泼尼松龙与地塞米松介导腰椎骨量降低的差异及其对成骨成脂基因表达的影响

Difference investigation of the lumbar bone-loss level induced by prednisolone or dexamethasone and its effects on osteogenic and adipogenic gene expression

目的：比较泼尼松龙（PRE）和地塞米松（DXM）诱导腰椎骨量丢失差异程度并利用成脂成骨经典信号通路探讨其可能机制。方法：选取3月龄SPF级雌性大鼠24只,随机分成4组：基线组（BL组）6只、年龄对照组（CON组）6只、泼尼松龙组（PRE组）6只、地塞米松组（DXM组）6只。BL组于实验开始时麻醉处死,其余3组正常喂养,其中CON组不作任何药物干预,PRE组予5mg/kg PRE每天一次皮下注射、DXM组以1mg/kg DXM每周两次皮下注射。干预3个月后麻醉下取材。取材时立即分离右侧股骨,获取髓腔内骨髓细胞进行涂片,油红“O”检测骨髓性状;取L6椎体作反转录式-聚合酶连锁反应（RT-PCR）检测骨保护素（OPG）及过氧化物酶体增殖物激活受体γ（PPAR-γ）表达;分离L1~L3椎体检测骨密度（BMD）。结果：在两种糖皮质激素（GC）分别干预3个月后,其BMD值均较CON组有明显下降（P〈0.05）,DXM组下降更为显著（P〈0.01）,且明显低于PRE组（P〈0.05）。DXM组骨组织OPG表达量明显低于其余三组（P〈0.05）,但PPAR-γ则组间无明显差异。骨髓油红“O”涂片发现,两种GC组涂片阳性细胞数量多于BL组和CON组,但其组间无明显差异。结论：两种不同的糖皮质激素在诱导大鼠骨量丢失模型中,地塞米松诱导腰椎骨量减少的效果较泼尼松龙强,这可能与DXM通过OPG/RANKL/RANK信号通路中更大程度地抑制OPG表达有关。

Objectives： To investigate tile mechanism of lumbar bone loss induced by prednisolone（PRE） or dexamethasone（DXM） through the osteogenesis and adipogenesis pathway. Methods： 24 female SD rats aged 3 months was divided into 4 groups randomly as below, baseline group（BL group, 6 rats）, age-matched control group（CON group, 6 rats）, prednisolone-treated group（PRE group, 6 rats）, dexamethasone-treated group（DXM group, 6 rats）. BL group were euthanized at the beginning of the experiment and CON group rats were feed normally with no treatment. PRE group and DXM group were injected with PRE in a dose of 5mg/kg per day and DXM in a dose of lmg/kg twice per week, respectively and lasted for 3 months. The bone marrow in right femur was collected for Oil red staining to observe the cell types, lumbar 6 was collected for testing the activity of osteoprotegerin（OPG） and peroxisome proliferator activated receptor-3,（PPAR-y） by reverse transcrip- tion-polymerase chain reaction（RT-PCR）, lumbar 1-3 were collected for BMD at the end of treatment. Re- suits： BMD in PRE and DXM rats were lower than CON rats, and decreased more significantly in DXM rats （P〈0.01）. Moreover, DXM rats decreased more significantly compared with PRE rats in BMD. Although the expression level of PPAR-γ had no significant difference among 4 groups, OPG in DXM rats was lower than that in other groups. The amount of red-staining cell in two glucocorticoid treated rats were more than that of BL group, but there was no obvious difference between the treated groups. Conclusions： The effect of DXM on lumbar bone mass decrease is more powerful than that of PRE, which expression of OPG more significantly through OPG/RANKL/RANK pathway.