Diazoxide pretreatment induces delayed preconditioning in astrocytes against oxygen glucose deprivation and hydrogen peroxide-induced toxicity

Nishadi Rajapakse, Bela Kis, Takashi Horiguchi, James Snipes, David Busija

Research output: Contribution to journalArticle

42 Citations (Scopus)

Abstract

Recent studies suggest that activation of mitochondrial ATP-sensitive potassium channels (mKATP) with diazoxide can protect neurons against ischemic stress. However, it is not yet known whether astrocytes, which are more resilient against ischemia, respond similarly to diazoxide. We exposed cultured astrocytes to oxygen-glucose deprivation (OGD) or hydrogen peroxide (H2O2) with or without pretreatment with the mKATP opener diazoxide. Marked decreases in astrocyte viability were evident after 9 and 12 hr of OGD [76% ± 3% (n = 50) and 60% ± 1% (n = 50)] and 400 and 600 μM H2O2 [40% ± 2% (n = 16) and 25% ± 2% (n = 16)], respectively, compared with no treatment (100% ± 1%). Diazoxide treatment (3 days of sequential application) dramatically reversed the negative effects of OGD and H2O2, resulting in complete blockade of astrocyte cell death. Effects of diazoxide were blocked by the mKATP blocker 5-hydroxydecanoic acid (5-HD). Furthermore, incubation of astrocytes with diazoxide resulted in loss of mitochondrial membrane potential monitored by tetramethylrhodamineethylester fluorescence. Additionally, generation of reactive oxygen species was observed in response to diazoxide, assessed using the oxidation-sensitive dye hydroethidine, and this effect was abolished by antioxidants, catalase, and a superoxide dismutase mimetic, M40401. Finally, diazoxide increased the protein level of phosphorylated protein kinase C (PKC) revealed by immunoblot analysis. Our findings demonstrate that opening of mKATP by diazoxide identifies a delayed preconditioning effect that is protective against two types of injury in astrocytes and that diazoxide may deliver protection via mitochondrial depolarization, free radical production, and PKC activation.

Original languageEnglish
Pages (from-to)206-214
Number of pages9
JournalJournal of neuroscience research
Volume73
Issue number2
DOIs
Publication statusPublished - 2003 Jul 15
Externally publishedYes

Keywords

  • Diazoxide
  • Hydroethidine
  • Mitochondrial membrane potential
  • Potassium channel
  • Tetramethylrhodamine ethyl ester

ASJC Scopus subject areas

  • Cellular and Molecular Neuroscience

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