脉冲电磁场对去卵巢骨质疏松症大鼠成骨细胞和破骨细胞凋亡的影响

目的观察脉冲电磁场（PEMF）对去卵巢骨质疏松症（OVX-OP）大鼠成骨细胞、破骨细胞凋亡的影响，并探讨PEMF治疗OVX-OP的作用机制。方法取6月龄雌性未孕Wistar大鼠40只，随机分为假手术组、卵巢切除组（模型组）、卵巢切除＋雌激素替代治疗组（雌激素组）和卵巢切除＋PEMF治疗组（电磁场组）。模型组、电磁场组和雌激素组均行双侧卵巢切除术，假手术组不切除卵巢。术后第9周开始治疗：雌激素组采用苯甲酸雌二醇肌肉注射，剂量为0．5mg／kg体重，每2周注射1次；电磁场组大鼠暴露于PEMF中，每日1次，每次1h。模型组和假手术组动物不予以任何治疗。治疗10周后处死各组实验动物，取左侧胫骨上1／3进行骨形态计量学检查。采用原位DNA末端标记染色法（TUNEL法）和透射电镜检测L6椎体成骨细胞、破骨细胞的凋亡情况。采用免疫组织化学法检测k椎体成骨细胞、破骨细胞中Fas、Bax和Bcl-2的表达。结果①透射电镜观察显示，电磁场组成骨细胞活性增强，无明显凋亡征象；而破骨细胞活性减弱，可见典型细胞凋亡征象。②电磁场组的成骨细胞凋亡指数明显低于模型组（P〈0．05），而破骨细胞凋亡指数明显高于模型组（P〈0．05）。③电磁场组Fas阳性成骨细胞数明显少于模型组，Fas阳性破骨细胞数明显多于模型组（P〈0．05），成骨细胞Bax／Bcl-2显著降低（P〈0．05），破骨细胞Bax／Bcl-2显著增高（P〈0．05）。④电磁场组OVX-OP大鼠骨小梁面积百分数、骨小梁厚度、骨小梁数量明显高于模型组，而骨小梁分离度明显低于模型组（P〈0．05）。结论PEMF对OVX-OP大鼠成骨细胞凋亡具有抑制作用，对破骨细胞凋亡具有促进作用，汶可能县苴治疗OVX-0P的机制之一。

Impact of pulsed electromagnetic fields on osteoblast and osteoclast apoptosis of ovariectomy osteoporosis rats

Objective To observe the impact of pulsed electromagnetic fields on osteoblast and osteoclast apoptosis of ovariectomy osteoporosis (OVX-OP) rats and to explore the mechanism of the therapeutic effect of electromagnetic fields in postmanupausal osteoporosis. Methods Forty six-month old female Wistar rats were randomly divided into 4 different groups according to body mass: ovariectomy group ( OVX) , Sham operation group ( Sham) , E group ( Estrogen OVX) and PEMF group ( PEMF OVX). All rats were subjected to bilateral ovariectomy except those in the sham operation group. At 8 weeks after the operation, E group rats were given estrogen 0. 5 mg/kg body weight, once every 2 weeks. PEMF group rats were exposed to bionics electromagnetic fields for 1 h /d. OVX and Sham group rats were given no intervention. All the treatments were being kept for 10 weeks. After the treatments finished, specimens of left tibia were collected for histomorphometry analysis,the osteoblast and osteoclast apoptosis condition in lumbar vertebrae by transmission electric microscope and TUNEL technique. At the same time, the expression of apoptosis controlling gene Fas, Bax, Bcl-2 protein were determined by immunochemistry. Results Compared with OVX group, %Tb, Ar, Tb, Th, Tb, N, significantly increased (P<0. 01) in EMF group. On the other hand, Tb, Sp significantly were lower than those in the OVX group (P < 0. 05). Observation of transmission electric microscope and TUNEL examination showed that PEMF stimulation exposure attenuated the apoptosis of osteoblast, elevated the apoptosis of osteoclast (P <0.05). PEMF stimulation exposure significantly attenuated Fas and Bax expression and increased Bcl-2 protein expression in osteoblast. PEMF stimulation exposure significantly increased Fas and Bax protein expression and decreased Bcl-2 protein expression in osteoclast. Conclusion The PEMF stimulation exposure could restrain Fas and Bax protein expression and facilitate Bcl-2 protein expression in osteoblast, and facilitate Fas and Bax protein expression and restrain Bcl-2 protein expression in osteoclast, promote the osteoclast apoptosis and control osteoblast apoptosis.