The effect of chronic bladder outlet obstruction on neuronal nitric oxide synthase expression in the intramural ganglia of the guinea pig bladder.
OBJECTIVE
We examined the effect of chronic partial outlet obstruction on expression of neuronal nitric oxide synthase (nNOS) in the intramural ganglion cells of the guinea pig bladder.


METHODS
Partial urethral ligation was done in young male guinea pigs. The animals were sacrificed 2, 4, 6, 8 and 12 weeks after partial outlet obstruction and nNOS immunohistochemistry was done in the intramural neurons of the bladder. This was compared to controls (normal and sham operated). In addition, the mRNA expression of nNOS in bladders of 4-week sham operated and operated animals was also investigated using real-time quantitative reverse transcriptase-polymerase chain reaction.


RESULTS
Two weeks after urethral obstruction a decrease in the number of nNOS positive intramural neurons was detected. This decrease was most drastic at 4 weeks. Cell counting showed a 60.6% decrease in the number of nNOS positive neurons compared to controls. Some neurons appeared to undergo degenerative changes, such as irregular outline, vacuolation and lysis. At 6 weeks the number of nNOS positive neurons increased from the nadir level at 4 weeks and the increase was sustained until 12 weeks, when the number of nNOS positive neurons was almost at the level of controls. Quantitative reverse transcriptase-polymerase chain reaction also showed 42.4% down-regulation of nNOS expression 4 weeks after obstruction comparing with sham operation.


CONCLUSIONS
Partial urethral ligation resulted in an initial decrease in nNOS positive neurons, which have been due to actual neuronal loss and/or enzyme down-regulation. This may be attributable to regional hypoxia as a result of decreased blood flow consequent to high intravesical pressure created by partial ligation. The decrease in nNOS expression followed by a compensatory increase in nNOS positive neurons also suggests an attempt or mechanism to up-regulate nitric oxide bioactivity following increased bladder outlet resistance.
Hu
Jin
J
Department of Surgery, Faculty of Medicine, National University of Singapore, 5 Lower Kent Ridge Road, Singapore 119074.
Chin
Chong-Min
CM
Png
Jin-Chye
JC
Ng
Yee-Kong
YK
Ling
Eng-Ang
EA
D000818:Animals; D002452:Cell Count; D002908:Chronic Disease; D005724:Ganglia / Q000201:enzymology*; D006168:Guinea Pigs; D007150:Immunohistochemistry; D008297:Male; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009474:Neurons / Q000201:enzymology / Q000473:pathology; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052248:Nitric Oxide Synthase Type I; D009929:Organ Size; D020133:Reverse Transcriptase Polymerase Chain Reaction; D001743:Urinary Bladder / Q000294:innervation* / Q000473:pathology; D001748:Urinary Bladder Neck Obstruction / Q000201:enzymology* / Q000473:pathology
D009419:Nerve Tissue Proteins; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I