1% Tween-20) for 1 h at room temperature. The membrane was then incubated with antibodies overnight at 4°C. The membrane
was washed and incubated with horseradish peroxidase-conjugated secondary antibody Selleckchem ALK inhibitor for 1 h. The blots were finally detected by enhanced chemiluminescence (Amersham Biosciences, Pittsburgh, PA, USA). Six-wk-old male Imprinting Control Region (ICR) mice were obtained from Orientbio (Seongnam, Korea). The slow release pellets (Innovative Research of America, Sarasota, FL, USA) of GC (2.1 mg/kg/d prednisolone pellet) were subcutaneously implanted for 5 wks. The GC-implanted mice were divided into four groups: (1) negative control; (2) GC pellet implantation control; (3) GC treated with 100 mg/kg/d of KRG; and (4) GC treated with 500 mg/kg/d of
KRG. After 1 wk of GC implantation, mice were orally administered with 100 mg/kg/d or 500 mg/kg/d KRG or saline. After 4 wks of treatment, the mice were euthanized for bone analysis. Radiographic images were taken with a SkyScan1173 microcomputed tomography system (SkyScan, Kontich, Belgium). All animal experimental procedures were approved by the Experimental Animal Ethics Committee at Gachon University, Seongnam, Korea. All experiments were performed in triplicate. Each value was presented Selleck Selinexor as the mean ± standard deviation. Significant differences were determined using the Sigmaplot program (version 6.0). Optimal KRG concentrations for MC3T3-E1 cell viability were determined by the MTT assay. MC3T3-E1 cells (1 × 104 cells/well) were seeded in a plate and treated with various concentrations of KRG for 48 h. The MTT assay indicated that KRG did not affect the cell viability of MC3T3-E1 at concentrations of 1 mg/mL or lower (Fig. 1). To elucidate whether Dex, an active GC analog, would promote the apoptosis of
MC3T3-E1 cells or not, the absorbance of cells was measured by MTT assay. MC3T3-E1 cells were seeded in a 24-well plate for 24 h and then treated with various Sclareol concentrations of Dex (0μM, 50μM, 125μM, and 250μM) for 48 h. No significant morphological changes occurred at 50μM Dex that could be observed under a light microscope. However, cells treated with 125–250μM Dex underwent apoptosis (data not shown). The MTT assay verified that Dex inhibited cell growth in a dose-dependent manner (Fig. 2). The absorbance of Dex at 125μM in the MTT assay was significantly lower than that of the control group, indicating that the concentration of Dex required to induce half of the MC3T3-E1 cells to go through apoptosis was approximately 125μM. To determine whether KRG has protective effects on MC3T3-E1 cells against Dex-induced apoptosis or not, cells were exposed to 100μM Dex and KRG for 48 h. Cell viability was estimated by the MTT assay. A significant decrease in the cell viability of MC3T3-E1 treated with 100μM Dex was observed compared to that of Dex- and KRG-free cells.