Nobiletin attenuates neurotoxic mitochondrial calcium overload through K+ influx and ∆Ψm across mitochondrial inner membrane

Ji Hyung Lee, Khulan Amarsanaa, Jinji Wu, Sang Chan Jeon, Yanji Cui, Sung Cherl Jung, Deok Bae Park, Se Jae Kim, Sang Heon Han, Hyun Wook Kim, Im Joo Rhyu, Su Yong Eun

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Mitochondrial calcium overload is a crucial event in determining the fate of neuronal cell survival and death, implicated in pathogenesis of neurodegenerative diseases. One of the driving forces of calcium influx into mitochondria is mitochondria membrane potential (∆Ψm). Therefore, pharmacological manipulation of ∆Ψm can be a promising strategy to prevent neuronal cell death against brain insults. Based on these issues, we investigated here whether nobiletin, a Citrus polymethoxylated flavone, prevents neurotoxic neuronal calcium overload and cell death via regulating basal ∆Ψm against neuronal insult in primary cortical neurons and pure brain mitochondria isolated from rat cortices. Results demonstrated that nobiletin treatment significantly increased cell viability against glutamate toxicity (100 µM, 20 min) in primary cortical neurons. Real-time imaging-based fluorometry data reveal that nobiletin evokes partial mitochondrial depolarization in these neurons. Nobiletin markedly attenuated mitochondrial calcium overload and reactive oxygen species (ROS) generation in glutamate (100 µM)-stimulated cortical neurons and isolated pure mitochondria exposed to high concentration of Ca2+ (5 µM). Nobiletin-induced partial mitochondrial depolarization in intact neurons was confirmed in isolated brain mitochondria using a fluorescence microplate reader. Nobiletin effects on basal ∆Ψm were completely abolished in K+-free medium on pure isolated mitochondria. Taken together, results demonstrate that K+ influx into mitochondria is critically involved in partial mitochondrial depolarization–related neuroprotective effect of nobiletin. Nobiletin-induced mitochondrial K+ influx is probably mediated, at least in part, by activation of mitochondrial K+ channels. However, further detailed studies should be conducted to determine exact molecular targets of nobiletin in mitochondria.

Original languageEnglish
Pages (from-to)311-319
Number of pages9
JournalKorean Journal of Physiology and Pharmacology
Volume22
Issue number3
DOIs
Publication statusPublished - 2018 May

Keywords

  • Calcium
  • Mitochondrial K+ channels
  • Mitochondrial calcium
  • Mitochondrial membrane potential
  • Nobiletin

ASJC Scopus subject areas

  • Physiology
  • Pharmacology

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