Expression of manganese superoxide dismutase in rat submandibular gland demonstrated by in situ hybridization and immunohistochemistry

Superoxide, an active oxygen species, plays an important role in protecting against bacterial infection. However, it also has adverse effects on healt h. Manganese superoxide dismutase (Mn-SOD) is a scavenger of superoxide. An tioxygen enzymes such as Mn-SOD exist in various tissues, and provide prote ctions against oxidative injury. We investigated both the expression of Mn- SOD mRNA and the localization of Mn-SOD in adult rat submandibular glands u sing in situ hybridization and immunohistochemistry. Both Mn-SOD mRNA and M n-SOD were detected in striated duct cells, and in some granular duct cells and excretory duct cells. With immunoelectron microscopy, many immunolabel ings were observed on the mitochondria. These findings suggest that the exp ression of Mn-SOD mRNA and the localization of Mn-SOD in submandibular glan ds correlate with the number of mitochondria in cells.