title: Intermittent hypoxia conditioning protects mitochondrial cytochrome c oxidase of rat cerebellum from ethanol withdrawal stress.
abstract: Intermittent hypoxia (IH) conditioning minimizes neurocognitive impairment and stabilizes brain mitochondrial integrity during ethanol withdrawal (EW) in rats, but the mitoprotective mechanism is unclear. We investigated whether IH conditioning protects a key mitochondrial enzyme, cytochrome c oxidase (COX), from EW stress by inhibiting mitochondrially directed apoptotic pathways involving cytochrome c, Bax, or phosphor-P38 (pP38). Male rats completed two cycles of a 4-wk ethanol diet (6.5%) and 3 wk of EW. An IH program consisting of 5-10 bouts of 5-8 min of mild hypoxia (9.5-10% inspired O(2)) and 4 min of reoxygenation for 20 consecutive days began 3 days before the first EW period. For some animals, vitamin E replaced IH conditioning to test the contributions of antioxidant mechanisms to IH's mitoprotection. During the second EW, cerebellar-related motor function was evaluated by measuring latency of fall from a rotating rod (Rotarod test). After the second EW, COX activity in cerebellar mitochondria was measured by spectrophotometry, and COX, cytochrome c, Bax, and pP38 content were analyzed by immunoblot. Mitochondrial protein oxidation was detected by measuring carbonyl contents and by immunochemistry. Earlier IH conditioning prevented motor impairment, COX inactivation, depletion of COX subunit 4, protein carbonylation, and P38 phosphorylation during EW. IH did not prevent cytochrome c depletion during EW, and Bax content was unaffected by EW ± IH. Vitamin E treatment recapitulated IH protection of COX, and P38 inhibition attenuated protein oxidation during EW. Thus IH protects COX and improves cerebellar function during EW by limiting P38-dependent oxidative damage.
authors.affiliation: Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, Texas 76107-2699, USA.
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Ju
authors.forename: Robert T
authors.initials: RT
authors.lastname: Mallet
authors.forename: H Fred
authors.initials: HF
authors.lastname: Downey
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Metzger
authors.forename: Marianna E
authors.initials: ME
authors.lastname: Jung
mesh_terms: D000428:Alcohol Drinking / Q000009:adverse effects*; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis; D001522:Behavior, Animal; D015153:Blotting, Western; D002531:Cerebellum / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology / Q000503:physiopathology; D045304:Cytochromes c / Q000378:metabolism; D004195:Disease Models, Animal; D003576:Electron Transport Complex IV / Q000378:metabolism*; D000431:Ethanol / Q000009:adverse effects*; D000860:Hypoxia / Q000201:enzymology* / Q000473:pathology / Q000503:physiopathology / Q000523:psychology; D007093:Imidazoles / Q000494:pharmacology; D008297:Male; D008928:Mitochondria / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D009043:Motor Activity; D018384:Oxidative Stress / Q000187:drug effects; D010766:Phosphorylation; D050050:Protein Carbonylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time; D013053:Spectrophotometry; D013375:Substance Withdrawal Syndrome / Q000201:enzymology / Q000209:etiology / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control* / Q000523:psychology; D013997:Time Factors; D014810:Vitamin E / Q000494:pharmacology; D051028:bcl-2-Associated X Protein / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D000975:Antioxidants; C494828:Bax protein, rat; D007093:Imidazoles; D047428:Protein Kinase Inhibitors; D011725:Pyridines; D051028:bcl-2-Associated X Protein; D014810:Vitamin E; D000431:Ethanol; D045304:Cytochromes c; D003576:Electron Transport Complex IV; D048051:p38 Mitogen-Activated Protein Kinases; C093642:SB 203580