Age-related changes of P2X 1 receptor mRNA in the bladder detrusor from men with and without bladder outlet obstruction

Abstract

The urinary bladder purinergic system is reported to change with age and with bladder dysfunction. Here, we examined the expression of purinergic P2X 1 receptors in detrusor and mucosa (urothelium + lamina propria) from male control bladder and investigated age-related P2X 1 receptor mRNA expression in control and obstructed detrusor. Biopsy specimens were obtained at cystoscopy from control patients ( n = 46, age range 30–86 years) and patients diagnosed with outlet obstruction ( n = 29, 46–88 years). Calponin expression (measured by RT-PCR) was similar in control and obstructed detrusor and did not change with age. Quantitative competitive RT-PCR was used to measure P2X 1 receptor and GAPDH mRNA in control and obstructed detrusor. P2X 1 receptor mRNA expression was 9-fold ( p < 0.0001) higher in the detrusor than in the mucosa. Expression of mRNA for the internal control GAPDH remained stable with age and across control and obstructed detrusor. No difference in P2X 1 receptor expression was observed between control and obstructed detrusor ( p = 0.35). However, an age-related decrease in P2X 1 mRNA expression was observed in control ( n = 27; p = 0.0054; Spearman coefficient r = −0.520) but not obstructed detrusor ( n = 19; p = 0.093; r = −0.396). Downregulation of P2X 1 mRNA expression might occur as a result of an increased component of neural ATP release in the aging bladder.