膳食缺鐵與補鐵影響大鼠肝臟和肌肉IRPs與Aconitase活性

Dietary Iron Depletion and Repletion on the IRPs and Aconitase Activity in the Liver and Muscles of Rats

黃惠玲(Huei-Ling Huang) ； 康碩芬(Shuo-Fen Kang) ； 蕭寧馨(Ning-Sing Shaw)

《中華民國營養學會雜誌》 25卷1期 (2000/03) Pp. 47-61

https://doi.org/10.6691/JCNS.200003_25(1).0006

摘要

已知膳食缺鐵快速增加大鼠肝臟的IRPs（iron regulatory proteins）自發活性（spontaneous activity），同時經由對IRE（iron responsive element）的結合而減少鐵蛋白（ferritin）與粒線體aconitase（m-ACO）活性，但是鐵補充對其影響的分子機制則尚無資料，加以肌肉鐵利用調節受膳食鐵營養影響的分子機制亦所知有限，故以大鼠缺鐵－補鐵實驗探討肝臟與肌肉中IRPs、鐵蛋白、粒線體與細胞質aconitase活性等隨時間之變，並做兩組織間的比較。離乳Wistar雄鼠30隻，任取5隻為正常控制組，，飼以AIN-76飼料，其餘25隻先飼以缺鐵AIN-76飼料17天使缺鐵貧血後，隨機取5隻與控制組5隻同時犧牲。其餘大鼠隨機分為兩組，其中一組改飼以鐵正常飼料而為補鐵組，於補鐵第2與9天各組取5隻大鼠犧牲。犧牲時收集血液與血清，取出肝臟和後肢肌肉，分離其細胞質與粒線體以供分析。結果可見，缺鐵時肝臟與肌肉中IRP1與IRP2自發活性顯著高於正（1.47~1.9倍），補充鐵對肝臟與肌肉兩型IRP1與IRP2有選別性的影響（differential regulation）；缺鐵時肝臟和肌肉m-ACO活性有下降的趨勢（60%~72%），補充鐵則有明顯的增高；缺鐵使肝臟細胞質c-ACO增加，卻使肌肉c-ACO減少，可能反映肌肉鐵硫蛋白之生合成有所變化。

關鍵字

肝臟 ； 肌肉 ； 鐵營養 ； 大鼠

並列摘要

It is known that hepatic IRP spontaneous activity increases rapidly and ferritin and mitochondrial aconitase concentration decrease differentially in iron deficient rats. Since there is limited information concerning the molecular response of the liver and muscles to iron repletion in vivo, this study was designed to compare the time-course IRPs, mitochondrial and cytosolic aconitases response in the liver and muscles to iron depletion and repletion using a rat model. Among thirty weanling male Wistar rats, five were assigned as control group feeding on an AIN-76 diet, and the rest were rendered anemic by feeding an iron-free AIN-76 diet for 17 days. Then the 5 control rats and 5 anemic rats were killed for analysis. The remaining 20 anemic rats were randomly assigned into two groups: a depletion group continuing on the iron-free diet, and a repletion diet switching to the normal AIN-76 diet. Five rats from each group were killed at the second and the ninth days after iron repletion, and blood , liver and muscle from hind limb were collected. Cytosol and mitochondria were fractionated and used for analysis. Iron depletion resulted in increased spontaneous activity of IRP1 and IRP2 (1.47 to 1.9 times of the control) and reduced specific activity of mitochondrial aconitase (60% to 72% of the control) from both liver and muscle. IRP1 and IRP2 activities were differentially affected by iron repletion, and liver and muscle had different patterns of time-course response. Activity of mitochondrial aconitase increased during iron repletion in both liver and muscle. During iron depletion, the activity of cytosolic aconitase increased in liver, while it decreased in muscle, which implied impaired assembly of iron-sulfur proteins due to lactic acidosis in the muscle.

並列關鍵字

IRPs ； aconitase ； liver ； muscle ； dietary iron ； rats