Effects of vitamin C intake on gingival oxidative stress in rat periodontitis

Preventive effects of a cocoa-enriched diet on gingival oxidative stress in experimental periodontitis

BACKGROUND

Oxidative stress affects the progression of periodontitis. Cocoa is a rich source of flavonoids with antioxidant properties, which could suppress gingival oxidative stress in periodontal lesions. The purpose of the present study was to investigate the effects of a cocoa-enriched diet on gingival oxidative stress in a rat-periodontitis model.

METHODS

In this 4-week study, rats were divided into three groups (n = 8/group): a control group (fed a regular diet) and two periodontitis groups (fed a regular diet or cocoa-enriched diet [10% of food intake]). Periodontitis was induced by ligature placement around the mandibular first molars. Serum levels for reactive oxygen metabolites were measured at baseline and 2 and 4 weeks. At 4 weeks, the levels of 8-hydroxydeoxyguanosine and reduced/oxidized glutathione ratio were determined to evaluate gingival oxidative damage and antioxidant status, respectively.

RESULTS

Rats with experimental periodontitis that were fed a regular diet showed an increase in the level of serum reactive oxygen metabolites in a time-dependent manner. These rats also had an increased 8-hydroxydeoxyguanosine level and decreased reduced/oxidized glutathione ratio in the gingival tissue, inducing alveolar bone loss and polymorphonuclear leukocyte infiltration. Although experimental periodontitis was induced in the rats fed a cocoa-enriched diet, they did not show impairments in serum reactive oxygen metabolite level and gingival levels for 8-hydroxydeoxyguanosine and reduced/oxidized glutathione ratio. Alveolar bone loss and polymorphonuclear leukocyte infiltration after ligature placement were also inhibited by cocoa intake.

CONCLUSION

Consuming a cocoa-enriched diet could diminish periodontitis-induced oxidative stress, which, in turn, might suppress the progression of periodontitis.

Effects of obesity on gingival oxidative stress in a rat model

BACKGROUND

Studies indicate a correlation between obesity and periodontitis. Oxidative stress is involved in the progression of periodontitis. The purpose of this study was to investigate the effects of obesity on gingival oxidative stress in a rat periodontitis model.

METHODS

The obese Zucker rats (n = 14) and their lean littermates (n = 14) were each divided into two groups of seven rats. In one of each group, periodontitis was induced by ligature for 4 weeks, whereas the other group was left unligated. The level of 8-hydroxydeoxyguanosine and the ratio of reduced/oxidized glutathione were determined to examine gingival oxidative stress. The serum level of reactive oxygen metabolites and the gingival gene-expression pattern related to oxidative/metabolic stress, inflammation, and cell behavior were also evaluated.

RESULTS

The obese rats weighed more than the lean rats at 4 weeks. Compared to lean rats, obese rats had enhanced gingival 8-hydroxydeoxyguanosine levels and a decreased ratio of reduced/oxidized glutathione in the gingival tissue, with increasing serum reactive oxygen metabolites. However, there were no significant differences in the degree of alveolar bone loss between lean and obese rats, except for teeth with and without ligatures in both rats. In addition, the periodontal lesion in obese rats showed higher 8-hydroxydeoxyguanosine levels and polymorphonuclear leukocyte infiltration than the inflamed ones in lean rats, with downregulation of multiple cytochrome P450 gene expression.

CONCLUSIONS

Obesity induced gingival oxidative stress with increasing serum reactive oxygen metabolites in rats. In the periodontal lesion, gene expressions related to a capacity for xenobiotic detoxification were downregulated in the obese model.