Bladder outlet obstruction influences mRNA expression of cholinergic receptors on sensory neurons in mice

AimsIn patients with bladder outlet obstruction (BOO), dysregulation of bladder afferent neurons seems to contribute to irritative symptoms. Cholinergic receptors, addressed by both neuronal and non-neuronal (urothelial) acetylcholine, can alter neuronal excitability. Thus we investigated the influence of BOO on the expression of muscarinic (mAChR) and nicotinic (nAChR) acetylcholine receptors in the lumbosacral dorsal root ganglia (DRG) of mice.Main methodsBOO was induced in 13 C57/BL6 mice by partial suturing of the urethra. Eleven mice were sham-operated (loose/freely movable suture around the urethra), and eleven untreated mice served as controls. Cystometry was performed five weeks later in conscious mice. DRG at segmental levels L5-S2 were dissected and real-time quantitative PCR was performed. Expression of mAChR subtypes M1–M5 and nAChR subunits α2–7, α9–10, β2–4 was examined.Key findingsExpression of all mAChR subtypes and nAChR subunits α3–7, α10, β2–4 was detected. Expression of α2 and α9 was absent. Rank order of expression was M2 > M4 > M3 > M5 > M1, α3 ≥ α6 > α7 > α4 > α10 > α5 and β2 > β4 > β3 in untreated animals. BOO mice presented distinct obstruction with development of residual urine. Sham mice showed only minimal BOO. Relative mRNA expression of nAChR subunits revealed significant reduction of α3, α5, α6, α10 and β4 in sham-operated vs. untreated mice. In BOO vs. sham-operated mice, reduction of nAChR subunits α10 (p = 0.038) and α5 (p = 0.053) was found.SignificanceBOO has a considerable impact on nAChR, but not on mAChR mRNA expression in sensory neurons. We hypothesize that a reduction in mRNA expression of nAChR subunits represents a link to altered sensitivity under non-obstructive conditions.