Coenzyme Q10 (CoQ10) is a fat‑soluble vitamin‑like substance used for the treatment of a variety of disorders, including osteoporosis. The exact mechanism underlying CoQ10‑mediated protection against osteoporosis remains to be elucidated. The present study aimed to evaluate the effect of CoQ10 on osteoblastic cell proliferation and differentiation, and therapeutic effects on a rat model of osteoporosis. Following treatment with different concentrations of CoQ10, cell proliferation and differentiation of rat bone marrow stromal cells (BMSCs), and expression of osteoblastogenic markers, were measured. Rats with osteoporosis subjected to ovariectomy (OVX) were treated with different concentrations of CoQ10. Serum levels of estrogen and bone metabolism markers were measured. Micro computed tomography scans were used to analyze morphological changes in bones. In addition, mRNA and protein levels of phosphatidylinositol 3,4,5‑trisphosphate 3‑phosphatase and dual‑specificity protein phosphatase PTEN (PTEN)/phosphatidylinositol 4,5‑bisphosphate 3‑kinase (PI3K)/RAC‑alpha serine/threonine‑protein kinase(AKT), were determined. CoQ10 significantly increased the proliferation and osteogenic differentiation of BMSCs in a dose‑dependent manner, with an increased expression of osteogenic markers. CoQ10 significantly decreased bone resorption but exhibited no effect on serum E2 levels in vivo. CoQ10 markedly enhanced bone formation. Furthermore, the abundance of p‑PI3K and p‑AKT increased while PTEN levels decreased in a dose‑dependent manner following administration of CoQ10. CoQ10 stimulates the proliferation and differentiation of BMSCs and is effective for the treatment of OVX‑induced osteoporosis in rats. The above effects of CoQ10 may be mediated by activation of the PTEN/PI3K/AKT pathway.

Coenzyme Q10 (CoQ10) has been reported to improve bone density and the number of trabeculae in postmenopausal osteoporosis, but the mechanism remains to be elucidated. We aimed to investigate the effects of CoQ10 on receptor activator of NF-κB ligand (RANKL)-induced osteoclastogenesis and the underlying molecular mechanisms. RAW264.7 cells were treated with different concentrations of RANKL to differentiate into osteoclasts, and then these cells were treated with different concentrations of CoQ10 with or without H 2 O 2 . Tartrate-resistant acid phosphatase staining was performed to detect osteoclasts. Cell viability was tested by 3-(4,5dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, cell apoptosis was examined by flow cytometry, and the effects of CoQ10 on protein and messenger RNA expression of mitochondrial apoptosis-associated proteins and osteoclast marker proteins were measured by quantitative reverse transcription polymerase chain reaction and western blot, respectively. Furthermore, enzyme-linked immunosorbent assay was conducted to analyze the activities of malondialdehyde (MDA), superoxide dismutase (SOD), and catalase (CAT). RANKL significantly induced osteoclastogenesis in RAW264.7 cells, with the greatest efficiency at 50 ng/ml. CoQ10 had no significant effects on cell viability but it significantly increased the percentages of cell apoptosis.Mechanically, CoQ10 statistically decreased the levels of Bcl-2 and cytochrome C in mitochondria and upregulated the levels of Bax, cleaved caspase 3, and cytochrome C in the cytoplasm. Moreover, CoQ10 significantly decreased RANKL-induced osteoclastogenesis regardless of exposure to H 2 O 2 . In addition, CoQ10 statistically reduced MDA activity and elevated the activities of SOD and CAT, as well as the expression of oxidative stress-related proteins. CoQ10 may inhibit RANKL-induced osteoclastogenesis by regulation of mitochondrial apoptosis and oxidative stress in RAW264.7 cells.