Nitric oxide synthase gene and protein expression are upregulated by Bacille Calmette-Guerin in the rat bladder

Objective: We hypothesize that Bacille Calmette-Guerin (BCG) may act through the regulation of various isoforms of nitric oxide synthase (NOS) [inducible (iNOS), endothelial (eNOS), and neuronal (nNOS)] genes and protein expression in rat bladder. Methods: Adult female Sprague-Dawley rats (200-250 g)were injected transurethrally with BCG (22 rats) and phosphate-buffered saline (22 control rats), and after 2, 4, 6, and 12 h, and 1, 2, 3, 5, 7, 10, and 14 days, the bladders were harvested. Normal and BCG-treated rat bladders were analyzed for mRNA expression for iNOS, eNOS, and nNOS by reverse-transcriptase polymerase chain reaction. Protein expression was determined by Western blotting and immunohistochemistry. Results: mRNA expression for iNOS was induced after 2 h of BCG injection in the rat bladder. Gene expression for iNOS was highest at 6 h to 1 day followed by decreased expression, reaching its lowest level at 5 days. eNOS mRNA expression was detected in control bladders, but its level was higher in the BCG-treated animals, nNOS mRNA expression was present in all samples, bur did not change after BCG treatment. Western blotting confirmed these findings. Immunohistochemistry analysis demonstrated that eNOS was present mainly in endothelium, while iNOS was detected in stroma and nNOS in epithelium and smooth muscle of the rat bladder. Conclusion: The present study demonstrates, for the first time, that BCG treatment up-regulates gene and protein expression of iNOS and eNOS in normal rat bladders, suggesting that BCG action may be mediated through NOS pathways. Copyright (C) 2001 S. Karger AG, Basel.