17β-雌二醇对青年期ISA蛋鸡骨代谢的影响

Effect of 17 beta-estradiol on bone metabolism of adolescent period ISA hens

背景:青年期蛋鸡在性成熟前形成髓质骨,体内雌激素水平的升高对骨代谢有直接的影响。目的:观察外源性17β-雌二醇对青年期ISA蛋鸡骨代谢的影响。设计、时间及地点:随机分组设计、动物对照观察,于2007-10/2008-02在南京农业大学动物医学院畜禽骨骼生物学实验室完成。材料:92日龄青年期ISA蛋鸡180羽。17β-雌二醇由美国Cayman公司提供,玉米油为国产分析纯。方法:180羽蛋鸡按随机数字表法分成3组,空白对照组、溶剂对照组、雌激素组,每组60羽。空白对照组蛋鸡,不做任何处理;溶剂对照组为每天肌肉注射玉米油1mL,雌激素组为每天肌肉注射2g/L17β-雌二醇玉米油溶液1mL。两组均注射20d。主要观察指标:于实验第0,5,10,15,20天,每组取12只鸡翼静脉采血5mL,用半自动生化分析仪测定血Ca、P和碱性磷酸酶活性。分光光度计测定抗酒石酸酸性磷酸酶活性。采用放射免疫法,运用智能放射免疫γ测量仪测定血浆雌二醇与睾酮。每个时间点取血后,麻醉后处死,取股骨中段样本,厚度为4mm,置于扫描仪上直接扫描后,运用ImageJ图像处理系统分析扫描图像,计算皮质骨厚度、皮质骨面积和皮质骨面积比例、皮质骨骨内径、皮质骨骨外径。结果:从实验第5天开始,雌激素组雌二醇显著高于空白对照组和溶剂对照组,睾酮水平显著低于空白对照组和溶剂对照组,差异有显著性意义(P<0.05)。实验第10,15,20天雌激素组碱性磷酸酶活性显著高于空白对照组和溶剂对照组,差异有显著性意义(P<0.05)。实验第15,20天雌激素组血钙、血磷水平显著高于空白对照组和溶剂对照组,差异有显著性意义(P<0.05)。实验第15,20天雌激素组抗酒石酸酸性磷酸酶活性显著低于空白对照组和溶剂对照组,差异有显著性意义(P<0.05)。空白对照组和溶剂对照组之间差异无显著性意义(P>0.05)。雌激素组皮质骨厚度、皮质骨面积、皮质骨面积比例、骨内径及骨外径与空白对照组和溶剂对照组比较,差异均无显著性意义(P>0.05)。结论:外源性雌激素能够促进青年期蛋鸡骨形成,抑制骨吸收,促进骨骼发育。

BACKGROUND： During the formation of medullary bone in adolescent period hens, increased estradiol levels has dirent effects on bone metabolism. OBJECTIVE： To observe the effect of exogenous 17β-estradiol on bone metabolism in adolescent period ISA hens. DESIGN, TIME AND SETTING： This randomized controlled animal experiment was conducted at Laboratory of Bone Biology, College of Veterinary Medicine, Nanjing Agricultural University from October in 2007 to February in 2008. MATERIALS： 180 adolescent period ISA hens （92 days） were selected. 17β-estradiol was obtained from Cayman, USA. Corn oil was Chinese-made analytical pure. METHODS： 180 hens were equally and randomly divided into 3 groups： blank control, solvent control and 17β-estradiol groups. Hens in the blank control group were left intact. Hens in the solvent control group were injected 1 mL corn oil daily for 20 days, i.m. Hens in the 17β-estradiol group were injected 2 g/L 17β-estradiol with 1 mL corn oil as solvent every day of 20 days duration, i,m. MAIN OUTCOME MEASURES： Blood samples （5 mL） were obtained from 12 hens of each group at 0, 5, 10, 15, 20 days. Serum calcium, phosphorus and alkaline phosphatase activities were measured by semi-automati＇c biochemistry analyzer. Tartrate-resistant acid phosphatase were measured using spectrophotometer. Plasma estradiol and testosterone were measured by Intelligent radioimmunoassay Gamma Counter. After blood collection at each time point, hens were anesthetized and sacrificed to collect middle femur sample, 4 mm depth. The sample was scanned on a scanner. Presentation was analyzed using Image J image processing system to calculate cortical depth, cortical area, cortical area proportion, cortical inside radius and cortical outside radius. RESULTS： From the 5~ day, estradiol levels were significantly higher, but testosterone levels were significantly lower in the 17β-estradiol group compared with the blank control and solvent control groups （P 〈 0.05）. At 10, 15 and 20 days, alkaline phosphatase activities were significantly higher in the 17β-estradiol group compared with the blank control and solvent control groups （P 〈 0.05）. At 15 and 20 days, concentrations of Ca and P were significantly higher in the 17β-estradiol group compared with the blank control and solvent control groups （P 〈 0.05）. At 15 and 20 days, tartrate-resistant acid phosphatase activities were significantly lower in the 17β-estradiol group compared with the blank control and solvent control groups （P 〈 0.05）. There were no significant differences between the blank control and solvent control groups （P 〉 0.05）. No significant difference was detected in cortical depth, cortical area, cortical area proportion, cortical inside radius and cortical outside radius in 17β-estradiol group compared with the blank control and solvent control groups （P 〉 0.05）. CONCLUSION： Exogenous 17β-estradiol can stimulate osteoblast bone formation, inhibit osteoblast bone resorption and improve the bone development in hens.