Molecular and pharmacological detection of dopaminergic receptors in the human male urinary tract

Aims: Evidence indicates that dopamine (DA) and DA receptors play a role in the central nervous system (CNS) control of micturition; however, while the central DAergic role in the micturition physiology has been extensively investigated, the expression and the function of DA receptors in the urinary tract are still under investigation. Here, we studied the distribution of DA receptor subtypes in different parts of the human male urinary tract. Methods: Fragments were collected from 34 men. The mRNAs encoding DA receptors were assessed by RT-PCR, followed by densitometric analysis. Adenylyl cyclase (AC) activity was evaluated using a commercially available RIA kit. Statistical analysis was carried out using one-way ANOVA, with the Bonferroni’s post hoc test. Results: Results obtained indicated that RT-PCR products of D1, D4, and D5 subtypes were obtained in each part studied, while no signal was observed for the D2 and D3 receptor subtypes. The pharmacological characterization demonstrated that the expressed DA receptors were linked to AC. Conclusions: DA receptors were expressed throughout the human male urinary tract, from the ureter to the prostatic urethra. In particular, we observed a distinctive DA receptor subtype distribution, with evidence of the presence of mRNA encoding both subtypes of the D1-like DA receptor family (D1 and D5), while the D4 receptors were the only expressed subtype of the D2-like family. These results suggested that DAergic drugs used for the treatment of a number of diseases may influence the micturition physiology not only in the CNS, but at the peripheral level as well.