左归丸调控DKK1靶点防治糖皮质激素性骨质疏松

摘要

背景:中医药可有效防治糖皮质激素性骨质疏松,但其防治机制尚不明确.DKK1是Wnt/β-catenin信号通路的抑制剂,糖皮质激素可诱导其上调.因此,DKK1蛋白是防治糖皮质激素性骨质疏松的重要靶点.目的:探讨左归丸防治糖皮质激素性骨质疏松中对DKK1的调控作用.方法:18只3月龄雌性SD大鼠随机均分为3组:空白组、模型组和左归丸组.模型组和左归丸组大鼠皮下注射地塞米松建立糖皮质激素性骨质疏松模型;空白组给予等体积生理盐水;左归丸组皮下注射地塞米松同时给予左归丸水提液灌胃.1 个月后取大鼠腰椎进行 micro-CT 检测骨量及骨微细结构、压缩试验检测生物力学性能,qPCR测定腰椎DKK1、Runx2和CTSK mRNA表达;血清检测碱性磷酸酶活性.结果与结论: ①与空白组比较,模型组体积骨密度、相对骨体积、骨小梁数量和骨小梁厚度显著降低(P ＜0.05),骨小梁间距和结构模型指数较空白组显著增大(P ＜ 0.05),血清碱性磷酸酶活性较空白组呈降低趋势, DKK1 mRNA表达显著上调(P ＜ 0.05),成骨相关因子Runx2 mRNA表达呈下调趋势,破骨相关因子CTSK mRNA呈上调趋势;②与模型组比较,左归丸组体积骨密度、相对骨体积和骨小梁数量显著提升(P ＜ 0.05),结构模型指数显著降低(P ＜ 0.05),骨小梁间距有减小趋势但差异无显著性意义,血清碱性磷酸酶活性较模型组呈升高趋势,DKK1 mRNA表达显著下调(P ＜ 0.05),Runx2 mRNA表达呈上调趋势,CTSK mRNA呈下调趋势;③与模型组比较,左归丸组椎体压缩强度显著提升(P ＜ 0.05);④结果说明,左归丸可能通过下调DKK1的表达防治糖皮质激素性骨质疏松.%BACKGROUND: Chinese medicine is effective for preventing and treating glucocorticoid-induced osteoporosis, however, the underlying mechanism remains unclear. DKK1, an inhibitor of Wnt/β-catenin signaling pathway, can be up-regulated by glucocorticoid. Thereafter, DKK1 is an important target in the prevention and treatment of osteoporosis. OBJECTIVE: To explore the regulatory effect of Zuogui pill on DKK1 in the prevention and treatment of glucocorticoid-induced osteoporosis. METHODS: Eighteen three-month-old female Sprague-Dawley rats were randomly divided into three groups: control group, model group and Zuogui pill group. Rats in the model and Zuogui pill groups received the subcutaneous injection of dexamethasone to establish the model of glucocorticoid-induced osteoporosis. The Zuogui pill group rats were administrated Zuogui pill extracts, and the control rats were given the same volume of normal saline. At 1 month after modeling, the lumbar vertebrae were removed to test the bone mass and microstructures by micro-CT scanning. The biomechanical properties were detected by compression test. The mRNA expression levels of DKK1, Runx2 and CTSK were determined by Qpcr. The serum alkaline phosphatase activity was tested. RESULTS AND CONCLUSION: Compared with the control group, in the model group, the volumetric bone mineral density, trabecular bone volume fraction, trabecular number, and trabecular thickness were significantly decreased (P ＜ 0.05), the trabecular separation and structure model index were significantly increased (P ＜ 0.05). The serum alkaline phosphatase activity was on a decline. The mRNA expression level of DKK1 showed a significant up-regulation (P ＜ 0.05). The mRNA expression level of Runx2 showed a down-regulated trend while mRNA expression level of CTSK showed an up-regulated trend. Compared with the model group, the Zuogui pill group showed significantly enhanced volumetric bone mineral density, trabecular bone volume fraction, and trabecular number (P ＜ 0.05); the structure model index was significantly decreased (P ＜ 0.05); the trabecular separation was reduced; the serum alkaline phosphatase activity was enhanced; the mRNA expression level of DKK1 showed a significant down-regulation (P ＜ 0.05); the mRNA expression level of Runx2 showed an up-regulated trend while mRNA expression level of CTSK showed a down-regulated trend. The vertebral compressive strength in the Zuogui pill group was significantly higher than that in the model group (P＜0.05). In summary, Zuogui pill prevents and treats glucocorticoid-induced osteoporosis possibly through the down-regulation of mRNA expression of DKK1.