Development of active fibroblast growth factor and its CNS action

摄入食物或注射葡萄糖后，脑脊液中的酸性和碱性成纤维细胞生长因子（EGF）均升高，这可以通过高灵敏度的Hydra生物测定法和生长因子标准测定法检测，即对BALB/c 3T3细胞的DNA合成刺激活性（Hanai等，1987,1989;Hanai 1989）。免疫细胞化学结果显示，ig葡萄糖可显著改变aFGF在脑内的分布。在下丘脑外侧区应用抗afgf抗体可显著增加大鼠前3小时的进食量。这些结果表明，aFGF是大脑中负责调节食物摄入的内源性物质之一（Oomura et al., 1989）。在体内实验中，FGF明显抑制了有意识和再意识大鼠下丘脑外侧的化学敏感神经元活动。为了观察FGF如何直接作用于下丘脑外侧神经元，我们对酶处理后急性分离的下丘脑外侧神经元进行了连续的研究。在电压箝位条件下，采用膜片钳技术在全细胞模式下进行电记录。FGF对Na、K、Ca等电压依赖性离子通道和兴奋性氨基酸门控通道均无影响。由于细胞内ATP浓度的降低，GABA反应逐渐减弱。在FGF存在的情况下，50%的细胞内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CA1神经元、淀粉样神经元和孤束核神经元的电学和药理学特性（Akaike et al., 1989; Tokutomi et al., 1989; Shirasakiet al., 1990）。

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).