Lycium barbarum polysaccharides alleviate kidney injury and oxidative stress in unilateral ureteral obstruction rats

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Objective To investigate the effect of lycium barbarum polysaccharides (LBP) on oxidative stress in renal tissue of rats with renal interstitial fibrosis (RIF). Methods The RIF rat model was established by unilateral ureteral obstruction (UUO). A total of 108 specified pathogen free (SPF) class healthy adult male Sprague-Dawley (SD) rats were randomly divided into sham operation group, UUO model group and treatment group. The treatment group was further divided into low, medium and high dose of LBP groups and benazapril group. From the next day of the operation, the rats were given continuous intragastric administration for 3 weeks. The LBP low, medium and high dose groups were given 400, 600, 800 mg·kg-1·d-1 LBP, respectively. The benazapril group was administered with 1.05 mg·kg-1·d-1 benazepril hydrochloride. The sham operation group and UUO model group were daily fed normal saline solution by gavage. Six rats were sacrificed randomly at 7, 14 and 21 days after operation. Their blood samples were collected to detect the serum creatinine (Scr) and the kidney organ index was calculated. The pathological changes on the surgical side were observed by both HE staining and Masson staining. Meanwhile, the levels of malondialdehyde (MDA) and superoxide dismutase (SOD) in the renal tissue were detected by colorimetry detection. The expression of transforming growth factor-β1 (TGF-β1) protein was detected by immunohistochemical staining and the expression of TGF-β1 mRNA was detected by real time PCR. Results (1) Compared with the sham group, the Scr and kidney organ index of the UUO model group and treatment groups increased at each time point (all P<0.05). Compared with the UUO model group, the kidney organ index of LBP low dose group in the 7th days, the LBP medium and high dose group in the 21st days as well as benazapril group in the 7th and 21st days were significantly lower (all P<0.05). (2) Renal pathological change: compared with the sham operation group, both the renal tubular interstitial injury index and collagen positive area of the else groups were higher at each time point (all P<0.05). Compared with the UUO group, the tubulointerstitial injury index and collagen staining positive area of LBP dose groups and benazapril group significantly decreased at different time points (all P<0.05). (3) Compared with the sham group, in renal tissue of the other groups the level of MDA increased, SOD level decreased, while the expressions of TGF-1 mRNA and protein increased (all P<0.05). Compared with the UUO model group, LBP low, medium and high dose group as well as benazapril group had lower MDA level, higher SOD level as well as lower expressions of TGF-1 mRNA and protein at each time point (all P<0.05). Conclusions The pathological injury in UUO rats can be improved by the LBP. The LBP can alleviate the oxidative stress status of the kidney tissue by decreasing MDA and increasing SOD. The further study on the LBP delaying the progression of RIF is to be conducted. Key words: Fibrosis; Ureteral obstruction; Oxidative stress; Lycium barbarum polysaccharides