77 Vanilloid receptor expression in body and trigone of female urinary bladder: changes in urgency without detrusor overactivity

Abstract

Introduction: Patients with sensory urgency (SU): the symptom complex of urgency associated with pain, burning or discomfort, often accompanied by frequency and nocturia, are difficult to treat. Vanilloid receptors on afferent neurons and on urothelium may participate in signalling from the bladder. Our aim was to examine whether changes in VR1 expression occur in bladder from SU patients compared with controls.Patients: Biopsies from body and trigone were obtained from patients with SU (female, aged 21–82) who had undergone videourodynamics to exclude detrusor overactivity and define first sensation. Asymptomatic age‐matched females with prior history of carcinoma acted as controls. Biopsies were collected into ‘RNALater’. Specimens were dissected into two layers, mucosa and detrusor muscle, before RNA extraction and quantitative competitive RT‐PCR (Mansfield et al 2005 Br J Pharmacol 144: 1089–99).Results: In control biopsies, VR1 mRNA was present in greater density in mucosa than in detrusor muscle (15.3 × 105cf. 4.6 × 105 copies/μg RNA, both n = 15, P < 0.01). In SU, VR1 mRNA expression was significantly higher in trigonal mucosa than in body mucosa (19.1 × 105 cf. 7.4 × 105 copies/μg RNA, n = 21‐‐23, P < 0.01). There was no significant change in VR1 expression in body mucosa from SU specimens compared with matched controls. In SU patients, the level of VR1 expression in trigonal mucosa (but not body mucosa) was significantly inversely correlated with the volume at first bladder sensation (r2 = 0.41, P < 0.01).Conclusion: We hypothesise that excessive afferent signalling via VR1 receptors in the trigone region may be related to an early first bladder sensation and sensory urgency.