Effects of Astragalus polysaccharides on expression of retinal inflammatory factors and neuronal oxidative damage in rats with diabetes mellitus

Abstract

Objective To determine the effects of Astragalus polysaccharide (APS) on the expression of retinal inflammatory factors and neuronal oxidative damage in rats with diabetes mellitus (DM) . Methods Sixty SD rats were randomly divided into the blank control group, model group, low-, medium- and high-dose APS groups and metformin hydrochloride group (n=10 each) . After 2 weeks of gavage, the expression levels of serum tumor necrosis factor α (TNF-α) , interleukin-6 (IL-6) , CRP, superoxide dismutase (SOD) and malondialdehyde (MDA) in the eyeballs of rats were determined by enzyme-linked immunosorbent assay. The changes of the protein expression in the retinal tissues were determined by HE staining. The expression levels of nuclear transcription factor κB (NF-κB) and glutathione peroxidase (GSH-Px) in the retinal tissues were determined by immunohistochemistry. Results Compared with the blank group, the levels of serum TNF-α, IL-6, CRP and MDA in the model group increased (P<0.05) , while the level of SOD decreased (P<0.05) . Compared with the model group, the expression levels of serum TNF-α, IL-6, CRP and MDA significantly decreased in different doses of the APS groups and the metformin hydrochloride group, while the expression level of SOD significantly increased (all P<0.05) . The indexes in the high-dose APS group and the metformin hydrochloride group were significantly higher than those in the low- and medium-dose APS groups (P<0.05) . The immunohistochemical staining showed that compared with the blank group, the expression of NF-κB increased in the retinal tissues of the model group and all of the treatment groups, while the expression of GSH-Px decreased, all P<0.05. Compared with the model group, the expression levels of NF-κB decreased in different doses of the APS groups and the metformin hydrochloride group, while the expression level of GSH-Px increased, all P<0.05. Conclusion APS can protect retinal tissues by reducing the inflammatory reaction in the retina of DM rats. It can reduce the oxidative damage of retinal neurons by increasing the antioxidative effect, and the decrease of NF-κB and TNF-α expression may be one of the mechanisms of retinal protection. Key words: Astragalus polysaccharide; Diabetes mellitus; Retina; Inflammatory factor