Brain-derived neurotrophic factor prevents changes in Bcl-2 family members and caspase-3 activation induced by excitotoxicity in the striatum

J Neurochem. 2005 Feb;92(3):678-91. doi: 10.1111/j.1471-4159.2004.02904.x.

Abstract

Brain-derived neurotrophic factor (BDNF) prevents the loss of striatal neurons caused by excitotoxicity. We examined whether these neuroprotective effects are mediated by changes in the regulation of Bcl-2 family members. We first analyzed the involvement of the phosphatidylinositol 3-kinase/Akt pathway in this regulation, showing a reduction in phosphorylated Akt (p-Akt) levels after both quinolinate (QUIN, an NMDA receptor agonist) and kainate (KA, a non-NMDA receptor agonist) intrastriatal injection. Our results also show that Bcl-2, Bcl-x(L) and Bax protein levels and heterodimerization are selectively regulated by NMDA and non-NMDA receptor stimulation. Striatal cell death induced by QUIN is mediated by an increase in Bax and a decrease in Bcl-2 protein levels, leading to reduced levels of Bax:Bcl-2 heterodimers. In contrast, changes in Bax protein levels are not required for KA-induced apoptotic cell death, but decreased levels of both Bax:Bcl-2 and Bax:Bcl-x(L) heterodimer levels are necessary. Furthermore, QUIN and KA injection activated caspase-3. Intrastriatal grafting of a BDNF-secreting cell line counter-regulated p-AKT, Bcl-2, Bcl-x(L) and Bax protein levels, prevented changes in the heterodimerization between Bax and pro-survival proteins, and blocked caspase-3 activation induced by excitotoxicity. These results provide a possible mechanism to explain the anti-apoptotic effect of BDNF against to excitotoxicity in the striatum through the regulation of Bcl-2 family members, which is probably mediated by Akt activation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Brain-Derived Neurotrophic Factor / pharmacology*
  • Caspase 3
  • Caspases / metabolism*
  • Cell Death / drug effects
  • Corpus Striatum / drug effects*
  • Corpus Striatum / metabolism*
  • Dimerization
  • Enzyme Activation / drug effects
  • Excitatory Amino Acid Agonists / toxicity
  • Kainic Acid / toxicity
  • Male
  • Mice
  • Mice, Knockout
  • Microinjections
  • Neurotoxins / toxicity*
  • Protein Serine-Threonine Kinases / metabolism
  • Proto-Oncogene Proteins / metabolism
  • Proto-Oncogene Proteins c-akt
  • Proto-Oncogene Proteins c-bcl-2 / metabolism*
  • Quinolinic Acid / toxicity
  • Rats
  • Rats, Inbred F344
  • bcl-2-Associated X Protein
  • bcl-X Protein

Substances

  • Bax protein, mouse
  • Bax protein, rat
  • Bcl2l1 protein, mouse
  • Bcl2l1 protein, rat
  • Brain-Derived Neurotrophic Factor
  • Excitatory Amino Acid Agonists
  • Neurotoxins
  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-bcl-2
  • bcl-2-Associated X Protein
  • bcl-X Protein
  • Akt1 protein, rat
  • Protein Serine-Threonine Kinases
  • Proto-Oncogene Proteins c-akt
  • Casp3 protein, mouse
  • Casp3 protein, rat
  • Caspase 3
  • Caspases
  • Quinolinic Acid
  • Kainic Acid