Protective Effect And Mechanism Of Potentilla Anserina Polysaccharide In Cadmium Induced Thymic Damages

Objective:To explore the protective effect of Potentilla anserina.polysaccharide(PAP)and possible mechanism on acute and chronic cadmium(Cd)induced thymus injuries in mice,to provide experimental basis for clinical application of PAP in the prevention and treatment of Cd toxication.Methods:1.PAP of Potentilla anserina L.produced in Yushu of Qinghai Province was extracted by water,precipitated by ethanol and deproteinized with Sevage method.The content of polysaccharide was detected by phenol-sulfuric acid method and the composition of PAP was determined by high performance liquid chromatography(HPLC)method.The PAP injection was prepared.2.Cd-exposed animal model was established,the changes of body weight and relative thymus weight was recorded.The thymus pathological sections was prepared and pathological changes was observed by HE staining.Thymic lymphocyte suspension was prepared and the cell viability was determined by CCK-8 method.The flow cytometry was used for positive rate of CD molecules of thymic lymphocyte,relevant parameters and indicators was finally established.3.80 male Balb/c mice were randomly divided into acute group and chronic group(n=10),each group included Control,Cd,PAP,PAP+Cd subgroups.The acute group was intervened for 7 days including 3 days with Cd(3 mg/kg/d).The chronic group was intervened with Cd(2 mg/kg/d)for 30 days.All the dosage of PAP was 10 mg/kg/d.After sacrificed,thymus tissue was collected and histological sections was prepared for HE staining and immunohistochemistry staining with anti-Fas.Tissue homogenate was prepared for GSH-px and MDA level with kits by ELISA method.The cell suspension was prepared and the cell viability was determined by CCK-8 method.The positive rate of relative CD molecule was detected by flow cytometry.The total cell protein was extracted,and the western blotting method was used to determine the expression of anti-and proapoptotic protein(bcl-2/bax).Results:1.The extraction rate of PAP was 5.18%.The content of polysaccharide in PAP was 64.22%.PAP was mainly composed of Glu,Gal-UA,Ara,and Gal-N,Glc,Rha,Gal,Xyl,and the proportion was 71.58%,9.80%,7.40%,4.83%,2.71%,1.76%,1.54%,0.38% respectively.2.The administration and dose of Cd,relevant parameters and indicators were established in Cd exposed animal model.3.Animal experimental results showed: compared with the Control group,acute and chronic Cd exposure significantly decreased the body weight of mice,the relative thymus weight,the cell viability of thymus lymphocyte,the expression of CD molecule in thymus lymphocytes and pathological morphology changes were observed.Acute and chronic Cd exposure changed the GSH-px activity and MDA content,increased the expression of Fas protein in thymus and decreased the ratio of bcl-2/bax.Compared with the Cd group,parameters in the PAP+Cd group were significantly improved.In addition,no significant damage was observed in both acute and chronic group by PAP treated alone.Conclusions:1.The content of polysaccharide extracted from traditional Chinese medicine Potentilla anserina L.was 64.22%.PAP may be composed of Glu,Gal-UA,Ara,Gal-N,Glc,Rha,Gal,Xyl.2.Acute and chronic Cd exposure animal model could be established according to the dose and time of Cd(3 mg/kg/d×3d,2 mg/kg/d×30d)via administration of intraperitoneal injection with CdCl2 parenteral solution,and this model was repeatable and controllable with stable results and simple methods.3.PAP could effectively alleviate the injuries of thymus induced by acute and chronic Cd exposure.PAP showed significant immunoregulation effects.The underlying mechanisms might be involved with improving antioxidant,relieving inflammatory responses and regulating the expression of Fas,bcl-2,bax protein for anti apoptosis.