Effect of SQW on the bladder function of mice lacking TRPV1.

BACKGROUND: Suo Quan Wan (SQW) is an effective traditional Chinese prescription on treated lower urinary tract symptoms (LUTS), and has been proved have modulation effect on the expression of transient receptor potential vanilloid 1 (TRPV1) in accordance with the recovery of bladder function of overactive bladder rat. This study further investigated the mechanism of SQW modulated TRPV1 signaling and bladder function using TRPV1 knockout (KO) mice.

METHODS: Study was conducted using wild type and TRPV1 KO mice. The KO animals were grouped into KO group and SQW treated group. We applied in vivo cystometrogram recording techniques to analyze voiding control of the urinary bladder, as well as in vitro organ bath to study bladder distension response to various compounds, which subsequently elicited normal smooth muscle excitation. Real-time polymerase chain reaction and western blot analysis were performed to quantify the expression of TRPV1 and P2X3 in the bladder. ATP released from bladder strips was measured using the luciferin-luciferase ATP bioluminescence assay kit.

RESULTS: KO preparation inhibited decrease micturition times, while micturition interval and volume were increased. Results of urodynamic record of the TRPV1-/- mice during NS infusion showed reduced bladder pressure and contraction which exhibited decreased response to α, β-me ATP, KCl, and carbachol and no response to CAP. The ATP released by the TRPV1-/- mice from strips of bladder smooth muscles was significantly reduced, along with no TRPV1 expression and reduced expression level of P2X3 in the bladder. SQW could increase ATP release in some degree, while had no effect on TRPV1 and P2X3 expression. SQW could improve bladder pressure slightly, while make no significantly effects on the force response to α,β-meATP, CAP, carbachol in gradient concentration, and KCl, as well as MBC and voiding activities.

CONCLUSIONS: TRPV1 plays an important role in urinary bladder mechanosensitivity. The effective SQW is hard to play its proper role on bladder function of mice without TRPV1.