Efeitos dos treinamentos aeróbio e resistido na qualidade do osso alveolar em modelo de osteopenia induzida por ovariectomia e movimentação dentária

Abstract

Increased longevity has been accompanied by conditions associated with sex hormone deficiency, including changes in bone homeostasis and bone tissue integrity, which contribute to the development of osteopenia and osteoporosis. In this context, non-pharmacological interventions, such as physical exercise, have been extensively investigated for their ability to modulate bone remodeling. However, important gaps remain regarding the effects of exercise on skeletal sites beyond those subjected to direct mechanical loading. Therefore, this study evaluated the effects of aerobic and resistance exercise on alveolar bone quality, a skeletal site not directly exposed to mechanical loading, in the absence and presence of orthodontic tooth movement (OTM), using an ovariectomy (OVX)-induced osteopenia model in female mice. Fifty-four female C57BL/6 mice underwent either ovariectomy (OVX) or sham surgery (SHAM). Animals from each surgical group were then allocated to one of three experimental groups (n = 9/group): untrained, resistance training (loaded ladder climbing), or aerobic training (treadmill running). The training protocols were conducted over eight weeks, with orthodontic tooth movement (OTM) induced during the final 14 days. Bone microarchitecture and orthodontic tooth movement were evaluated, along with the expression of genes involved in bone remodeling (RUNX2, RANKL, and OPG) and the quantification of osteoblasts, osteocytes, and osteoclasts by conventional light microscopy. Body weight, physical performance, and systemic inflammatory status were also assessed based on the ratio of serum levels of IL-1β, IL-6, TNF-α, and IL-10. Both exercise modalities improved bone parameters compared with untrained OVX mice. Notably, resistance training induced greater increases in bone mineral density, bone volume, and bone volume fraction, whereas aerobic training was primarily associated with reduced trabecular separation (p < 0.05). Both exercise protocols attenuated OTM, with a more pronounced decrease observed in aerobically trained mice, while untrained OVX mice showed the highest tooth displacement (p < 0.05). Untrained OVX mice, particularly those subjected to OTM, exhibited increased RANKL expression and a higher RANKL/OPG ratio, whereas exercise increased OPG expression and mitigated the pro-resorptive imbalance (p<0,05). OVX mice and untrained SHAM controls showed comparable increases in osteoclast numbers and decreases in osteoblast numbers, whereas in the exercise-trained groups, exercise reduced osteoclastogenesis and increased osteoblastic activity. In OVX mice, OTM further increased osteoclast numbers across all groups (p < 0.05). Systemically, untrained OVX mice displayed a pro-inflammatory profile, partially mitigated by resistance training, while aerobic training increased the IL-6/IL-10 ratio. The present results show that both resistance and aerobic exercise improve alveolar bone quality and reduce OTM in the context of estrogen deficiency-induced osteopenia. These benefits appear to involve local modulation of bone remodeling, including reduced osteoclastogenesis, increased osteoblastic activity, and regulation of the OPG/RANKL axis, as well as systemic inflammatory adaptations. Overall, these findings indicate that physical exercise is an effective strategy to preserve craniofacial bone health in hypoestrogenic conditions.