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Background A periodontal lesion is a consequence of chronic inflammatory processes, itself triggered by a bacterial infection of the pulpal and endodontic microenvironment. Evidence suggests that periodontal lesion induction could alter inflammatory cytokines leading to behavior changes. These effects in the context of anxiety and depressive behavior have been not full investigated. We aimed to observe anxiety- and depressive-like behavioral in rodent subjected to periapical dental lesions. Methods Pro-inflammatory cytokines levels also were investigated in the frontal cortex and hippocampus. Parameters related to hypothalamic–pituitary–adrenal (HPA) axis activation also were evaluated. Wistar rats were divided in groups: control/saline; control/imipramine; periapical lesion/saline; and periapical lesion/imipramine. Three weeks after induction of the periapical dental lesion, they were subjected to behavioral tests. Results In the periapical lesion group was demonstrated anhedonic behavior and depressive-like behavior. In the elevated plus-maze test the periapical lesion group had an increase in the number of entries and spent more time in the closed arms. Imipramine treatment was able to reverse depressive- and anxiety-like behaviors. In the hippocampus and frontal cortex tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6, and serum adrenocorticotropic hormone (ACTH) levels were higher in the periapical lesion group. However, rats treated with imipramine had lower IL-1β and ACTH levels. Conclusions Our results revealed depressive- and anxiety-like behaviors following induction of a specific dental lesion. These effects could be associated to higher levels of brain pro-inflammatory cytokines and HPA axis changes. Antidepressants treatments could be an alternative to treat comorbidities associated to periodontal lesions.

Introduction: Mortality and morbidity from bacterial meningitis in African adults is significantly higher than those in better resourced settings. At the same time, the periodontal diseases are highly prevalent and can affect up to 90% of the population. Dental caries in Uganda was recorded in 40% and 62.5% of the children and adults, respectively. We hypothesize that pneumococcal meningitis could interfere in the development of periapical lesion. The aim of this study was to evaluate periapical lesion in Wistar rats subjected to pneumococcal meningitis. Materials and Methods: The animals were divided in control, control/periapical lesion, meningitis, and meningitis/periapical lesion groups. The surgical exposure of molars and the infection of the dental pulp were from the oral environment. Pulp necrosis was induced on the left mandibular first molars during adulthood. Dental pulps were exposed by drilling cavities on the central portion of the occlusal surface with a 1011 HL round bur in high speed to a depth nearly equal to the bur diameter. Animals were subjected to behavioral task and evaluation of the size of periodontal ligament. Data from periodontal ligament space and open field task were reported as mean ± SEM and analysed by Two-way ANOVA and paired Student’s t-test, respectively. Results and Conclusion: Meningitis/periapical increased the periodontal ligament space by 61% when compared with control/ periapical. In the open-field task, there were no differences in the number of crossings and rearing movements between training and test session in meningitis and periapical lesion groups demonstrating habituation memory impairment. Bacterial meningitis and periapical lesion may play an important role in development of cognitive impairment.