Remifentanil Negatively Regulates RANKL-Induced Osteoclast Differentiation and Bone Resorption by Inhibiting c-Fos/NFATc1 Expression.

Remifentanil is commonly used in operating rooms and intensive care units for the purpose of anesthesia and sedation or analgesia. Although remifentanil may significantly affect the bone regeneration process in patients, there have been few studies to date on the effects of remifentanil on bone physiology. The purpose of this study was to investigate the effects of remifentanil on osteoclast differentiation and bone resorption. Bone marrow-derived macrophages (BMMs) were cultured for 4 days in remifentanil concentrations ranging from 0 to 100 ng/ml, macrophage colony-stimulating factor (M-CSF) alone, or in osteoclastogenic medium to induce the production of mature osteoclasts. To determine the degree of osteoclast maturity, tartrate-resistant acid phosphatase (TRAP) staining was performed. RT-PCR and western blotting analyses were used to determine the effect of remifentanil on the signaling pathways involved in osteoclast differentiation and maturation. Bone resorption and migration of BMMs were analyzed to determine the osteoclastic activity. Remifentanil reduced the number and size of osteoclasts and the formation of TRAP-positive multinuclear osteoclasts in a dose-dependent manner. Expression of c-Fos and NFATC1 was most strongly decreased in the presence of RANKL and remifentanil, and the activity of ERK was also inhibited by remifentanil. In the bone resorption assay, remifentanil reduced bone resorption and did not significantly affect cell migration. This study shows that remifentanil inhibits the differentiation and maturation of osteoclasts and reduces bone resorption.

Propofol protects against oxidative-stress-induced COS-7 cell apoptosis by inducing autophagy.

BACKGROUND: In oxidative stress, reactive oxygen species (ROS) production contributes to cellular dysfunction and initiates the apoptotic cascade. Autophagy is considered the mechanism that decreases ROS concentration and oxidative damage. Propofol shows antioxidant properties, but the mechanisms underlying the effect of propofol preconditioning (PPC) on oxidative injury remain unclear. Therefore, we investigated whether PPC protects against cell damage from hydrogen peroxide (H2O2)-induced oxidative stress and influences cellular autophagy. METHOD: COS-7 cells were randomly divided into the following groups: control, cells were incubated in normoxia (5% CO2, 21% O2, and 74% N2) for 24 h without propofol; H2O2, cells were exposed to H2O2 (400 µM) for 2 h; PPC + H2O2, cells pretreated with propofol were exposed to H2O2; and 3-methyladenine (3-MA) + PPC + H2O2, cells pretreated with 3-MA (1 mM) for 1 h and propofol were exposed to H2O2. Cell viability was determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide thiazolyl blue (MTT) reduction. Apoptosis was determined using Hoechst 33342 staining and fluorescence microscopy. The relationship between PPC and autophagy was detected using western blot analysis. RESULTS: Cell viability decreased more significantly in the H2O2 group than in the control group, but it was improved by PPC (100 µM). Pretreatment with propofol effectively decreased H2O2-induced COS-7 cell apoptosis. However, pretreatment with 3-MA inhibited the protective effect of propofol during apoptosis. Western blot analysis showed that the level of autophagy-related proteins was higher in the PPC + H2O2 group than that in the H2O2 group. CONCLUSION: PPC has a protective effect on H2O2-induced COS-7 cell apoptosis, which is mediated by autophagy activation.

Remifentanil induces autophagy and prevents hydrogen peroxide-induced apoptosis in Cos-7 cells.

BACKGROUND: This study investigated the effect of remifentanil pretreatment on Cos-7 cells exposed to oxidative stress, and the influence of remifentanil on intracellular autophagy and apoptotic cell death. METHODS: Cells were divided into 4 groups: (1) Control: non-pretreated cells were incubated in normoxia (5% CO2, 21% O2, and 74% N2). (2) H2O2: non-pretreated cells were exposed to H2O2 for 24 h. (3) RPC+H2O2: cells pretreated with remifentanil were exposed to H2O2 for 24 h. (4) 3-MA+RPC+H2O2: cells pretreated with 3-Methyladenine (3-MA) and remifentanil were exposed to H2O2 for 24 h. We determined the cell viability of each group using an MTT assay. Hoechst staining and FACS analysis of Cos-7 cells were performed to observe the effect of remifentanil on apoptosis. Autophagy activation was determined by fluorescence microscopy, MDC staining, and AO staining. The expression of autophagy-related proteins was observed using western blotting. RESULTS: Remifentanil pretreatment increased the viability of Cos-7 cells exposed to oxidative stress. Hoechst staining and FACS analysis revealed that oxidative stress-dependent apoptosis was suppressed by the pretreatment. Additionally, fluorescence microscopy showed that remifentanil pretreatment led to autophagy-induction in Cos-7 cells, and the expression of autophagy-related proteins was increased in the RPC+H2O2 group. CONCLUSIONS: The study showed that remifentanil pretreatment stimulated autophagy and increased viability in an oxidative stress model of Cos-7 cells. Therefore, we suggest that apoptosis was activated upon oxidative stress, and remifentanil preconditioning increased the survival rate of the cells by activating autophagy.