The Effect And Mechanism Of Sacral Nerve/sacral Nerve Electrical Stimulation On Visceral Hypersensitivity In Rats

Projectl.Effects and mechanisms of sacral nerve stimulation/tibial nerve stimulation on visceral hypersensitivy in ratsPart I Sacral nerve stimulation with optimized parameters improves visceral hypersensitivity in rats mediated via the autonomic mechanismsAims:Sacral nerve stimulation(SNS)has been applied for the treatment of dysfunction of bladder and fecal incontinence;however,it is unclear whether it may play a role in controlling visceral hypersensitivity that is major problem of irritable bowel syndrome which affects millions of people around the world.The purpose of this study was to determine effects and mechanisms of SNS on visceral hypersensitivity in a rodent model of colonic hypersensitivity.Methods:(1)Visceral sensitivity during colorectal distension(CRD)was assessed by the measurement of abdominal withdrawal reflux(AWR)and abdominal electromyogram(EMG)in regular rats.SNS was performed with different sets of parameters for 30 minutes before the recordings of AWR and EMG.(2)Real/sham SNS with the optimized parameters was performed in the acute visceral hypersensitivity rats induced by restraint stress and the rats with colonic hypersensitivity induced by acetic acid during the neonatal period.EMG and heart rate variability(HRV)in response to SNS and shamSNS were assessed and compared.(3)Twenty rats with colonic hypersensitivity were treated by SNSor shamSNS daily for a period of 7 days for the assessment of the chronic effect of SNS.Results:(1)Six sets of different parameters were tested at a stimulation strength of 90%of motor threshold(MT)and none showed any significant SNS effect on the AWR during CRD.When the stimulation amplitude was reduced to 65%or 40%or 25%MT,SNS with certain parameters showed an inhibitory effect on AWR.The best stimulation parameters for SNS was "14Hz,330us,and 40%MT".(2)SNS with the optimized parameters significantly reduced the AWR scores and EMG response to CRD in restraint stressedinduced hypersensitized rats.Concurrently,SNS decreased low frequency(LF,sympathetic)and increased high frequency(HF,vagal)assessed from the spectral analysis of HRV.Similar inhibitory effects were noted with SNS in rats with colonic hypersensitivityinduced by acetic acid and the inhibitory effect was blocked by naloxone.(3)Chronic SNS significantly reduced the EMG response to CRD at 60mmHg and 80mmHg,decreased LF and increased HF in rats with colonic hypersensitivity.Conclusions:SNS with reduced stimulation strength may be used to treat colonic hypersensitivity and the best stimulation parameters seem to be"14Hz,330μs and 40%MT".SNS with optimized parameters improved visceral hypersensitivity in rodent models of colonic hypersensitivity mediated via the autonomic and opioid mechanisms.Part Ⅱ.Tibial nerve stimulation improves visceral hypersensitivity in rats mediated via the autonomic mechanismsAims:Tibial nerve stimulation(TNS)has been applied for the treatment of urinary incontinence and fecal incontinence;however,it has not been investigated in controlling visceral hypersensitivity.The purpose of this study was to determine effects and mechanisms of TNS on visceral hypersensitivity in a rodent model of colonic hypersensitivity.Methods:(1)Visceral sensitivity during colorectal distension(CRD)was assessed by the measurement of abdominal withdrawal reflux(AWR)and abdominal electromyogram(EMG)in regular rats.TNS was performed with different sets of parameters for 30 minutes before the recordings of AWR and EMG.(2)Real/sham TNS was performed in the acute visceral hypersensitivity rats induced by restraint stress and the rats with colonic hypersensitivity induced by acetic acid during the neonatal period,AWR score,EMG and heart rate variability(HRV)in response to TNS and sham TNS were assessed and compared.Results:(1)Five sets of different parameters were tested at a stimulation strength of 90%or 40%of motor threshold(MT)and none showed any significant TNS effect on the AWR and EMG response to CRD.(2)TNS with the parameter "14Hz,330us 40%MT" significantly reduced the AWR scores and EMG response to CRD in the restraint stressedinduced hypersensitized rats.Concurrently,TNS decreased LF and increased HF assessed from the spectral analysis of HRV.(3)Similar inhibitory effects were noted with TNS in the rats with colonic hypersensitivityinduced by acetic acid and the inhibitory effect was blocked by naloxone.TNS decreased LF and increased HF in the acetic acid induced rats.Conclusions:It seemed to be no any significant TNS effect on visceral hypersensitivity in regular rats.TNS with the parameter "14Hz 330μs 40%MT" could improve visceral hypersensitivity in rodent models of colonic hypersensitivity mediated via the autonomic and opioid mechanisms.Project 2.Tibial nerve stimulation with optimized parameter improves constipation in rats mediated via the autonomic mechanismsAims:Tibial nerve stimulation(TNS)has been applied for the treatment of overactive bladder syndrome,urinary incontinence and fecal incontinence;however,effects of TNS on constipation are controversial.The purpose of this study was to determine effects and mechanisms of TNS on constipation in a rodent model of constipation.Methods:(1)Real/sham TNS was performed with different sets of parameters for 30 minutes in six regular rats,distal colonic transit time(dcTT)in response to TNS and sham TNS was assessed and compared.Atropine was pretreated before real/sham TNS with optimized parameter 30 minutes to block the effect of TNS on dcTT.Heart rate variability(HRV)in response to TNS and sham TNS was assessed and compared.(2)Constipation rats were inducedby subcutaneous injection of loperamide hydrochloride in saline at the dose of 2 mg/kg body weight,twice per day for seven days;pellets number,wet weight,water content of feces,Bristol score,food intake and dcTT were measured.Sixteenconstipation rats were treated by real or sham TNS 30minutes daily for a period of 7 days,the feces characteristics,Bristol score,food intake,dcTT and HRVin response to TNS and sham TNS were assessed and compared.Results:(1)Five sets of different parameters were tested.TNS with the parameter"25Hz 500us 2s on 3s off 90%MT" significantly reduced the dcTT in the regular rats compared with sham TNS and the prokinetic effect was blocked by atropine.LF was decreased and HF was increased during and after TNS with the optimized parameter assessed from the spectral analysis of HRV.(2)After seven days’ treatment of loperamide,pellets numbers,wet weight,water content,and Bristol scorewere significantly decreased,dcTT were delayed.TNS could normalize these changes,but sham TNS had no similar effect.There were no significant difference in food intake daily among baseline,after loperamide treatment,and after real/sham TNS.Concurrently,TNS decreased LF and increased HF compared with sham TNS in the constipation rats.Conclusions:TNS with the parameter "25Hz 500us 2s on 3s off 90%MT" could shortdistal colonic transit time and improve feces characteristics in constipation rats,mediated via the autonomic function and cholinergic pathway.Project 3.Esophageal dynamics analysis in the patients with refractory gastroesophageal reflux disease Part I Role of altered esophageal intraluminal baseline impedance levels in patients with gatroesophageal reflux disease refractory to proton pump inhibitorsAims:Numerous studies have investigated utility of esophageal intraluminal baseline impedance levels(BILs)in gastroesophageal reflux disease(GERD).However,effect of BILs in refractory GERD(RGERD)has not been well investigated.The aim of this study is to evaluate role of BILs in RGERD patients.Methods:We retrospectively reviewed the impedance-pH data and endoscopy findings in patients with refractory gastroesophageal reflux symptoms.Reflux parameters and BILs were compared among differentsubgroups:acid reflux,nonacid reflux and functional heartburn subgroups,and reflux esophagitis(RE)and non-erosive reflux disease(NERD)subgroups.We analyzed the correlation among distal esophageal BILs and reflux parameters.Results:Total 62 subjects with refractory gastroesophageal reflux symptoms underwent 24-h impedance-pH monitoring and gastroendoscopy.Distal BILs in acid reflux type were significantly lower than those in nonacid reflux type and FH group.Distal BILs of RE patients were lower than those of NERD patients,while there were no statistical significance between two groups.Patients with severe esophagitis had lower distal BILs than those with mild esophagitis and NERD patients,and patients with severe esophagitis in acid reflux type had the lowest distal BILs.Distal BILs were significantly negatively correlated with DeMeester score,episodes of acid reflux,and acid exposure time,but no correlated with episodes of nonacid reflux.Conclusions:Characteristics of BILs in RGERD patients were similar with those in GERD patients,but might be more complicated.Evaluating BILs in RGERD patients could achieve a better understanding of pathophysiology in refractory gastroesophageal reflux disease.Part Ⅱ Esophageal Body Motility for Clinical Assessment in Patients with Refractory Gastroesophageal Reflux SymptomsAims:Little data exists about esophageal body dysmotility and reflux patterns in refractory gastroesophageal reflux disease(RGERD)patients off therapy.We aimed to evaluate effects of esophageal body dysmotility on reflux parameters in RGERD patients by combining impedance-pH monitoring and high-resolution manometry(HRM).Methods:We retrospectively reviewed the impedance-pH data and HRM metrics in patients with refractory gastroesophageal reflux symptoms.Impedance-pH monitoring and manometric data were compared between 2 groups:ineffective esophageal motility(IEM)and normal motility.Results:Fourty-eight patients(30 males,mean age 54.5 years)were included(16 erosive esophagitis,24 non-erosive reflux disease,and 8 functional heartbum),amongst which 24 subjects showed IEM,and others had normal motility.Number of patients who had large break in IEM group was significantly higher than that of normal motility.IEM group had more patients with weakly acid reflux and long term acid reflux than normal group(P=0.008,P=0.004,respectively).There were no statistical difference in BILs fromz4 to z6 between 2 groups(all P>0.05).Acid exposure time,numbers of long term acid reflux and weakly acid reflux showed strong negative correlation with esophageal body motility and/or lower esophageal sphincter function.Conclusions:IEM associated more with acid exposure,abnormal weakly acid reflux and long term acid reflux in RGERD patients.These data suggested the role of esophageal body dysmotility in the pathophysiological mechanisms of RGERD patients.PartⅢRole of esophageal baseline impedance levels in patients with proton pump inhibitor nonresponsive nonerosive reflux diseaseAims:Pathological mechanisms of refractory nonerosive reflux disease(NERD)are multifactorial and remaining unclear.Esophageal baseline impedance level(BIL)has been considered as an indicator of esophageal mucosal integrity.We aimed to evaluatethe role of BILs in refractory NERD patients.Methods:In this retrospective study,MⅡ-pH monitoring results and endoscopy findings were reviewed.Reflux parameters and BILs were compared between NERD/PPI responders and NERD/PPI nonresponders,correlation among distal esophageal BILs and acid exposure time was analyzed.Receiver operator characteristic(ROC)curves were used to evaluate optimum cutoffvalues for evaluation of the ability of distal BILs todiscriminate NERD/PPI nonresponders.Esophageal BILs were compared among three subgroups(acid reflux,nonacid reflux,and functional heartburn)of NERD/PPI nonresponders.Results:25 patients were identified as NERD/PPI nonresponders(10 acid reflux and 15 nonacid reflux),10 patients were functional heartburn(FH),and 9 patients were NERD/PPI responders.DeMeester score,AET,and reflux episodes were similar between NERD/PPI responders and NERD/PPI nonresponders.Distal BILs were lower in NERD/PPI responders than nonresponders.Distal BIL was a good diagnostic marker of NERD/PPI nonresponders,with an area under the curve(AUC)of 0.773[950%confidence interval(CI)0.617-0.930].Distal BILs were lower in acid reflux group than nonacid reflux and FH group,and distal BILs were negatively correlated to acid exposure time(r=-0.390,P=0.009,n=44).Conclusions:Assessment of esophageal BILs could represent a marker for reflux induced changes to the esophageal mucosa,and could help to identify NERD/PPI nonresponders.