DHA inhibits ER Ca 2+ release and ER stress in astrocytes following in vitro ischemia

Gulnaz Begum, Douglas Kintner, Yan Liu, Samuel W. Cramer, Dandan Sun

Research output: Contribution to journalArticlepeer-review

33 Scopus citations

Abstract

Docosahexaenoic acid (DHA) has neuroprotective effects in several neurodegenerative disease conditions. However, the underlying mechanisms are not well understood. In the present study, we investigated the effects of DHA on astrocyte Ca 2+ signaling under in vitro ischemic conditions (oxygen/glucose deprivation and reoxygenation, OGD/REOX). OGD (2 h) triggered a Ca 2+ ER store overload (∼1.9-fold). Ca 2+ uptake by the Ca 2+ ER stores was further augmented during REOX and Ca 2+ ER was elevated by ∼4.7-fold at 90 min REOX. Interestingly, Ca 2+ ER stores abruptly released Ca 2+ at ∼120 min REOX and emptied at 160 min REOX. Depletion of Ca 2+ ER stores led to delayed elevation of intracellular Ca 2+ concentration (Ca 2+ cyt) and cell death. Activation of the purinergic receptor P2Y1 was responsible for the release of Ca 2+ ER. Most importantly, DHA blocked the initial Ca 2+ ER store overload, the delayed depletion of Ca 2+ ER, and rise in Ca 2+ cyt, which was in part via inhibiting d-myo-inositol 1,4,5-triphosphate receptors. The DHA metabolite DiHDoHE exhibited similar effects. DHA also attenuated expression of phosphorylated eukaryotic initiation factor 2α and activating transcription factor-4, two ER stress markers, following in vitro ischemia. Taken together, these findings suggest that DHA has protective effects in astrocytes following in vitro ischemia, in part, by inhibiting Ca 2+ dysregulation and ER stress.

Original languageEnglish (US)
Pages (from-to)622-630
Number of pages9
JournalJournal of Neurochemistry
Volume120
Issue number4
DOIs
StatePublished - Feb 2012

Keywords

  • ER Ca
  • ER stress
  • IP receptor
  • polyunsaturated fatty acid
  • ryanodine receptor

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