Abstract：
Oxidative stress is an important contributor to the development of osteoporosis. Melatonin, an indoleamine secreted by the pineal gland, has antioxidant properties. This study aims to explore whether melatonin can promote bone formation and elucidate the mechanisms underlying this process. In this study, we used an in vitro hydrogen peroxide (H2O2)-induced oxidative stress model in MC3T3-E1 cells and an in vivo ovariectomized osteoporotic bone defect model in rats to explore the protective effects of melatonin against osteoporotic bone defects along with the mechanism underlying these effects. We found that melatonin significantly increased alkaline phosphatase activity, mineralization capacity, and the expression of BMP2, RUNX2, and OPN in MC3T3-E1 cells treated with H2O2. Furthermore, melatonin was found to activate SIRT1, SIRT3 and inhibit p66Shc, reduce the intracellular reactive oxygen species levels, stabilize mitochondria, reduce malondialdehyde levels, increase superoxide dismutase activity, and reduce apoptosis in MC3T3-E1 cells treated with H2O2. Intriguingly, these effects could be reversed by the SIRT1 inhibitor EX527. In vivo experiments confirmed that melatonin improves the microstructure and bone mineral density of the distal femoral bone trabecula and promotes bone formation. Meanwhile, melatonin activated SIRT1, inhibited p66Shc and increased SIRT3 expression. Taken together, our findings showed that melatonin can restrain oxidative damage in MC3T3-E1 cells and promote osteogenesis by activating SIRT1 which regulate the activity of SIRT3 and inhibit the expression of p66Shc, suggesting that melatonin could be a potential therapeutic agent for osteoporosis-related bone metabolic diseases.
摘要：
氧化应激是骨质疏松症发展的重要因素。褪黑激素,松果体分泌的吲哚胺，具有抗氧化性能。本研究旨在探讨褪黑素是否可以促进骨形成，并阐明这一过程的潜在机制。在这项研究中,我们采用过氧化氢(H2O2)诱导的MC3T3-E1细胞氧化应激模型和大鼠去卵巢骨质疏松性骨缺损模型,探讨褪黑素对骨质疏松性骨缺损的保护作用及其机制.我们发现褪黑素显著增加碱性磷酸酶活性，矿化能力，H2O2处理的MC3T3-E1细胞中BMP2、RUNX2和OPN的表达。此外，发现褪黑激素激活SIRT1，SIRT3并抑制p66Shc，降低细胞内活性氧的水平，稳定线粒体，降低丙二醛水平，增加超氧化物歧化酶活性，并减少H2O2处理的MC3T3-E1细胞的凋亡。有趣的是，这些效应可被SIRT1抑制剂EX527逆转.体内实验证实，褪黑素改善了股骨远端骨小梁的微观结构和骨矿物质密度，并促进了骨形成。同时,褪黑素激活SIRT1，抑制p66Shc并增加SIRT3表达。一起来看,我们的发现表明，褪黑素可以通过激活SIRT1来调节SIRT3的活性并抑制p66Shc的表达，从而抑制MC3T3-E1细胞的氧化损伤并促进成骨。提示褪黑素可能是骨质疏松症相关骨代谢疾病的潜在治疗药物。
