title: Distinct time courses of secondary brain damage in the hippocampus following brain concussion and contusion in rats.
abstract: Secondary brain damage (SBD) is caused by apoptosis after traumatic brain injury that is classified into concussion and contusion. Brain concussion is temporary unconsciousness or confusion caused by a blow on the head without pathological changes, and contusion is a brain injury with hemorrhage and broad extravasations. In this study, we investigated the time-dependent changes of apoptosis in hippocampus after brain concussion and contusion using rat models. We generated the concussion by dropping a plumb on the dura from a height of 3.5 cm and the contusion by cauterizing the cerebral cortex. SBD was evaluated in the hippocampus by histopathological analyses and measuring caspase-3 activity that induces apoptotic neuronal cell death. The frequency of abnormal neuronal cells with vacuolation or nuclear condensation, or those with DNA fragmentation was remarkably increased at 1 hr after concussion (about 30% for each abnormality) from the pre-injury level (0%) and reached the highest level (about 50% for each) by 48 hrs, whereas the frequency of abnormal neuronal cells was increased at 1 hr after contusion (about 10%) and reached the highest level (about 40%) by 48 hrs. In parallel, caspase-3 activity was increased sevenfold in the hippocampus at 1 hr after concussion and returned to the pre-injury level by 48 hrs, whereas after contusion, caspase-3 activity was continuously increased to the highest level at 48 hrs (fivefold). Thus, anti-apoptotic-cell-death treatment to prevent SBD must be performed by 1 hr after concussion and at latest by 48 hrs after contusion.
authors.affiliation: Department of Veterinary Medicine, Nihon University College of Bioresonance Bioresource Science, Kanagawa, Japan. y09064823383@yahoo.co.jp <y09064823383@yahoo.co.jp>
authors.forename: Yuko
authors.initials: Y
authors.lastname: Nakajima
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Horiuchi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kamata
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Yukawa
authors.forename: Masato
authors.initials: M
authors.lastname: Kuwabara
authors.forename: Takashi
authors.initials: T
authors.lastname: Tsubokawa
mesh_terms: D000818:Animals; D001924:Brain Concussion / Q000150:complications* / Q000201:enzymology / Q000473:pathology*; D053148:Caspase 3 / Q000378:metabolism; D003288:Contusions / Q000150:complications* / Q000201:enzymology / Q000473:pathology*; D053938:DNA Fragmentation; D006624:Hippocampus / Q000201:enzymology / Q000293:injuries* / Q000473:pathology*; D020287:In Situ Nick-End Labeling; D008279:Magnetic Resonance Imaging; D008297:Male; D009474:Neurons / Q000473:pathology; D051381:Rats; D011916:Rats, Inbred F344; D013997:Time Factors
chemical_list: D053148:Caspase 3