Possible role of hydrogen sulfide as an endogenous relaxation factor in the rat bladder and prostate

To clarify the roles of hydrogen sulfide (H₂ S), an endogenous gasotransmitter, in the rat bladder and prostate, we investigated the distribution of enzymes related to H₂ S biosynthesis (cystathionine β-synthase [CBS], cystathionine γ-lyase [CSE], 3-mercaptopyruvate sulfurtransferase [MPST], cysteine aminotransferase [CAT], and D-amino acid oxidase [DAO]) and the content of H₂ S. We also investigated the effects of H₂ S donors (NaHS and GYY4137) on the contractility of both tissues and on micturition.

The distribution of these enzymes was investigated by real-time PCR, Western blot, and immunohistochemistry. Tissue H₂ S content was measured by the methylene blue method. The effects of NaHS (1 × 10^-9 to 3 × 10^-4  M) were evaluated on carbachol (10^-5  M)-induced pre-contracted bladder strips, and on noradrenaline (10^-5  M)-induced pre-contracted prostate strips, which were pretreated with propranolol (10^-6  M). In addition, in urethane-anesthetized male Wistar rats, the effects of intravesically instilled GYY4137 (10^-8 , 10^-7 , and 10^-6  M) on micturition were evaluated by cystometry.

MPST and CAT were detected in the bladder and prostate, CBS was only detected in the prostate, while CSE and DAO were not detected in both tissues. Immunoreactivity of these enzymes was mainly detected in the urothelium and smooth muscle layer of the bladder and in the prostate glandular epithelium. H₂ S was detected in both tissues. NaHS dose-dependently induced relaxation of pre-contracted bladder and prostate strips. Intravesically instilled GYY4137 significantly prolonged intercontraction intervals.

It is possible that H₂ S can function as an endogenous relaxation factor in the rat bladder and prostate.