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 throug h the regulation of various isoforms of nitric oxide synthase (NOS) [induci ble (iNOS), endothelial (eNOS), and neuronal (nNOS)] genes and protein expr ession in rat bladder. Methods: Adult female Sprague-Dawley rats (200-250 g)were injected transure thrally 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 bladd ers were harvested. Normal and BCG-treated rat bladders were analyzed for m RNA 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 foll owed by decreased expression, reaching its lowest level at 5 days. eNOS mRN A expression was detected in control bladders, but its level was higher in the BCG-treated animals, nNOS mRNA expression was present in all samples, b ur did not change after BCG treatment. Western blotting confirmed these fin dings. Immunohistochemistry analysis demonstrated that eNOS was present mai nly in endothelium, while iNOS was detected in stroma and nNOS in epitheliu m and smooth muscle of the rat bladder. Conclusion: The present study demonstrates, for the first time, that BCG tr eatment up-regulates gene and protein expression of iNOS and eNOS in normal rat bladders, suggesting that BCG action may be mediated through NOS pathw ays. Copyright (C) 2001 S. Karger AG, Basel.