title: Heme oxygenase-1 aggravates heat stress-induced neuronal injury and decreases autophagy in cerebellar Purkinje cells of rats.
abstract: We previously reported that heat stroke induces autophagy as a protection mechanism against neurodegeneration in the brain. Heme oxygenase (HO)-1 is a stress protein and can be induced by heat stress (HS). Cerebellar Purkinje cells are selectively vulnerable to heat-induced injury. In this study, we first validated an animal model of HS (38°C for 4 h) in which sustained increase of Purkinje cell injury, HO-1 expression up to 24 h post HS (HS₂₄), and hyperthermia reaching a rectal temperature 41.52 ± 0.32 were observed. In subsequent experiments, we investigated the effects of HO-1 on HS-induced Purkinje cell injury. Rats were divided into four groups: one normothermic control group receiving saline vehicle (1 mL/kg, intraperitoneal [i.p.]) and exposed to 25 for 4 h; and three HS groups receiving saline, or HO-1 inducer haemin (30 mg/kg, i.p.) or HO-1 inhibitor tin protoporphyrin (SnPP, 30 mg/kg, i.p.), respectively, at 12 h prior to HS. HS-induced Purkinje cell injury was further enhanced by HO-1 inducer but attenuated by HO-1 inhibitor as evaluated by immunoreactivity of apoptosis marker (active caspase-3) as well as Fluoro-Jade B histochemistry (staining for degenerating neurons), suggesting a detrimental role of HO-1. Interestingly, the protective autophagy was reduced by HO-1 inducer but enhanced by HO-1 inhibitor as demonstrated by autophagy markers including Beclin-1 and microtubule-associated protein light chain 3 in Purkinje cells. Double immunofluorescent labelling of Beclin-1 or 8-hydroxydeoxyguanosine (an oxidative DNA damage marker) with HO-1 immunoreactivity not only demonstrated their co-localization, but also confirmed that HO-1 negatively regulated Beclin-1 but increased oxidative stress in the same Purkinje cell. Taken together, our results indicate that HO-1 aggravates HS injury in cerebellar Purkinje cells. Our findings shed new light on cell damage mechanisms by HS in central nervous system and may help to provide potential therapeutic foci.
authors.affiliation: Graduate Institute of Life Sciences, National Defense Medical Center, Taipei 114, Taiwan, ROC.
authors.forename: Chuan-Wang
authors.initials: CW
authors.lastname: Li
authors.forename: Yuh-Feng
authors.initials: YF
authors.lastname: Lin
authors.forename: Tsung-Ta
authors.initials: TT
authors.lastname: Liu
authors.forename: Jia-Yi
authors.initials: JY
authors.lastname: Wang
mesh_terms: D000080242:8-Hydroxy-2'-Deoxyguanosine; D000818:Animals; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D001343:Autophagy; D000071186:Beclin-1; D001831:Body Temperature; D053148:Caspase 3 / Q000378:metabolism; D002452:Cell Count; D003681:Dehydration / Q000150:complications / Q000473:pathology; D003849:Deoxyguanosine / Q000031:analogs & derivatives / Q000378:metabolism; D015536:Down-Regulation; D018869:Heat-Shock Response; D051547:Heme Oxygenase-1 / Q000378:metabolism*; D006624:Hippocampus / Q000201:enzymology / Q000473:pathology; D006979:Hyperthermia, Induced; D008297:Male; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D009410:Nerve Degeneration / Q000150:complications / Q000201:enzymology / Q000473:pathology; D018384:Oxidative Stress; D011689:Purkinje Cells / Q000201:enzymology* / Q000473:pathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
chemical_list: D000080242:8-Hydroxy-2'-Deoxyguanosine; D051017:Apoptosis Regulatory Proteins; D000071186:Beclin-1; D053148:Caspase 3; D003849:Deoxyguanosine; D051547:Heme Oxygenase-1; D008869:Microtubule-Associated Proteins; C512829:Becn1 protein, rat; C526109:Anxa3 protein, rat
keywords: Purkinje cells; autophagy; heat stress; heme oxygenase-1; injury