Where is TRPV1 expressed in the bladder, do we see the real channel?

Transient receptor potential channel-vanilloid subfamily member 1 (TRPV1) is an important target in the treatment of bladder overactivity. This receptor is suggested to function as a mechanosensor in the normal bladder and to mediate the development of bladder overactivity during cystitis. Our aim was to determine the cellular distribution of TRPV1 in mouse and rat bladder tissue. We used three different commercial TRPV1 antibodies to perform immunohistochemistry on bladder tissue from rats and wild-type and TRPV1−/− mice, using trigeminal ganglia as a control tissue for TRPV1 expression. Although two of the antibodies seemed to react specifically in trigeminal ganglion tissue, all the antibodies produced a similar staining pattern in the urothelium of wild-type and TRPV1−/− mice. These data show that TRPV1 antibodies can cause an aspecific immunostaining in bladder tissue, urging for additional research to confirm the exact distribution of TRPV1 in bladder. In conclusion, we think that the use of negative controls on knockout mice, whenever available, is mandatory when conducting immunohistochemical localization studies.