title: Prolonged hypothermia exposure diminishes neuroprotection for severe ischemic-hypoxic primary neurons.
abstract: This study aimed to identify optimal mild hypothermic (MH) condition that would provide the best protection for neuronal cells undergoing severe ischemia and hypoxia. We also sought to determine if longer exposure to mild hypothermia would confer greater protection to severe ischemia and hypoxia in these cells. We designed a primary neuronal cell model for severe glucose and oxygen deprivation/reoxygenation (OGD/R) to simulate the hypoxic-ischemic condition of patients with severe stroke, trauma, or hypoxic-ischemic encephalopathy. We evaluated the viability of these neurons following 3 h of OGD/R and variable MH conditions including different temperatures and durations of OGD/R exposure. We further explored the effects of the optimal MH condition on several parts which are associated with mitochondrial apoptosis pathway: intracellular calcium, reactive oxygen species (ROS), and mitochondrial transmembrane potential (MTP). The results of this study showed that the apoptosis proportion (AP) and cell viability proportion (CVP) after OGD/R significantly varied depending on which MH condition cells were exposed to (p < 0.001). Further, our findings showed that prolonged MH reduced the neuroprotection to AP and CVP. We also determined that the optimal MH conditions (34 °C for 4.5 h) reduced intracellular calcium, ROS, and recovered MTP. These findings indicate that there is an optimal MH treatment strategy for severely hypoxia-ischemic neurons, prolonged duration might diminish the neuroprotection, and that MH treatment likely initiates neuroprotection by inhibiting the mitochondrial apoptosis pathway.
authors.affiliation: Department of Neurology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, China; Department of Neurology, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong, China.
authors.forename: Xiao-Ya
authors.initials: XY
authors.lastname: Gao
authors.affiliation: Department of Neurology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, China.
authors.forename: Shu-Zhen
authors.initials: SZ
authors.lastname: Zhu
authors.affiliation: Department of Neurology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, China; Department of Neurology, Guangzhou General Hospital of Guangzhou Military Command, Guangzhou, Guangdong, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Xiang
authors.affiliation: Department of Neurology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, China.
authors.forename: Kai-Bin
authors.initials: KB
authors.lastname: Huang
authors.affiliation: Department of Neurology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, China.
authors.forename: Ya-Fang
authors.initials: YF
authors.lastname: Hu
authors.affiliation: Department of Neurology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Gu
authors.affiliation: Department of Neurology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, China. Electronic address: pansuyue82@126.com.
authors.forename: Su-Yue
authors.initials: SY
authors.lastname: Pan
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology; D002118:Calcium / Q000378:metabolism; D015687:Cell Hypoxia / Q000502:physiology*; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D005947:Glucose / Q000378:metabolism; D007035:Hypothermia / Q000378:metabolism / Q000503:physiopathology*; D007036:Hypothermia, Induced / Q000379:methods*; D053078:Membrane Potential, Mitochondrial; D008928:Mitochondria / Q000378:metabolism; D023421:Models, Animal; D009474:Neurons / Q000166:cytology* / Q000502:physiology; D000066829:Neuroprotection / Q000502:physiology*; D010100:Oxygen / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D017382:Reactive Oxygen Species; D005947:Glucose; D010100:Oxygen; D002118:Calcium
keywords: Apoptosis; Cerebral infarction; Head trauma; Hypothermia; OGD/R; Primary neuron