脊髓损伤大鼠骨组织微环境中RANKL/OPG表达的改变

目的研究脊髓损伤(SCI)大鼠骨组织微环境中RANKL/OPG表达的改变,探讨SCI对骨代谢的影响。方法 20只雄性6wSD大鼠,分为SCI组和Sham组。饲养3w后收集右侧胫骨测定骨密度,左侧胫骨切取后立刻液氮冷冻保存,一部分用于骨组织提取RNA,半定量RT-PCR分析RANKL、OPG、Col1α1、OCN基因的表达变化;另一部分用于酶免疫分析(EIA)方法测量骨组织中RANKL和OPG的含量。结果 3w时SCI组胫骨的骨密度明显低于Sham组,骨密度的下降既发生在胫骨近端干骺端(-26.3%,P0.05),又发生在胫骨干(-21.2%,P0.05)。RT-PCR检测表明,SCI后3w大鼠胫骨近端骨组织微环境中RANKL的表达显著上调(+122.2%,P0.01),OPG(-22.1%,P0.05)和OCN(-25.3%,P0.05)的表达显著下调。RANKL和OPG的表达改变也得到了EIA的证实。结论 SCI时RANKL过表达及OCN和OPG表达下调,提示SCI时易发生骨质疏松。

The expressions of RANKL/OPG in bone tissue in spinal cord injury rats

Objective To investigate the effect of spinal cord injury（SCI） on the expressions of receptor activator of nuclear factor κB ligand（RANKL）, osteoprotegerin（OPG）and OCN in bone microenvironment in SCI rats. Methods 20 male SD rats were randomly allocated to two groups：SCI and Sham. All animals were sacrificed 3 weeks after SCI. Right tibiae were used for bone desity measurement, left tibiae were collected to study the expressions of RANKL, OPG, Col1α1 and OCN genes by RT-PCR and the contents of RANKL and OPG proteins by enzyme immunoassay（EIA）. Results The bone density value of tibiae was lower in SCI group than in Sham （proximal metaphyses： -26.3%,P〈0.05; shaft： -21.2%,PP〈0.05）. Expression levels of RANKL, OPG, and OCN genes in proximal tibiae were significantly downregulated in SCI group than in sham rats （RANKL ＋122.2%,P〈0.01; OPG -22.1%,P〈0.05; OCN -25.3%,P〈0.05）. The changes of RANKL and OPG protein expressions in the tibiae by EIA were also coincident with RT-PCR results. Conclusion The overexpression of RANKL gene and downexpression of OCN and OPG genes caused by SCI might be related to the occurrence mechanism of osteoporosis.