鸡松果体切除年龄与脊柱侧凸发生的关系

Correlation between the age of pinealectomy and the development of scoliosis in chickens

背景：大部分制造鸡脊柱侧凸的松果体切除均在孵化后3d内实施,关于或迟或早进行松果休切除后对鸡发生脊柱侧凸是否有影响目前仍不清楚。目的：分析实施松果体切除的时间与鸡脊柱侧凸的发生率和严重程度之间的关系。同时,对比进行松果体切除后发生侧凸和未发生侧凸的鸡午夜血清褪黑素水平。设计、时间及地点：随机对照动物实验,于2004-03/2006-08在解放军第二军医大学动物实验中心完成。材料：将60只小绍兴鸡随机分为6组：孵化后第2,4,11,18天施行松果体切除组,每组12只,对照组（n=6）及假手术组（n=6）。方法：4个施行松果体切除组分别在孵化后第2,4,11,18天施行松果体切除,假手术组仅暴露松果体、不切除,对照组不进行任何处理。主要观察指标：每月对鸡的脊柱进行一次俯卧位X射线检查。第3个月时,应用ELASA方法检测午夜鸡血清褪黑素水平。结果：在孵化后3个月时,孵化后第2,4,11,18天施行松果体切除的小鸡脊柱侧凸的发生率分别为：66.7%,66.7%,63.6%及66.7%。4组动物的平均Cobb角分别为：32.6°,29.8°,23.8°及22.3°。4组施行松果体切除的小鸡在脊柱侧凸发生率、严重程度以及侧凸的类型上无统计学差异。施行松果体切除鸡的夜间褪黑素浓度明显低于对照组和假手术组（P〈0.01）,施行松果体切除的发生脊柱侧凸与未发生脊柱侧凸鸡的血清褪黑素浓度无明显差别。结论：孵化18d内的鸡实施松果体切除后脊柱侧凸的发生率为63.6%-66.7%,并且不受施行手术时年龄的影响。施行松果体切除后鸡的血清褪黑素浓度较低,但发生与未发生脊柱侧凸鸡的血清褪黑素浓度无差异。

BACKGROUND： Most studies regarding scoliosis following pinealectomy is performed within 3 days after hatching. However, whether early or late pinealectomy has effect on scoliosis is poorly understood. OBJECTIVE： To investigate the correlation between the age of pinealectomy and the development of sceliosis, meantime, to compare the differences of Melatonin level in blood serum. DESIGN, TIME AND SETTING： A randomized controlled experiment was performed at the Experimental Animal Center of the Second Military Medical University from March 2004 to August 2006. MATERIALS： A total of 60 Shaoxing chickens were divided into 2, 4, 11, or 18 days pinealectomy groups, with 12 animals in each group. A control group and a sham operation group were set. METHODS： Animals in the pinealectomy groups was performed pinealectomy at 2, 4, 11, or 18 days after hatching. The pineal body in the sham operation group was exposed without ablation. There was no treatment in the control group. MAIN OUTCOME MEASURES： Ventrodosals radiogragms of the spine were obtained at per month. At the third month, the serum melatonin concentration was measured by ELASA method. RESULTS： At the third month, the incidence rates of scoliosis in 2, 4, 11, or 18 days pinealectomy groups were 66.7%, 66.7%, 63.6% and 66.7%, and the Cobb angles averaged 32.6°, 29.8°, 23.8° and 22.3°, respectively. There were no significant differences in the incidence rates of scoliosis and the type of curvature among the pinealectomy groups. The serum melatonin levels at the middle of the dark cycle in the pinealectomized chickens were significantly lower than those of the chickens in the control and sham operation groups （P 〈 0.01）. However, there were no differences in the serum melatonin levels between scoliotic and nonscoliotic pinealectomized chickens. CONCLUSION： The incidence rates of scoliosis after pinealectomized within 18 days after hatching is 63.6 %-66.7 %, which is not influenced by the age of performed pinealectomy. The serum melatonin level of pinealectomized chicken is lower than the normal. However, it has no difference between scoliotic and nonscoliotic pinealectomized chickens.