Neuregulin-1β prevents Ca(2+) overloading and apoptosis through PI3K/Akt activation in cultured dorsal root ganglion neurons with excitotoxicity induced by glutamate

Cell Mol Neurobiol. 2011 Nov;31(8):1195-201. doi: 10.1007/s10571-011-9721-2. Epub 2011 Jun 14.

Abstract

Neuregulin (NRG) plays an important role on the genesis and differentiation of neurons in the dorsal root ganglion (DRG). Whether NRG-1β regulates Ca(2+) homeostasis and apoptosis of cultured DRG neurons with excitotoxicity induced by Glu remains unknown. In this study, primary cultured DRG neurons were used to determine the effects of NRG-1β on Ca(2+) overload and apoptosis of DRG sensory neurons with excitotoxicity induced by Glu. The primary cultured DRG neurons at 48 h of culture age were then exposed to Glu (0.2 mmol/l), Glu (0.2 mmol/l) plus NRG-1β (20 nmol/l), or Glu (0.2 mmol/l) plus NRG-1β (20 nmol/l) and phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 (10 μmol/l) for additional 12 h. After that, intracellular Ca(2+) concentration ([Ca(2+)](i)) in isolated DRG neurons using the fluorescent Ca(2+) indicator fluo-3 was measured by confocal laser scanning microscope. Apoptotic neurons were monitored by Hoechst 33342 staining. Expression of caspase-3, procaspase-3, and pAkt was detected by Western blot assay. Administration of 0.2 mmol/l Glu evoked an increase in [Ca(2+)](i), confirming the excitatory effect of Glu. Compared with the control group, apoptotic (condensed and fragmented nuclei) neurons were observed in Glu-treated cells after Hoechst 33342 staining. The increase caspase-3 of and decrease of procaspase-3 expression levels after administration of 0.2 mmol/l Glu suggested the apoptotic effects of Glu. These effects could be inhibited by the presence of NRG-1β. The effects of NRG-1β could be blocked by PI3K inhibitor LY294002. These results implicated that NRG-1β could prevents Ca(2+) overload and apoptosis by activating PI3K/Akt pathway of primary cultured DRG neurons with excitotoxicity induced by Glu.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / drug effects
  • Calcium / metabolism*
  • Caspase 3 / metabolism
  • Chromones / pharmacology
  • Enzyme Inhibitors / pharmacology
  • Ganglia, Spinal / cytology*
  • Glutamic Acid / metabolism*
  • Morpholines / pharmacology
  • Neuregulin-1 / pharmacology*
  • Neurons / cytology
  • Neurons / drug effects*
  • Neurons / physiology
  • Phosphatidylinositol 3-Kinase / metabolism*
  • Proto-Oncogene Proteins c-akt / metabolism*
  • Rats
  • Rats, Wistar

Substances

  • Chromones
  • Enzyme Inhibitors
  • Morpholines
  • Neuregulin-1
  • neuregulin beta
  • 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one
  • Glutamic Acid
  • Phosphatidylinositol 3-Kinase
  • Proto-Oncogene Proteins c-akt
  • Caspase 3
  • Calcium