Neurobiology of Disease (Sep 2006)

Selective injury to dopaminergic neurons up-regulates GDNF in substantia nigra postnatal cell cultures: Role of neuron–glia crosstalk

  • Ana Saavedra,
  • Graça Baltazar,
  • Paulo Santos,
  • Caetana M. Carvalho,
  • Emília P. Duarte

Journal volume & issue
Vol. 23, no. 3
pp. 533 – 542

Abstract

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The effect of selective injury to dopaminergic neurons on the expression of glial cell line-derived neurotrophic factor (GDNF) was examined in substantia nigra cell cultures. H2O2, mimicking increased oxidative stress, or l-DOPA, the main symptomatic treatment for Parkinson's disease, increased GDNF mRNA and protein levels in a time-dependent mode in neuron–glia mixed cultures. The concentration dependence indicated that mild, but not extensive, injury induced GDNF up-regulation. GDNF neutralization with an antibody decreased dopaminergic cell viability in H2O2-treated cultures, showing that up-regulation of GDNF was protecting dopaminergic neurons. Neither H2O2 nor l-DOPA directly affected GDNF expression in astrocyte cultures, but conditioned media from challenged mixed cultures increased GDNF mRNA and protein levels in astrocyte cultures, indicating that GDNF up-regulation was mediated by neuronal factors. Since pretreatment with 6-OHDA completely abolished H2O2-induced GDNF up-regulation, we propose that GDNF up-regulation is triggered by failing dopaminergic neurons that signal astrocytes to increase GDNF expression.

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