Marchand-Libouban H, Le Drévo M A, Chappard D
LUNAM Universite, GEROM - LHEA Groupe d'Etudes Remodelage Osseux et bioMateriaux, IRIS-IBS Institut de Biologie en Sante, CHU d'Angers, 49933 ANGERS Cedex, France.
J Musculoskelet Neuronal Interact. 2013 Mar;13(1):27-36.
Molecular events occurring in the bone marrow microenvironment of an immobilized mouse limb after Botulinum toxin (BTX) injection haven't been characterized. BTX injection induces a localized disuse in which the tissue events have well been characterized.
BTX injection was performed in the right quadriceps; saline injection in the left side was used as control. Mice were sacrificed at 0, 7, 14, 21 and 28 days; tibias were used for microCT analysis; bone marrow from femurs for RT-PCR analysis.
MicroCT revealed bone loss and microarchitectural damages on the immobilized side as from 7d; cortical area tended to be lower on the immobilized limb at 28d. Gene expression of formation factors was altered as from 7 days post-BTX: alkaline phosphatase, Tgfβ1, Lrp5, Sfrp2. Only Sfrp2 and Lrp5 were maintained altered until 28d. Expression of Dkk1 increased from 21d and represented a late inhibitor of formation. Gene expression of resorption markers increased as from 7d (Rankl, Tracp, Il1α, Il1β and Il6) and was maintained until 28d for Tracp and Il6.
A localized disuse induces rapid modifications in the bone marrow gene expression leading to bone loss due to an early decrease of formation associated with an increase in resorption.
肉毒杆菌毒素（BTX）注射后固定小鼠肢体骨髓微环境中发生的分子事件尚未得到表征。BTX注射会引发局部废用，其中组织事件已得到充分表征。
在右股四头肌中注射BTX；左侧注射生理盐水作为对照。在第0、7、14、21和28天处死小鼠；取胫骨进行显微CT分析；取股骨骨髓进行逆转录聚合酶链反应（RT-PCR）分析。
显微CT显示，从第7天起，固定侧出现骨质流失和微结构损伤；在第28天，固定肢体的皮质面积趋于降低。BTX注射后7天起，成骨因子的基因表达发生改变：碱性磷酸酶、转化生长因子β1（Tgfβ1）、低密度脂蛋白受体相关蛋白5（Lrp5）、分泌型卷曲相关蛋白2（Sfrp2）。只有Sfrp2和Lrp5在第28天前一直保持改变状态。Dickkopf相关蛋白1（Dkk1）的表达从第21天开始增加，是一种晚期成骨抑制剂。骨吸收标志物的基因表达从第7天起增加（核因子κB受体活化因子配体（Rankl）、抗酒石酸酸性磷酸酶（Tracp）、白细胞介素1α（Il1α）、白细胞介素1β（Il1β）和白细胞介素6（Il6）），Tracp和Il6一直保持到第28天。
局部废用会导致骨髓基因表达迅速改变，由于早期成骨减少与骨吸收增加相关，从而导致骨质流失。
