Antioxidant status of the rat nasal cavity.

Despite extensive interest in the rodent nasal cavity as a target organ for toxicity, there is very limited information regarding nasal defenses against oxidative stress and xenobiotic-derived oxidants. Using immunohistochemistry, we have examined the distribution of Cu,Zn and Mn superoxide dismutase (SOD), catalase, glutathione (GSH) peroxidase, and DT-diaphorase in rat nasal tissues. In addition, we have determined the concentrations of ascorbate and alpha-tocopherol and the activities of SOD (combined Cu,Zn and Mn forms), catalase, GSH peroxidase, GSH reductase, and DT-diaphorase in nasal respiratory epithelium (RE), olfactory epithelium (OE), and in lung. Immunohistochemistry demonstrated that all four enzymes were similarly distributed, with the greatest staining intensity in dorsal-medial regions of the nasal cavity. In respiratory epithelium, ciliated columnar cells and subepithelial glands stained positively, while in olfactory tissue the enzymes were detected in the sustentacular cells and Bowman's glands. With the exception of SOD, enzyme activities were higher in RE than OE, while concentrations of ascorbate and alpha-tocopherol were higher in OE than RE. With the exception of catalase, nasal activities were either higher than or comparable to those of the lung. Thus, the rat nasal cavity appears to be well protected against oxidative damage.