title: Time-dependent changes in bladder function and plantar sensitivity in a rat model of fibromyalgia syndrome induced by hydrochloric acid injection into the gluteus.
abstract: OBJECTIVE
  To examine the correlation between muscular pain and bladder hypersensitivity in order to clarify the pathogenesis of comorbidity of bladder pain syndrome/interstitial cystitis with other chronic pain conditions such as fibromyalgia syndrome (FMS).
  
  
  METHODS
  Under isoflurane anaesthesia, 0.2 mL of hydrochloric acid (HCl) solution (pH 4.0) was injected into the bilateral gluteus muscles of female Sprague-Dawley rats to produce an FMS model, as the gluteus is one of the specific tender points in patients with FMS. Control rats received saline injection (0.2 mL). The mechanical sensitivity of the plantar was evaluated using the mean number of bilateral hindlimb withdrawals in response to tactile stimulation with a 2.0-g von Frey filament at 1, 2 and 3 weeks after the HCl injection. In a separate rat group, cystometry was performed with the rats awake during saline infusion (0.06 mL/min) into the bladder before and after 1% lidocaine injection (0.2 mL) into the bilateral gluteus 1, 2 and 3 weeks after the HCl injection.
  
  
  RESULTS
  The mean number of hindlimb withdrawals was significantly higher in FMS rats than in controls at 1 and 2 weeks. Using cystometry, we found that the intercontraction interval (ICI) and voided volume (VV) were significantly lower in FMS rats than in controls at 1 and 2 weeks. In addition, the voiding threshold pressure, ICI and VV were significantly higher after lidocaine injection in FMS rats, but not in controls, at 1 and 2 weeks.
  
  
  CONCLUSIONS
  HCl injection (pH 4.0) into the gluteus can induce plantar hypersensitivity and urinary frequency for up to 2 weeks after the injection, suggesting that somatic (gluteus)-to-visceral (bladder) cross-sensitization might underlie bladder hypersensitivity in patients with FMS. Moreover, intervention at specific tender points outside the bladder could be effective in treating urinary frequency because lidocaine injection into the gluteus normalized bladder function in FMS rats for up to 2 weeks.
authors.affiliation: Department of Urology, Jikei University School of Medicine, Tokyo, Japan. a-furuta@rf7.so-net.ne.jp
authors.forename: Akira
authors.initials: A
authors.lastname: Furuta
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Mariko
authors.initials: M
authors.lastname: Honda
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Koike
authors.forename: Takehito
authors.initials: T
authors.lastname: Naruoka
authors.forename: Koji
authors.initials: K
authors.lastname: Asano
authors.forename: Michael
authors.initials: M
authors.lastname: Chancellor
authors.forename: Shin
authors.initials: S
authors.lastname: Egawa
authors.forename: Naoki
authors.initials: N
authors.lastname: Yoshimura
mesh_terms: D000779:Anesthetics, Local / Q000494:pharmacology; D000818:Animals; D016022:Case-Control Studies; D059350:Chronic Pain; D004195:Disease Models, Animal; D005260:Female; D005356:Fibromyalgia / Q000139:chemically induced / Q000503:physiopathology*; D006614:Hindlimb; D006851:Hydrochloric Acid; D008012:Lidocaine / Q000494:pharmacology; D018482:Muscle, Skeletal / Q000187:drug effects / Q000503:physiopathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D001743:Urinary Bladder / Q000187:drug effects / Q000503:physiopathology*; D053201:Urinary Bladder, Overactive / Q000503:physiopathology; D014554:Urination / Q000187:drug effects / Q000502:physiology
chemical_list: D000779:Anesthetics, Local; D008012:Lidocaine; D006851:Hydrochloric Acid