Effects of IL-6 secreted from astrocytes on the survival of dopaminergic neurons in lipopolysaccharide-induced inflammation

Neurosci Res. 2009 Nov;65(3):252-8. doi: 10.1016/j.neures.2009.07.007. Epub 2009 Jul 30.

Abstract

The role of astrocytes in microglia-induced neuronal death remains controversial. In this study, astrocytes and astrocyte-derived conditioned media (ACM) supported the survival of dopaminergic neurons, and the former was more effective than the latter. In the presence of astrocytes, low concentrations of LPS enhanced the survival of dopaminergic neurons, while high concentrations attenuated survival. LPS dramatically induced astrocytes to secrete IL-6 in a dose-dependent manner with no effect on secretion of GDNF. Neuron-astrocyte cultures had highest secretion of GDNF, followed by ACM-treated neuron-enriched cultures. After neuron-astrocyte cultures treated with IL-6-neutralizing antibody, both effects of the enhanced and attenuated survival of dopaminergic neurons were abolished. Our results indicate that astrocytes play a protective role in the LPS-induced damage of dopaminergic neurons in certain circumstances, and the interaction between astrocytes and dopaminergic neurons may enhance the protective effect of astrocytes. Suitable activation of astrocytes increases the protective effect while excessive activation attenuates it, and IL-6 might mediate this dual action. The underlying mechanisms related to the secretion of GDNF and proinflammatory factors warrant further investigation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Newborn
  • Astrocytes / drug effects
  • Astrocytes / metabolism*
  • Cell Communication / drug effects
  • Cell Communication / immunology
  • Cell Survival / drug effects
  • Cell Survival / immunology
  • Cells, Cultured
  • Coculture Techniques
  • Cytoprotection / immunology
  • Dopamine / metabolism
  • Dose-Response Relationship, Drug
  • Encephalitis / immunology
  • Encephalitis / metabolism*
  • Encephalitis / physiopathology
  • Glial Cell Line-Derived Neurotrophic Factor / metabolism
  • Inflammation Mediators / pharmacology
  • Interleukin-6 / metabolism*
  • Lipopolysaccharides / pharmacology
  • Neurons / immunology
  • Neurons / metabolism*
  • Parkinson Disease / immunology
  • Parkinson Disease / metabolism
  • Parkinson Disease / physiopathology
  • Rats
  • Rats, Sprague-Dawley
  • Substantia Nigra / immunology
  • Substantia Nigra / metabolism
  • Substantia Nigra / physiopathology

Substances

  • Glial Cell Line-Derived Neurotrophic Factor
  • Inflammation Mediators
  • Interleukin-6
  • Lipopolysaccharides
  • Dopamine