Relationships between periodontal inflammation, lipid peroxide and oxidative damage of multiple organs in rats

Gingival response to periodontal inflammation generates excessive lipid peroxide and such a condition may augment systemic health through increased circulating lipid peroxide. The purpose of the present study was to investigate whether the generation of lipid peroxide in periodontal inflammation could induce tissue injury in the liver, heart, kidney and brain using a rat model. Twelve Wistar rats (8 week-old male) were divided into 2 groups: the periodontal inflammation group, receiving topical application of lipopolysaccharide and proteases to the gingival sulcus for 4 weeks, and the control group using instead pyrogen-free water. After blood samples were collected, specimens from the brain, heart, liver and kidney were resected to determine the concentration of 8-hydroxydeoxyguanosine (an indicator of oxidative DNA damage). Gingival and serum levels for hexanoyl-lysine were measured to evaluate lipid peroxide. Administration of lipopolysaccharide and proteases induced periodontal inflammation, with increasing gingival and serum levels of hexanoyl- lysine. The level of 8-hydroxydeoxyguanosine increased 2.27, 2.01, 1.49 and 1.40 times in mitochondrial DNA from the liver, heart, kidney and brain of rats with periodontal inflammation, respectively. The results reveal that excessive production of lipid peroxide following periodontal inflammation is involved in oxidative DNA damage of the brain, heart, liver and kidney.