Treadmill training mitigates bone deterioration via inhibiting NLRP3/Caspase1/IL-1β signaling in aged rats

Introduction Although aerobic physical exercise may improve osteoporosis during ageing, the underlying mechanism of the favorable effects remains unclear. The aim of this study was to examine the localized and generalized proinflammatory indicators and the adaptive skeletal responses to treadmill training in aged rats to explore the potential mechanisms by which treadmill training impacts bone deterioration in a natural aged rat model. Materials and methods A total of 24 Sprague Dawley (SD) rats were included in this study. Sixteen of all these animals were twenty-four months natural aged male SD rats, which were distributed into two groups ( n = 8/group): AC group with sham treadmill training, and AT group with 8 weeks treadmill training. The remaining 8 were six months male SD rats matched subline and supplier, which were used as the adult control group with sham treadmill training (YC group, n = 8). The serum, bone marrow, fresh femur, tibia, and lumbar spine were harvested for molecular biological analysis, bone mineral density (BMD) testing, and micro-CT analysis after 8 weeks of treadmill training. Results After 8 weeks of intervention, the results showed that treadmill training increased BMD and inhibited deterioration of bone microarchitecture of hind limb bones. Further analysis showed that treadmill training increased serum P1CP concentration and decreased serum CTX-1level. Interestingly, treadmill training down-regulated the protein expressions of proinflammatory indicators, including NLRP3, proCaspase1, cleaved Caspase1, IL-1β, and GSDMD-N, and the mRNA levels of NLRP3, Caspase1, and IL-1β of the bone marrow. In addition, treadmill training also inhibited serum TNF-α and IL-1β concentration. However, 8 weeks of treadmill training did not increase BMD and bone microarchitecture in the lumbar spine. Conclusion Treadmill training mitigates the ageing-induced bone loss and reverses the deterioration of bone microarchitecture in hind limbs probably through inhibiting NLRP3/Caspase1/IL-1β signaling to attenuate low-grade inflammation and improve the inflammatory bone microenvironment.