title: Neuregulin-1β prevents Ca(2+) overloading and apoptosis through PI3K/Akt activation in cultured dorsal root ganglion neurons with excitotoxicity induced by glutamate.
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.
authors.affiliation: Department of Anatomy, Shandong University School of Medicine, Jinan 250012, Shandong, China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Liu
authors.forename: Hao
authors.initials: H
authors.lastname: Li
authors.forename: Weiwei
authors.initials: W
authors.lastname: Zhang
authors.forename: Yizhao
authors.initials: Y
authors.lastname: Li
authors.forename: Huaxiang
authors.initials: H
authors.lastname: Liu
authors.forename: Zhenzhong
authors.initials: Z
authors.lastname: Li
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D053148:Caspase 3 / Q000378:metabolism; D002867:Chromones / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005727:Ganglia, Spinal / Q000166:cytology*; D018698:Glutamic Acid / Q000378:metabolism*; D009025:Morpholines / Q000494:pharmacology; D020890:Neuregulin-1 / Q000494:pharmacology*; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D058539:Phosphatidylinositol 3-Kinase / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D002867:Chromones; D004791:Enzyme Inhibitors; D009025:Morpholines; D020890:Neuregulin-1; C117467:neuregulin beta; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D018698:Glutamic Acid; D058539:Phosphatidylinositol 3-Kinase; D051057:Proto-Oncogene Proteins c-akt; D053148:Caspase 3; D002118:Calcium