Poster, Podium & Video Sessions
Presentation Authors: William Akakpo*, Biljana Musicki, Arthur Burnett, Baltimore, MD
Introduction: The pathophysiology of detrusor overactivity remains unclear. We hypothesized that dysregulation of S-nitrosylation, a process that mediates proteins activity, contributes to the pathogenesis of this disorder. We aim to investigate detrusor function and cAMP activation as a possible treatment for detrusor overactivity in an experimental model lacking a key denitrosylation enzyme, S-nitrosoglutathione reductase (GSNOR).
Methods: GSNOR-deficient (GSNOR-/-) (n=30) and wild-type (WT) mice (n=26) were treated for 7 days with the cAMP activator, Colforsin (1mg/kg), or vehicle intraperitoneally. Cystometric studies or molecular analyses of bladder specimens were performed. Bladder function indices and expression levels of proteins that regulate detrusor relaxation (nitric oxide synthase pathway) or contraction (RhoA/Rho-kinase pathway) and oxidative stress were assessed. Student t-test and one-way ANOVA were used.
Results: GSNOR-/- mice showed a significant increase (p<0.05) in voiding and non-voiding contraction frequencies compared to WT mice (figure 1, arrows indicate voiding contractions). Colforsin normalized these abnormalities. Western blot analyses showed an up-regulation of the RhoA/Rho-kinase pathway reflected by a significant increase (p<0.05) of phosphorylated-MYPT1 expression in GSNOR-/- mouse bladders, which was reversed by Colforsin treatment (figure 2). An increased level (p<0.05) of gp91phox expression in bladders of GSNOR-/- mice was observed without significant change after Colforsin treatment. Neuronal and endothelial nitric oxide synthase phosphorylation on Ser-1412 and Ser-1177, respectively, did not differ between GSNOR-/- and WT mouse bladders irrespective of Colforsin treatment.
Conclusions: Impaired denitrosylation contributes to detrusor overactivity in association with upregulated RhoA/Rho-kinase signaling. Colforsin reverses physiologic and molecular abnormalities. This study describes a novel model of detrusor overactivity and suggests a possible basis for its treatment.
Source Of Funding: This study was supported by a grant from the National Health Institute (R01DK067223).
William Akakpo received international mobility grants from the French Association of Urology (AFU) and the French Society of Urodynamics (SIFUD-PP).
Johns Hopkins University
William Akakpo, MD, Urology Resident in Paris (France) and past research fellow at Johns Hopkins University. He did this fellowship in the laboratory of Neuro-Urology directed by Dr Arthur L. Burnett.
He is doing his last year of residency then will work in the Department of Urology at Pitie Salpetriere Hospital (Paris).
Tuesday, May 16
9:40 AM – 9:50 AM