Takei N, Sasaoka K, Inoue K, Takahashi M, Endo Y, Hatanaka H
Department of Applied Biology, Kyoto Institute of Technology, Japan.
J Neurochem. 1997 Jan;68(1):370-5. doi: 10.1046/j.1471-4159.1997.68010370.x.
Differentiation and survival of neurons induced by neurotrophins have been widely investigated, but little has been reported about the long-term effect of brain-derived neurotrophic factor (BDNF) on synaptic transmission. Among many steps of neurotransmission, one important step is regulated release of transmitters. Therefore, the release of glutamate and GABA from cortical neurons cultured for several days with or without BDNF was measured by an HPLC-fluorescence method. Although BDNF had little effect on the basal release of glutamate, high K(+)-evoked release was greatly increased by BDNF. BDNF also tended to increase evoked release of GABA. Recently, several proteins involved in the step of "regulated release" have been identified. Thus, the effect of BDNF on the levels of these proteins was then investigated. Neurons were cultivated with or without BDNF, collected, and electrophoresed for western blotting. BDNF increased levels of synaptotagmin, synaptobrevin, synaptophysin, and rab3A, which were known as vesicle protein. Levels of syntaxin, SNAP-25, and beta-SNAP were also increased by BDNF. In addition, the numbers of cored and clear vesicles in nerve terminals or varicosities were also increased by BDNF. These results raise the possibility that BDNF increases regulated release of neurotransmitters through the up-regulation of secretory mechanisms.
神经营养因子诱导的神经元分化和存活已得到广泛研究，但关于脑源性神经营养因子（BDNF）对突触传递的长期影响却鲜有报道。在神经传递的众多步骤中，一个重要步骤是递质的调节性释放。因此，采用高效液相色谱-荧光法测定了在有无BDNF的情况下培养数天的皮质神经元中谷氨酸和γ-氨基丁酸的释放。尽管BDNF对谷氨酸的基础释放影响不大，但BDNF可显著增加高钾诱发的谷氨酸释放。BDNF也倾向于增加γ-氨基丁酸的诱发释放。最近，已鉴定出几种参与“调节性释放”步骤的蛋白质。因此，随后研究了BDNF对这些蛋白质水平的影响。将神经元在有无BDNF的情况下培养，收集后进行电泳用于蛋白质印迹分析。BDNF增加了已知为囊泡蛋白的突触结合蛋白、突触小泡蛋白、突触素和rab3A的水平。BDNF还增加了 syntaxin、SNAP-25和β-SNAP的水平。此外，BDNF还增加了神经末梢或膨体中芯泡和清亮小泡的数量。这些结果提示BDNF可能通过上调分泌机制来增加神经递质的调节性释放。
