激素与去卵巢诱导大鼠骨质疏松症的差异及其分子机制探讨

摘要

Objective To compare the effect between glucocorticoid and ovariectomy on bone mass, bone turnover markers, estrogen level, and adipogenic differentiation by BMSCs, and to analyze the possible molecular mechanism. Methods Thirty six 3-month⁃old female Sprague Dawley rats were randomly divided to 3 groups, control group, methylprednisolone group ( MP) , and ovariectomized group ( OVX) . The rats in 3 groups were sacrificed in 8 weeks. The body mass, adrenal weight, and uterus weight were detected. BMD, BMC, and BA of the left femurs were detected using dual energy X⁃ray absorptiometry. The serum levels of PINP,β⁃CTX, and estrogen were determined using ELISA. Meanwhile, adipogenic differentiation by BMSCs was observed by oil red staining of the right femurs. The mRNA expression of Runx2, Col1α1, and MMP9 in the left tibia was detected using RT⁃PCR. Results In 8 weeks after the operation, the body mass in rats of MP group was significantly lower than that in control group and OVX group, while the body mass of OVX group was significantly higher than that in control group (P<0�05). BMC, BMD, and BA in rats of MP group and BMC and BMD in rats of OVX group were significantly lower than those in control group (P<0�05). In addition, BMC, BMD, and BA in MP group were significantly lower than those in OVX group (P<0�05). The levels of PINP and β⁃CTX in both groups were higher than those in control group, and they were significantly higher in MP group than in OVX group (P<0�05). The estrogen level in both groups were significantly lower than that in control group (P<0�05). The fat in bone marrow of both groups was more than that in control group. The expression of Runx2 mRNA in both groups was significantly down⁃regulated comparing with that in control group (P<0�05). The expression of Col1α1 and MMP9 mRNA was higher than that in control group, but the difference was not significant. Conclusion Both glucocorticoid and ovariectomy can induce high⁃turnover osteoporosis in rat, and glucocorticoid⁃induced bone loss is more severe. Both models can down⁃regulate estrogen level and promote adipogenic differentiation by BMSCs. The molecular mechanism may be related to the expression level of Runx2 mRNA.%目的：比较激素及去卵巢对大鼠骨量、骨转换指标、雌激素水平、骨髓细胞成脂分化水平的影响，并探讨两种模型可能的分子机制。方法3月龄雌性SD大鼠36只，随机分为空白组、甲强龙组（ MP组）、去卵巢组（ OVX组）。3组大鼠于8w后处死，测量体重及子宫、肾上腺重量；双能X线骨密度仪测量左股骨BMD、BMC、BA；ELISA法测量血清PINP、β⁃CTX及雌激素水平；油红“O”染色观察右股骨骨髓间充质干细胞（ BMSCs）成脂情况。 RT⁃PCR检测左胫骨Runx2、Col1α1、MMP9 mRNA表达。结果术后8w，MP组体重显著低于空白组及OVX组，OVX组体重明显高于空白组（P＜0�05）。 MP组BMC、BMD、BA及OVX组BMC、BMD均较空白组明显降低，且MP组BMC、BMD、BA明显低于OVX组（ P＜0�05）。两组血清PINP、β⁃CTX均较空白组显著升高，且MP组明显高于OVX组，两组雌激素水平均显著低于空白组（P＜0�05）。两组骨髓脂滴均较空白组增多，骨组织Runx2 mRNA表达均较空白组显著下调（P＜0�05），Col1α1、MMP9 mRNA表达较空白组高，但比较差异无统计学意义。结论激素及去卵巢均可诱导大鼠高转换型骨质疏松症，以激素导致的骨量丢失更严重，且两者均可下调大鼠血清雌激素水平、促进骨髓细胞成脂分化，其机制可能均与调控骨组织Runx2 mRNA表达水平密切相关。