Protective effect of α-lipoic acid against antimycin A cytotoxicity in MC3T3-E1 osteoblastic cells

Oxidative stress represents a major cause of cellular damage and death in the process of osteoporosis. Antimycin A (AMA) has been shown to stimulate mitochondrial superoxide anions and reactive oxygen species (ROS). alpha-Lipoic acid (alpha-LA) is a naturally occurring essential coenzyme in mitochondrial multienzyme complexes and acts as a key player in mitochondrial energy production. However, whether alpha-LA affects the cytotoxicity of AMA in osteoblastic cells is unknown. In this study, we investigated the protective effects of alpha-LA against AMA-induced cytotoxicity using the MC3T3-E1 osteoblast-like cell line. Our results indicated that alpha-LA treatment attenuated AMA-induced cytotoxicity and LDH release in a dose-dependent manner. Notably, a significant recovery effect of alpha-LA on mineralization inhibited by AMA was found. Our results also demonstrated that treatment with 50 mu M AMA leads to a reduction of mitochondrial membrane potential (MMP) and the complex IV dysfunction, which was inhibited by pretreatment with alpha-LA in a dose-dependent manner. In addition, treatment with alpha-LA significantly reduced the generation of ROS and mitochondrial superoxide production induced by AMA. In addition, our result suggests that PI3K/Akt and CREB pathways are related to the protective effect of alpha-LA. Importantly, Hoechst 33258 staining results indicated that pretreatment with alpha-LA prevented AMA-induced apoptosis. Mechanistically, we found that alpha-LA prevents MC3T3-E1 cells from apoptosis through attenuating cytochrome C release and reducing the level of cleaved caspase-3.