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脑源性神经营养因子通过一种突触后发动蛋白介导的机制,使下丘脑神经内分泌细胞上的GABA突触沉默。

Brain-derived neurotrophic factor silences GABA synapses onto hypothalamic neuroendocrine cells through a postsynaptic dynamin-mediated mechanism.

作者信息

Hewitt Sarah A, Bains Jaideep S

机构信息

Hotchkiss Brain Institute and Department of Physiology and Biophysics, University of Calgary, Calgary, Canada T2N 4N1.

出版信息

J Neurophysiol. 2006 Apr;95(4):2193-8. doi: 10.1152/jn.01135.2005. Epub 2006 Jan 11.

Abstract

In the paraventricular nucleus of the hypothalamus (PVN), experimental stress paradigms that suppress gamma-aminobutyric acid (GABA) inputs to parvocellular neuroendocrine cells (PNCs) also increase the expression of brain-derived neurotrophic factor (BDNF). In the adult CNS, BDNF regulates the efficacy of GABAergic transmission, but its contributions to functional changes at inhibitory synapses in the PVN have not been investigated. Analysis of quantal transmission revealed a decrease in the frequency of miniature inhibitory postsynaptic currents (mIPSCs) in response to BDNF with no accompanying changes in their amplitude. These effects were completely blocked by prior inclusion of the TrKB receptor antagonist K252a in the patch pipette. Inclusion of a dynamin inhibitory peptide in the patch pipette also blocked the effects of BDNF, consistent with an all-or-none removal of clusters of postsynaptic GABAA receptors. Finally, to confirm a decrease in the availability of postsynaptic GABAA receptors, we tested the effects of BDNF on focal application of the GABAA agonist muscimol. Postsynaptic responses to muscimol were reduced after BDNF. Collectively, these data indicate that BDNF remodels functional synaptic contacts putatively by reducing the surface expression of postsynaptic GABAA receptors.

摘要

在下丘脑室旁核(PVN)中,抑制向小细胞神经内分泌细胞(PNC)输入γ-氨基丁酸(GABA)的实验性应激范式也会增加脑源性神经营养因子(BDNF)的表达。在成体中枢神经系统中,BDNF调节GABA能传递的效能,但其对PVN中抑制性突触功能变化的作用尚未得到研究。量子传递分析显示,BDNF作用下微小抑制性突触后电流(mIPSC)频率降低,但其幅度无伴随变化。在膜片钳电极中预先加入TrKB受体拮抗剂K252a可完全阻断这些效应。在膜片钳电极中加入发动蛋白抑制肽也可阻断BDNF的作用,这与突触后GABAA受体簇的全或无式去除一致。最后,为了证实突触后GABAA受体的可用性降低,我们测试了BDNF对局灶性应用GABAA激动剂蝇蕈醇的影响。BDNF作用后,对蝇蕈醇的突触后反应降低。总体而言,这些数据表明BDNF可能通过降低突触后GABAA受体的表面表达来重塑功能性突触联系。

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