不同频率给予地塞米松对大鼠胫骨皮质骨和松质骨的影响

Effect of dexamethasone at different frequency on cortical and cancellous bone of rat tibia

目的研究不同频率给予地塞米松(Dex)对大鼠胫骨皮质骨和松质骨骨质疏松的影响。方法 3月龄雌性SD大鼠肌注给予Dex 1mg·kg-1,给药频率分别为每周2次、4次和6次,共计给药30d。取胫骨上段和中段进行石蜡包埋,HE染色观察骨结构变化,结合骨形态计量学检测松质骨的骨小梁面积百分数(%Tb.Ar)、骨小梁宽度(Tb.Wi)、骨小梁数量(Tb.N)和骨小梁分离度(Tb.Sp),以及皮质骨的骨组织总面积(T.Ar)、皮质骨厚度(Ct.Th)、皮质骨面积(Ct.Ar)、骨髓腔面积(Ma.Ar),以及骨外膜面周长(P-Pm)和骨内膜面周长(E-Pm)。结果①胫骨上段松质骨:HE染色结果显示,正常对照组骨小梁排列密集,小梁较宽;每周2次组与之相比无明显变化,4次和6次组Tb.Wi变窄(P<0.05)。骨形态计量学进一步确认,与正常组相比,2次组无明显变化;4次及6次组%Tb.Ar和Tb.Wi均明显减少(P<0.05),而Tb.N和Tb.Sp无显著变化。②胫骨中段皮质骨:HE染色结果发现,正常对照组皮质骨切片呈现淡红色、中空环状结构;与正常对照组相比,2次和4次组未见明显差异;6次组Ct.Th和Ct.Ar百分比相对减少(P<0.05)。骨形态计量学确认,与正常对照组相比,6次组T.Ar,P-Pm,Ct.Th和Ct.Ar均明显减少(P<0.05),Ma.Ar,E-Pm无变化,Ma.Ar明显变大(P<0.05)。2次组T.Ar和Ct.Th显著减少(P<0.05),4次组仅T.Ar减少(P<0.05),其他指标均无显著差异。结论 Dex的给药频率影响骨质疏松,增加糖皮质激素给药的频率,可以缩短骨质疏松形成时间。

OBJECTIVE To explore the effect of dexamethasone （Dex） at different frequency on cortical and cancellous bone of the rat tibia osteoporosis model. METHODS Three-month-old female SD rats were given Dex 1 mg· kg^-1 intramuscularly for 30 d, and divided into three groups： Dex-treat- merit twice a week group, Dex-treatment four times a week group and Dex-treatment six times a week group. The middle part of tibia shaft （TX） and proximal tibia metaphyses （PTM） were taken for HE stai- ning after decalcification and paraffin-embedded procedure. HE staining was used to observe changes in bone structure, Bone histomorphometry was used to measure the percentage of the trabecular area （ % Tb. At）, trabecular width （Tb. Wi）, trabecular number （ Tb. N） and trabecular separation （Tb. Sp） of cancellous bone, and the total tissue area （T. At）, cortical area （Ct. Ar）, marrow area （Ma. At）, cortical bone thickness （Ct. Th）, periosteal perimeter （P-Pm） and endocortical perimeter （E-Pm） of cortical bone. RESULTS ① In PTM, HE staining turnouts showed wide trabeculae in the dense distribution in normal control group and there was no statistically significant difference compared with twice a week group. The %Tb. Ar and Tb. Wi in four and six times a week groups were remarkably decreased （ P 〈 0.05）, but Tb. N and Tb. Sp didn＇t change significantly as shown by HE staining and further bone histo- morphometry. ② In HX, HE staining turnouts showed that the cortical bone section looked like a pink hollow ring and no difference was found between twice and four times a week groups and normal control group, but in six times a week group, Ct. Th and Ct. Ar were decreased （ P 〈 0.05）. Ascertained by bone histomorphometry, %T. Ar, P-Pm, Ct. Th and Ct. Ar were significantly reduced, while Ma, Ar and E-Pm remained unchanged, but the percentage of Ma. Ar was increased （ P 〈 0.05）. The % T. Ar and Ct. Th in twice a week group were both decreased （P〈0. 05） compared with normal control group, and in four times a week group only %T. Ar was decreased （ P 〈0.05）. CONCLUSION The frequency of Dex administration affects the osteoporosis model. The modeling time can be shortened by increasing administration frequency of glucocorticoid.