title: [Influences of repeated lower +Gz exposures on high +Gz exposure induced brain injury in rats].
abstract: Objective. To explore the influence of repeated lower +Gz exposures on high +Gz exposure induced brain injury in rats. Method. Forty SD male rats were randomly divided into control group (5 rats), +10 Gz/5 min group (5 rats) +4 Gz exposure one time, three times and five times group (10 rats each group). After 1 d or 6 d of +4 Gz exposure each group were exposed to +10 Gz again. Three days after +10 Gz exposure the neuron damage was observed by light microscope in HE stained section. Result. There was no brain damage after repeated +4 Gz/3 min exposure 5 times so it was reasonable to use this exposure intensity as ischemia stimulation. +10 Gz/5 min exposure could result in irreversible neuron damage such as neuron degeneration and coagulation necrosis. The experiment results suggested that after +10 Gz/5 min exposure there were degenerated neurons in cortex, hippocampus and thalamus. The number of degenerated neurons were obviously decreased in cortex, hippocampus and thalamus when exposed to +10 Gz/5 min again after repeated +4 Gz/3 min 3-5 times. Conclusion. The degree of neuron damage was obviously slight at the time of exposure to +10 Gz/5 min again after repeated +4 Gz/3 min 3-5 times. The ischemia tolerance at the time of exposure to +Gz was similar to other brain ischemia.
authors.affiliation: Department of Aerospace Biodynamics, The Fourth Military Medical University, Xi'an, China.
authors.forename: Jin-sheng
authors.initials: JS
authors.lastname: Li
authors.forename: Xi-qing
authors.initials: XQ
authors.lastname: Sun
authors.forename: Xing-yu
authors.initials: XY
authors.lastname: Wu
authors.forename: Zhi-ren
authors.initials: ZR
authors.lastname: Rao
authors.forename: Hui-ling
authors.initials: HL
authors.lastname: Liu
authors.forename: Xiao-ping
authors.initials: XP
authors.lastname: Xie
mesh_terms: D000818:Animals; D001921:Brain / Q000473:pathology; D001930:Brain Injuries / Q000209:etiology* / Q000473:pathology*; D002545:Brain Ischemia / Q000209:etiology / Q000473:pathology*; D002540:Cerebral Cortex / Q000473:pathology; D006624:Hippocampus / Q000473:pathology; D018471:Hypergravity / Q000009:adverse effects*; D008297:Male; D009336:Necrosis; D009410:Nerve Degeneration / Q000209:etiology / Q000473:pathology; D009474:Neurons / Q000473:pathology* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013788:Thalamus / Q000473:pathology