The role of anandamide in the development of inflammatory hyperalgesia and visceral hyperreflexia was studied in the rat urinary bladder. Animals were given intraperitoneal cyclophosphamide injection, which evokes painful hemorrhagic cystitis accompanied by increased bladder reflex activity. The vanilloid receptor 1 [transient receptor potential vanilloid 1 (TRPV1)] antagonist capsazepine, applied onto the serosal surface of bladders, significantly reduced the hyperreflexia. Mass spectrometric analysis revealed that cyclophosphamide injection significantly and persistently increased the anandamide content of bladder tissues. The increase in the anandamide content paralleled the development of reflex hyperactivity. Anandamide (1-100 μm), applied onto the serosal surface of naive bladders, increased the reflex activity in a concentration-dependent manner. Repeated anandamide applications did not produce desensitization of the response. The anandamide-evoked effect was blocked by capsazepine or by instillation of resiniferatoxin, the ultrapotent TRPV1 agonist, into the bladders 24 hr before the anandamide challenge. The cannabinoid 1 receptor antagonist SR141716A [N-piperidino-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methylpyrazole-3-carboxamide] significantly increased the potency of anandamide in enhancing bladder reflex activity in naive but not in cyclophosphamide-injected animals. Application of the fatty acid amide hydrolyze inhibitor palmitoylisopropylamine onto the serosal surface of bladders also increased the reflex activity both in naive and cyclophosphamide-injected rats. This latter effect in naive animals was blocked by capsazepine and by resiniferatoxin pretreatment. Finally, intravesical instillation of anandamide (50 μm) increased c-fosexpression in the spinal cord, which was reduced by capsazepine or by resiniferatoxin pretreatment.These results suggest that anandamide, through activating TRPV1, contributes to the development of hyperreflexia and hyperalgesia during cystitis.

We evaluated the role of transient receptor potential vanilloid subfamily 1 for the generation of noxious bladder input and bladder overactivity associated with cystitis. Spinal c-fos expression triggered by innocuous bladder distention (10 cm water) was studied in sham and lipopolysaccharide inflamed transient receptor potential vanilloid subfamily 1 +/+ and -/- mice. Bladder reflex activity was studied using urethane anesthesia in sham and lipopolysaccharide inflamed transient receptor potential vanilloid subfamily 1 +/+ and -/- mice. Inflammatory changes in the bladder of transient receptor potential vanilloid subfamily 1 +/+ and -/- mice were identical. Bladder distention in sham inflamed +/+ mice induced a mean +/- SD of 4 +/- 2 Fos cells per section. Bladder distention after lipopolysaccharide inflammation increased Fos cells to 34 +/- 5 (p 0.05). During saline infusion of sham inflamed bladders in +/+ mice 0.46 +/- 0.14 contractions per minute were documented. In lipopolysaccharide inflamed +/+ mice that frequency was increased to 1.13 +/- 0.12 contractions per minute (p 0.05). Our data demonstrate that transient receptor potential vanilloid subfamily 1 is essential for the generation of noxious bladder input and bladder overactivity associated with cystitis.

We evaluated the effects of GRC-6211, an orally active TRPV1 antagonist, on the function and noxious input of naïve and inflamed bladders. In urethane (Sigma(R)) anesthetized rats 0.5 ml GRC-6211 (0.001, 0.01, 0.1 and 1 mg/kg weight) or its vehicle (0.5% methylcellulose) were administered through a duodenal catheter and cystometry was done during infusion of saline, 100 microM capsaicin or 0.5% acetic acid (Merck, Feltham, United Kingdom). Cystometry was also performed in WT and TRPV1 knockout mice treated with 1 mg/kg GRC-6211. Cystometry was done in rats inflamed with lipopolysaccharide after receiving 0.1 mg/kg GRC-6221 or vehicle. Spinal c-fos expression induced by 0.5% acetic acid was investigated after 0.1 mg/kg GRC-6211 or vehicle administration. TRPV1 immunoreactivity was evaluated in the bladder after GRC-6211 administration. The reflex activity of rat and WT mice naïve bladders was unchanged by GRC-6211 up to a dose of 0.1 mg/kg. At 1 mg/kg contractions were transiently suppressed in naïve rats and WT mice but not in TRPV1 knockout mice. GRC-6211 (0.1 mg/kg) completely prevented capsaicin induced irritation, while the 0.001, 0.01 or 0.1 mg/kg dose decreased the mean +/- SD frequency of bladder contractions during acetic acid infusion from 1.5 +/- 0.3 to 1.35 +/- 0.35 (not significant), 0.9 +/- 0.2 (p <0.05) and 0.8 +/- 0.2 (p <0.05), respectively. Lipopolysaccharide inflamed rats had 1.4 +/- 0.4 and 0.8 +/- 0.1 contractions per minute after vehicle and GRC-6211, respectively (p <0.05). The c-fos expression induced by acetic acid was decreased by GRC-6211 (85.5 +/- 19.1 to 46.7 +/- 9.4, p <0.05). GRC-6211 did not change bladder TRPV1 immunoreactivity. GRC-6211 counteracts the bladder hyperactivity and noxious input induced by cystitis. At high doses it suppresses normal bladder activity by a TRPV1 dependent mechanism. TRPV1 antagonists might be useful for cystitis.

OBJECTIVE: To evaluate the effect of intravesical resiniferatoxin on spinal c ‐ fos expression and bladder volume at reflex micturition in rats with chronic urinary bladder inflammation. MATERIALS AND METHODS: Of three groups of female Wistar rats, group 1 received cyclophosphamide (75 mg/kg body weight) intraperitoneally every third day (cyclophosphamide is an antitumoral agent that induces bladder inflammation after urinary excretion of its metabolite, acrolein); group 2 comprised sham‐inflamed rats that received saline instead of cyclophosphamide, and group 3 received cyclophosphamide, as group 1, every third day but plus 10 nmol/L resiniferatoxin intravesically, through a urethral catheter, at 7 days. At 8 days, under urethane anaesthesia, a needle was inserted in the bladder dome and saline infused at 6 mL/h for 2 h. Finally the animals were perfusion‐fixed through the ascending aorta with 4% paraformaldehyde. Transverse sections cut from L6 spinal cord segments were immunoreacted for Fos protein and positive cells in the dorsal horn counted. In a further set of equal groups the bladders were prepared in the same way under urethane anaesthesia and after 30‐min of stabilization, saline was infused at 6 mL/h and the volume evoking reflex micturition determined. RESULTS: The mean ( Sd ) number of positive c‐ fos cells per spinal cord section was 85 (21), 42 (9) ( P = 0.002) and 55 (10) in groups 1 to 3, respectively; the values for group 2 and 3 were similar ( P = 0.22) and statistically less than that of group 1 ( P = 0.02). Reflex micturition occurred at, respectively, 0.26 (0.09), 0.49 (0.18) and 0.52 (0.11) mL, being similar in group 2 and 3 ( P = 0.74) but lower in group 1 ( P = 0.003). CONCLUSION: Intravesical resiniferatoxin decreases c‐fos expression and increases bladder capacity in chronically inflamed rat bladders. These findings suggest that desensitizing the vanilloid receptor type 1 by intravesical resiniferatoxin is relevant to the treatment of pain and voiding frequency in patients with chronic inflammatory bladder conditions.

We investigated the expression and functional status of TRPV1 receptor in human urothelial cells. Human urothelium was cultured and TRPV1 receptor expression was studied by immunocytochemistry and reverse transcriptase-polymerase chain reaction. The influence of inflammatory mediators on TRPV1 mRNA levels was also studied. Functional assays (cobalt uptake measurements and whole cell voltage clamp records) were used to study the response of urothelial cells to capsaicin, temperature, low pH and inflammatory mediators. Capsaicin induced adenosine triphosphate release from urothelial cells was assessed by bioluminescence. TRPV1 protein and mRNA were detected in human urothelial cells and mRNA more than tripled in the presence of inflammatory mediators. Nerve growth factor treatment alone did not affect TRPV1 mRNA expression. Capsaicin (100 nM and 1 microM) and heat (41C and 45C) evoked cobalt uptake and inflammatory mediators lowered the temperature threshold for TRPV1 activation to 37C. Capsaicin (1 microM) induced TRPV1 desensitization to further applications of the agonist. In whole cell patch clamp experiments 1 microM capsaicin and a heat ramp from 37C to 50C caused inward currents. The same concentration of capsaicin induced the release of about 7 fmol adenosine triphosphate per mg. TRPV1 receptors expressed by human urothelial cells respond to capsaicin and thermal stimuli. Capsaicin evoked release of adenosine triphosphate suggests that human urothelial TRPV1 is involved in the afferent branch of the micturition reflex. Inflammatory mediators decrease the TRPV1 thermal threshold of activation to body temperature and increase its expression. This finding may be relevant for symptoms associated with cystitis.

Purpose: We compared the efficacy and safety of trigonal injections of onabotulinumtoxinA and saline in patients with bladder pain syndrome/interstitial cystitis. Materials and Methods: This phase II study enrolled women who had had bladder pain syndrome/interstitial cystitis for more than 6 months and pain for 4 months or longer on a visual analogue scale of 0 to 10, which were refractory to common treatment. OnabotulinumtoxinA 100 U in 10 or saline as placebo in 9 was administered as 10 trigonal injections of 1 ml. The primary study end point was the change from baseline pain intensity reported at week 12. Additional end points included O'Leary-Sant scores, micturition frequency, quality of life at week 4, 8 and 12, and the treatment benefit scale at week 12. Safety assessments included urinary tract infection, post-void residual urine and the initiation of clean intermittent catheterization. Results: At week 12 onabotulinumtoxinA had significantly reduced pain compared with saline (mean +/- SD -3.8 +/- 2.5 vs -1.6 +/- 2.1, p < 0.05). The proportion of patients who achieved a 50% or greater reduction in the pain visual analog scale was 60% for onabotulinumtoxinA vs 22% for placebo. OnabotulinumtoxinA significantly improved O'Leary-Sant scores and quality of life over placebo at weeks 4, 8 and 12. Important numerical reductions in voiding frequency were also observed with the toxin. OnabotulinumtoxinA was well tolerated. Urinary tract infections developed in 3 patients who received onabotulinumtoxinA vs 2 who received saline. Mean post-void residual urine at week 12 was 5 +/- 13 ml for onabotulinumtoxinA vs 0 ml with saline. This study had the limitations inherent to a single center trial with a small number of patients enrolled. Conclusions: OnabotulinumtoxinA 100 U caused significant and clinically relevant improvements in bladder pain and quality of life in patients with bladder pain syndrome/interstitial cystitis refractory to common therapy. It was also well tolerated.