Atividade física voluntária e doença periodontal induzida por ligadura em camundongos

Abstract

Periodontal disease (PD), an infection initiated by the presence of biofilm, may present alveolar bone resorption (ABR) and eventual tooth loss. Physically active individuals are less prone to PD when compared to sedentary individuals, due to the anti-inflammatory potential of physical activity.The present study investigated the relationship between the voluntary physical activity and the evolution of PD in mice, as well as the influence of PD on voluntary physical activity behavior. Thirty-two male C57BL6 isogenic mice, eight weeks old, maintained under standard conditions were distributed in four groups: Control (C); Voluntary Physical Activity (VPA); Periodontal Disease (PD) and Periodontal Disease and Voluntary Physical Activity (PD/VPA). The animals of the VPA and PD/VPA groups had itsvoluntary activity in a free running wheel registered in an automated acquisition system for 30 days. On the 15th day the PD and PD/VPA groups received a nylon thread around the second maxillary molar for PD induction. On the 30th day of the experiment, all animals were anesthetized and euthanized for tissue collection. Local inflammatory response (cytokinesIL-1β, IL-6 and TNF-α), ABR (RANKL - receptor activator of nuclear factor kappa-Β ligand and OPG - osteoprotegerin) and hypothalamic expression of genes associated with locomotor behavior (BDNF – brain-derived neurotrophic factor, GAD65 – glutamate decarboxylase, HRCT – orexin, e MCH – melanin-concentrating hormone)were analyzed by the real-time PCR(Polimerase chain reaction) technique.ABR was also analyzed by morphometry. The voluntary physical activity pattern was analyzed by the total volume of voluntary physical activity (total laps) and average speed (laps/minute) in each period (light or dark). Total inactive hours were also calculated.The data were compared by Two-way ANOVA for comparison of means between groups in factorial model 2x2 (induced to PD or not, with access to the free running wheel or not), followed by Bonferronipost hoc test when necessary (p<0.05).The groups with PD induction presented greater alveolar bone resorption (ABR), higher RANKL gene expression, and lower OPG in the gingival tissue than the other groups.However, the PD/VPA group presented increasedgene expression of OPG in the gingival tissue. PD induction increased the expression of the inflammatory cytokines IL-1β, IL-6 and TNF-α, but VPA modulated the expression of IL-1β and TNF-α at levels similar to group C. After induction to PD, the PD/VPA group presented a reduction in mean velocity and total volume of laps, as well as a longer time of inactivity in both periods (nocturnal and diurnal) when compared to the AFV group.Gene expression of BDNF and MCH in the hypothalamus were higher in the PD and PD/VPA groups. The gene expression of orexin in the hypothalamus was higher in the exercised groups. Expression of GAD65 was higher in the PD, VPA and PD/VPA groups. It is concluded that voluntary physical activity has protective effects against inflammation and ABR due to PD, and that PD reduces voluntary physical activity, probably viamodulation of hypothalamic genes, especially MCH.