Aerobic Exercise Combined With Oyster Peptide Delays Renal Aging By Reducing Oxidative Stress

Objective:Discuss the intervention and interaction effects of aerobic exercise and Oyster peptide(OP)on D-galactose(D-gal)-induced renal aging formation,and explore the possible mechanisms of aerobic exercise and OP supplementation in delaying renal aging from the changes in the Sirt1/Klotho-FoxO-SOD/CAT signaling pathway.Provide experimental evidence for the application of aerobic exercise and OP supplementation in delaying renal aging.Methods:Twelve-week-old healthy SD rats were randomly divided into five groups:normal control group(NC,n=10),renal aging control group(RAC,n=10),renal aging aerobic exercise intervention group(RAE,n=10),renal aging Oyster peptide intervention group(RAOP,n=10),and renal aging aerobic exercise+Oyster peptide intervention group(RAEOP,n=10).The NC group did not undergo exercise training,while the RAC,RAE,RAOP,and RAEOP groups were induced to develop renal aging by intraperitoneal injection of D-gal and oral administration of sodium nitrite,with the RAOP and RAEOP groups receiving daily oral administration of OP solution at a dose of 1.0g/kg body weight in the morning.The RAE and RAEOP groups underwent 60 minutes of non-weight-bearing swimming training every afternoon,5 times a week,while the RAC and RAOP groups did not undergo exercise training for a total of 8 weeks.Body weight was measured weekly.After 8 weeks,rat body weight and kidney weight were measured,and ELISA was used to detect the content of malondialdehyde(MDA)and catalase(CAT)in the kidneys.The kidney tissue structure was observed using HE staining,and the mRNA expression of Sirtl,Klotho,FoxO1a,and FoxO3a in the kidney was detected using RT-PCR.Western blot was used to detect the protein expression of SOD2,FoxO1a,Sirt1,and Klotho in the kidney.Results:(1)Compared with the NC group,the kidney weight and kidney index in the RAC group were significantly decreased(p=0.02,p=0.006);compared with the RAC group,the kidney weight and kidney index in the RAOP,RAE,and RAEOP groups were significantly increased(p=0.020,p=0.000,p=0.002;p=0.008,p=0.000,p=0.000),and the kidney weight in the RAEOP group showed a further increasing trend without significance(p=0.241),but the kidney index was significantly increased(p=0.000).HE staining showed that compared with the NC group,the number of glomeruli in the RAC group was significantly reduced,with sparse distribution,decreased glomerular volume and irregular shape,and a certain degree of dilation in the glomerular cavity and tubular lumen.The RAE,RAOP,and RAEOP groups showed significant improvement compared with the RAC group.At the same time,compared with the NC group,the number and area of glomeruli in the RAC group were significantly reduced(p=0.021,p=0.025);compared with the RAC group,the RAE,RAOP,and RAEOP groups showed an increasing trend in the number of glomeruli,but there was no significant difference,while the glomerular area in the RAE and RAEOP groups was significantly increased(p=0.016,p=0.021),and the RAOP group showed an increasing trend without significance;compared with the RAE group,the RAEOP group showed a further increasing trend in the number and area of glomeruli without significant difference(p=0.587,p=0.888).(2)Compared with the NC group,the SOD2 protein expression and CAT content were significantly decreased(p=0.045,p=0.037),while the MDA content was significantly increased(p=0.023)in the RAC group.Compared with the RAC group,the SOD2 protein expression was significantly upregulated(p=0.000)in the RAEOP group,while there was no significant upregulation in the RAE and RAOP groups(p=0.053,p=0.116);the CAT content was significantly increased(p=0.000)and the MDA content was significantly decreased(p=0.002,p=0.000,p=0.000)in the RAOP,RAE,and RAEOP groups.Compared with the RAE group,the CAT content showed a further increasing trend and the MDA content showed a further decreasing trend in the RAEOP group,but without significance(p=0.570,p=0.776),while the SOD2 protein expression was significantly increased(p=0.000).(3)Compared with the NC group,the Klotho,Sirt1,FoxO1a mRNA and protein expression,as well as FoxO3a mRNA expression were significantly decreased(p=0.018,p=0.036;p=0.018,p=0.000;p=0.000,p=0.003;p=0.038)in the RAC group.Compared with the RAC group,the Klotho mRNA and protein expression were significantly increased(p=0.035,p=0.003,p=0.007;p=0.000,p=0.001,p=0.000)in the RAOP,RAE,and RAEOP groups;the Sirt1 mRNA expression and FoxO1a protein expression were significantly increased(p=0.015,p=0.010;p=0.003,p=0.045)in the RAE and RAEOP groups,while the Sirt1 mRNA expression and FoxO1a protein expression showed no significant increase in the RAOP group(p=0.083,p=0.765);the Sirtl protein expression and FoxO3a mRNA expression were significantly increased(p=0.003,p=0.000,p=0.000;p=0.017,p=0.008,p=0.045)in the RAOP,RAE,and RAEOP groups.Compared with the RAE group,the Klotho,Sirt1,FoxO1a mRNA and protein expression,as well as FoxO3a mRNA expression showed a further increasing trend in the RAEOP group,but without significant difference(p=0.514,p=0.180;p=0.910,p=0.753;p=0.566,p=0.215;p=0.476).Conclusions:(1)D-gal can enhance renal oxidative stress,leading to renal atrophy and effectively induce renal aging.However,aerobic exercise combined with OP supplementation can significantly inhibit renal oxidative stress and delay the onset of renal aging.Furthermore,the effect of aerobic exercise combined with OP supplementation is better than that of aerobic exercise alone to some extent.(2)The inhibition of the Sirtl/Klotho-FoxO1a/FoxO3a-SOD2/CAT signaling pathway in the kidney may be one of the physiological mechanisms underlying D-gal-induced renal aging.Aerobic exercise and/or OP supplementation significantly improve the Sirt1/Klotho-FoxOs-SOD2/CAT signaling pathway,reduce oxidative stress in the kidney,and delay the onset of renal aging.This may be an important biological mechanism by which aerobic exercise and OP supplementation delay renal aging.