Studies Of Biomodulation Of Red Light And Statins On Glucocorticoid Induced Decrease Of Protein Content Of C2C12 Myotubes

Purpose: Glucocorticoid (GC) inhibits protein synthesis and stimulates protein degradation inskeletal muscle and is an important factor in the development of muscle wasting invarious catabolic conditions such as atrophy and steroid myopathy. Dexamethasone(DEX), a synthetic GC, has been widely used to induce muscle proteolysis either in vivoor in cell culture. This study was to establish a cellular model of DEX induced decreaseof protein content, and to study the biomodulation of red light (640±17nm) from lightemitting diode array (RLED) and statins on protein content on mice C2C12 myotubes,respectively.Method:1. The total protein content of C2C12 myoblasts differentiated for 2 to 9 days wasevaluated by bicinchoninic acid (BCA) assay. The C2C12 myotubes differentiated for 8days were used to do following experiments.2. In order to establish a cellular model of DEX induced decrease of protein content,C2C12 myotubes were incubated with DEX at 0, 25nm, 100nM, 1μM and 10μM,respectively, in medium of 2% horse serum. The content of total protein and a-actinprotein were evaluated by BCA assay and Western Blot, respectively.3. In order to study the modulation of RLED on DEX induced decrease of protein content,C2C12 myotubes were irradiated by RLED at 3.5mW/cm~2 for 0, 110s, 300s, 900sand1800s, respectively, just after incubated with DEX at 1μM, and then were incubatedwith DEX for 24h. The total content of total protein and a-actin protein were evaluatedby BCA assay and Western Blot, respectively.4. In order to study the biomodulation of simvastatin on DEX induced decrease of proteincontent, C2C12 myotubes were treated with simvastatin at 100nM, 1μM and 10μM inmedium of DEX at 0 nM and 100 nM for 24h, respectively. The protein content wasevaluated by BCA assay.Result:1. The protein content of differentiated C2C12 myotubes increased gradually in the first 4days and became stable after day 4.2. Protein content of C2C12 myotubes incubated with DEX decreased significantly (P＜0.05) in a DEX concentration dependence.3. The DEX induced decrease of protein content of C2C12 myotubes were inhibited by RLED at 3.5mW/cm~2 in a sine function of radiation time.4. Simvastain at 100nM, 1μM and 10μM significantly promoted the DEX induceddecrease of protein content of C2C12 myotubes.Conclusion:DEX at different concentration could induce the decrease of protein content of C2C12myotubes. The DEX induced decrease of protein content was inhibited by RLED at3.5mW/cm~2 in a sine function of radiation time, but was promoted by simvastatinsignificantly in a concentration dependence.