糖皮质激素与卵巢摘除后对大鼠骨量及骨代谢影响的对比研究

A comparative study of the effects of glucocorticoid and ovariectomy on bone mass and metabolism in rats

目的探讨不同剂量糖皮质激素(GC)对大鼠骨量及骨代谢的影响,以及比较GC诱导骨质疏松模型(GICP模型)与卵巢摘除骨质疏松模型(0VX模型)对大鼠骨量及骨代谢影响的区别。方法 75只4个月龄雌性SD大鼠。随机分成五组,A组为正常对照组(Sham组,生理盐水灌胃);B组为低剂量GC组(泼尼松龙每天2.5 mg/kg)灌胃;C组为中剂量GC组(泼尼松龙每天5 mg/kg灌胃);D组为高剂量GC组(泼尼松龙每天10 mg/kg灌胃);E组为卵巢切除组(OVX组)。每天1次,GC组连续灌胃12周。分别于灌胃/去势后第4、8、12周从每组中各随机抽出5只SD大鼠,处死。取股骨干骺端进行不脱钙骨制片;利用显微CT扫描大鼠腰1段;利用酶联免疫吸附测定法(Elisa)检测静脉血中TRACP、G-ALP、BGP及尿液中DPD。结果 (1)各实验组4周后骨小梁排列渐稀疏,数目开始减少,小梁明显变细,间距加宽。随着给药时间的延长,改变更加明显;(2)骨密度检测:与对照组相比,GC低剂量组骨流失从给药后第8周开始明显(P<0.05),而GC中剂量和高剂量组骨流失从给药后4周就开始显现(P<0.05)。中剂量组与高剂量组各时间段差异均无统计学意义(P>0.05);与中等剂量和高等剂量相比,去势组第4周骨量流失差异有统计学意义(P<0.05),第8、12周差异无统计学意义(P>0.05)。(3)骨代谢生化指标的测定结果 :灌胃及摘除卵巢4周后,C组、D组、E组骨形成标记物(G-ALP、BGP)、骨吸收标记物(TRACP、DPD)与正常对照组差异有统计学意义(P<0.05)。结论 (1)大鼠骨量的流失可随着糖皮质激素剂量的增加而增加(呈浓度依赖性)。(2)在OVX模型中,骨重建能力上升,而在GIOP模型中,骨重建能力下降。

Objective To investigate the effects of different dosages of glucocorticoid （GC） on bone mass and metabolism in rats, and to compare the different effects on bone mass and metabolism in rats between GC-induced osteoporosis model （GIOP model） and ovariectomy-induced osteoporosis model （OVX model）. Methods A total of 75 4-month-old female Sprague-Dawley （SD） rats were randomly divided into 5 groups： group A （the control group） was treated with salt solution lavage （group Sham）; group B was treated with low-dose GC （2.5 mg/kg prednisolone lavage each day）; group C was treated with moderate-dose GC （5 mg/kg prednisolone lavage each day）; group D was treated with high-dose GC （10 mg/kg prednisolone lavage each day）; group E received ovariectomy （group OVX）. The rats in the GC groups received lavage once per day, which lasted for 12 weeks. 5 SD rats were chosen randomly from all the groups at the 4th, 8th and 12th weeks after receiving lavage or castrating. They were sacrificed to collect the femoral metaphysis to process undecalcified bone histomorphometry and examine the lumbar 1 section by micro-CT. Enzyme-linked immunosorbent assay （ELISA） was used to test the tartrate-resistant acid phosphatase （TRACP）, alkaline phosphatase （G-ALP）, bone gla protein （BGP） in venous blood and deoxypyridinoline （DPD） in urine. Results （1） After 4 weeks, the trabecular bone of the experimental groups was gradually sparse and apparently necking, along with the widened spacing. With the prolongation of medication, the changes became more obvious. （2） Detection of bone mineral density： bone loss of the low-dose GC group became obvious after 8 weeks’ treatment, when compared with that of the control group （P〈0.05）, and while bone loss of the medium-dose GC and high-dose GC groups was significantly obvious after 4 weeks’ treatment （P〈0.05）. There were no significant differences in bone loss between the medium-dose GC group and high-dose GC group in each time period （P〉0.05）. When compared with that of the medium-dose GC and high-dose GC groups, bone loss of the castration group （group E） was significantly different at the 4th week after treatment （P〈0.05）, without significantly differences at the 8th and 12th weeks （P〉0.05）. （3） An overview of biochemical markers of bone metabolism： 4 weeks after lavage and ovariectomy, the differences in bone formation markers （G-ALP and BGP） and bone resorption markers （TRACP and DPD） of the group C, group D and group E were statistically significant, when compared with that of the control group （group A） （P〈0.05）. Conclusions （1） Bone loss in rats will increase along with the increasing dose of GC in a concentration-dependent manner. （2） Bone reconstruction ability in the OVX model is obviously increased, which is reduced in the GIOP model.