抄録
There is a large body of evidence supporting the involvement of active oxygens in smoking-related diseases such as lung cancer and other respiratory diseases. Hydrogen peroxide (H_2O_2), one of active oxygens, has been reported to be generated from cigarette smoke. Furthermore, in the mouth, H_2O_2 is not only formed by bacteria colonizing the mucous membranes but also by the cells of the salivary glands. These reports suggest that in the mouth, there is a special need for defense against H_2O_2. In the present study, the effect of cigarette smoking on H_2O_2-degrading enzyme (catalase and peroxidase) activities in human saliva was studied. Cigarette smoking resulted in a dramatic decrease of catalase activity in the saliva. This decrease was found to be attributed to a decrease in catalase protein. On the other hand, cigarette smoking resulted also in a dramatic decrease of peroxidase activity. These results suggest that a decrease of salivary catalase and peroxidase by cigarette smoking leads to the accumulation of H_2O_2 in the saliva and then H_2O_2 attacks mucosal cells lining the oral cavity.
