The distribution of neuronal and inducible nitric oxide synthase in urethral stricture formation.
OBJECTIVE
The distribution of neuronal (n) and inducible (i) nitric oxide synthase (NOS) may have a role in the maintenance of normal urethral spongiosum and during the development of spongiofibrosis in urethral stricture disease.


METHODS
Eight normal and 33 strictured human bulbar urethras were studied by histological and immunohistochemical techniques for the neuronal markers S-100, nNOS and iNOS. The smooth muscle-to-collagen ratio was calculated by morphometric analysis of Masson's trichrome sections. Immunohistochemical staining patterns of the neuronal markers in normal urethral tissue was compared to that in urethral stricture tissue with spongiofibrosis.


RESULTS
The smooth muscle-to-collagen ratio was significantly lower in the strictured urethra compared to that in the control group (p = 0.001). In the strictured bulbar urethra nNOS immunoreactivity was decreased compared to that in normal urethral tissue. The severity of spongiofibrosis corresponded to the loss of nNOS immunoreactivity. iNOS immunoreactivity was found in strictured urethral epithelium and spongiosal tissue, whereas the control group was nonimmunoreactive to iNOS.


CONCLUSIONS
Urethral stricture formation is a fibrotic process associated with significant changes in NOS metabolism. Abnormal collagen synthesis following urethral trauma may be stimulated by inappropriate iNOS activity. A functional nerve supply to the urethral spongiosum seems to be crucial in the maintenance of the unique ultrastructure of the urethral spongiosum.
Cavalcanti
Andre G
AG
Department of Urology and Pediatrics, University of California-San Francisco Children's Medical Center, University of California-San Francisco, 94143, USA.
Yucel
Selcuk
S
Deng
Donna Y
DY
McAninch
Jack W
JW
Baskin
Laurence S
LS
D000328:Adult; D000368:Aged; D005355:Fibrosis; D006801:Humans; D008297:Male; D008875:Middle Aged; D019001:Nitric Oxide Synthase / Q000032:analysis / Q000502:physiology*; D052248:Nitric Oxide Synthase Type I; D009418:S100 Proteins / Q000032:analysis; D014525:Urethral Stricture / Q000201:enzymology* / Q000209:etiology* / Q000473:pathology
D009418:S100 Proteins; C496320:NOS1 protein, human; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I