Differential gene expression of cholinergic muscarinic receptor subtypes in male and female normal human urinary bladder

Objectives. To study the mRNA expression of each muscarinic receptor subtype in bladder areas involved in micturition, such as the bladder dome, neck, and trigone. Our study focused on the analysis of the gene expression of muscarinic receptors in the human male and female urinary bladder. Other than the well-known role of bladder parasympathetic innervation, an extensive study of the muscarinic receptor mRNA distribution in male and female urinary bladder is still lacking. Methods. The study was carried out on 5 female (age 56 +/- 10 years) and 5 male (age 70 +/- 9 years) patients. The patients selected for this study did not have any lower urinary tract symptoms, as determined by International Prostate Symptom Score questionnaire. The mRNAs encoding muscarinic receptor subtypes were assessed by reverse transcription-polymerase chain reaction, followed by Southern blot analysis. Results. Using a molecular approach, we demonstrated the presence of all muscarinic receptor subtypes in the different urinary bladder areas involved in micturition; in particular, our data indicated that mRNAs encoding muscarinic receptors are largely expressed in all examined bladder areas, both in men and women, although with some remarkable differences and a peculiar distribution. Conclusions. Our results indicate that the pharmacology of the human bladder may be more complex than previously recognized. Furthermore, the choice to study each biopsy as a single sample and not use a pool of tissues allowed us to point out the individual variability between subjects and sex-related differences in the expression profile of muscarinic receptor subtype mRNAs.