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Neuronal nitric oxide synthase proteolysis limits the involvement of nitric oxide in kainate‐induced neurotoxicity in hippocampal neurons
Author(s) -
Araújo Inês M.,
Ambrósio António F.,
Leal Ermelindo C.,
Santos Paulo F.,
Carvalho Arsélio P.,
Carvalho Caetana M.
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.1471-4159.2003.01731.x
Subject(s) - neurotoxicity , ampa receptor , nbqx , kainate receptor , chemistry , nitric oxide synthase , glutamate receptor , excitotoxicity , pharmacology , nitric oxide , biochemistry , receptor , toxicity , biology , organic chemistry
In this work, we investigated the role of nitric oxide (NO) in neurotoxicity triggered by α‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionate (AMPA) receptor activation in cultured hippocampal neurons. In the presence of cyclothiazide (CTZ), short‐term exposures to kainate (KA; 5 and 15 min, followed by 24‐h recovery) decreased cell viability. Both NBQX and d ‐AP‐5 decreased the neurotoxicity caused by KA plus CTZ. Long‐term exposures to KA plus CTZ (24 h) resulted in increased toxicity. In short‐, but not in long‐term exposures, the presence of NO synthase (NOS) inhibitors ( l ‐NAME and 7‐NI) decreased the toxicity induced by KA plus CTZ. We also found that KA plus CTZ (15‐min exposure) significantly increased cGMP levels. Furthermore, short‐term exposures lead to decreased intracellular ATP levels, which was prevented by NBQX, d ‐AP‐5 and NOS inhibitors. Immunoblot analysis revealed that KA induced neuronal NOS (nNOS) proteolysis, gradually lowering the levels of nNOS according to the time of exposure. Calpain, but not caspase‐3 inhibitors, prevented this effect. Overall, these results show that NO is involved in the neurotoxicity caused by activation of non‐desensitizing AMPA receptors, although to a limited extent, since AMPA receptor activation triggers mechanisms that lead to nNOS proteolysis by calpains, preventing a further contribution of NO to the neurotoxic process.