Login to Access Video or Poster Abstract: MP42-18
Sources of Funding: NIH R01 DK 066349

Introduction

Endocannabinoids exert potent analgesic and anti-inflammatory effects and may suppress clinical symptoms of painful inflammatory bladder diseases. 2-arachidonoyl glycerol (2-AG) is the most abundant endocannabinoid and the activity of 2-AG in the bladder has not been previously described. We investigated whether 2-AG has the potential to prevent visceral pain associated with experimental cystitis in mice.

Methods

Expression of diacylglycerol lipase-α and -β (DAGL-α and -β, primary enzymes of 2-AG synthesis) and monoacylglycerol lipase (MAGL, primary enzyme of 2-AG degradation) in urothelium was examined by real-time RT-PCR and immunohistochemistry. Cystitis was induced by intraperitoneal injection of cyclophosphamide (CYP, 150 mg/kg), and mechanical sensitivity of hind paws was determined. Effects of 2-AG were also evaluated in cultured human urothelial cells.

Results

DAGL-α, -β and MAGL were present in the mouse urothelium. CYP (3 hours) induced cystitis in mice characterized by submucosal edema. Pretreatment with a specific MAGL inhibitor JZL 184 (8 mg/kg/day, sc, 6 days) prior to CYP treatment did not appear to affect bladder inflammation. Mechanical sensitivity threshold was significantly reduced after CYP treatment in mice that received vehicle (basal: 2.9 ± 0.1 g; vehicle: 0.6 ± 0.1 g; n =6; p<0.01 vs basal). However, the increase of mechanical sensitivity was attenuated in JZL184-treated mice (basal: 2.8±0.1 g; JZL 184: 1.4±0.6 g; n =6, p<0.05 vs basal and vehicle-treated animals). CYP augmented expression of IL-6 mRNA in urothelium (151.8±34.1 fold increase compared to control animals, n=6, p<0.01 vs control) and JZL 184 inhibited increased IL-6 expression (79.5±23.4, p<0.05 vs control and vehicle-treated animals). In cultured human urothelial cells, 2-AG attenuated LPS-induced increased TNF-α mRNA expression in a concentration-dependent manner.

Conclusions

We demonstrated the presence of the 2-AG pathway in the bladder, and this is the first available evidence that treatment with a MAGL inhibitor decreased visceral pain associated with cystitis. Urothelial cells play an important role in the activity of 2-AG in bladder. Manipulation of 2-AG may provide a novel therapeutic option for treatment of bladder pain.

Funding

NIH R01 DK 066349