大鼠脑区贮存铁分布与长期运动的影响

Influence of long-term exercise on iron distribution in the brain region of rats

目的:铁在脑内的分布具有区域特点,脑铁稳态在脑正常功能活动包括不同发育时期的脑功能中发挥重要作用。观察长期游泳运动对大鼠脑内铁分布的影响。方法:实验于2005-10/2006-06在江苏大学医学院铁代谢研究室完成。①实验分组:选取清洁级Sprague-Dawley雌性大鼠20只,3月龄,体质量180～200g,随机数字表法分为游泳运动组和静息对照组,每组10只。②实验方法:游泳运动组大鼠游泳5d/周,120min/d。静息对照组除运动外,其余处理同游泳运动组。3个月运动期满后,于最后一次运动后,大鼠被禁食24h,肝素化后乙醚麻醉处死。③实验评估:取血用于测定血红蛋白、红细胞压积、血浆铁、血浆总铁结合力,并迅速分离各脑区贮存在-70℃冰箱中用于随后的非血红素铁测定。采用氰化钾法测定血红蛋白浓度。毛细管离心法测量红细胞压积。试剂盒及原子吸收分光光度法测量血浆铁和血浆总铁结合力。采用原子吸收分光光度法测定各脑区组织非血红素铁含量。结果:20只大鼠全部进入结果分析,无脱失。①游泳运动组大鼠的血红蛋白值、血浆铁浓度和血浆转铁蛋白铁饱和度均低于静息对照组(P<0.05,P<0.01),呈现明显的血液学低铁状态;而红细胞压积和总铁结合力水平两组间无显著差异(P>0.05)。②游泳运动组大鼠海马和延髓中非血红素铁水平高于静息对照组(P<0.01,P<0.05),而下丘脑中非血红素铁水平低于静息对照组(P<0.01),其余各脑区非血红素铁水平与静息对照组无明显差异(P>0.05)。结论:长期游泳运动可诱导大鼠的血液学低铁状态,改变脑区铁贮存水平,导致不同脑区之间铁贮存的重分布。这种重分布机制及其在运动生理学中的意义有待于进一步研究。

AIM： Iron distribution in brain shows region characters. Iron steady state in brain plays an important role in brain normal functional activities during different development stages. This study observed the effects of long-term swimming on iron distribution in the brain region of rats.METHODS： The experiment was performed at the Iron Metabolism Laboratory of School of Medicine, Jiangsu University between October 2005 and June 2006. （1）Twenty 3-month-old female Sprague-Dawley rats of clean grade and 180- 200 g were selected and randomly assigned to exercise group and resting control group （n =10）. （2）Rats in the exercise group swam 120 minutes daily, 5 days a week, and the rats in the control group were given the same treatment except exercise. Animals were fasted for 24 hours after the last exercise regimen and then heparinized and executed after anesthetized with ether. ^（3）Fasting blood samples were collected for the determination of hemoglobin （Hb）, hematocrit （Hct）, plasma iron concentration （PI） and total iron-binding capacity （TIBC）. The different regions of brain of rats were removed immediately, and stored in a freezing chamber at -70 ℃ for subsequent determination of nonheme iron （NHI） contents. Hb concentration was determined by cyanmethemoglobin method; Hct was measured using microhematocrit centrifuge; PI and TIBC using commercial kits and atomic absorption spectrophotometry; NHI concentrations using atomic absorption spectrophotometry. RESULTS： All the 20 rats were involved in the results analysis without drop out.（1）Compared with control group, the exercise group had a significantly lower Hb concentration, PI concentration, and plasma transferrin saturation （P 〈 0.05, P 〈 0.01）, indicating a lower hematological iron status. But no obvious difference was found in Hct and TIBC （P 〉 0.05）. （2）The NHI levels in the hippocampus and medulla oblongata in exercise group were significantly higher than control group （P〈 0.01, P〈 0.05）, but lower NHI levels were found in the hypothalamus compared with control group （P〈 0.01）. There was no significant change in the other regions of the brain of rats （P〉 0.05）. CONCLUSION： Long-term swimming may induce a lower hematological iron status in rats and alter iron storage levels, finally leading the redistribution of storage iron among different regions of the brain. The mechanisms and physiological significance of such redistribution remain further investigation.