17β-雌二醇对大鼠破骨细胞内钙浓度影响的研究

Effects of estrogen on intracellular calcium concentration in isolated rat osteoclasts

目的 探讨雌激素调节破骨细胞活性机制。方法 以 Chamber方法加以改良 ,常规体外培养新生 Wister大鼠破骨细胞 ( Osteoclast,OC)。镜下观察细胞形态 ,测定不同浓度 17β-雌二醇 ( 17βE2 )在有钙与无钙溶液中对破骨细胞钙浓度 ( OC[Ca2 +]i)的影响。结果 30 min后 OC贴壁生长 ,胞浆伸展。2 h后细胞形态为多形性 ,有片状或丝状伪足 ,常规生存 52 h。17βE2 使细胞变小。除去 17βE2 ,OC形态恢复原状。不同浓度 17βE2 在不同时间 ,有钙与无钙溶液中均可诱发 OC[Ca2 +]i 升高。结论 OC是 17βE2的靶细胞。 [Ca2 +]i升高是细胞外 Ca2 +流动与细胞内存钙释放的综合作用。OC[Ca2 +]i 升高后 ,细胞变小 ,伪足回缩 ,骨吸收活性被抑制。 17βΕ2 可能是通过 OC[Ca2 +]i

To further elucidate whether estrogen mediates osteoclastic activity by the way of intracellular calcium concentration([Ca 2+ ] i),isolated newborn Wistar rat osteoclasts were involved in our study.[Ca 2+ ] i was measured by spectrofluorometer after osteoclasts were loaded by acetoxymethylester of fura 2(Fura 2/AM).We demonstrated that 17β estradiol(E 2) acted on [Ca 2+ ] i in osteoclasts.17βE 2 induced changes of osteoclastic shapes,and stimulated the elevation of [Ca 2+ ] i buffered in calcium and calcium free medium.Increase of [Ca 2+ ] i induced by 17βE 2 resulted from Ca 2+ influx from extracelluar milieu and Ca 2+ release from internal stores.The reasons might be as follows:Ca 2+ itself,Ca 2+ receptors and G protein or protein kinase may be activated after 17βE 2 has combined with its membrane receptors.In addition,second messenger may be involved.Gelsolin,a calcium dependent actin regulating protein present in osteoclst podosomes,after completing calcium,is capable of fragmenting pre existing microfilaments and nucleating new ones,thereby contributing to the rearrangement of the microfilament network of the cells.The podosomes start to shrink.Then osteoclasts do not attach the bone surface and their activity is suppressed.