NADPH oxidase activity is necessary for acute intermittent hypoxia-induced phrenic long-term facilitation
NADPH oxidase activity is necessary for acute intermittent hypoxia-induced phrenic long-term facilitation
复制标题
DOI：
10.1113/jphysiol.2008.165597
复制
发表时间：
2009-05-01
影响因子：
5.5
通讯作者：
Mitchell, G. S.
中科院分区：
文献类型：
--
作者：
MacFarlane, P. M.;Satriotomo, I.;Mitchell, G. S.
急性间歇性缺氧（AIH）后的膈长期促进（pLTF）是脊髓的一种形式，依赖于血清素的突触可塑性，需要活性氧（ROS）的形成。我们验证了脊髓NADPH氧化酶活性是pLTF ROS的必要来源的假设。aih后60分钟（3次5分钟发作，频率为11% O-2，间隔5分钟），综合膈和舌下（XII）神经破裂幅度较基线增加，表明膈和XII LTF。鞘内注射（类似于C-4）夹竹叶碱或二苯二氯铵（DPI），两种结构和功能上不同的NADPH氧化酶复合物抑制剂，可减弱膈肌，但不能减弱XII， LTF。来自腹侧C-4脊柱节段的可溶性（胞质）和颗粒（膜）部分的免疫印迹显示，NADPH氧化酶催化亚基gp91（phox）主要在膜上定位，而调节亚基p47（phox）和RAC1在膜上和胞质上均有表达。固定组织的免疫组织化学分析显示，在C-4腹角的膈运动神经元中存在相同的亚基，但在邻近的星形胶质细胞或小胶质细胞中没有。总的来说，这些数据表明，位于膈运动神经元内的NADPH氧化酶亚基是aih诱导pLTF所需的ROS的主要来源。因此，NADPH氧化酶活性是脊髓突触可塑性的关键调节因子，可能是开发呼吸功能不全患者治疗策略的有用药物靶点，例如颈椎损伤。
Phrenic long-term facilitation (pLTF) following acute intermittent hypoxia (AIH) is a form of spinal, serotonin-dependent synaptic plasticity that requires reactive oxygen species (ROS) formation. We tested the hypothesis that spinal NADPH oxidase activity is a necessary source of ROS for pLTF. Sixty minutes post-AIH (three 5-min episodes of 11% O-2, 5 min intervals), integrated phrenic and hypoglossal (XII) nerve burst amplitudes were increased from baseline, indicative of phrenic and XII LTF. Intrathecal injections (similar to C-4) of apocynin or diphenyleneiodonium chloride (DPI), two structurally and functionally distinct inhibitors of the NADPH oxidase complex, attenuated phrenic, but not XII, LTF. Immunoblots from soluble (cytosolic) and particulate (membrane) fractions of ventral C-4 spinal segments revealed predominantly membrane localization of the NADPH oxidase catalytic subunit, gp91(phox), whereas membrane and cytosolic expression were both observed for the regulatory subunits, p47(phox) and RAC1. Immunohistochemical analysis of fixed tissues revealed these same subunits in presumptive phrenic motoneurons of the C-4 ventral horn, but not in neighbouring astrocytes or microglia. Collectively, these data demonstrate that NADPH oxidase subunits localized within presumptive phrenic motoneurons are a major source of ROS necessary for AIH-induced pLTF. Thus, NADPH oxidase activity is a key regulator of spinal synaptic plasticity, and may be a useful pharmaceutical target in developing therapeutic strategies for respiratory insufficiency in patients with, for example, cervical spinal injury.