title: Kainic acid dose affects delayed cell death mechanism after status epilepticus.
abstract: Kainic acid (KA)-induced status epilepticus (SE) produces hippocampal neuronal death, which varies from necrosis to apoptosis or programmed cell death (PCD). We examined whether the type of neuronal death was dependent on KA dose. Adult rats were induced SE by intraperitoneal injection of KA at 9 mg/kg (K9) or 12 mg/kg (K12). Hippocampal neuronal death was assessed by TUNEL staining, electron microscopy, and Western blotting of caspase-3 on days 1, 3 and 7 after SE induction. K12 rats showed higher a mortality rate and shorter latency to the onset of SE when compared with K9 rats. In both groups, acidophilic and pyknotic neurons were evident in CA1 at 24h after SE and neuronal loss developed from day 3. The degenerated neurons became TUNEL-positive on days 3 and 7 in K9 rats but not in K12 rats. Caspase-3 activation was detected on days 3 and 7 in K9 rats but was undetectable in K12 rats. Ultrastructural study revealed shrunken neurons exhibiting pyknotic nuclei containing small and dispersed chromatin clumps 24h after SE in CA1. No cells exhibited apoptosis. On days 3 and 7, the degenerated neurons were necrotic with high electron density and small chromatin clumps. There were no ultrastructural differences between the K9 and K12 groups. These results revealed that differences in KA dose affected the delayed cell death (3 and 7 days after SE); however, no effect was seen on the early cell death (24h after SE). Moderate-dose KA induced necrosis, while low-dose KA induced PCD.
authors.affiliation: Department of Pediatrics, Osaka City University Graduate School of Medicine, Osaka 545-8585, Japan. m1155519@med.osaka-cu.ac.jp
authors.forename: Daisuke
authors.initials: D
authors.lastname: Tokuhara
authors.forename: Satoru
authors.initials: S
authors.lastname: Sakuma
authors.forename: Hideji
authors.initials: H
authors.lastname: Hattori
authors.forename: Osamu
authors.initials: O
authors.lastname: Matsuoka
authors.forename: Tsunekazu
authors.initials: T
authors.lastname: Yamano
mesh_terms: D000818:Animals; D053148:Caspase 3 / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D003292:Convulsants / Q000633:toxicity; D004305:Dose-Response Relationship, Drug; D018690:Excitatory Amino Acid Agonists / Q000633:toxicity; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology*; D007608:Kainic Acid / Q000633:toxicity*; D008297:Male; D046529:Microscopy, Electron, Transmission; D009410:Nerve Degeneration / Q000139:chemically induced / Q000378:metabolism / Q000503:physiopathology*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D017966:Pyramidal Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D051381:Rats; D017208:Rats, Wistar; D013226:Status Epilepticus / Q000139:chemically induced / Q000378:metabolism* / Q000503:physiopathology*; D013997:Time Factors
chemical_list: D003292:Convulsants; D018690:Excitatory Amino Acid Agonists; D053148:Caspase 3; D007608:Kainic Acid