Effects Of Polysaccharides Of Dendrobium Candidum On Protects Of Retinal In Diabetic Rats

ObjectiveRecently,more and more researches suggest that diabetic retinopathy is an inflammatory disease,in other way,inflammation plays an indispensable role in the early development of DR.By this token,anti-inflammatory therapy may be the potential process to prevent the development and treatment of DR. Shi-Hu as well as Dendrobium,a rare and precious Chinese medicine with various medicinal and health care effects is used primarily to replenish yin formaintaining gastric tonicity,and improving eyesight.Polysaccharide is one of the main medicinal active ingredients of Dendrobium,and this component is reported to have effect on anti-inflammatory,antioxidant and anticancer,have attracted much attention on its chemical composition and pharmacological activity.we research the link between Polysaccharides of Dendrobium and diabetic rats retinal function as well as its possible mechanisms under high glucose by animal experimentsMethodsAnimal experiments:The rats were then randomized into five groups for the experiment and given treatment as follows:(1) normal(nondiabetic) rats,(2) diabetic rats,(3)diabetic rats treated with low doages Polysaccharides of Dendrobium [100 mg /(kg?d),(4) diabetic rats treated with middle doages Polysaccharides of Dendrobium [200 mg/(kg?d)],(5)diabetic rats treated with lhigh doages Polysaccharides of Dendrobium [300mg/(kg?d)].Rats were categorized as diabetic when blood glucose exceeded 16.7mmol/L after intraperitoneal administration with 55mg/kg streptozotocin at 48 h.after 6 weeks,diabetic rats treated with Polysaccharides of Dendrobium groups Oral three differents doses of the drug for 8 weeks.The protein expression of Interleuldn-6(IL-6),tumor necrosis factor-α(TNF-α),vascular endothelial growth factor(VEGF) and tight junction proteins(ZO-1、Occludin、Claudin-5)were detected by Western blot;the expression of IL-6、TNF-α in the serum of rats were determined by Enzyme-Linked Immunosorbent Assay(ELISA);the expression of NF-κB p65 of rential were determined by immuno-histochemistry and analyze the blood-retinal barrier function of rats by Evans blue.ResultsCompared with the normal,the protein level of IL-6、TNF-α、VEGF in diabetic group increased(P<0.05).while,the protein level of IL-6 、 TNF-α 、 VEGF in Polysaccharides of Dendrobium groups decressed much more than diadetic group(P<0.05).The protein level of tight junction proteins(ZO-1、Occludin、Claudin-5) in diabetic group increased(P<0.05),while decressed much more than in diadetic group(P<0.05).The secretion of serum of IL-6、TNF-αin diabetic group was higher than that in the norma I group(P<0.05)and Polysaccharides of Dendrobium groups have decressed(P<0.05).Compared with the normal,Even blue content were elevated in diabetic group,showing statistical differences between two groups(P<0.05), However,the Even blue content were decressed in comparison with diabetic group.There was no positive staining of NF-κB in normal group,and the expression of NF-κB significantly lower in Polysaccharides of Dendrobium groups than in diabetic group.ConclusionPolysaccharides of Dendrobium can suppress the increase of the blood-retinal barrier permeability in STZ-induced diabetic rat by lowing the levels of inflammatory cytokines(IL-6、TNF-α),inhibit the VEGF expression.The mechanism might he associated with NF-κB pathway.These results suggest that Polysaccharides of Dendrobium would has a therapeutic effect on DR.