Chen Xue-ying, Jiang Xing-hua, Lai Xiao-yang, Fang Xiang-nan, Yang Ya
Department of Cardiovascular Medicine, Second Affiliated Hospital to Nanchang University, Nanchang 330066, China.
Zhonghua Fu Chan Ke Za Zhi. 2012 Nov;47(11):833-8.
To investigate the effect of estrogen on expression of matrix GLA protein (MGP) in ovariectomized Sprague-Dawley (SD) rats and the role of estrogen in improving postmenopausal osteoporosis.
Thirty-six SD female rats were allocated into 3 groups randomly, every 12 rats in ovariectomized group (OVX group), estrogen group (E group) and control group (sham group). Rats in OVX and E group all underwent bilateral ovariectomy, those rats in E group were given by estradiol benzoate intramuscularly after 3 weeks of ovariectomy. Rats in sham group underwent bilateral lipectomy near the ovary. All rats were kept the urine and the serum every three weeks and were sacrificed after 15 weeks. The pathology changes of uterus, lumbar vertebral bones were observed by immunohistochemistry. Bone mineral density (BMD) of lumbar vertebra of rats was determined by dual energy X ray absorptiometry (DEXA). The content of MGP in serum and urine was determined by ELISA. Expression of undercarboxylated matrix GLA Protein (MGP) was detected by immunohistochemistry. Relative quantification of MGP mRNA expression in lumbar vertebra bone was detected by Fluorescent real-time quantitative polymerase chain reaction.
(1) After 15 weeks of ovariectomized, the endometrium of uterus and lumbar vertebra exhibit remarkable pathologic changes in OVX group. The serum estrogen of (454 ± 66) pmol/L in OVX group were lower than in (527 ± 77) pmol/L in sham group and (556 ± 80) pmol/L in E group significantly (P < 0.05). The BMD of lumbar vertebra of (0.263 ± 0.030) g/cm(2) in OVX group were lower than (0.295 ± 0.024) g/cm(2) in sham group and (0.279 ± 0.024) g/cm(2) in E group significantly (P < 0.01). (2) The serum MPG protein in OVX group and E group showed decreased trends after ovariectomized, which were (104 ± 64) ng/L in OVX group and (134 ± 6) ng/L in E group at 9 weeks, which reached statistical difference (P < 0.05). However, MGP in urine in sham group did not exhibit significant difference after 15 weeks of surgery (P > 0.05). The MGP in urine of E group showed increased trends after 12 weeks of surgery, which reached (110.0 ± 3.4) ng/L at 15 weeks, in the mean time, it was found that (86.5 ± 2.5) ng/L of MGP in urine in OVX group, which showed significant difference (P < 0.05). (3) MGP could be observed in lumbar vertebra in OVX group by immunochemistry staining. In the other two groups, the expression of MGP was not dominant. (4) Relative quantification of MGP mRNA expression in lumbar vertebra was defined as 1 in OVX group, when compared with 0.289 ± 0.260 in E group and 0.103 ± 0.098 in sham group, the difference showed statistically significant (P < 0.01).
Estrogen could increase the expression of MGP mRNA and protein in ovariectomized rats and might play an important role in improving postmenopausal osteoporosis.
探讨雌激素对去卵巢Sprague-Dawley（SD）大鼠基质Gla蛋白（MGP）表达的影响以及雌激素在改善绝经后骨质疏松中的作用。
将36只SD雌性大鼠随机分为3组，每组12只，分别为去卵巢组（OVX组）、雌激素组（E组）和对照组（假手术组）。OVX组和E组大鼠均行双侧卵巢切除术，E组大鼠在卵巢切除术后3周给予苯甲酸雌二醇肌肉注射。假手术组大鼠行双侧卵巢附近脂肪切除术。每3周采集所有大鼠的尿液和血清，15周后处死大鼠。通过免疫组织化学观察子宫、腰椎的病理变化。采用双能X线吸收法（DEXA）测定大鼠腰椎骨密度（BMD）。采用酶联免疫吸附测定法（ELISA）测定血清和尿液中MGP的含量。通过免疫组织化学检测羧化不全基质Gla蛋白（MGP）的表达。采用荧光实时定量聚合酶链反应检测腰椎骨中MGP mRNA表达的相对定量。
（1）去卵巢15周后，OVX组大鼠子宫和腰椎出现明显病理变化。OVX组血清雌激素为（454±66）pmol/L，显著低于假手术组的（527±77）pmol/L和E组的（556±80）pmol/L（P<0.05）。OVX组大鼠腰椎BMD为（0.263±0.030）g/cm²，显著低于假手术组的（0.295±0.024）g/cm²和E组的（0.279±0.024）g/cm²（P<0.01）。（2）OVX组和E组大鼠去卵巢后血清MPG蛋白呈下降趋势，9周时OVX组为（104±64）ng/L，E组为（134±6）ng/L，差异有统计学意义（P<0.05）。然而，假手术组大鼠术后15周尿液中MGP无显著差异（P>0.05）。E组大鼠术后12周尿液中MGP呈上升趋势，15周时达到（110.0±3.4）ng/L，同时发现OVX组大鼠尿液中MGP为（86.5±2.5）ng/L，差异有统计学意义（P<0.05）。（3）免疫组织化学染色显示OVX组大鼠腰椎中有MGP表达。在其他两组中，MGP表达不明显。（4）OVX组大鼠腰椎中MGP mRNA表达的相对定量定义为1，与E组的0.289±0.260和假手术组的0.103±0.098相比，差异有统计学意义（P<0.01）。
雌激素可增加去卵巢大鼠MGP mRNA和蛋白的表达，可能在改善绝经后骨质疏松中起重要作用。
