Mitochondrial nitric oxide mediates decreased vulnerability of hippocampal neurons from immature animals to NMDA
Mitochondrial nitric oxide mediates decreased vulnerability of hippocampal neurons from immature animals to NMDA
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DOI：
10.1523/jneurosci.1450-05.2005
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发表时间：
2005-07-13
影响因子：
5.3
通讯作者：
Wang, J
中科院分区：
文献类型：
--
作者：
Marks, JD;Boriboun, C;Wang, J
线粒体膜电位 (Delta Psi(m)) 依赖性 Ca2+ 摄取在 NMDA 受体激活后的神经退行性变中起着核心作用。 NMDA 引起的 Delta Psi(m) 耗散在出生后发育过程中增加，与 NMDA 的脆弱性增加相一致。 NMDA 受体激活还会产生一氧化氮 (NO)，它可以抑制线粒体呼吸，耗散 Delta Psi(m)。由于 Delta Psi(m) 耗散会减少线粒体 Ca2+ 的摄取，因此我们假设 NO 介导了 NMDA 诱导的未成熟神经元中的 Delta Psi(m) 耗散，从而降低了神经元对兴奋性毒性的脆弱性。使用从 5 日龄和 19 日龄大鼠培养的海马神经元，我们测量了 NMDA 诱导的 [Ca2+]（细胞质）、Delta Psi（m）、NO 和 [Ca2+]（线粒体）的变化。在出生后第 5 天 (P5) 神经元中，NMDA 以 NO 合酶 (NOS) 依赖性方式轻度消散 Delta Psi(m)，并增加 NO。 NMDA 诱导的 NO 增加被羰基氰化物 4-(三氟甲氧基)苯基腙消除并受 [Ca2+](mito) 调节。抑制线粒体 Ca2+ 摄取可防止 NO 增加，而抑制线粒体 Ca2+ 排出则会增加 NO 增加。与这种线粒体调节一致，NOS 和细胞色素氧化酶免疫反应性证明了 NOS 的线粒体定位。此外，NOS 阻断增加了 NMDA 期间线粒体 Ca2+ 的摄取。最后，在生理 O-2 张力（3% O-2）下，NMDA 对 P5 神经元的存活影响不大，但 NMDA 期间的 NOS 阻断显着恶化存活率，这表明线粒体 NO 具有显着的神经保护作用。在 P19 神经元中，NMDA 以 NO 不敏感的方式消散 Delta Psi(m)。 NMDA 诱导的 NO 产生不受 Delta Psi(m) 调节，NOS 免疫反应性是胞质内的，没有线粒体定位。 NOS 阻断还保护 P19 神经元免受 NMDA 的影响。这些数据表明，线粒体 NOS 在很大程度上介导了未成熟海马神经元对 NMDA 的脆弱性降低，而胞质 NOS 则导致了成熟神经元中 NMDA 的毒性。
Mitochondrial membrane potential (Delta Psi(m))-dependent Ca2+ uptake plays a central role in neurodegeneration after NMDA receptor activation. NMDA-induced Delta Psi(m) dissipation increases during postnatal development, coincident with increasing vulnerability to NMDA. NMDA receptor activation also produces nitric oxide ( NO), which can inhibit mitochondrial respiration, dissipating Delta Psi(m). Because Delta Psi(m) dissipation reduces mitochondrial Ca2+ uptake, we hypothesized that NO mediates the NMDA-induced Delta Psi(m) dissipation in immature neurons, underlying their decreased vulnerability to excitotoxicity. Using hippocampal neurons cultured from 5- and 19-d-old rats, we measured NMDA-induced changes in [Ca2+](cytosol), Delta Psi(m), NO, and [Ca2+](mito). In postnatal day 5 (P5) neurons, NMDA mildly dissipated Delta Psi(m) in a NO synthase ( NOS)-dependent manner and increased NO. The NMDA-induced NO increase was abolished with carbonyl cyanide 4-(trifluoromethoxy) phenyl-hydrazone and regulated by [Ca2+](mito). Mitochondrial Ca2+ uptake inhibition prevented the NO increase, whereas inhibition of mitochondrial Ca2+ extrusion increased it. Consistent with this mitochondrial regulation, NOS and cytochrome oxidase immunoreactivity demonstrated mitochondrial localization of NOS. Furthermore, NOS blockade increased mitochondrial Ca2+ uptake during NMDA. Finally, at physiologic O-2 tensions (3% O-2), NMDA had little effect on survival of P5 neurons, but NOS blockade during NMDA markedly worsened survival, demonstrating marked neuroprotection by mitochondrial NO. In P19 neurons, NMDA dissipated Delta Psi(m) in an NO-insensitive manner. NMDA-induced NO production was not regulated by Delta Psi(m), and NOS immunoreactivity was cytosolic, without mitochondrial localization. NOS blockade also protected P19 neurons from NMDA. These data demonstrate that mitochondrial NOS mediates much of the decreased vulnerability to NMDA in immature hippocampal neurons and that cytosolic NOS contributes to NMDA toxicity in mature neurons.