The expression of Smac and XIAP in rat hippocampus following limbic seizure induced by kainic acid injection into amygdaloid nucleus.
- Author:
Tian-Fu LI
1
;
Yu-Min LUO
;
Chuan-Zhen LU
Author Information
1. Department of Neurology, Huashan Hospital, Fudan University, Shanghai 200040, China.
- Publication Type:Journal Article
- MeSH:
Amygdala;
physiology;
Animals;
Caspase 9;
Caspases;
biosynthesis;
genetics;
Complement Membrane Attack Complex;
Complement System Proteins;
Glycoproteins;
biosynthesis;
genetics;
Hippocampus;
metabolism;
Kainic Acid;
Limbic System;
Male;
Microinjections;
Protein Biosynthesis;
Proteins;
genetics;
Rats;
Rats, Sprague-Dawley;
Seizures;
chemically induced;
metabolism;
X-Linked Inhibitor of Apoptosis Protein
- From:
Acta Physiologica Sinica
2004;56(2):172-177
- CountryChina
- Language:Chinese
-
Abstract:
To determine whether Smac/DIABLO (second mitochondrial activator of caspases/direct inhibitor of apoptosis protein-binding protein of low isoelectric point [PI]) and XIAP (X-chromosome-linked inhibitor of apoptosis protein) serve to regulate neuronal apoptosis following seizures, we investigated seizure-induced changes in caspase-9, Smac/DIABLO and XIAP protein expression and the in vivo effect of caspase-9 inhibition. Animals received unilateral intra-amygdaloid injection of kainic acid (0.5 microg) to induce seizures for 1 h. The seizures were then terminated by diazepam (30 mg/kg). Animals were killed 0, 2, 4, 8, 24 or 72 h following diazepam administration. The apoptotic and surviving neurons in hippocampus were observed by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) and cresyl violet staining, the expression of Smac/DIABLO, XIAP and caspase-9 was detected with immunofluorescence and western blot. The results showed that the levels of XIAP and the 46-kDa proenzyme form of caspase-9 were unaffected by the seizures. The expression of Smac increased at 2 h and the 37-kD cleaved fragment of caspase-9 was detected at 4 h, TUNEL-positive neurons appeared at 8 h and reached maximal at 24 h following seizure cessation within the ipsilateral (the same side as the intra-amygdaloid injection of kainic acid) CA3 subfield of the hippocampus. Intracerebroventricular infusion of caspase-9 inhibitor z-LEHD-fluoromethyl ketone (z-LEHD-fmk) significantly decreased TUNEL-positive neurons and increased the number of surviving cells. Caspase-9 immunoreactivity increased and Smac/DIABLO, XIAP immunoreactivity became extensive within the ipsilateral CA3 neurons. TUNEL-positive neurons and the alterations of the expression of Smac/DIABLO and XIAP within the ipsilateral CA3 were not detected within the contralateral hippocampus. These results suggest that seizures lead the translocation of Smac/DIABLO into the cytosol, the activation of caspase-9 and the change of subcellular locoalization of XIAP. These changes may play a role in the brain damage induced by seizures. Caspase-9 is possibly a potential therapeutic target in the treatment of brain injury associated with seizures.
