RT Journal Article
SR Electronic
T1 Inhibition of Acetylcholine Synthesis and Tyrosine Nitration Induced by Peroxynitrite Are Differentially Prevented by Antioxidants
JF Molecular Pharmacology
JO Mol Pharmacol
FD American Society for Pharmacology and Experimental Therapeutics
SP 838
OP 846
VO 60
IS 4
A1 Lydie Guermonprez
A1 Claire Ducrocq
A1 Yvette Morot Gaudry-Talarmain
YR 2001
UL http://molpharm.aspetjournals.org/content/60/4/838.abstract
AB Evidence of an overload of reactive oxygen species and peroxynitrite, a derivative of nitric oxide, in sporadic amyotrophic lateral sclerosis suggests that peroxynitrite could impair cholinergic functions. Because of the impossibility of obtaining synaptosomes from vertebrate neuromuscular junctions, we used cholinergic synaptosomes purified fromTorpedo marmorata electroneurons to characterize the defects triggered by peroxynitrite in more detail. Addition of peroxynitrite or its donor 3-morpholinosydnonimine abolished high-affinity choline uptake and synthesis of acetylcholine from acetate. T. marmorata choline acetyltransferase (ChAT) was impaired to the same extent as bovine brain ChAT. A hallmark of peroxynitrite action is the nitration of tyrosine residues in proteins. Peroxynitrite induced a concentration-dependent appearance of nitrotyrosines in several neuronal proteins from synaptosomes and, more readily, from synaptic vesicles. Peroxynitrite also triggered tyrosine nitrations in purified ChAT. Peroxynitrite-dependent nitrations were impaired when synaptosomes were pretreated with thioreductants (glutathione, N-acetyl cysteine, dithiothreitol) or antioxidants (uric acid, melatonin, bovine serum albumin, desferrioxamine). Deleterious effects of peroxynitrite on choline transport and ChAT activity were prevented by the thioreductants but only partially by the antioxidants, suggesting a mechanism other than tyrosine nitration, which may involve cysteine oxidation. Further development of protective agents acting on choline transport and on ChAT activity may offer interesting therapeutic possibilities with respect to cholinergic dysfunction occurring in neurodegenerative diseases. The American Society for Pharmacology and Experimental Therapeutics