Relationship between Periodontitis and Depression: Preclinical In Vivo Study

Objectives: To develop an in vivo preclinical model to determine whether animals with induced periodontitis and depression present higher counts of periodontal pathogens in the brain.
Methods: An in vivo preclinical model was developed in 40 Wistar rats. Periodontitis was induced by oral gavages with Porphyromonas gingivalis and Fusobacterium nucleatum (12 weeks) followed by a period of depression induction by exposure to chronic mild stress model (3 weeks). Four groups with 10 rats per group were obtained: periodontitis and depression (P+D+); periodontitis without depression (P+D-), depression without periodontitis (P-D+) and negative control (P-D-). The sacrifice was performed and the fresh brain tissue was obtained. Brain was analyzed by real-time quantitative PCR (qPCR) targeting detection of P. gingivalis and F. nucleatum. Descriptive statistics and ANOVA test was used for data analysis. Data were expressed by means of colony forming units per milliliter (CFU/mL).
Results: The groups with periodontitis (P+D+ and P+D-) showed higher values for clinical periodontal variables (p < 0.01). After depression, no statistically significant differences were observed for periodontal variables comparing the groups P+D+ vs P+D-, but the two groups with depression (P-D+ y P+D+) lost more weight compared to the other two groups. Presence of F. nucleatum was observed in the brain tissue of two rats in the P+D+ group (7.69x10¹ and 1.17x10² CFU/mL).
Conclusions: Presence of periodontal bacteria (F. nucleatum) was observed in brain of rats with periodontitis and depression, in an in vivo preclinical model.