黄芪多糖保护去卵巢大鼠成骨细胞功能活性的机制研究

目的　探讨黄芪多糖对去卵巢大鼠成骨细胞功能活性和核因子E2相关因子（Nrf2）/血红素氧合酶-1（HO-1）/醌氧化还原酶1（NQO1）通路的影响。方法　双侧卵巢切除法构建骨质疏松大鼠模型并分为模型组、雌二醇（0.1 mg/kg）组、黄芪多糖组（20 mg/kg）、黄芪多糖（20 mg/kg）+全反式维甲酸（ARTA，7 mg/kg）组，另选健康大鼠作为假手术组（生理盐水灌胃），每组15只，干预8周。采用X线小动物骨密度仪检测大鼠胫骨骨密度、骨矿量，三点弯曲法测定生物力学性质；分离各组大鼠骨髓间充质干细胞（BMSCs）并诱导成骨细胞分化，MTT法检测成骨细胞活性，Bradford法检测碱性磷酸酶（ALP）活性，邻甲酚酞络合酮法测定钙沉积量，酶联免疫吸附试验检测骨成型蛋白2（BMP2）、骨钙素（BGP）、骨保护素（OPG）、超氧化物歧化酶（SOD）、丙二醛（MDA）水平，Western blot检测Nrf2、HO-1和NQO1表达。结果　与假手术组相比，模型组骨密度、骨矿量、最大载量、断裂能、成骨细胞活性、ALP活性、钙沉积量和BMP2、BGP、OPG、SOD、Nrf2、HO-1、NQO1水平降低，MDA水平升高（P＜0.05）；与模型组比较，雌二醇组、黄芪多糖组大鼠骨密度、骨矿量、最大载量、断裂能、成骨细胞活性、ALP活性、钙沉积量及BMP2、BGP、OPG、SOD、Nrf2、HO-1、NQO1水平均升高，MDA水平降低（P＜0.05），而与黄芪多糖组比较，黄芪多糖+ARTA组大鼠上述指标变化趋势相反（P＜0.05）。结论　黄芪多糖可改善去卵巢大鼠成骨细胞功能，机制可能与激活Nrf2/HO-1/NQO1通路有关。

Study on the protective mechanism of astragalus polysaccharides on functional activity of osteoblasts in ovariectomy rats

Objective　To explore the effects of astragalus polysaccharides (APS) on the functional activity of osteoblasts and nuclear factor E2 related factor (Nrf2)/heme oxygenase-1 (HO-1)/quinone oxidoreductase 1 (NQO1) pathways in ovariectomy rats. Methods　The rat model of osteoporosis was constructed by bilateral ovariectomy, and model rats were divided into the model group, the estradiol (0.1 mg/kg) group, the APS group (20 mg/kg) and the APS (20 mg/kg) + all-trans retinoic acid (ATRA) (7 mg/kg) group, 15 rats in each group. Fifteen healthy rats were enrolled as the sham operation group (normal saline). After 8 weeks of intervention, tibia density and bone mineral content were detected by X-ray absorptiometry. The characters of biomechanics were detected by three-point bending method. The bone mesenchymal stem cells (BMSCs) were isolated and osteoblast differentiation was induced in each group. The activity of osteoblasts was detected by MTT. The activity of alkaline phosphatase (ALP) was detected by Bradford method. The calcium deposition was measured by o-cresolphthalein complexone. The levels of bone morphogenetic protein 2 (BMP2), bone gla protein (BGP), osteoprotegerin (OPG), superoxide dismutase (SOD) and malondialdehyde (MDA) were detected by enzyme linked immunosorbent assay (ELISA). The expression levels of Nrf2, HO-1 and NQO1 were detected by Western blot assay. Results　Compared with the sham operation group, bone mineral density, bone mineral content, maximum load, fracture energy, activities of osteoblasts, ALP, calcium deposition, levels of BMP2, BGP, OPG, SOD, Nrf2, HO-1 and NQO1 were decreased in the model group (P＜0.05), while MDA level increased (P＜0.05). Compared with the model group, the bone mineral density, bone mineral content, maximum load, fracture energy, osteoblast activity, ALP activity, calcium deposition and BMP2, BGP, OPG, SOD levels increased in the estradiol group and the astragalus polysaccharide group, the level of MDA decreased (P＜0.05). Compared with the astragalus polysaccharide group, the above indicators showed the opposite trend in the astragalus polysaccharide+ARTA group (P＜0.05). Conclusion　APS can improve osteoblast function in ovariectomy rats, which may be related to activating Nrf2/HO-1/NQO1 pathways.