, a periodontitis causing bacterium, induces memory impairment and age-dependent neuroinflammation in mice.

BACKGROUND

A possible relationship between periodontitis and Alzheimer's disease (AD) has been reported. However, there is limited information on the association between the () periodontal infection and the pathological features of AD. The hypothesis that periodontal infection may cause cognitive impairment via age-dependent neuroinflammation was tested.

RESULTS

Thirty 4-week-old (young) female C57BL/6 J mice were randomly divided into two groups, the control group and the experimental group. Thirty 12-month-old (middle-aged) were grouped as above. The mouth of the mice in the experimental group was infected with . Morris water maze(MWM) was performed to assess the learning and memory ability of mice after 6 weeks. Moreover, the expression levels of the pro-inflammatory cytokines TNF-α, IL-6, and IL-1β in the mice brain tissues were determined by Quantitative real-time polymerase chain reaction (qRT-PCR), Enzyme Linked Immunosorbent Assay(ELISA) and immunohistochemistry. Our results showed that the learning and memory abilities of the middle-aged infected mice were impaired. Moreover, the expression levels of the pro-inflammatory cytokines TNF-α, IL-6, and IL-1β in the brain tissues of the middle-aged infected mice were increased.

CONCLUSIONS

These results suggest that periodontal infection may cause cognitive impairment via the release of the pro-inflammatory cytokines TNF-α, IL-6, and IL-1β in the brain tissues of middle-aged mice.