Mitochondrial apoptotic cell death and moderate superoxide generation upon selective activation of non-desensitizing AMPA receptors in hippocampal cultures.
In the present work we investigated the effect of selective stimulation of non-desensitizing alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptors in the intracellular processes leading to hippocampal neuronal death and production of reactive oxygen species (ROS). Activation of AMPA receptors in the presence of cyclothiazide (CYZ), a blocker of AMPA receptor desensitization, resulted in the death of approximately 25% of neurones, which was prevented by 2,3-dihydroxy-6-nitro-7-sulphamoyl-benzo(f)quinoxaline (NBQX), an AMPA-preferring receptor antagonist. (+)-5-Methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine hydrogen maleate (MK-801) protected the neurones from necrotic death induced by AMPA or NMDA receptor activation. Neurodegeneration caused by selective activation of non-desensitizing AMPA receptors, in the presence of AMPA, CYZ and MK-801, significantly decreased the number of Co2+-positive neurones, used as a cytochemical marker of Ca2+-permeable AMPA receptors, but maintained intracellular ATP/ADP. The AMPA-mediated apoptotic cell death involved mitochondrial cytochrome c release and the activation of caspases-1 and -3, which was prevented by NBQX. Interestingly, although selective activation of AMPA receptors was not associated with production of intracellular peroxides, a moderate increase in superoxide production was observed upon exposure to antimycin A (AA). Furthermore, increased activity of Mn- superoxide dismutase (SOD) was observed on selective activation of non-desensitizing AMPA receptors. Taken together, these data make important contributions to the elucidation of the downstream pathways activated in AMPA receptor-mediated excitotoxicity in cultured rat hippocampal neurones.
Rego
A Cristina
AC
Institute of Biochemistry, Faculty of Medicine, University of Coimbra, Coimbra, Portugal. acrego@cnc.cj.uc.pt
Monteiro
Nuno M
NM
Silva
Ana P
AP
Gil
Joana
J
Malva
João O
JO
Oliveira
Catarina R
CR
D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D020169:Caspases / Q000378:metabolism; D002478:Cells, Cultured; D003574:Cytochrome c Group / Q000378:metabolism; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D006624:Hippocampus / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D016202:N-Methylaspartate / Q000494:pharmacology; D009336:Necrosis; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D018091:Receptors, AMPA / Q000187:drug effects / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism*; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000494:pharmacology
D003574:Cytochrome c Group; D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D018091:Receptors, AMPA; D013481:Superoxides; D000244:Adenosine Diphosphate; D016202:N-Methylaspartate; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; D000255:Adenosine Triphosphate; D013482:Superoxide Dismutase; D020169:Caspases