Excitatory effects of human immunodeficiency virus 1 Tat on cultured rat cerebral cortical neurons
Excitatory effects of human immunodeficiency virus 1 Tat on cultured rat cerebral cortical neurons
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DOI：
10.1016/j.neuroscience.2007.11.031
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发表时间：
2008-02-06
期刊：
影响因子：
3.3
通讯作者：
Dun, N. J.
中科院分区：
文献类型：
--
作者：
Brailoiu, G. C.;Brailoiu, E.;Dun, N. J.
人类免疫缺陷病毒1型(HIV-1)Tat蛋白是参与HIV-1相关性神经元疾病发病机制的神经毒素之一。采用电生理和光学成像相结合的方法，研究HIV-1Tat30-86是否直接或间接地通过谷氨酸的释放起作用，或两者兼而有之，并检测其对培养的大脑皮层神经元自发量子事件特性的影响。全细胞膜片记录由培养的大鼠皮质神经元在电流或电压钳模式下进行。Tat30-86(50-1000 nM)可引起皮层神经元长时间的去极化，并伴随膜电阻的降低，并持续在含有河豚毒素的Krebs液中。谷氨酸受体拮抗剂6-氰基-7-硝基-2，3-二酮(CNQX)(10 mU/M)和D-2-氨基-5-磷酸-5-磷酸(AP-5)(50 mU/M)可使去极化轻微减弱，在无钙Krebs液中显著降低，差异有统计学意义。Tat30-86诱发的内向电流在-30 mV至0 mV之间具有反转电位。较低浓度的Tat30-86(10 NM)虽然没有引起明显的去极化，但增加了膜的兴奋性，表现为对阶跃去极化脉冲反应的神经元放电数量增加。Tat30-86(10 NM)可增加自发微小兴奋性突触后电流(MEPSCs)的频率，但对其幅度无明显影响。Tat30-86(10 NM)可适度增加自发性微小抑制性突触后电流(MIPSCs)的频率和幅度。比值钙成像研究表明，Tat30-86产生三种类型的钙反应：1)快速和短暂的升高，2)钙振荡，3)快速升高后平台期；谷氨酸受体拮抗剂消除了钙反应的晚期成分。结果提示，Tat30-86是一种活性片段，它通过从邻近神经元释放谷氨酸，直接或间接地兴奋皮层神经元。(C)2007年IBRO。爱思唯尔有限公司出版。保留所有权利。
Human immunodeficiency virus 1 (HIV-1) Tat protein is one of the neurotoxins involved in the pathogenesis of HIV-1 -associated neuronal disorders. Combined electrophysiological and optical imaging experiments were undertaken to investigate whether HIV-1 Tat30-86, herein referred to as Tat30-86, acted directly or indirectly via the release of glutamate or both and to test its effect on the properties of spontaneous quantal events in cultured cortical neurons. Whole-cell patch recordings were made from cultured rat cortical neurons in either current- or voltage-clamp mode. Tat30-86 (50-1000 nM) induced in a population of cortical neurons a long-lasting depolarization, which was accompanied by a decrease of membrane resistance and persisted in a Krebs solution containing tetrodotoxin (TTX, 0.5 mu M). Depolarizations were slightly reduced by pretreatment with glutamate receptor antagonists 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) (10 mu M) and D-2-amino-5-phosphonovaleric acid (AP-5) (50 mu M), and were markedly reduced in a Ca2+-free Krebs solution; the differences were statistically significant. Tat30-86-induced inward currents had a reversal potential between -30 and 0 mV. While not causing a noticeable depolarization, lower concentrations of Tat30-86 (10 nM) increased membrane excitability, as indicated by increased numbers of neuronal discharge in response to a step depolarizing pulse. Tat30-86 (10 nM) increased the frequency of spontaneous miniature excitatory postsynaptic currents (mEPSCs), while not significantly affecting their amplitude. Tat30-86 (10 nM) moderately increased the frequency as well as the amplitude of spontaneous miniature inhibitory postsynaptic currents (mIPSCs). Ratiometric Ca2+ imaging studies showed that Tat30-86 produced three types of Ca2+ responses: 1) a fast and transitory increase, 2) Ca2+ oscillations, and 3) a fast increase followed by a plateau; the glutamate receptor antagonists eliminated the late component of Ca2+ response. The result suggests that Tat30-86 is an active fragment and that it excites cortical neurons directly and indirectly via releasing glutamate from adjacent neurons. (c) 2007 IBRO. Published by Elsevier Ltd. All rights reserved.