title: Hyperthermia conditioned astrocyte-cultured medium protects neurons from ischemic injury by the up-regulation of HIF-1 alpha and the increased anti-apoptotic ability.
abstract: It has been demonstrated that conditioned medium from astrocytes challenged by in vitro ischemia (oxygen-glucose deprivation, OGD) improved neuronal survival. In addition, preconditioning stimuli can be cross-tolerant, safeguarding against other types of injury. We therefore hypothesized that hyperthermia-conditioned astrocyte-cultured medium (ACM) might also have protective effect on neurons against ischemic injury. The cultured-media, named 38ACM and 40ACM respectively, were collected after astrocytes had been incubated at 38 °C or 40 °C for 6h, followed by incubation at 37 °C for 24h. It was found that ischemia for 6h induced a significant reduction in the number of neuronal cells and cell-viability, and an increase in lactate dehydrogenase (LDH) release and the percentage of apoptotic nuclei in neurons. Pre-treatment with 38ACM or 40ACM for 24h significantly diminished ischemia injury, enhanced cell viability, reduced LDH release and reversed apoptosis. Western blot analysis showed that treatment with 38ACM or 40ACM for 24h led to a significant increase in hypoxia-inducible factor-1 (HIF-1) alpha expression. The EMSA demonstrated that the ACM increased the binding activity of HIF-1 in ischemic neurons. The data implied that hyperthermia-conditioned ACM protects neurons from ischemic injury by up-regulating HIF-1 alpha, and the increased binding activity of HIF-1 and anti-apoptotic ability.
authors.affiliation: School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, NT, Hong Kong.
authors.forename: Fang
authors.initials: F
authors.lastname: Du
authors.forename: Xiao Mei
authors.initials: XM
authors.lastname: Wu
authors.forename: Qi
authors.initials: Q
authors.lastname: Gong
authors.forename: Xuan
authors.initials: X
authors.lastname: He
authors.forename: Ya
authors.initials: Y
authors.lastname: Ke
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001253:Astrocytes / Q000166:cytology*; D002545:Brain Ischemia / Q000378:metabolism / Q000473:pathology*; D015687:Cell Hypoxia / Q000235:genetics; D002470:Cell Survival / Q000187:drug effects; D017077:Culture Media, Conditioned / Q000494:pharmacology; D004921:Erythropoietin / Q000235:genetics / Q000378:metabolism; D006979:Hyperthermia, Induced; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism*; D019194:Ischemic Preconditioning; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D051379:Mice; D009474:Neurons / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism / Q000473:pathology; D020218:Response Elements / Q000235:genetics; D015854:Up-Regulation / Q000187:drug effects*
chemical_list: D017077:Culture Media, Conditioned; C497443:Hif1a protein, mouse; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D004921:Erythropoietin; D007770:L-Lactate Dehydrogenase