides were peritoneal injected every postoperative day in experimental group, keeping on 7 days; the same volume of saline was administrated in the control group. Detect the proliferation ability of splenic T cells and macrophages with MTT method. The content of IL-1βin serum and in supernatants of spleenocytes and macrophages was measured by Sandwich ELISA. To reserve the supernatants gathered from macrophages for further study.(2) To isolate and cultivate Schwann cell from 10 female Wistar neonate rats with pancreatinum zymine digestion manner and diversity velocity adherence approach. Schwann cell must be identified. Exerting the supernatants of macrophages gathered from previous steps on the third generation cultural cells for 48 hours, then measured the proliferation ability of Schwann cell by MTT method and determined cell cycle status by flow cytometry. Results In vivo: There are 57 rats in statistic. The recovery rate of sciatic motor nerve conduction velocity, nerve fiber appearance, the maturity of myelin sheath, muscle fiber morphous and the triceps surae muscle cuadros index were significantly better in high and moderate dose astragalus polysaccharides group than in control (P<0.05), and the foregoing indexs has no significant deviation in the low dose APS group and the control group (P>0.05) in weeks of operative intervals respectively. The expression of NGF has significant deviation in groups. The expression of CD34 was significantly higher in high and moderate dose astragalus polysaccharides group than that in control (P<0.05), and the foregoing indexs has no difference in the low dose APS group and the control (P>0.05) on postoperative 4th week.In vitro: (1) The proliferation ability of splenic T cells and macrophages in APS group was higher than that of control group (P<0.05). APS enhance the cellular immune function and macrophage proliferation function. The content of IL-1βin supernatants of spleenocytes and macrophages in APS group was higher than in control (P<0.05). The content of IL-1βin serum has no significant deviation in two groups (P>0.05). APS increase IL-1βcontent excreted by spleenocytes and macrophages in rats'Wallerian degeneration sciatic nerves. (2) Schwann cell proliferation encouraged with the supernatants of macrophages. Proliferation capability of Schwann cell synergismed by astragalus polysaccharides & lipopolysaccharide in chorus; then, the majority of Schwann cells were in the athletic S+G2+M phase.Conclusions (1)Astragalus polysaccharides has the effect of promoting regeneration of injuried peripheral nerve and shows up the effect during the earlier regeneration period. (2) APS enhances peripheral nerve regeneration in rats in the dose- dependent manner to some extent. 40mg/kg/d or 20mg/kg/d APS by peritoneal administrating brings about nerve regeneration enhancement. 20mg/kg/d APS exhibits such action already, while 10mg/kg/d APS does not take on visible nerval recovery effects. (3)APS hasten NGF expression and angiopoiesis in regenerate nerve. (4) APS accommodates the cellular immunoloregulation in rats. Also APS activates macrophage secretion to promote Schwann cell proliferation in Wallerian degeneration sciatic nerves in rats, and perhaps in this manner to encourage nerve regeneration.
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