Different pattern of brain c-Fos expression following re-exposure to ethanol or sucrose self-administration environment

Naunyn Schmiedebergs Arch Pharmacol. 2003 Nov;368(5):331-41. doi: 10.1007/s00210-003-0811-7. Epub 2003 Oct 22.


Exposure of alcohol addicts to alcohol-related environmental cues may elicit alcohol-seeking behavior and lead to relapse to heavy drinking. The aim of the present study was to identify brain regions activated by alcohol (ethanol)-related stimuli in Wistar rats trained to lever press for 8% ethanol solution in operant self-administration cages. Ethanol self-administration was stabilized in a maintenance phase, which lasted for 30 days. c-Fos protein expression was used as a marker of neuronal activation.Re-exposure to ethanol self-administration environment after 30-day but not after 24-h abstinence increased the number of Fos-positive nuclei in the thalamic paraventricular nucleus, granular insular cortex and medial prefrontal cortex. In general, no differences were found in c-Fos protein expression between the rats allowed to self-administer alcohol and the subjects exposed only to alcohol-related stimuli. In contrast, no increase in c-Fos immunoreactivity was observed in rats trained to lever press for sucrose solution and exposed to sucrose-related environmental stimuli after 30-day abstinence. Taken together, these results suggest that at least some thalamo-cortical circuits become more responsive to ethanol-paired stimuli after prolonged abstinence and that ethanol- and sucrose-seeking behavior may be regulated by partially different neural mechanism(s).

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Body Weight / drug effects
  • Brain / metabolism*
  • Conditioning, Operant / drug effects
  • Ethanol / administration & dosage
  • Ethanol / pharmacology*
  • Extinction, Psychological
  • Gene Expression
  • Immunohistochemistry
  • Male
  • Organ Specificity
  • Proto-Oncogene Proteins c-fos / biosynthesis*
  • Proto-Oncogene Proteins c-fos / genetics
  • Rats
  • Self Administration
  • Sucrose / administration & dosage
  • Sucrose / pharmacology*


  • Proto-Oncogene Proteins c-fos
  • Ethanol
  • Sucrose