| Background and purposeNeurogenic bladder(NB)is the abbreviation of bladder dysuria caused by the lesion or injury of central nervous system and/or peripheral nervous system controlling urination.Common congenital factors causing NB include congenital spina bifida,spinal meningocele,tethered cord,etc.,and acquired factors are common in spinal cord trauma,brain trauma,peripheral nerve injury,etc.Dysmicturition,urinary retention,frequent micturition and urinary incontinence are the most common clinical symptoms of NB,and repeated urinary infection is a common complication.If standardized treatment is not received in time,irreversible damage will occur to the kidney,and the renal function will decrease progressively.Patients in advanced stage often die of renal failure and complications,which will bring heavy burden to the family and society.The etiology of NB is very complex.In recent years,although the medical level has developed rapidly and new technologies,new materials and new ideas have been updated constantly,there is little breakthrough in the treatment of NB,so it is particularly important to study the pathogenesis of NB.Severe spinal cord injury(SCI),especially irreversible damage to the anatomical structure of the lower lumbar segment of the spinal cord,can lead to NB.Studies have shown that the incidence of NB in SCI patients is 70%～84%.Unlike NB with Over active bladder(OAB)as the main symptom caused by nerve center damage(ischemic stroke,brain injury,etc.),NB caused by SCI often shows bladder dysuria and urinary retention,which makes the bladder keep in a high pressure state,and finally progresses to bladder fibrosis,kidney fibrosis,renal failure and even death.The complete bladder micturition contraction process is completed by the cooperation of central nerve and peripheral nerve,which is closely related to the complex pelvic floor plexus.The specific neural control mechanism is still unclear.Once SCI occurs,there is no effective treatment to restore the regeneration of injured spinal nerves,and it is impossible to fundamentally rebuild the control of nerve center on bladder,which makes NB treatment caused by SCI more difficult.The spinal nerve anastomosis therapy proposed by Professor Chuanguo Xiao has attracted worldwide attention and brought a glimmer of light to the treatment of NB,but its therapeutic effect is controversial and its clinical application value is very limited.At present,intermittent catheterization is still the main symptomatic treatment to maintain the dynamic balance of bladder and maximize the protection of bladder function.The diagnosis of NB is not difficult,and it is usually confirmed by urodynamic examination.Urodynamic examination includes urinary flow rate,intravesical pressure,imaging urodynamics and pressure-flow rate measurement.The bladder pressure,bladder contractility,synergic function of detrusor-urethral dilators,ureteral dilatation and reflux can be intuitively understood through the shape and related parameters of urodynamic pressure measurement curve,which is the gold standard for the diagnosis of NB.Regular urodynamic testing to evaluate bladder function has become a routine clinical examination item for NB patients.The animal model of NB is the basis of studying the mechanism of NB,and how to establish a simple and effective NB model is crucial.Generally,adult female SD rats are selected for spinal nerve transection to establish NB animal model.SD rat strain is stable and cheap,has strong immune resistance,recovers quickly after surgical trauma and is highly similar to human urinary system,which is an ideal choice for NB model.Compared with male SD rats,female SD rats have relatively large bladder,which is beneficial to cystostomy and urodynamic pressure tube placement,and short urethra is convenient for crede manual urination after operation.The NB model of spinal nerve transection rats can well simulate the cause,course development,outcome and prognosis of NB caused by SCI,which is a mature NB model.Specific surgical methods are generally divided into T10 and L6 spinal nerve transection.T10 spinal nerve is relatively thick,so the operation is simple,but the amount of bleeding during the operation is large.After the operation,the stress response of rats is strong and the recovery is slow,and there is a certain probability of paralysis of both hind limbs when T10 spinal nerve is severed,which is generally used for short-term observation of NB model.L6 spinal nerve is relatively thin,so the operation is complicated,but the amount of bleeding during operation is small,and the stress response of rats after operation is slight,which is beneficial to postoperative recovery and will not have any effect on both hind limbs.It is generally used for long-term observation of NB model.Therefore,in the first part of this study,the NB model was constructed by transecting L6 spinal cord of adult female SD rats with bilateral spinal nerve transection,and crede was artificially urinated for a long time after operation,which provided an animal model for further exploring the mechanism of NB induced by SCI and its influence on bladder and kidney structure and function.Interstitial cells of Cajal(ICCs)are a special type of interstitial cells,which were first discovered in gastrointestinal tract by Spanish anatomist Romon Cajal.Previous studies have suggested that ICC cells can conduct slow wave potential in smooth muscle of gastrointestinal tract and undergo spontaneous depolarization.ICC cells have a certain degree of autonomy,and can transmit neural signals into smooth muscle to cause contraction,which plays an important role in maintaining the peristaltic contraction function of smooth muscle of gastrointestinal tract.The proliferation and differentiation functions of ICC are closely related to the activation of its specific surface receptor c-kit.C-kit receptor is a glycoprotein encoded by c-kit protooncogene,which is located on the surface of cell membrane and belongs to tyrosine kinase receptor.There is evidence that the activation of c-kit depends on its ligand-stem cell fact(SCF).SCF/c-kit pathway plays an important role in the proliferation,differentiation and function regulation of ICC.In addition,the combination of SCF and c-Kit receptor can lead to the signal transduction of Janus kinase(JAK)and the activation of transcription activator(STAT).ICC has also been found in bladder stroma in recent years,and its morphology,structure and function are similar to ICC cells in gastrointestinal tract.ICC cells in bladder are the starting cells of bladder contraction,but the relationship between structural state and NB is rarely reported.Therefore,the second part of this study explores the possible molecular mechanism of NB by studying the changes of ICC cells and the changes of c-kit-related signal pathway of cell membrane surface specific receptor after SCI.After the occurrence of NB caused by SCI,due to the lack of effective clinical treatment measures,all patients will have different degrees of bladder fibrosis over time,and the severity of bladder fibrosis is also one of the key factors hindering the therapeutic effect of NB.At present,the exact molecular mechanism of bladder fibrosis is still controversial.How to prevent and delay bladder fibrosis is an urgent problem to be solved in NB treatment.Transforming growth factor-β(TGF-β)is a member of transforming growth factor superfamily(composed of three subtypes:TGF-β1,TGF-β2 and TGF-β3),which is a multifunctional dimeric peptide and can regulate cell proliferation,apoptosis,autophagy and differentiation.TGF-β is a recognized fibrotic regulator,which can not only regulate epithelial-mesenchymal transition(EMT),but also directly regulate the synthesis of single matrix(collagen,proteoglycan and glycoprotein).Smad3 is the key mediator in the downstream of TGF-β.Smad3 phosphorylates and enters the nucleus,which regulates the generation of collagen fibers.In liver and myocardium,up-regulation of TGFβ1/Smad signaling pathway can directly up-regulate the protein expression of collagen Ⅰ and collagen Ⅲ,which leads to fibrosis.The elevated expression of TGF-β in obstructive bladder leads to bladder fibrosis,suggesting that there is a classical TGF-β 1/Smad 3 signal pathway in bladder,but the relationship between TGF-β 1/Smad signal pathway and NB is rarely reported.Therefore,in the third part of this study,we will explore the effect of NB on bladder structure and function and the role of TGFβ 1/Smad signaling pathway in bladder fibrosis.In NB patients with end-stage disease,renal fibrosis is inevitable.Renal fibrosis is closely related to cytokine TGF-β1.It is generally believed that TGF-β1 develops and transforms into fibroblasts by stimulating the activation of epithelial cells,macrophages,intrinsic cells,endothelial cells and mesangial cells in kidney.These fibroblasts can induce the occurrence of EMT,stimulate the deposition of extracellular matrix,inhibit its degradation,and promote the apoptosis and loss of tubular cells in kidney tissue,eventually leading to renal fibrosis.At present,the model of unilateral ureteral obstruction(UUO)is generally used in the study of renal fibrosis.UUO-induced renal fibrosis is an acute process,and obvious renal fibrosis usually occurs one week after modeling.But clinically,the process from NB to renal fibrosis is extremely slow,which usually lasts for months or even years,so it is necessary to establish NB chronic renal fibrosis model.Up to now,no animal model of renal fibrosis caused by NB has been reported.Therefore,in the fourth part of this study,the occurrence of renal fibrosis was finally observed through long-term observation of the NB model and adherence to Crede manual urination twice a day for more than half a year(24 weeks).It is the first time to prove that Nb model can be used in the study of chronic renal fibrosis,and preliminarily explore the influence of Nb on renal structure and function and the key molecules involved in renal fibrosis.The purpose of this study is as follows:(1)Constructing a simple and effective NB animal model;(2)Exploring the possible molecular mechanism of NB occurrence;(3)To study the effect of NB on bladder structure and function;(4)To explore the effect of NB on renal structure and function.Part 1 Establishment of neurogenic bladder modelMaterials and methods1.36adult SD female rats(250g±20g,12 weeks old)were randomly divided into experimental group(nerve transection group)and control group(sham operation group)according to the random number table method.Experimental group:24 rats were anesthetized,L6 spinal cord was transected and bilateral spinal nerves were severed,and the neurogenic bladder model was established by creds assisted urination(12 rats in each time point were divided into 6 weeks and 12 weeks).Sham group:12 rats were anesthetized,the spinal canal was opened,and L6 bilateral spinal nerves were exposed,and then sutured and closed quickly,without nerve disconnection.2.Bladder ostomy was performed in all groups of rats,and urodynamic tests were performed by placing pressure tubes.3.Statistical analysis.All experimental data were analyzed by SPSS 21.0 statistical software,and measurement data were expressed as mean ± standard deviation.Comparison of mean between two groups was performed by t-test,comparison between multiple groups was performed by one-way ANOVA,and further pair comparison was performed by Bonferroni.P<0.05 is statistically significant.ResultsUrodynamics showed that on the 3rd day after nerve transection(Ampu-3d),the basal Intravesical pressure(BP)increased slightly,the interval of urination increased,the time of urination became longer,the bladder showed involuntary urination which was not controlled by the brain,and the maximum systolic pressure of bladder decreased.With the passage of time,the basal bladder pressure gradually increased at 6 weeks(Ampu-6w)and 12 weeks(Ampu-12w)after nerve transection,which were(6.5±2.1)cmH2O and(14.7±4.2)cmH2O,respectively,and the difference was statistically significant compared with the negative control group(0.1±0.01)cmH2O.BLPP appeared irregularly and gradually increased,which were(19.8±2.3)cmH2O and(25.5±5.1)cmH2O,respectively,with statistical difference between the two groups(P<0.05).The above results prove that the NB model is successfully constructed.Part 2 the cause of neurogenic bladderMaterials and methods1 NB induced changes in the number,morphology and structure of bladder ICC cells and related pathway proteins1.1 48 adult SD female rats(250g±20g,12 weeks)were randomly divided into NB group,control group and sham group according to random number table method.Group NB:16 rats underwent L6 spinal cord transection and bilateral spinal nerve transection after anesthesia and were divided into 6-week group and 12-week group,with 8 rats in each group.Control group:16 rats were anesthetized,and the spinal canal was opened,exposing L6 bilateral spinal nerves without nerve transection.Sham group:16 rats received no treatment.1.2 All rats underwent cystostomy and urodynamic test.1.3 the rats were killed by cervical dislocation,and the bladder tissue was stained with c-kit immunofluorescence.the changes of ICC cells in each group were observed under microscope.The bladder ICC cells of each group were extracted,and the ultrastructural changes of ICC cells were observed under electron microscope.1.4 the mRNA expression of SCF/c-kit in bladder tissue of each group was detected by qPCR technique.The expressions of SCF/c-kit and JAK-STAT related proteins in bladder tissues were detected by Western blot.2 To verify that SCF/c-kit can influence the proliferation of bladder ICC cells by regulating JAK/STAT3 signaling pathway2.1 bladder ICC of normal healthy rats was extracted for primary culture,and CCK-8 proliferation test was used to detect the effect of SCF/C-kit on ICC proliferation.The effect of SCF/C-kit on JAK-STAT signaling pathway was detected by Western blot.The effect of JAK-STAT signaling pathway on ICC proliferation was detected by CCK-8 proliferation test.2.2 64 adult SD female rats(250g±20g,12 weeks)were randomly divided into 8 groups with 8 rats in each group.Sham group:normal feeding.Group NB:L6 spinal nerve was severed.In SCF group,Stem Cell Factor(SCF)was dissolved in PBS solution and injected intraperitoneally at 0.2 g/kg/d.SCF+DMSO group:SCF and dimethyl sulfoxide(DMSO)were mixed and injected intraperitoneally in rats at 0.2 g/kg/d.Group SCF+Glivec:0.2g/kg/d rats were intraperitoneally injected with SCF+Glivec(c-kit inhibitor)150 mg/kg/d rats.Group SCF+ISCK03:0.2 g/kg/d rats were intraperitoneally injected with SCF+ISCK03(SCF/C-kit inhibitor)500 mg/kg/d rats for oral administration.Group SCF+Ruxolitinib:0.2 g/kg/d rats were intraperitoneally injected with SCF+Ruxolitinib(JAK inhibitor)150 mg/kg,twice a day.Scf+nifuroxide group:0.2 g/kg/d rats were intraperitoneally injected with SCF+Nifuroxazide(STAT3 inhibitor)150 mg/kg,twice a day.2.3 The rats in each group were killed by cervical dislocation,and the bladder tissue was stained with c-kit immunofluorescence.The changes of ICC cells in each group were observed under microscope.2.4 Statistical analysis.All experimental data were analyzed by SPSS 21.0 statistical software,and measurement data were expressed as mean ± standard deviation.Comparison of mean between two groups was performed by t-test,comparison between multiple groups was performed by one-way ANOVA,and further pair comparison was performed by Bonferroni.P<0.05 is statistically significant.Results1.Urodynamic results showed that the active contractile function of rat bladder disappeared and the basal Intravesical pressure increased gradually after spinal nerve transection.Compared with Sham group,the maximum bladder volume(MCC)of Ampu-6w group and Ampu-12w group first increased and then decreased to(12.6±1.22)ml and(5.7±0.66)ml,respectively,which was significantly different from that of Sham group(1.0±0.12)ml(P<0.05).After NB,BLPP appeared and gradually increased,and Ampu-6w and Ampu-12w were(22.6±2.12)cmH2O and(33.8±4.12)cmH2O,respectively,with significant difference(P<0.05).Bladder Compliance(BC)increased first and then decreased.The BC value of AMPU-6W and AMPU-12W were(0.21±0.03)mL/cmH2O and(0.42±0.05)mL/cmH2O,respectively,and the difference was statistically significant compared with that of Sham group(0.12±0.04)mL/cmH2O(P<0.05).2.C-kit immunofluorescence showed that compared with Control group and Sham group,the number of ICC cells in NB group decreased significantly.Under electron microscope,after NB,with the passage of time,the original lobulated ICC nucleus gradually merged and contracted granularly;Mitochondria gradually edema and then disintegrate;The cell membrane gradually sagged and ruptured.The whole ICC cells undergo apoptosis and disintegration.3.RT-qPCR results showed that SCF/C-kit mRNA was down-regulated after NB(p<0.05).Western blot showed that SCF/C-kit protein expression decreased significantly after NB.JAK-STAT is the downstream signaling pathway of SCF/C-kit,and the expression of pathway-related proteins p-JAK/JAK,p-STAT1/STAT1,p-STAT3/STAT3 is obviously inhibited(P<0.05).4.CCK-8 and western blot confirmed that JAK-STAT is the downstream signal pathway of SCF/C-kit.After SCF/c-kit was inhibited,JAK-STAT signal pathway was down-regulated and ICC cell proliferation was inhibited.5.C-KIT immunofluorescence confirmed that down-regulation of SCF/c-KIT could inhibit JAK-STAT signaling pathway and ICC cell apoptosis.Part 3 the effect of neurogenic bladder on bladder structure and functionMaterials and methods1.48 adult female SD rats(250±20g,12 weeks)were randomly divided into NB group and Sham group.Experimental group:32 rats underwent L6 spinal cord transection and bilateral spinal nerve transection to establish neurogenic bladder model.crede technique was used to assist urination.They were divided into 3-week,6-week,12-week and 24-week groups with 8 rats in each group.In Sham group,16 rats opened L6 spinal canal to expose spinal cord,and then closed suture immediately.2.All rats underwent cystostomy and urodynamic test.3.The rats were killed by cervical dislocation,the whole bladder was taken out,the bladder capacity and weight were measured,and the bladder wall thickness was measured by slitting the bladder longitudinally.4.Masson staining,Sirius red staining and immunohistochemical staining were performed on bladder tissue.Microscopic examination,image acquisition and analysis.5.The expression of TGF-±1,Smad2,Smad6,C ollagen Ⅰ,Collagen Ⅲ protein in bladder tissue of rats in each group was detected by Western blot.6.Statistical analysis.All experimental data were analyzed by SPSS 21.0 statistical software,and measurement data were expressed as mean ± standard deviation.Comparison of mean between two groups was performed by t-test,comparison between multiple groups was performed by one-way ANOVA,and further pair comparison was performed by Bonferroni.P<0.05 is statistically significant.Results1.Urodynamc test showed that active bladder contraction disappeared and BLPP appeared irregularly after the occurrence of NB.The BLPP of NB group at 3,6,12 and 24 weeks was(29±3.11)cmH2O,(13± 1.31)cmH2O,(27±2.31)cmH2O,and(39±3.69)cmH2O with statistical significance(P<0.05).The basal bladder pressure of(21±2.4)cmH2O,(19±1.9)cmH2O,(32±2.9)cmH2O and(40±3.7)cmH2O in the NB group at 3,6,12 and 24 weeks was significantly higher than that of the control group(1.21±0.17)cmH2O,(1.67±0.34)cmH2O,(2.05±0.29)cmH2O and(1.87±0.21)cmH2O,with statistical significance(P<0.05).The maximum bladder volume at 3,6,12 and 24 weeks in NB group was(21±1.69)ml,(46±3.54)ml,(31±2.88)ml,(13.8± 1.64)ml,which was significantly higher than that in control group(0.9±0.04)ml,(1.1±0.06)ml,(1.2±0.07)ml,(1.5±0.09)ml,with statistical significance(P<0.05).2.Compared with the control group,the bladder volume of SD rats at 3,6,12 and 24 weeks in NB group increased firstly(3,6 weeks)and then decreased contracture(12,24 weeks),and the bladder wall thickness decreased firstly(3,6 weeks)and then increased(12,24 weeks),which were(0.371±0.034)vs.(1.27±0.125)mm,(0.578±0.051)vs.(1.41±0.129)mm,(1.478±0.181)vs.(1.51±0.161)mm,(2.83±0.331)vs.(1.71±0.162)mm,respectively;Bladder weight was gradually increased to(0.37±0.05)vs.(0.20g±0.06)g,(0.66g±0.06)vs.(0.23±0.04)g,(1.17±0.15)vs.(0.27g±0.07)g,(1.64±0.14)vs.(0.24g±0.05).The difference was statistically significant(P<0.05).3.Masson staining of bladder tissue showed that compared with the control group,normal fibrous connective tissue in the bladder wall of rats at 3,6,12,and 24 weeks of nerve dissociation was gradually disordered,and the layered structure of the bladder wall gradually disintegrated.Over time,the bladder wall thins first,then thickens,the lamina propria decreases,smooth muscle hypertrophy and thickening,intermuscular collagen fibers gradually increase,and the staining becomes deeper.4.Sirius scarlet staining of bladder tissue showed that collagen Ⅲ was significantly increased in bladder tissue at 24 weeks after nerve dissection,and the ratio of collagen Ⅲ/collagen Ⅰ was significantly higher than that of the control group(3.21±0.82)vs.(0.91±0.19)(P<0.01).5.Immunohistochemical staining of bladder tissue showed that there was little difference in the staining results of TGF-β,smad2 and smad6 in bladder tissues at 3,6,12 and 24 weeks in the control group.Therefore,we selected the control group at 12w as a control.Compared with this control group,the expression of TGF-β1 and the key protein smad2 in the bladder smooth muscle cells in the NB group at 3,6,12 and 24 weeks gradually increased over time,and the inhibitory protein smad6 of fibrosis pathway gradually decreased over time.6.Western blot of bladder tissue showed that the amount of TGF-β 1 protein after nerve transection(6w,12w,24w)was significantly higher than that of the control group of the same age,and increased with the time of nerve transection.The amount of smad2 protein after nerve transection(6w,12w,24w)was significantly higher than that of the control group of the same age,and increased with the time of nerve transection.The expression of Smad6 was significantly lower than that of sham operation group,and showed a downward trend with time.After nerve transection(6w,12w,24w),the expression levels of Collagen Ⅰ and Collagen Ⅲ were higher than those of the control group and increased with time.Collagen Ⅲ increased more sharply,so the ratio of Collagen Ⅲ/Collagen Ⅰ increased in a time-dependent manner(P<0.05).Part 4 the effect of neurogenic bladder on renal structure and functionMaterials and methods1.48 female SD rats were randomly divided into experimental group and control group by random number table,including 36 rats in NB group(nerve transection)and 12 rats in Sham group(sham operation group).There were 12 NB rats at 3 time points(6 weeks,12 weeks and 24 weeks after nerve transection).Sham group(close suture immediately after opening spinal canal and exposing spinal cord)was routinely raised for 24 weeks.Kidney condition of all rats was detected by B-ultrasound.2.Blood sample collection:Rats in each group were killed by cervical dislocation,blood was collected from inferior vena cava,and serum creatinine(Scr)and urea nitrogen(BUN)were measured by automatic biochemical analyzer.3.HE staining,Masson staining and immunohistochemical staining were performed on kidney tissue;microscope observation;image collection and analysis.4.Western blot was used to detect the expression of AngⅡ/TGF-β1 signaling pathway related proteins in kidney tissue.5.Statistical analysis.All experimental data were analyzed by SPSS 21.0 statistical software,and measurement data were expressed as mean± standard deviation.Comparison of mean between two groups was performed by t-test,comparison between multiple groups was performed by one-way ANOVA,and further pair comparison was performed by Bonferroni.P<0.05 is statistically significant.Results1.Compared with Sham group,B-ultrasound showed that kidney in NB group gradually showed renal sinus separation,and the low density shadow area of renal pelvis and calyces increased(hydronephrosis image).As time went by,the renal cortex became thinner,the renal parenchyma became thicker and the echo increased,and the adjacent calyces merged with each other.After 24 weeks of nerve amputation,hydronephrosis caused urine to leak under the renal capsule.2.Biochemical results showed that compared with the Sham group,the rats’serum BUN and Scr increased at 6,12,and 24 weeks after nerve dissociation,and the difference increased with time(P<0.05).3.Masson staining of kidney tissue showed that the morphology of kidney tissue in Sham group was normal,and a little collagen deposition(blue staining)could be seen around blood vessels and dilated renal tubules after 6 weeks of nerve transection.At 12 weeks,collagen deposition became more serious,blue staining became more obvious,and renal tubule epithelial cells(red staining)gradually faded.By the 24th week,the glomerular vascular endothelium was obviously denatured,the tubular lumen was filled with cell debris and cellulose,the interstitial inflammatory cells infiltrated,and the fibrous connective tissue of renal cortex was obviously proliferated.4.HE staining of kidney tissue showed that the morphology of kidney tissue in Sham group was normal,showing small tubular lumen,small interstitial area,close arrangement between renal tubules,and no obvious inflammatory cell infiltration in renal interstitium.Compared with Sham group,in NB group,the area of renal tubulointerstitium increased at 6th week,and inflammatory cells infiltrated in renal interstitium and around blood vessels,which became more obvious with the prolongation of disconnection time.In NB group,diffuse inflammatory cells infiltrated in renal interstitium at 24th week,some glomeruli disintegrated,the lumen of renal tubules became larger,renal tubules shrank and renal parenchyma was destroyed.5.Immunohistochemical staining showed that AT1(AngⅡ receptor 1)was mainly located in cytoplasm and membrane,TGF-βR1 was mainly located in cytoplasm,pSmad2 and Smad6 were located in nucleus,and these proteins were mainly distributed in epithelial cells of distal tubule and collecting duct of kidney.In Sham group,ATI,TGF-βR1 and pSmad2 were expressed at a low level,while Smad6 was expressed at a high level.with the prolongation of disconnection time,the expressions of ATI,TGF-βR1 and pSmad2 were gradually increased(P<0.01),while Smad 6 played a competitive inhibitory role and gradually decreased(P<0.01).Therefore,AT1,TGF-βR1,pSmad2 and Smad6 are consistent in the occurrence and progression of renal fibrosis induced by neurogenic bladder.6.Western blot analysis showed that the expressions of ATI and TGF-βR1 in NB group at 6 weeks,12 weeks and 24 weeks were significantly higher than those in Sham group and increased with time(P<0.05).The expression of Smad2 in NB group at 6 weeks,12 weeks and 24 weeks was also significantly higher than that in Sham group and increased with time(P<0.05).On the contrary,the expression of Smad6 in NB group was significantly lower than that in Sham group(P<0.05).In addition,the expression levels of collagen Ⅰ and collagen Ⅲ in NB group were higher than those in Sham group at 6 weeks,12 weeks and 24 weeks(P<0.05).Conclusions1.L6 spinal cord transection and bilateral spinal nerve transection can be used for NB model and long-term observation.2.After spinal nerve injury,SCF/C-kit protein is inhibited,causing down-regulation of JAK-STAT3 signaling pathway,leading to bladder ICC cell apoptosis,bladder contraction dysfunction,and neurogenic bladder.3.After the occurrence of neurogenic bladder,the TGF-β1/Smads signaling pathway is activated,and the bladder fibrosis occurs.4.After the occurrence of neurogenic bladder,bladder voiding dysfunction and urinary retention lead to increased pressure in the bladder,causing hydronephrosis,increased renal pressure,up-regulation of renal AngⅡ/TGF-β1 signaling pathway,and renal fibrosis. |
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