Influence of varying degrees of malnutrition on IGF-I expression in the rat diaphragm.
Influence of varying degrees of malnutrition on IGF-I expression in the rat diaphragm.
复制标题
不同程度的营养不良对大鼠膈肌IGF-I表达的影响。
DOI：
10.1152/japplphysiol.00916.2002
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
Fournier,Mario
中科院分区：
文献类型：
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作者：
Lewis,MichaelI;Li,Hongyan;Huang,Zhi-Shen;Biring,ManmohanS;Cercek,Bojan;Fournier,Mario
本研究评估了不同程度的长期营养不良对肋膈肌局部胰岛素样生长因子- i （IGF-I）系统的影响。在3周内，给成年大鼠提供正常食物摄入量的60%或40%。将营养剥夺（ND）动物（即ND60和ND40）与自由喂养的对照（Ctl）大鼠进行比较。用组织化学方法测定肋膈纤维类型和横截面积。采用RT-PCR检测肋膈肌IGF-I mRNA水平。采用大鼠特异性放射免疫法测定血清和肌肉igf - 1肽水平。Ctl大鼠体重增加5%，ND60和ND40大鼠体重分别减少16%和26%。与Ctl相比，ND60和ND40动物的膈肌重量分别减少了17%和27%。膈纤维比例不受ND方案的影响。ND60组IIa型和IIx型纤维均出现明显萎缩，ND40组膈肌3种纤维均出现萎缩。与Ctl相比，ND60和ND40大鼠血清IGF-I水平分别降低了62%和79%。ND组膈肌IGF-I mRNA水平与Ctl相似。与Ctl相比，ND60和ND40组膈肌IGF-I浓度分别降低了36%和42%。我们得出结论，局部（自分泌/旁分泌）肌肉igf - 1系统在我们的长时间ND模型中受到影响。我们认为这导致肌肉蛋白质周转紊乱和肌肉恶病质与肌肉纤维萎缩。鉴于最近的数据表明自分泌/旁分泌系统在肌肉生长和维持纤维大小中的重要性，这一点尤其如此。
This study evaluated the impact of varying degrees of prolonged malnutrition on the local insulin-like growth factor-I (IGF-I) system in the costal diaphragm muscle. Adult rats were provided with either 60 or 40% of usual food intake over 3 wk. Nutritionally deprived (ND) animals (i.e., ND60 and ND40) were compared with control (Ctl) rats fed ad libitum. Costal diaphragm fiber types and cross-sectional areas were determined histochemically. Costal diaphragm muscle IGF-I mRNA levels were determined by RT-PCR. Serum and muscle IGF-I peptide levels were determined by using a rat-specific radioimmunoassay. The body weights of Ctl rats increased by 5%, whereas those of ND60 and ND40 animals decreased by 16 and 26%, respectively. Diaphragm weights were reduced by 17 and 27% in ND60 and ND40 animals, respectively, compared with Ctl. Diaphragm fiber proportions were unaffected by either ND regimen. Significant atrophy of both type IIa and IIx fibers was noted in the ND60 group, whereas atrophy of all three fiber types was observed in the diaphragm of ND40 rats. Serum IGF-I levels were reduced by 62 and 79% in ND60 and ND40 rats, respectively, compared with Ctl. Diaphragm muscle IGF-I mRNA levels in both ND groups were similar to those noted in Ctl. In contrast, IGF-I concentrations were reduced by 36 and 42% in the diaphragm muscle of ND60 and ND40 groups, respectively, compared with Ctl. We conclude that the local (autocrine/paracrine) muscle IGF-I system is affected in our models of prolonged ND. We propose that this contributes to disordered muscle protein turnover and muscle cachexia with atrophy of muscle fibers. This is particularly so in view of recent data demonstrating the importance of the autocrine/paracrine system in muscle growth and maintenance of fiber size.