Development of active fibroblast growth factor and its CNS action

在食物摄入或葡萄糖注射后，酸性和碱性成纤维细胞生长因子（EGF）在脑脊液中均升高，这通过使用Hydra的高灵敏度生物测定法和生长因子的标准测定法检测，BALB/c 3 T3细胞的DNA合成刺激活性（Hanai等人，1987，1989; Hanai 1989）。用抗aFGF抗体免疫细胞化学法显示，腹腔注射葡萄糖后aFGF在脑内的分布发生了显著变化。将抗aFGF抗体应用于下丘脑外侧区显著增加大鼠前3小时的食物摄入。这些结果表明aFGF是负责调节脑中食物摄入的内源性物质之一（Oomura等人，1989年）。在体内实验中，FGF明显抑制清醒和再清醒大鼠下丘脑外侧区化学敏感神经元的活动。为了观察FGF对下丘脑外侧区神经元的直接作用，我们对酶处理后急性分离的下丘脑外侧区神经元进行了连续的研究。在电压钳条件下，采用膜片钳技术，以全细胞模式进行电记录。FGF对Na、K、Ca等电压依赖性离子通道以及兴奋性氨基酸门控通道无影响。GABA反应显示通过降低细胞内ATP浓度而下降。在FGF存在下使用的50%的细胞中，细胞内ATP敏感的GABA反应受到保护。还研究了下丘脑神经元、浦肯野细胞、海马CA 1神经元、杏仁体神经元和孤束核神经元的电学和药理学特性（Akaike et al.，1989; Tokutomi等人，1989; Shirasakiet al.，1990年）。

Both acidic and basic fibroblast growth factors(EGF) are elevated in the cerebrospinal fluid after food intake or glucose injection, that was detected both by a highly sensitive bioassay with Hydra and by a standard assay for growth factors, DNA synthesis-stimulating activity for BALB/c 3T3 cells (Hanai et al., 1987, 1989; Hanai 1989). The distribution of aFGF in the brain was dramatically changed with i.p. glucose injection, which was revealed by immunocytochemistry with anti-aFGF antibody. Application of the anti-aFGF antibody into the lateral hypothalamic area significantly increased the food intake first 3 h in rats. These results show that aFGF is one of the endogenous substances responsible for the regulation of food intake in the brain (Oomura et al., 1989). In in vivo experiments, FGF clearly suppressed the chemo-sensitive neuronal activities in the lateral hypothalamus of the conscious and reconscious rats. In order to see how FGF acts directly on the lateral hypothalamic neurons, the successive studies were made on the neurons acutely isolated from the lateral hypothalamus after the enzyme treatment. The electrical recordings were made in whole-cell mode by patch-clamp technique under the voltage-clamp condition. FGF had no effects on voltage-dependent ionic channels such as Na, K and Ca, and also on excitatory amino acids-gated channels. The GABA response shows run-down by decreasing intracellular ATP concentration. The intracellular ATP-sensitive GABA response was protected in 50% cells used in the presence of FGF. The electrical,and phartpacological properties of hypothalamic neurons, Purkinje cells, hippocampal CA1 neurons, amyglaloid neurons, and nucleus tractus solitarii neurons were also investigated (Akaike et al., 1989; Tokutomi et al., 1989; Shirasakiet al., 1990).