Differential regulation of ionotropic glutamate receptor subunits following cocaine self-administration

Brain Res. 2005 Dec 7;1064(1-2):75-82. doi: 10.1016/j.brainres.2005.09.051. Epub 2005 Nov 8.

Abstract

Previous examination of binge cocaine self-administration and 2 week withdrawal from cocaine self-administration on ionotropic glutamate receptor subunit (iGluRs) protein levels revealed significant alterations in iGluR protein levels that differed between the mesocorticolimbic and nigrostriatal pathways. The present study was undertaken to extend the examination of cocaine-induced alterations in iGluR protein expression by assessing the effects of acute withdrawal (15-16 h) from limited access cocaine self-administration (8 h/day, 15 days). Western blotting was used to compare levels of iGluR protein expression (NR1-3B, GluR1-7, KA2) in the mesolimbic (ventral tegmental area, VTA; nucleus accumbens, NAc; and prefrontal cortex, PFC) and nigrostriatal pathways (substantia nigra, SN and dorsal caudate-putamen, CPu). Within the mesolimbic pathway, reductions were observed in NR1 and GluR5 immunoreactivity in the VTA although no significant alterations were observed in any iGluR subunits in the NAc. In the PFC, NR1 was significantly upregulated while GluR2/3, GluR4, GluR5, GluR6/7, and KA2 were decreased. Within the nigrostriatal pathway, NR1, NR2A, NR2B, GluR1, GluR6/7 and KA2 were increased in the dorsal CPu, whereas no significant changes were observed in the SN. The results demonstrate region- and pathway-specific alterations in iGluR subunit expression following limited cocaine self-administration and suggest the importance for the activation of pathways that are substrates of the reinforcing and motoric effects of cocaine.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Brain / cytology
  • Brain / drug effects
  • Brain / metabolism*
  • Caudate Nucleus / cytology
  • Caudate Nucleus / drug effects
  • Caudate Nucleus / metabolism
  • Cocaine / administration & dosage*
  • Dopamine Uptake Inhibitors / administration & dosage
  • Male
  • Neural Pathways / cytology
  • Neural Pathways / drug effects
  • Neural Pathways / metabolism*
  • Nucleus Accumbens / cytology
  • Nucleus Accumbens / drug effects
  • Nucleus Accumbens / metabolism
  • Protein Subunits / metabolism
  • Putamen / cytology
  • Putamen / drug effects
  • Putamen / metabolism
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, Glutamate / drug effects
  • Receptors, Glutamate / metabolism*
  • Reinforcement, Psychology*
  • Self Administration
  • Substance Withdrawal Syndrome / metabolism
  • Ventral Tegmental Area / cytology
  • Ventral Tegmental Area / drug effects
  • Ventral Tegmental Area / metabolism

Substances

  • Dopamine Uptake Inhibitors
  • Protein Subunits
  • Receptors, Glutamate
  • Cocaine