Junttila T, Rechardt L, Cao Y, Hökfelt T, Pelto-Huikko M
Department of Anatomy, University of Tampere, Finland.
Brain Res. 1996 Jan 22;707(1):81-7. doi: 10.1016/0006-8993(95)01227-3.
Acidic fibroblast growth factor (aFGF) is a mitogenic, angiogenic and neurotrophic growth factor which promotes proliferation, but delays differentiation of cultured myoblasts. Its mRNA is expressed in the skeletal muscle, however, the distribution of aFGF in the postnatal skeletal muscle is poorly characterized. In the present study, the distribution of aFGF-like immunoreactivity (LI) was examined in developing and adult rat skeletal muscle fibers. In addition, the effect of the transection of the sciatic nerve on aFGF-LI in calf muscle fibers was examined. From the first postnatal day on, aFGF-immunoreactive (IR) muscle fibers were observed in different calf muscles. From the 7th postnatal day on a large number of muscle fibers exhibited aFGF-LI in the soleus muscle, some in plantaris and only few in gastrocnemius and extraocular muscles. Double-labelling with fast-myosin antibody showed that aFGF-LI was restricted to the slow oxidative muscle fibers. aFGF-IR intrafusal muscle fibers were seen in developing and mature muscle spindles. In addition, aFGF-IR nerve fibers and myoneural junctions were observed in different muscles. Transection of the sciatic nerve did not noticeably alter the expression pattern of aFGF-LI in calf muscles during two-week period. The present study demonstrates aFGF-LI in the rat slow oxidative muscle fibers where it may have fiber-type specific functions in addition to its known trophic effects.
酸性成纤维细胞生长因子（aFGF）是一种促有丝分裂、促血管生成和神经营养性生长因子，可促进增殖，但会延迟培养的成肌细胞的分化。其mRNA在骨骼肌中表达，然而，出生后骨骼肌中aFGF的分布特征尚不明确。在本研究中，我们检测了发育中和成年大鼠骨骼肌纤维中aFGF样免疫反应性（LI）的分布。此外，还检测了坐骨神经横断对小腿肌肉纤维中aFGF-LI的影响。从出生后的第一天开始，就在不同的小腿肌肉中观察到了aFGF免疫反应性（IR）肌肉纤维。从出生后第7天开始，比目鱼肌中有大量肌肉纤维呈现aFGF-LI，跖肌中有一些，而腓肠肌和眼外肌中只有少数。与快肌球蛋白抗体的双重标记显示，aFGF-LI仅限于慢氧化型肌肉纤维。在发育中和成熟的肌梭中都可见到aFGF-IR梭内肌纤维。此外，在不同肌肉中还观察到了aFGF-IR神经纤维和肌神经接头。坐骨神经横断在两周内并未明显改变小腿肌肉中aFGF-LI的表达模式。本研究证明了大鼠慢氧化型肌肉纤维中存在aFGF-LI，除了其已知的营养作用外，它可能还具有纤维类型特异性功能。
