Kainate excitotoxicity in organotypic hippocampal slice cultures: evidence for multiple apoptotic pathways.
The mechanisms underlying kainate (KA) neurotoxicity are still not well understood. We previously reported that KA-mediated neuronal damage in organotypic cultures of hippocampal slices was associated with p53 induction. Recently, both bax and caspase-3 have been demonstrated to be key components of the p53-dependent neuronal death pathway. Caspase activation has also been causally related to the release of mitochondrial cytochrome c (Cyto C) in the cytoplasm as a result of the collapse of the mitochondrial membrane potential (Deltapsi(M)) and the opening of mitochondrial permeability transition pores (mPTP). In the present study, we observed a rapid induction of bax in hippocampal slice cultures after KA treatment. In addition, the levels of Cyto C and caspase-3 were increased in the cytosol while the level of the caspase-9 precursor was decreased. There was also a complete reduction of Rhodamine 123 fluorescence after KA treatment, an indication of Deltapsi(M) dissipation. Furthermore, inhibition of mPTP opening by cyclosporin A partially prevented Cyto C release, caspase activation and neuronal death. These data suggest the involvement of bax, several caspases, as well as Cyto C release in KA-elicited neuronal death. Finally, inhibition of caspase-3 activity by z-VAD-fmk only partially protected neurons from KA toxicity, implying that multiple mechanisms may be involved in KA excitotoxicity.
Liu
W
W
Department of Pharmacology, School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA.
Liu
R
R
Chun
J T
JT
Bi
R
R
Hoe
W
W
Schreiber
S S
SS
Baudry
M
M
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D001927:Brain Diseases / Q000378:metabolism* / Q000503:physiopathology; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D002478:Cells, Cultured / Q000187:drug effects / Q000201:enzymology; D016572:Cyclosporine / Q000494:pharmacology; D003574:Cytochrome c Group / Q000187:drug effects / Q000378:metabolism; D003600:Cytosol / Q000187:drug effects / Q000201:enzymology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D006624:Hippocampus / Q000187:drug effects / Q000201:enzymology* / Q000503:physiopathology; D007150:Immunohistochemistry; D007608:Kainic Acid / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008928:Mitochondria / Q000187:drug effects / Q000201:enzymology / Q000473:pathology; D009410:Nerve Degeneration / Q000201:enzymology* / Q000503:physiopathology; D009474:Neurons / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D018696:Neuroprotective Agents / Q000494:pharmacology; D009498:Neurotoxins / Q000494:pharmacology*; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2; D017966:Pyramidal Cells / Q000187:drug effects / Q000201:enzymology / Q000473:pathology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D051028:bcl-2-Associated X Protein
D000590:Amino Acid Chloromethyl Ketones; C494828:Bax protein, rat; D061945:Caspase Inhibitors; D003574:Cytochrome c Group; D004791:Enzyme Inhibitors; D018690:Excitatory Amino Acid Agonists; D018696:Neuroprotective Agents; D009498:Neurotoxins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D051028:bcl-2-Associated X Protein; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D016572:Cyclosporine; D020169:Caspases; D007608:Kainic Acid