Effects Of 8-week Swimming Exercise On Kidney Of DDAH1 Gene Knockout Mice

ObjectiveDimethylarginine dimethylamino hydrolase1(DDAH1)is one of the major enzymes that degrade nitric oxide synthase(NOS)inhibitor asymmetric dimethylarginine(ADMA).Inhibition of DDAH1 activity or decreased expression can increase ADMA levels,which are associated with accelerated development and mortality of kidney disease.Studies have shown that aerobic exercise can promote the recovery of the disease,but the role of DDAH1 / ADMA on the kidneys in aerobic exercise is unclear.Therefore,this study will take DDAH1 gene knockout mice and C57 mice as the research objects,and use 8 weeks of swimming exercise intervention to study the effect of DDAH1 gene knockout on mouse kidney and explore the effects on DDAH1/ADMA related pathway.MethodsThere were 12 male 8-week-old C57BL/6 mice and 12 DDAH1 knockout mice,and the C57 mice were randomly divided into the quiet control group(C57 group,n=6)and C57 exercise group(C57 E group,n=6).The DDAH1 knockout mice were randomly divided into the DDAH1 knockout quiet group(DDAH1 KO group,n=6)and the DDAH1 knockout exercise group(DDAH1 KO E group,n=6).The mice in the quiet group were raised normally,and the mice in the exercise group started formal training after adapting to it for a week.The mice were trained 5 days a week,each time for 60 minutes,for 8 weeks of swimming intervention.After 8 weeks of exercise,the mice were anesthetized and the kidney tissues were obtained.The kidney tissue was histologically examined,including the use of hematoxylin-eosin(HE)staining to observe pathomorphological changes of the kidney tissues.the use of Masson tricolor staining to observe the changes in renal fibrosis,In addition,enzyme-linked immunosorbent assay(ELISA)was performed on the kidney tissues of mice to detect the concentration of renal ADMA.Western blot assay was used to detect the expression of renal proteins in mice,including DDAH1 protein and downstream pathway proteins(P-Akt,Akt,P-eNOS,eNOS,Ras),fibrosis-related proteins(Collagen I,Smad3,P-Smad3,TGF-?),and VEGF.Results(1)Compared with mice in group C57 and DDAH1 KO,no significant changes in renal morphology were observed under microscope.(2)Compared with C57 group,the mice in the DDAH1 KO group had significantly increased blue collagen deposition area,suggesting that the mice in the DDAH1 KO group may have kidney fibrosis;after 8 weeks of swimming,the DDAH1 KO E group had a smaller area of blue collagen fibers in the kidneys than the DDAH1 KO group,no conspicuous fibrosis.(3)Compared with C57 group,kidney ADMA concentration of mice in DDAH1 KO group was conspicuously increased(P < 0.01).After 8 weeks of swimming,kidney ADMA concentration of mice in DDAH1 KO E group was conspicuously decreased compared with that in DDAH1 KO group(P < 0.01).Compared with the mice kidney ADMA concentration in group C57,the ADMA concentration in group C57 E was also conspicuously decreased(P < 0.01).Renal ADMA concentration in DDAH1 KO E group was conspicuously higher than that in C57 E group(P < 0.01).(4)Compared with the C57 group,the Ras / PI3 K / Akt pathway in the kidney of DDAH1 KO group was conspicuously decreased(Ras,P < 0.01;p-Ak,P < 0.05),eNOS(P < 0.01),p-eNOS(P < 0.05),VEGF(P < 0.05)protein expression were conspicuously increased,TGF-? / Smad3 pathway(P < 0.05)and Collagen I(P < 0.05)protein expression were significantly increased;After 8 weeks of swimming,the expression of TGF-? / Smad3 pathway(P < 0.01)and Collagen I(P <0.05)in the DDAH1 KO E group were significantly reduced compared to the DDAH1 KO group,and the Ras / PI3 K / Akt pathway Significantly up-regulated(P < 0.01),eNOS(P < 0.01),eNOS phosphorylation level(P < 0.01),and VEGF(P < 0.01)protein expression levels were significantly increased.ConclusionsKnockout of the DDAH1 gene increased kidney fibrosis in mice,decreased angiogenesis,and decreased vascular function;8 weeks of swimming can effectively inhibit kidney fibrosis in mice,promote renal angiogenesis,and improve vascular function,the mechanism may be related to the activation of the DDAH1 /Ras/PI3K/Akt pathway,which may provide new ideas for the prevention and treatment of kidney diseases.