目的 基于SIRT3介导成骨细胞凋亡通路分析茶多酚对骨质疏松症（OP）的干预作用和相关分子机制。方法 40只大鼠于后肢臀部im氢化可的松建立OP大鼠模型，将造模大鼠随机分为模型组，茶多酚低剂、高（25、100 mg/kg）剂量组，阿仑膦酸钠（1 mg/kg）组，每组10只，另取10只正常饲养的大鼠设为对照组。造模成功后第2周各组大鼠均给药干预。采用Micro-CT分析大鼠骨密度（BMD）和骨微结构；苏木精–伊红（HE）染色观察大鼠股骨组织病理形态；ELISA法检测大鼠血清骨代谢指标和氧化应激指标；TUNEL染色检测大鼠股骨组织细胞凋亡指数（AI）；Western blotting法检测大鼠股骨组织中去乙酰化酶3（SIRT3）、B淋巴细胞瘤2（Bcl-2）、B淋巴细胞瘤-2相关蛋白（Bax）表达。结果 与模型组比较，茶多酚25、100 mg/kg组大鼠骨组织病理损伤明显减轻，大鼠BMD、骨体积分数（BV/TV）、骨小梁数量（Tb.N）、骨小梁厚度（Tb.Th）、骨连接密度（Conn.D）均显著升高，骨小梁分离度（Tb.Sp）显著降低；血清碱性磷酸酶（ALP）、Ⅰ型前胶原氨基端前肽（PⅠNP）水平和超氧化物歧化酶（SOD）、谷胱甘肽过氧化物酶（GSH-Px）活性均显著升高，Ⅰ型胶原羧基末端肽（CTX-Ⅰ）水平、丙二醛（MDA）含量均显著降低；大鼠股骨组织AI、Bax蛋白表达量显著降低，SIRT3和Bcl-2蛋白表达量显著升高，差异均有统计学意义（P＜0.05）。茶多酚100 mg/kg组大鼠上述指标均显著优于茶多酚25 mg/kg组，差异有统计学意义（P＜0.05）。结论 茶多酚可能通过调控SIRT3/Bcl-2信号通路调节骨代谢指标水平、减轻氧化应激、抑制成骨细胞凋亡，从而对OP产生良好的保护作用。

Objective The intervention effect of tea polyphenols on osteoporosis (OP) and related molecular mechanism were analyzed based on SIRT3 mediated osteoblast apoptosis pathway. Methods Forty rats were injected with hydrocortisone intramuscularly into the buttocks of the hind limbs to establish the OP rat model. The rats were randomly divided into model group, tea polyphenol low and high (25, 100 mg/kg) dose group, and alendronate sodium 1 mg/kg group, with 10 rats in each group. Another 10 normal rats were set as control group. The rats in each group were given drug intervention in the second week after successful modeling. Bone mineral density (BMD) and bone microstructure were analyzed by Micro-CT, HE staining was used to observe the pathological morphology of rat femur, serum bone metabolism and oxidative stress were detected by ELISA, TUNEL staining was used to detect the apoptosis index (AI) of rat femur, the expressions of d Sirtuin 3 (SIRT3), B-cell lymphoma-2 (Bcl-2), and B-cell-lymphoma-2 related protein (Bax) in rat femur were detected by Western blotting. Results Compared with model group, the pathological damage of bone tissue in tea polyphenol 25 and 100 mg/kg group was significantly reduced, and the BMD, BV/TV, Tb.N, Tb.Th, and Conn.D increased significantly, and Tb.Sp decreased significantly. The levels of ALP, PⅠNP, SOD, and GSH-Px increased significantly, while the levels of CTX-Ⅰ and MDA decreased significantly. The expression of AI and Bax protein in rat femur decreased significantly, while the expression of SIRT3 and Bcl-2 protein increased significantly, the difference was statistically significant (P < 0.05). Above indexes of rats in tea polyphenol 100 mg/kg group were significantly better than those in tea polyphenol 50 mg/kg group, and the difference was statistically significant (P < 0.05). Conclusion Tea polyphenols may regulate the level of bone metabolism, alleviate oxidative stress, and inhibit osteoblast apoptosis by regulating SIRT3/Bcl-2 signaling pathway, thus have a good protective effect on OP.

R965

张家港市青年科技项目(ZJGQNK201912)