Methylmercury enhances arachidonic acid release and cytosolic phospholipase A2 expression in primary cultures of neonatal astrocytes

Gouri Shanker, Lysette A. Mutkus, Stephen J. Walker, Michael Aschner

Research output: Contribution to journalArticle

60 Citations (Scopus)

Abstract

Cytosolic phospholipase A2 (cPLA2) stimulates the hydrolysis of sn-2 ester bond in membrane phospholipids releasing arachidonic acid (AA) and lysophospholipids. The present study examined the effect of methylmercury (MeHg) on cPLA2 activation and AA release in primary cultures of neonatal rat cerebral astrocytes. Astrocytes were preloaded overnight at 37°C with 3H-AA to metabolically label phospholipids. The effect of MeHg on the activation of cPLA2 was measured by the release of 3H-AA from astrocytes over 120 min. MeHg (5 μM) caused a significant increase in AA release at 10, 30, 60, and 120 min, whereas 2.5 μM MeHg significantly increased AA release only at 120 min. MeHg-induced increase in 3H-AA release was due to cPLA2 activation, since arachidonyl trifluoromethyl ketone (AACOCF3), a selective inhibitor of cPLA2, completely abolished MeHg's effect. Consistent with these observations, MeHg (5.0 and 10.0 μM) increased cPLA2 mRNA (6 h) and cPLA2 protein expression (5.0 and 10.0 μM; 24 h). The time-course of these effects suggests an immediate direct or indirect effect of MeHg on cPLA2 activation and 3H-AA release as well as a long-term effect involving the induction of cPLA2. Thin layer chromatographic analysis of 3H-AA-labeled phospholipids showed that MeHg-stimulated astrocyte 3H-AA release was not due to increased incorporation of 3H-AA into the putative substrates of cPLA2. These results invoke cPLA2 as a putative target for MeHg toxicity, and support the notion that cPLA2-stimulated hydrolysis and release of AA play a critical role in MeHg-induced neurotoxicity.

Original languageEnglish (US)
Pages (from-to)1-11
Number of pages11
JournalMolecular Brain Research
Volume106
Issue number1-2
DOIs
StatePublished - Oct 15 2002
Externally publishedYes

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Cytosolic Phospholipases A2
Arachidonic Acid
Astrocytes
Phospholipids
Hydrolysis
Lysophospholipids
Thin Layer Chromatography

Keywords

  • Arachidonic acid
  • Astrocytes
  • Cytosolic phospholipase A
  • In vitro
  • Methylmercury

ASJC Scopus subject areas

  • Molecular Biology
  • Cellular and Molecular Neuroscience

Cite this

Methylmercury enhances arachidonic acid release and cytosolic phospholipase A2 expression in primary cultures of neonatal astrocytes. / Shanker, Gouri; Mutkus, Lysette A.; Walker, Stephen J.; Aschner, Michael.

In: Molecular Brain Research, Vol. 106, No. 1-2, 15.10.2002, p. 1-11.

Research output: Contribution to journalArticle

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