Inducible nitric oxide synthase in the epithelial epididymal cells of the rat

The expression of mRNA for inducible nitric oxide synthase (iNOS) in rat epithelial cells of epididymis was investigated with reverse transcription followed by polymerase chain reaction. Immunocytochemical reaction for iNOS was performed to confirm the enzyme's localization in the epididymal epithelium. Additionally, an indirect spectrophotometric method for nitric oxide (NO) determination was applied for measurement of nitrite production by cultured epididymal epithelial cells. Inducible NOS mRNA was detected in freshly isolated epithelial cells, in cultured cells without stimulation as well as in cultured cells after stimulation by lipopolysaccharide and interferon-gamma. Inducible NOS immunoreactivity was observed in the apical part of epithelial cells of epididymal sections and in the cytoplasm of cells in culture. Release of nitrite was observed in vitro in both the unstimulated and stimulated cells of caput (1.44+/-0.94 v. 4.37+/-2.42 microM) and cauda (0.69+/-1.21 v. 5.21+/-2.76 microM) epididymis (P < 0.001). To the best of our knowledge, this is the first study to demonstrate iNOS in the epididymal epithelial cells of the rat. Nitric oxide released by epididymal epithelial cells may act on cells and tissues located nearby. The results may help explain epididymal function: sperm storage, passage and maturation. Excessive epididymal NO production may also play a role in the inflammatory infertility of the male.