Mechanisms underlying action of neurotrophic factors on postsynaptic glutamate and GABA receptors

神经营养因子对突触后谷氨酸和 GABA 受体作用的机制

基本信息

批准号：
14208094
负责人：
TSUMOTO Tadaharu
金额：
$ 34.86万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

项目摘要

Previously we found that brain-derived neurotrophic factor (BDNF) is released from presynaptic sites in an activity-dependent manner and acts on postsynaptic neurons. In this study we attempted to see whether actions of BDNF are different between glutamatergic excitatory synapses and GABAergic inhibitory synapses, and further to elucidate mechanisms underlying such actions. We obtained the following results.1.Using mixed neuron culture preparations obtained from green fluorescence protein (GFP) mice and BDNF knockout mice, we explored what actions presynaptic BDNF exerts on postsynaptic neurons. We found that presynaptic BDNF promotes dendritic development of postsynaptic GABAergic neurons.2.Actions of exogenous BDNF on GABAergic synapses were investigated in solitary GABAergic neurons cultured on glial microisland to completely exclude possible involvement of excitatory synapses from the observed effects of BDNF. We found that BDNF increased the number of active GABAergic synapses.3.Roles of endogenous BDNF in development of glutamatergic synapses were investigated in barrel cortex of BDNF knockout and wild type mice. We found that silent synapses, which consist only of NMDA receptors, are abnormally increased in BDNF knockout mice, and this is rescued by exogenously applied BDNF.4.Actions of exogenous BDNF on excitatory synapses on GABAergic neurons were not studied previously. We addressed this issue by using GAD67-GFP knock-in mice, in which GABAergic neurons are easily identified. We found that BDNF acutely depressed function of excitatory synapses to GABAergic neurons.

此前我们发现脑源性神经营养因子（BDNF）以活动依赖性方式从突触前位点释放并作用于突触后神经元。在这项研究中，我们试图了解 BDNF 的作用在谷氨酸能兴奋性突触和 GABA 能抑制性突触之间是否不同，并进一步阐明这种作用的机制。我们得到了以下结果： 1.利用绿色荧光蛋白（GFP）小鼠和BDNF敲除小鼠的混合神经元培养物，我们探讨了突触前BDNF对突触后神经元的作用。我们发现突触前BDNF促进突触后GABA能神经元的树突发育。2.在神经胶质微岛培养的孤立GABA能神经元中研究了外源性BDNF对GABA能突触的作用，以完全排除观察到的BDNF作用中兴奋性突触可能参与的可能性。我们发现BDNF增加了活跃GABA能突触的数量。3.在BDNF敲除小鼠和野生型小鼠的桶状皮层中研究了内源性BDNF在谷氨酸能突触发育中的作用。我们发现，仅由 NMDA 受体组成的沉默突触在 BDNF 敲除小鼠中异常增加，而这是通过外源性应用 BDNF 来挽救的。 4. 以前没有研究过外源性 BDNF 对 GABA 能神经元兴奋性突触的作用。我们通过使用 GAD67-GFP 敲入小鼠解决了这个问题，其中 GABA 能神经元很容易识别。我们发现 BDNF 严重抑制 GABA 能神经元的兴奋性突触功能。