Phosphodiesterase type 9 (PDE9) in the human lower urinary tract: an immunohistochemical study

What's known on the subject? and What does the study add? Localization of PDE9 in human LUT has not been reported in the literature, although PDE5 was reported to be abundantly present only in smooth muscle cells using immunohistochemistry. This is the first reported study which demonstrated the expression of PDE9 in the urothelium and neuron cells in the intramural ganglia of human LUT. Patterns of PDE9 localization were clearly different from those of PDE5, which suggest that functions of PDE9 were therefore considered to be different from those of PDE5 in human LUT. OBJECTIVES • To examine the roles of the one of the cyclic guanosine monophosphate (cGMP)‐specific phosphodiesterases (PDEs), PDE9, in human lower urinary tract (LUT), we performed immunohistochemistry (IHC) using autopsy specimens. • To demonstrate the potential functional differences between PDE5 and PDE9 in human LUT, the localization of PDE5 and PDE9 was also compared using laser‐capture microdissection (LCM)/reverse transcriptase‐polymerase chain reaction (RT‐PCR) method. MATERIALS AND METHODS • We immunolocalized PDE9 in human bladder (60 cases) and prostate (40) specimens using IHC. • We performed LCM/RT‐PCR evaluation in six human bladders to determine the differential expression patterns of PDE5 and PDE9. RESULTS • PDE9 immunoreactivity was detected in the bladder urothelium of all the cases and in 85% of the prostatic urethral urothelium. • PDE9 immunoreactivity was detected in the perikaryon of the intramural ganglia. • LCM/RT‐PCR evaluation showed that PDE5 mRNA was exclusively detected in smooth muscle cells but PDE9 mRNA was mainly detected in the urothelium of the human bladder. CONCLUSION • PDE9 is widely distributed in the urothelial epithelium of the human LUT and its potential roles may be different from those of PDE5.