Lipton S A, Wagner J A, Madison R D, D'Amore P A
Division of Neuroscience, Children's Hospital, Boston, MA 02115.
Proc Natl Acad Sci U S A. 1988 Apr;85(7):2388-92. doi: 10.1073/pnas.85.7.2388.
Postnatal rat retinal ganglion cells (RGCs) were identified with specific fluorescent labels and placed in culture. Under these conditions, the outgrowth of processes by RGCs was found to be promoted to a far greater degree by acidic fibroblast growth factor (aFGF) than by basic fibroblast growth factor (bFGF). The effect of aFGF and bFGF on process extension by solitary RGCs was quantified after 24 hr in culture, a time when neither a FGF nor bFGF enhanced RGC survival. The action of aFGF on process outgrowth was markedly potentiated by the addition of heparin (10 micrograms/ml) to the medium, but heparin alone had no effect. In the presence of heparin, half-maximal process outgrowth occurred at an aFGF concentration of less than 20 pg/ml (1 pM). Since all of the centrally projecting processes have already been formed in the living animal prior to use (at 7-12 days of age), at least a portion of the process outgrowth in culture appears to represent a regenerative phenomenon. Statistical analysis of the increase in process growth revealed that aFGF with heparin contributed to both neurite initiation and elongation. The mean number of glial cells, identified with polyclonal antiserum against glial fibrillary acidic protein, was slightly increased in cultures receiving aFGF plus heparin, but this effect was variable, and these glial cells were not in contact with the solitary RGCs that were scored for regeneration of processes. Thus, glial cells probably did not exert a direct physical influence on the degree of process outgrowth observed in the solitary RGCs, although a humoral effect cannot be totally excluded. These results suggest that aFGF has a potent influence on the outgrowth of processes by a neuron in the mammalian central nervous system. The potentiation of this effect by heparin leads us to speculate that the interaction of aFGF with a heparin-like molecule located in the extracellular matrix (such as heparan sulfate proteoglycan) may produce physiological effects in vivo. Furthermore, the lack of a substantial effect of bFGF in this system under these conditions shows that a specific population of mammalian central neurons may be differentially influenced by these two closely related peptide growth factors.
产后大鼠视网膜神经节细胞（RGCs）用特定荧光标记物进行鉴定并培养。在这些条件下，发现酸性成纤维细胞生长因子（aFGF）比碱性成纤维细胞生长因子（bFGF）更能显著促进RGCs突起的生长。培养24小时后对aFGF和bFGF对单个RGCs突起延伸的影响进行了量化，此时aFGF和bFGF均未提高RGCs的存活率。向培养基中添加肝素（10微克/毫升）可显著增强aFGF对突起生长的作用，但肝素单独作用则无效果。在有肝素存在的情况下，当aFGF浓度低于20皮克/毫升（1皮摩尔）时，突起生长达到最大值的一半。由于所有向中枢投射的突起在使用前（7 - 12日龄）的活体动物中就已形成，因此培养中至少一部分突起生长似乎代表一种再生现象。对突起生长增加的统计分析表明，aFGF与肝素共同作用于神经突的起始和延伸。用抗胶质纤维酸性蛋白的多克隆抗血清鉴定的胶质细胞平均数量，在接受aFGF加肝素的培养物中略有增加，但这种作用是可变的，且这些胶质细胞并未与被计分突起再生的单个RGCs接触。因此，胶质细胞可能并未对单个RGCs中观察到的突起生长程度产生直接的物理影响，尽管体液效应不能完全排除。这些结果表明，aFGF对哺乳动物中枢神经系统中神经元突起的生长有强大影响。肝素对这种作用的增强使我们推测，aFGF与位于细胞外基质中的肝素样分子（如硫酸乙酰肝素蛋白聚糖）的相互作用可能在体内产生生理效应。此外，在这些条件下bFGF在该系统中缺乏显著作用，表明这两种密切相关的肽生长因子可能对特定群体的哺乳动物中枢神经元产生不同影响。
