Bonsi P, Calabresi P, De Persis C, Papa M, Centonze D, Bernardi G, Pisani A
Clinica Neurologica, Dipartimento di Neuroscienze, Università di Roma Tor Vergata, Fondazione Santa Lucia, IRCCS, 00133 Rome, Italy.
Exp Neurol. 2004 Jan;185(1):169-81. doi: 10.1016/j.expneurol.2003.09.016.
Mitochondrial metabolism impairment has been implicated in the pathogenesis of several neurodegenerative disorders. In the present work, we combined electrophysiological recordings and microfluorometric measurements from cholinergic interneurons obtained from a rat neostriatal slice preparation. Acute application of the mitochondrial complex I inhibitor rotenone produced an early membrane hyperpolarization coupled to a fall in input resistance, followed by a late depolarizing response. Current-voltage relationship showed a reversal potential of -80 +/- 3 mV, suggesting the involvement of a potassium (K+) current. Simultaneous measurement of intracellular sodium [Na+]i or calcium [Ca2+]i concentrations revealed a striking correlation between [Na+]i elevation and the early membrane hyperpolarization, whereas a significant [Ca2+]i rise matched the depolarizing phase. Interestingly, ion and membrane potential changes were mimicked by ouabain, inhibitor of the Na+-K+ATPase, and were insensitive to tetrodotoxin (TTX) or to a combination of glutamate receptor antagonists. The rotenone effects were partially reduced by blockers of ATP-sensitive K+ channels, glibenclamide and tolbutamide, and largely attenuated by a low Na+-containing solution. Morphological analysis of the rotenone effects on striatal slices showed a significant decrease in the number of choline acetyltransferase (ChAT) immunoreactive cells. These results suggest that rotenone rapidly disrupts the ATP content, leading to a decreased Na+-K+ATPase function and, therefore, to [Na+]i overload. In turn, the hyperpolarizing response might be generated both by the opening of ATP-sensitive K+ channels and by Na+-activated K+ conductances. The increase in [Ca2+]i occurs lately and does not seem to influence the early events.
线粒体代谢损伤与多种神经退行性疾病的发病机制有关。在本研究中，我们结合了从大鼠新纹状体脑片制备中获得的胆碱能中间神经元的电生理记录和显微荧光测量。急性应用线粒体复合体I抑制剂鱼藤酮会导致早期膜超极化并伴有输入电阻下降，随后是晚期去极化反应。电流-电压关系显示反转电位为-80±3 mV，提示钾（K+）电流参与其中。同时测量细胞内钠[Na+]i或钙[Ca2+]i浓度发现，[Na+]i升高与早期膜超极化之间存在显著相关性，而显著的[Ca2+]i升高与去极化阶段相匹配。有趣的是，钠钾ATP酶抑制剂哇巴因可模拟离子和膜电位变化，且对河豚毒素（TTX）或谷氨酸受体拮抗剂的组合不敏感。ATP敏感性钾通道阻滞剂格列本脲和甲苯磺丁脲可部分减轻鱼藤酮的作用，而低钠溶液可使其作用大幅减弱。鱼藤酮对纹状体脑片影响的形态学分析显示，胆碱乙酰转移酶（ChAT）免疫反应性细胞数量显著减少。这些结果表明，鱼藤酮迅速破坏ATP含量，导致钠钾ATP酶功能下降，从而导致[Na+]i过载。反过来，超极化反应可能由ATP敏感性钾通道的开放和钠激活的钾电导产生。[Ca2+]i的增加出现较晚，似乎不影响早期事件。
