Influence of low-level laser irradiation on osteocalcin protein and gene expression in bone tissue1

Abstract Purpose: To evaluate osteocalcin gene and protein expression in vitro and in an in vivo model of ostectomy. Methods: Twenty Wistar rats were assigned into two groups A (n=10, laser) and B (n=10, control). Ostectomy was performed in the femur diaphysis; the twenty fragments removed, composed in vitro groups named as in vivo (A and B) and cultivated in CO2 atmosphere for thirteen days. Low-level laser irradiation was performed in groups A (in vivo and in vitro) by an GaAlAs device (λ=808 nm, dose of 2J/cm2, power of 200mW, power density of 0.2W/cm2, total energy of 1.25J, spot diameter of 0.02mm) for 5 seconds, at one point, daily. It was performed immunocytochemistry assays in vivo and in vitro groups. In vitro groups were also submitted to RNA extraction, cDNA synthesis and gene expression by quantitative PCR. Statistical analysis was realized with p摘要 目的：旨在体外（in vitro）与骨切除术（ostectomy）体内（in vivo）模型中，检测骨钙素（osteocalcin）的基因与蛋白表达情况。方法：将20只Wistar大鼠随机分为两组，A组（激光照射组，n=10）与B组（对照组，n=10）。于大鼠股骨干实施骨切除术，获取的20块切除骨块分别组建为对应体内A组、B组的体外培养亚组，置于二氧化碳（CO₂）培养箱中培养13天。对A组的体内及体外模型均采用GaAlAs激光设备实施低强度激光照射（low-level laser irradiation）：波长808nm，照射剂量2J/cm²，功率200mW，功率密度0.2W/cm²，总能量1.25J，光斑直径0.02mm，单点照射时长5秒，每日1次。对体内及体外各组均开展免疫细胞化学（immunocytochemistry）检测；体外培养亚组额外进行RNA提取、互补DNA（cDNA）合成及定量聚合酶链式反应（quantitative PCR）以检测基因表达水平。统计学分析采用p值开展（原文表述未完整）。