AMPA-induced excitotoxicity increases nuclear levels of CAD, endonuclease G, and acinus and induces chromatin condensation in rat hippocampal pyramidal neurons.
Programmed cell death has been linked to AMPA-receptor-mediated excitotoxicity in pyramidal neurons of the hippocampus. The intent of this study was to investigate the roles of caspase-dependent and independent nuclear death-related factors in mediating AMPA-induced nuclear changes in PyNs by use of immunohistochemistry and transmission electron microscopy (TEM). Data indicate increases in the nuclear levels of caspase-activated acinus and DNase and Endonuclease G (a caspase-independent endonuclease) in CA1 and CA3 PyN nuclei with different temporal patterns following an AMPA-insult. Hoechst staining and TEM confirm AMPA-induced chromatin condensation. The presence of active acinus in nuclei suggests it mediates chromatin condensation. Interestingly, a DNA fragmentation labeling protocol showed that there was no chromatin cleavage up to 90 min after AMPA-insult. Overall, we conclude that: 1) AMPA-induced excitotoxicity increases nuclear immunoreactivity of pro-death enzymes from multiple programmed cell death pathways, 2) differential chromatin condensation patterns occur between CA1 and CA3, and 3) there is no chromatin cleavage within our experimental timeframe.
Henne
W M
WM
Department of Physiology, Texas Tech University Health Sciences Center, Lubbock, TX, 79430, USA.
Oomman
S
S
Attridge
J
J
Finckbone
V
V
Coates
P
P
Bliss
R
R
Strahlendorf
H
H
Strahlendorf
J
J
D000818:Animals; D001562:Benzimidazoles / Q000378:metabolism; D016923:Cell Death / Q000502:physiology; D002467:Cell Nucleus / Q000378:metabolism*; D002843:Chromatin / Q000378:metabolism*; D003851:Deoxyribonucleases / Q000378:metabolism*; D004706:Endodeoxyribonucleases / Q000378:metabolism*; D006624:Hippocampus / Q000166:cytology; D020287:In Situ Nick-End Labeling; D009687:Nuclear Proteins / Q000378:metabolism*; D017966:Pyramidal Cells / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000378:metabolism*
D001562:Benzimidazoles; D002843:Chromatin; D009687:Nuclear Proteins; C447680:hoechst 32258; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; D003851:Deoxyribonucleases; D004706:Endodeoxyribonucleases; C109663:caspase-activated deoxyribonuclease; C052391:endonuclease G