Nuclear factor kappaB activation is mediated by NMDA and non-NMDA receptor and L-type voltage-gated Ca(2+) channel following severe global ischemia in rat hippocampus.
Recent studies suggest that nuclear factor NF-kappaB may be involved in excitotoxin-induced cell apopotosis. To analyze the variation of NF-kappaB, levels of NF-kappaB were measured after the rats were subjected to 30 min of four-vessel occlusion and sacrificed in selected reperfusion time points. Induction of NF-kappaB consisting mainly of p65 and p50 subunits was detected by Western blot with anti p65, p50 antibodies, respectively. DNA binding activity of NF-kappaB was performed by electrophoretic mobility-shift analysis. Our studies indicate that ischemia-induced NF-kappaB nuclear translocation is time-dependent. Inductions or binding activity of NF-kappaB in nucleus increased about 10-fold from 6 to 12 h as compared with that of the control group, then gradually declined in the following 24, 72 h. To further analyze the regulation by ionotropic glutamate receptor and L-type voltage-gated Ca(2+) channel (L-VGCC) in vivo, N-methyl-D-aspartate (NMDA) receptor antagonist ketamine, alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate/kainate receptor antagonist 6,7-dinitroquinoxaline-2,3 (1H,4H)-dione and L-VGCC antagonist nifedipine were given 20 min prior to 30 min of ischemia. The NF-kappaB nuclear translocation was completely blocked by these three antagonists in a dose-dependent manner after ischemia/reperfusion 6 h. Increased phosphorylation of the NF-kappaB regulatory unit IkappaB-alpha was detected by Western blot. Decrement of IkappaB-alpha was found after 3 h reperfusion in the cytoplasm following global ischemia, which was also blocked by such three antagonists. These results illustrate that glutamate-gated ionotropic NMDA or non-NMDA receptors and voltage-gated Ca(2+) channels are important routes to mediate NF-kappaB activation during brain ischemic injury. Active NF-kappaB may attend the excitotoxin-induced cell death in turn. Our studies also suggest that IkappaB-alpha is an important regulatory unit that controls the activation of NF-kappaB after its phosphorylation and degradation and resynthesis in rat hippocampus following global ischemia.
Shen
Wanhua
W
Research Center of Biochemistry and Molecular Biology, Xuzhou Medical College, 84 West Huai-hai Road, Xuzhou, Jinagsu 221002, China.
Zhang
Chunyi
C
Zhang
Guangyi
G
D000818:Animals; D002545:Brain Ischemia / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020746:Calcium Channels, L-Type / Q000187:drug effects / Q000502:physiology*; D003593:Cytoplasm / Q000378:metabolism; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D006624:Hippocampus / Q000378:metabolism*; D020672:I-kappa B Proteins / Q000502:physiology; D007649:Ketamine / Q000494:pharmacology; D008297:Male; D016328:NF-kappa B / Q000502:physiology*; D009543:Nifedipine / Q000494:pharmacology; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D018091:Receptors, AMPA / Q000037:antagonists & inhibitors / Q000502:physiology; D017459:Receptors, Amino Acid / Q000502:physiology*; D018092:Kainic Acid Receptors / Q000037:antagonists & inhibitors / Q000502:physiology; D016194:Receptors, N-Methyl-D-Aspartate / Q000502:physiology*; D015427:Reperfusion Injury / Q000378:metabolism; D013997:Time Factors
D002121:Calcium Channel Blockers; D020746:Calcium Channels, L-Type; D018691:Excitatory Amino Acid Antagonists; D020672:I-kappa B Proteins; D007649:Ketamine; D016328:NF-kappa B; D009543:Nifedipine; D011810:Quinoxalines; D018091:Receptors, AMPA; D017459:Receptors, Amino Acid; D018092:Kainic Acid Receptors; D016194:Receptors, N-Methyl-D-Aspartate; C056723:FG 9041