Wang Y, Floor E
Department of Biochemistry, Cell and Molecular Biology, University of Kansas, Lawrence 66045-2106, USA.
J Neurochem. 1998 Feb;70(2):646-52. doi: 10.1046/j.1471-4159.1998.70020646.x.
Hydrogen peroxide (H2O2) is produced from several sources in brain and may be involved in neurodegeneration and second messenger signaling. Little is known about the effects of H2O2 on transmitter storage in brain synaptic vesicles. Neurotransmitter uptake into synaptic vesicles is driven by an electrochemical proton gradient generated by the vacuolar H+-ATPase (V-ATPase) in the vesicle membrane. We report here that the VATPase in bovine brain synaptic vesicles is highly sensitive to inhibition by micromolar concentrations of H2O2. Glutamate uptake by the vesicles is also inhibited, very likely as a secondary consequence of ATPase inactivation. Dithiothreitol or reduced glutathione reverse H2O2-induced inhibition of the V-ATPase, and ATP or GTP partially protect the ATPase from inhibition by H2O2. These and other results suggest that the mechanism of inhibition of the V-ATPase by H2O2 involves oxidation of a reactive cysteine sulfhydryl group in the ATP binding site. Inhibition of V-ATPase activity would decrease the amount of transmitter stored in synaptic vesicles and thus down-regulate transmitter release during episodes of oxidative stress or in response to second messenger signaling.
过氧化氢（H2O2）在大脑中可由多种来源产生，可能参与神经退行性变和第二信使信号传导。关于H2O2对脑突触小泡中神经递质储存的影响，目前所知甚少。神经递质摄取到突触小泡是由泡膜上的液泡H + -ATP酶（V-ATP酶）产生的电化学质子梯度驱动的。我们在此报告，牛脑突触小泡中的VATP酶对微摩尔浓度的H2O2抑制高度敏感。小泡对谷氨酸的摄取也受到抑制，这很可能是ATP酶失活的次要后果。二硫苏糖醇或还原型谷胱甘肽可逆转H2O2诱导的V-ATP酶抑制，ATP或GTP可部分保护ATP酶免受H2O2抑制。这些及其他结果表明，H2O2抑制V-ATP酶的机制涉及ATP结合位点中反应性半胱氨酸巯基的氧化。V-ATP酶活性的抑制会减少储存在突触小泡中的神经递质数量，从而在氧化应激期间或对第二信使信号作出反应时下调神经递质释放。
