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Hydrogen peroxide induces loss of dopamine transporter activity: a calcium‐dependent oxidative mechanism
Author(s) -
Huang ChuenLin,
Huang NaiKuei,
Shyue SongKun,
Chern Yijuang
Publication year - 2003
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.2003.01936.x
Subject(s) - chemistry , intracellular , calcium , thapsigargin , dopamine transporter , egta , extracellular , calcium in biology , catalase , dopaminergic , dopamine , bapta , biochemistry , oxidative stress , pharmacology , microbiology and biotechnology , biophysics , endocrinology , biology , organic chemistry
H 2 O 2 dose dependently inhibited dopamine uptake in PC12 cells and in striatal synaptosomes. Treatment with H 2 O 2 resulted in a reversible reduction in V max , with no effect on its K m value. This suppressive effect of H 2 O 2 could be relieved by reducing agents (dithiothreitol and cysteine). Furthermore, an oxidizer (dithiodipyridine) also markedly suppressed the dopamine transporter (DAT). Oxidative stress therefore might contribute to the action of H 2 O 2 . H 2 O 2 appeared to modify DAT at both extracellular and intracellular sites because cumene‐H 2 O 2 (a radical generator mostly restricted to plasma membranes) at high concentrations also slightly suppressed DAT activity and the intracellular overexpression of catalase ameliorated the inhibitory effect of H 2 O 2 . Internalization was unlikely to be involved because concanavalin A, which blocked endocytosis, did not prevent the H 2 O 2 ‐evoked inhibition of DAT activity. Interestingly, H 2 O 2 treatment evoked a Ca 2+ influx in PC12 cells. Moreover, removal of external calcium by EGTA or reduction in the intracellular calcium level using BAPTA‐AM reversed the inhibitory effect of H 2 O 2 . Conversely, depletion of intracellular calcium stores using thapsigargin did not affect the reduction in DAT activity by H 2 O 2 . Collectively, our results indicate that the DAT, one of the most important proteins controlling the dopaminergic system, is also a redox sensor. In addition, H 2 O 2 might suppress the DAT by a Ca 2+ ‐dependent oxidative pathway.