不同强度跑台运动对注射谷氨酸单钠大鼠弓状核β-内啡肽神经元及血清相关激素的影响

目的:观察不同强度跑台运动对注射谷氨酸单钠(monosodium L-glutamate,MSG)导致骨质疏松大鼠骨组织及其下丘脑弓状核(arcuate nucleus,ARC)神经元和β-内啡肽(beta-endorphin,β-EP)免疫反应神经元及血清相关激素的影响。方法:将32只新生SD大鼠随机分为4组:生理盐水对照组(A)、谷氨酸单钠安静组(B)、谷氨酸单钠+中等强度运动组(C)、谷氨酸单钠+大强度运动组(D),每组8只。各组相应于皮下注射谷氨酸单钠和等体积生理盐水。10周后运动组大鼠分别进行10周大、中强度跑台运动。10周后处死取材,采用半自动图像数字化仪检测大鼠胫骨上段骨组织骨小梁面积百分数、宽度以及骨小梁数量和分离度;采用免疫组织化学方法计数下丘脑弓状核神经元和β-EP免疫反应神经元;采用放射免疫方法检测血清生长素、降钙素、骨钙素水平。结果:与A组比较,B组大鼠骨小梁面积百分数、骨小梁宽度和骨小梁数量明显减少,分离度明显增大(P<0.05)。与B组及D组大鼠比较,C组骨小梁面积百分数、骨小梁宽度和骨小梁数量明显增大,骨小梁分离度明显减少(P<0.05);下丘脑弓状核神经元和β-EP免疫反应阳性神经元数量明显增多(P<0.05);血清生长素、降钙素及骨钙素含量明显升高(P<0.05)。结论:中等强度运动能有效延缓骨量丢失,可能与下丘脑弓状核神经元及β-EP免疫反应阳性神经元数量增多,生长素等钙调激素水平升高有关。

Effect of Treadmill Exercise with Different Intensities on the Beta-endorphin Neurons in Arcuate Nucleus and the Levels of Related Hormones in Rats Injected with Monosodium L-glutamate

Objective The purpose of this study is to investigate the effect of treadmill exercise with different intensities on the bone tissue and neurons in arcuate nucleus and the beta-endorphin,level of growth hormone,bone gla-protein,and calcitonin in serum of osteoporotic rats. Methods Thirty two neonatal SD rats were divided into 4 groups randomly:(1)group A:injected with saline;(2)group B:injected with monosodium L-glutamate without exercise;(3)group C:injected with monosodium L-glutamate and performed moderate intensity exercise;(4)group D:injected with monosodium L-glutamate and performed high intensity exercise. Ten weeks later,the rats in groups C and D underwent moderate and high intensity treadmill exercises,respectively for ten weeks. All rats were killed after the completion of experiment. Proximal tibial trabecular area percentage,trabecular thickness,trabecular number and the trabecular separation were investigated by semi-automatic image assessment. Immunohistochemistry was used to observe the changes in neurons of arcuate nucleus and β-endorphin immunoreactive neurons of arcuate nucleus. Radioimmunoassay was performed to detect the serum levels of growth hormone,bone gla-protein and calcitonin. Results Trabecular area percentage,trabecular thickness,trabecular number were significantly lower,while trabecular separation significantly higher in group B than that in group A (P <0.05). Trabecular area percentage,trabecular thickness, trabecular number were significantly higher,while trabecular separation significantly lower in group C than that in groups B and D(P <0.05). The number of neurons in arcuate nucleus and β-endorphin immunoreactive positive neurons in arcuate nucleus were higher in group C than that in groups B and D(P <0.05). Growth hormone,bone gla-protein and calcitonin were significantly higher in group C than that in groups B and D (P <0.05). Conclusion Moderate intensity exercise could effectively delay the loss of bone mass possibly due to the higher number of neurons in arcu ate nucleus and β-endorphin immunoreactive positive neurons and the higher levels of growth hormone bone gla-pro-tein and calcitonin.