Cocaine-induced Fos expression is detectable in the frontal cortex and striatum of rats under isoflurane but not α-chloralose anesthesia: Implications for FMRI

Peter R. Kufahl, Nathan S. Pentkowski, Krista Heintzelman, Janet Neisewander

Research output: Contribution to journalArticle

18 Scopus citations

Abstract

The ability of intravenous cocaine to induce Fos protein expression in anesthetized rats was tested. Two anesthetic regimens commonly used for in vivo FMRI of animals, i.v. α-chloralose and gaseous isoflurane, were studied in separate cohorts. The first experiment included three groups that received the following treatments: saline i.v. and no anesthetic; 2 mg/kg cocaine i.v. and no anesthetic; and 2 mg/kg cocaine i.v. under 36 mg/kg/h α-chloralose anesthesia. The second experiment had a factorial design of four groups that were either nonanesthetized or isoflurane-treated and were either given saline or cocaine (2 mg/kg, i.v.). Anesthetized rats were maintained for 2 h under 2.5-3.5% isoflurane anesthesia, while nonanesthetized rats were kept in an alternative environment for the same time period. Rats were given 2 mg/kg cocaine or saline i.v., 30 min into the test session. Rats were perfused and their brains were processed for Fos immunohistochemistry 90 min after the i.v. treatment. In both experiments, the frontal cortex and striatum of the cocaine-treated nonanesthetized rats expressed Fos in greater amounts than the saline-treated nonanesthetized rats, as expected. The α-chloralose treatment prevented cocaine-induced Fos expression across all eight subregions of the striatum and frontal cortex that were examined. In contrast, isoflurane only partially attenuated Fos expression in the orbital and Cg2 subregions of frontal cortex. These results suggest a strong advantage for using isoflurane, as opposed to α-chloralose, when studying anesthetized rats for in vivo effects of psychostimulants.

Original languageEnglish (US)
Pages (from-to)241-248
Number of pages8
JournalJournal of Neuroscience Methods
Volume181
Issue number2
DOIs
StatePublished - Jul 30 2009

Keywords

  • Anesthesia
  • Cocaine
  • Fos
  • Immediate early gene
  • Isoflurane
  • c-fos
  • α-Chloralose

ASJC Scopus subject areas

  • Neuroscience(all)

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