目的 研究MGP在绝经后骨质疏松发病机制中的作用及维生素K2对MGP及基因表达的影响.方法 36只10个月龄雌性SD大鼠,随机分成3组,假手术组、去卵巢(OVX)组、去卵巢加维生素K2干预(OVX+ Vitamin K2)组,每组12只.OVX+ Vitamin K2组在手术2周后给予维生素K2灌胃(30mg/kg,每周5次,持续12周).各组大鼠在术后每3周留取血清及尿液.18周后处死大鼠,酶联免疫吸附(ELISA)法检测血清及尿液中MGP的浓度;病理切片观察大鼠腰椎组织结构变化,免疫组化法观察腰椎未羧化MGP的表达;荧光实时定量PCR观察腰椎MGP基因的表达水平.结果 (1)去卵巢18周后,各组血清MGP含量逐渐上升,维牛素K2组上升幅度较假手术组及OVX组大(P<0.05),尿液中MGP变化不明显;(2)免疫组化切片中OVX组未羧化MCP(ucMGP)呈阳性染色,维生素K2组较OVX组表达明显减少;(3)腰椎MGP mRNA的表达:OVX+ Vitamin K2组及假手术组明显低于OVX组(P<0.05),且OVX+ Vitamin K2组高于假手术组(P<0.05).结论 腰椎组织中MGP基因表达增高可能是绝经后骨质疏松发生的作用机制之一,调节MGP mRNA表达可能是维生素K2治疗骨质疏松的一种作用途径.%Objective To elucidate the mechanism of matrix Gla protein (MGP) in postmenopausal osteoporosis and to investigate the effect of vitamin K2 on the expression of MGP in the lumbar vertebra in ovariectomized rats. Methods Thirty-six 10-month-old female SD rats were allocated into 3 groups randomly, including sham operation group, ovariectomized (OVX) group, OVX + Vitamin K2 group, with 12 rats in each group. Rats in OVX + Vitamin K2 group were administered orally with vitamin K2 (30 mg/kg/d, 5 times a week) after 2 weeks of ovariectomy for 12 weeks. Serum and urine samples were collected from all rats every 3 weeks after ovariectomy. All rats were sacrificed after 18 weeks. MGP in serum and urine was determined using enzyme-linked immunosorbent assay (ELISA). Pathology sections were used to observe the tissue structure change in the rat lumbar vertebra. Expression of uncarboxylated matrix Gla protein (ucMGP) was detected with immunochistochemistry. MGP mRNA expression in the lumbar vertebra was detected using fluorescent real-time quantitative polymerase chain reaction ( Q-PCR ). Results 1 ) After 18 weeks of ovariectomy, serum MGP levels increased gradually. Serum MGP increased more in OVX + Vitamin K2 group than in sham operationgroup (P ＜ 0. 01 ) and in OVX group (P ＜ 0. 05 ). The change of urine MGP was not obvious. 2) ucMGP was positively stained in Immunochistochemical sections in OVX group. The expression was less in OVX + Vitamin K2 group than in OVX group. 3) Expression of MGP mRNA was significantly lower in OVX + Vitamin K2 group and in sham group than in OVX group (P ＜0.05), and was higher in OVX + VitaminK2 group than in sham group ( P ＜ 0. 05 ). Conclusion Up regulation of MGP may be one of the mechanisms of postmenopausal osteoporosis. Regulation of MGP mRNA expression by Vitamin K2 could be a pathway for the treatment of osteoporosis.
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