Yang H, Alnaqeeb M, Simpson H, Goldspink G
Department of Anatomy and Developmental Biology, Royal Free Hospital School of Medicine, London, UK.
J Anat. 1997 May;190 ( Pt 4)(Pt 4):613-22. doi: 10.1046/j.1469-7580.1997.19040613.x.
The relationship between IGF-1 and changes in muscle fibre phenotype in response to 6 d of stretch or disuse of the lower limb muscles of the rabbit was studied by combining in situ hybridisation and immunohistochemistry procedures. Passive stretch by plaster cast immobilisation of the muscle in its lengthened position not only induced an increase in IGF-I mRNA expression within the individual muscle fibres but also an increase in the percentage of fibres expressing neonatal and slow myosin. This change in phenotype was also found to be accompanied by a rapid and marked increase of muscle mass, total RNA content as well as IGF-I gene expression. In contrast, IGF-I appears not to be involved in muscle atrophy induced by immobilisation in the shortened position and the inactivity which results from this procedure. The level of increase in expression of IGF-I mRNA varied from fibre to fibre. By using adjacent serial sections, the fibres which expressed IGF-I mRNA at the highest levels were identified as expressing neonatal and the slow type 1 myosin. These data suggest that the expression of IGF-I within individual muscle fibres is correlated not only with hypertrophy but also with the muscle phenotypic adaptation that results from stretch and overload.
通过结合原位杂交和免疫组织化学方法,研究了兔下肢肌肉6天拉伸或废用后胰岛素样生长因子-1(IGF-1)与肌纤维表型变化之间的关系。通过石膏固定将肌肉被动拉伸至延长位置,不仅会导致单个肌纤维内IGF-I mRNA表达增加,还会使表达新生型和慢肌球蛋白的纤维百分比增加。还发现这种表型变化伴随着肌肉质量、总RNA含量以及IGF-I基因表达的快速显著增加。相比之下,IGF-I似乎不参与因固定在缩短位置及由此导致的不活动所引起的肌肉萎缩。IGF-I mRNA表达的增加水平因纤维而异。通过使用相邻连续切片,将表达IGF-I mRNA水平最高的纤维鉴定为表达新生型和慢1型肌球蛋白。这些数据表明,单个肌纤维内IGF-I的表达不仅与肥大相关,还与拉伸和超负荷导致的肌肉表型适应相关。