黄芪多糖通过PI3K/AKT/mTOR促进激素性骨质疏松症大鼠成骨细胞增殖

目的 探讨黄芪多糖在体内外通过PI3K/AKT/mTOR信号通路对糖皮质激素诱导的骨质疏松症（glucocorticoid-induced osteoporosis，GIOP）的保护作用。方法 从分化的骨髓间充质干细胞（bone marrow mesenchymal stem cells，BM-MSCs）中培养成骨细胞，分为PBS组、模型组、LY294002组、黄芪多糖组和LY294002+黄芪多糖干预组。通过CCK-8法和碱性磷酸酶（alkaline phosphatase，ALP）染色检测细胞增殖和分化。MDC染色观察自噬体的形成。Western blot检测Beclin-1、p62等信号通路及自噬相关因子的蛋白表达。大鼠分为对照组、模型组、LY294002组、黄芪多糖组和LY294002+黄芪多糖组。比较各组大鼠的骨密度、骨组织形态学参数、组织中通路和自噬相关因子的表达。结果 黄芪多糖促进成骨细胞的增殖和分化能力（P＜0.05）。与模型组相比，黄芪多糖组PI3K/AKT/mTOR通路相关磷酸化蛋白的表达、成骨细胞的增殖分化能力、自噬体及自噬相关因子的表达均升高，但在LY294002组中发现了相反的结果（P＜0.05）。在体内实验中，与模型组相比，GIOP大鼠通过黄芪多糖干预改善了骨密度和骨形态参数，并提高了软骨组织中自噬相关因子的表达，而LY294002干预则表现出相反的结果（P＜0.05）。LY294002部分逆转了黄芪多糖对GIOP中成骨分化和骨形态参数的影响。结论 黄芪多糖通过PI3K/AKT/mTOR通路对GIOP发挥保护作用，可能与诱导自噬和促进成骨细胞增殖有关。

Astragalus polysaccharide promotes the proliferation of osteoblasts in hormonal osteoporosis rats through PI3K/AKT/mTOR signaling pathway

Objective To investigate the protective effect of astragalus polysaccharide on glucocorticoid-induced osteoporosis (GIOP) through the PI3K/AKT/mTOR signaling pathway in vivo and in vitro. Methods Osteoblasts from the differentiated bone marrow mesenchymal stem cells (BM-MSCs) were cultured and were grouped as follows: the PBS group, the model group, the LY294002 group, the astragalus polysaccharide group, and the LY294002+astragalus polysaccharide intervention group. Cell proliferation and differentiation were detected with cell counting kit-8 (CCK8) assay and alkaline phosphatase (ALP) staining, respectively. The formation of autophagosome was observed with Monodansylcadaverine (MDC) staining. Expressions of signaling pathway and autophagy related factors such as Beclin-1 and p62 were detected with Western blotting. Then, the rats were grouped as the normal group, the model group, the LY294002 group, the astragalus polysaccharide group, and the LY294002+astragalus polysaccharide group. Bone mineral density and bone histomorphometry parameters of rats in each group were compared. In addition, the expressions of pathway and autophagy related factors in the cartilage tissue of rats in each groups were also detected. Results The proliferation and differentiation abilities of osteoblasts increased with an increasing concentration of astragalus polysaccharide in a dose-dependent manner. Compared to those in the model group, the expression of PI3K/AKT/mTOR pathway related phosphorylated proteins, the proliferation and differentiation abilities of osteoblasts, the expression of autophagosome and autophagy related factors increased in the astragalus polysaccharide group, but contrary results were found in the LY294002 group (all P<0.05). In vivo, GIOP rats had improved bone mineral density and bone morphology parameters, and elevated expressions of autophagy related factors in the cartilage tissue compared to rats in the model group through astragalus polysaccharide intervention. LY294002 intervention showed the opposite effects (all P<0.05). Moreover, LY294002 partially reversed the effects of astragalus polysaccharide on osteogenic differentiation and bone morphological parameters in GIOP. Conclusion Astragalus polysaccharide exerts protective effect on GIOP through the PI3K/AKT/mTOR pathway, which may be related to autophagy induction and enhanced proliferation of osteoblasts.