Protocatechualdehyde inhibits iron overload-induced bone loss by inhibiting inflammation and oxidative stress in senile rats.

The accumulating evidence has made it clear that iron overload is a crucial mechanism in bone loss. Protocatechualdehyde (PCA) has also been used to prevent osteoporosis in recent years. Whether PCA can reverse the harmful effects of iron overload on bone mass in aged rats is still unknown. Therefore, this study aimed to assess the role of PCA in iron overload-induced bone loss in senile rats. In the aged rat model, we observed that iron overload affects bone metabolism and bone remodeling, manifested by bone loss and decreased bone mineral density. The administration of PCA effectively mitigated the detrimental effects caused by iron overload, and concomitant reduction in MDA serum levels and elevation of SOD were noted. In addition, PCA-treated rats were observed to have significantly increased bone mass and elevated expression of SIRT3，BMP2，SOD2 and reduced expression of TNF-α in bone tissue. We also observed that PCA was able to reduce oxidative stress and inflammation and restore the imbalance in bone metabolism. When MC3T3-E1 and RAW264.7 cells induced osteoblast and osteoclasts differentiation, PCA intervention could significantly recover the restriction of osteogenic differentiation and up-regulation of osteoclast differentiation treated by iron overload. Further, by detecting changes in ROS, SOD, MDA, expression of SIRT3 and mitochondrial membrane potentials, we confirm that the damage caused to cells by iron overload is associated with decreased SIRT3 activity, and that 3-TYP have similar effects on oxidative stress caused by FAC. In conclusion, PCA can resist iron overload-induced bone damage by improving SIRT3 activity, anti-inflammatory and anti-oxidative stress.