Purpose: We evaluated the role of transient receptor potential vanilloid subfamily 1 for the generation of noxious bladder input and bladder overactivity associated with cystitis.
Materials and methods: 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.
Results: 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 <0.001). The number of Fos cells after bladder distention in sham and lipopolysaccharide inflamed -/- mice was similar (2 +/- 1 and 2 +/- 1, respectively, 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 <0.001). In sham and lipopolysaccharide inflamed -/- mice bladder frequency was similar (0.47 +/- 0.08 and 0.61 +/- 0.10, respectively, p >0.05).
Conclusions: 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.