Renal Protective Effects of Lanzhou Lily (Lilium davidii var. unicolor) Polysaccharide and Aerobic Exercise in Streptozotocin-Induced Diabetic Rats

objective: To investigate the protective effect of Lanzhou lily polysaccharide (LLP) and aerobic exercise (AE) on the kidney in a rat model of diabetic mellitus (DM). Methods: Fifty Wistar male rats are randomly divided into a normal control group (n = 10) and a DM model group (n = 40). The rats in the diabetic group were intraperitoneally injected with streptozocin (STZ, 60 mg/kg mb), whereas those in the control group were given the same amount of 0.1 mol/L citrate buffer solution at pH 4.2. After successful induction of diabetes, the diabetic rats were divided into a DM control group, a DM + AE group, a DM + LLP group, and a DM + LLP + AE group, each containing 10 animals. LLP was orally given at a dose of 150 mg/kg mb on a daily basis, and the same amount of distilled water was used as control. The rats in the DM + AE and DM + LLP + AE groups were subjected to swimming training for six weeks, and allowed to recover for 24 h after the last exercise. Afterwards, all rats were sacrificed and left ventricular blood was collected for biochemical testing. Bilateral kidneys were excised for histopathological observation. Results: Compared with the DM group, fasting blood glucose (FBG) in the DM + LLP + AE group significantly decreased (P < 0.05), serum insulin (INS) concentration significantly increased (P < 0.05), and serum total cholesterol (TC), triglyceride (TG), serum creatinine (SCr) and blood urea nitrogen (BUN) significantly decreased (P < 0.05). Moreover, the activity of superoxide dismutase (SOD) in the kidney increased significantly (P < 0.05), the content of malonaldehyde (MDA) decreased significantly (P < 0.05), and the structure and morphological characteristics of the renal tissue were improved. Western blot showed that the renal expressions of Bax/Bcl-2 and caspase-3 were significantly reduced in the DM+ LLP + AE group compared with the DM group (P < 0.05). Conclusion: Lanzhou lily polysaccharide combined with aerobic exercise can reduce FBG, increase insulin secretion, effectively reduce blood lipid levels, increase the activity of antioxidant enzymes in the kidney tissue of diabetic rats, improve and restore the structure and morphological characteristics of the kidney tissue, and significantly inhibit the apoptosis of kidney cells in diabetic rats.