Molecular characterization of M2 and M3 muscarinic receptor expression in bladder from women with refractory idiopathic detrusor overactivity.
OBJECTIVE
To examine the expression of muscarinic M2 and M3 receptors in human bladder detrusor and mucosa, from controls and patients with idiopathic detrusor overactivity (IDO), as antimuscarinic agents are the primary pharmacological treatment for IDO.


METHODS
Biopsies from the bladder body were collected at cystoscopy from 20 women with urodynamically confirmed refractory IDO (age range 25-86 years); biopsies were also collected from 30 asymptomatic female controls (age range 32-87 years). Samples were collected into RNA extraction medium and dissected into mucosa (urothelium plus lamina propria) and detrusor. RNA was extracted and the expression of M2 and M3 receptor mRNA determined by quantitative competitive reverse transcription-polymerase chain reaction. Results were normalized to beta-actin expression in the same sample.


RESULTS
Expression of M3 receptor mRNA, in mucosa of IDO patients (median 0.057 pg M3/100 ng total RNA; interquartile range 0.03-0.13, 12 samples), was four times (P = 0.039, Mann-Whitney) lower than from the control (median 0.22 pg M3/100 ng total RNA; 0.13-0.51, 11 samples). The expression of muscarinic M3 receptor mRNA was higher (14-35 times) in detrusor (control median 3.17; 26 samples) than in mucosa and did not change in IDO (median 2.03; 14 samples). M2 expression was not significantly different with region or with IDO.


CONCLUSIONS
These data show that M3 muscarinic receptor mRNA expression was significantly less in mucosa from IDO patients than from age-matched controls. The role of mucosal M3 receptors is unknown at present and elucidation of this role might provide a greater understanding of the aetiology of IDO.
Mansfield
Kylie J
KJ
Department of Physiology and Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, Australia.
Liu
Lu
L
Moore
Kate H
KH
Vaux
Kenneth J
KJ
Millard
Richard J
RJ
Burcher
Elizabeth
E
D000199:Actins / Q000378:metabolism; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy / Q000379:methods; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008875:Middle Aged; D009092:Mucous Membrane / Q000378:metabolism; D018727:Muscarinic Antagonists / Q000494:pharmacology*; D043585:Receptor, Muscarinic M2 / Q000378:metabolism*; D043587:Receptor, Muscarinic M3 / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D001743:Urinary Bladder / Q000378:metabolism / Q000473:pathology; D053201:Urinary Bladder, Overactive / Q000188:drug therapy / Q000209:etiology / Q000378:metabolism* / Q000473:pathology
D000199:Actins; D018727:Muscarinic Antagonists; D043585:Receptor, Muscarinic M2; D043587:Receptor, Muscarinic M3