Depolarization of in situ mitochondria due to hydrogen peroxide-induced oxidative stress in nerve terminals:: Inhibition of α-ketoglutarate dehydrogenase
Depolarization of in situ mitochondria due to hydrogen peroxide-induced oxidative stress in nerve terminals:: Inhibition of α-ketoglutarate dehydrogenase
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DOI：
10.1046/j.1471-4159.1999.0730220.x
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发表时间：
1999-07-01
影响因子：
4.7
通讯作者：
Adam-Vizi, V
中科院分区：
文献类型：
--
作者：
Chinopoulos, C;Tretter, L;Adam-Vizi, V
使用膜电位敏感探针JC-1在完整的分离的神经末梢中测定线粒体膜电位（Delta Psi（m））。H2 O2（0.1-1 mM）诱导的氧化应激仅导致Delta Psi（m）轻微降低。当呼吸链复合物I被鱼藤酮（2 μ M）抑制时，Δ Psi（m）不变，但随后加入H_2O_2时，Δ Psi（m）开始下降，并在与0.5mM H_2O_2孵育12分钟时崩溃。鱼藤酮和H_2O_2同时存在时，ATP水平和[ATP]/[ADP]比值大大降低。当在寡霉素（10 μ M）（F0 F1-ATPase的抑制剂）之后加入H2 O2时，也诱导Δ Psi（m）的显著降低。H2 O2（0.1或0.5 mM）抑制α-酮戊二酸脱氢酶，降低神经末梢稳态NAD（P）H水平。得出结论，在H2 O2存在下，至少有两个因素决定Δ Psi（m）：（a）由于铜-酮戊二酸脱氢酶的抑制而降低的NADH水平不足以确保最佳呼吸速率，这反映在当F0 F1-ATP酶不起作用时Δ Psi（m）的下降中。(b)在鱼藤酮和H_2O_2存在下ATP水平的显著降低阻止了F_0F_1-ATP酶对Delta Psi（m）的维持。结果表明，在H_2O_2诱导的氧化应激期间，为了维持神经末梢中的Delta Psi（m），复合物I和F_0F_1-ATP酶必须都是功能性的。当H2 O2过量产生且呼吸链复合物I同时受损时，Delta Psi（m）的崩溃可能是缺血或帕金森病中神经元损伤的关键事件。
Mitochondrial membrane potential (Delta Psi(m)) was determined in intact isolated nerve terminals using the membrane potential-sensitive probe JC-1. Oxidative stress induced by H2O2 (0.1-1 mM) caused only a minor decrease in Delta Psi(m). When complex I of the respiratory chain was inhibited by rotenone (2 mu M), Delta Psi(m) was unaltered, but on subsequent addition of H2O2, Delta Psi(m) started to decrease and collapsed during incubation with 0.5 mM H2O2 for 12 min, The ATP level and [ATP]/[ADP] ratio were greatly reduced in the simultaneous presence of rotenone and H2O2. H2O2 also induced a marked reduction in Delta Psi(m) when added after oligomycin (10 mu M), an inhibitor of F0F1-ATPase. H2O2 (0.1 or 0.5 mM) inhibited alpha-ketoglutarate dehydrogenase and decreased the steady-state NAD(P)H level in nerve terminals. It is concluded that there are at least two factors that determine Delta Psi(m) in the presence of H2O2: (a) The NADH level reduced owing to inhibition of cu-ketoglutarate dehydrogenase is insufficient to ensure an optimal rate of respiration, which is reflected in a fall of Delta Psi(m) when the F0F1- ATPase is not functional. (b) The greatly reduced ATP level in the presence of rotenone and H2O2 prevents maintenance of Delta Psi(m) by F0F1-ATPase, The results indicate that to maintain Delta Psi(m) in the nerve terminal during H2O2-induced oxidative stress, both complex I and F0F1- ATPase must be functional. Collapse of Delta Psi(m) could be a critical event in neuronal injury in ischemia or Parkinson's disease when H2O2 is generated in excess and complex I of the respiratory chain is simultaneously impaired.