title: Effects of acute sacral neuromodulation on bladder reflex in complete spinal cord injury rats.
abstract: BACKGROUND
  Neurogenic bladder associated with spinal cord injury (SCI) often results in serious disruption of lower urinary tract function. Compared to conventional therapies, sacral neuromodulation (SNM) may offer an alternative, non-destructive treatment for SCI patients with bladder dysfunction. Understanding bladder reflex changes following SCI and the effects of SNM may yield new insights for innovative use of this promising technique. Using a SCI rat model developed in this study, we investigated: 1) the bladder responses with different grades of bladder filling in intact and SCI rats; and 2) the effects of acute SNM on bladder reflex responses in SCI rats.
  
  
  METHODS
  An SCI rat model with overactive bladder was developed and evaluated in this study to examine the effects of acute SNM on bladder reflex in complete SCI rats. Twelve adult female Sprague-Dawley rats were divided into three groups; group I: spinally intact rats (N = 4), group II: transected (T9-T10) rats (N = 4), i.e., SCI rats, and group III: SCI rats with SNM treatment (N = 4). All rats were anesthetized and set up for continuous saline infusion. Cystometric parameters, including contraction period, contraction duration, bladder peak pressure, and number of uninhibited contractions, were analyzed and compared between groups and between conditions with and without SNM treatment for SCI rats.
  
  
  RESULTS
  In the intact rats, the frequency of bladder contraction was dependent upon the rate of bladder filling, while the spinal transected rats exhibited large fluctuation and demonstrated different patterns in response to saline infusion. Moreover, the bladder in SCI rats demonstrated an increased contraction period and a decreased contraction strength compared to the intact rats (all p < 0.05). In SCI rats under acute SNM treatment, bladder contraction period and duration tended to become longer, and the bladder peak pressure was decreased. The accumulating evidence indicated that acute SNM had inhibiting effects for bladder overactivity following SCI.
  
  
  CONCLUSIONS
  The spinal rat model developed in this study was suitable to investigate the effect of sacral neural stimulation on micturition reflex. The results of present study demonstrated that the micturition reflex can be modulated by sacral neural stimulation.
authors.affiliation: Institute of Rehabilitation Engineering, School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Shi
authors.forename: Xueyan
authors.initials: X
authors.lastname: Zhao
authors.forename: Jinwu
authors.initials: J
authors.lastname: Wang
authors.forename: Ning
authors.initials: N
authors.lastname: Lan
mesh_terms: D000818:Animals; D004599:Electric Stimulation Therapy / Q000379:methods; D005260:Female; D009119:Muscle Contraction / Q000502:physiology; D011312:Pressure; D051381:Rats; D017207:Rats, Sprague-Dawley; D012018:Reflex / Q000502:physiology*; D012445:Sacrococcygeal Region; D013119:Spinal Cord Injuries / Q000150:complications / Q000503:physiopathology*; D013127:Spinal Nerves / Q000503:physiopathology; D013997:Time Factors; D001743:Urinary Bladder / Q000503:physiopathology*; D053201:Urinary Bladder, Overactive / Q000209:etiology / Q000503:physiopathology* / Q000628:therapy*; D014554:Urination / Q000502:physiology
keywords: Bladder infusion; bladder reflex; sacral neuromodulation; spinal cord injury