Serotonin, but not dopamine, metabolites are increased in selected brain regions of subordinate male rats in a colony environment

D. Caroline Blanchard, Panrapee Cholvanich, Robert J. Blanchard, Daniel W. Clow, Ronald P. Hammer, J. K. Rowlett, Michael T. Bardo

Research output: Contribution to journalArticle

109 Scopus citations

Abstract

Subordinate male laboratory rats maintained in mixed-sex groups in a Visible Burrow System habitat show a complex pattern of stress-related changes including enhanced defensive behavior, early mortality and increased voluntary ethanol consumption. Analysis of serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) levels indicated that 5-HT levels do not differ between colony subordinates, colony dominants, and singly-housed control animals. However, 5-HIAA levels were higher in subordinates than either dominants or control animals in the preoptic area, amygdala, hippocampus, and spinal cord, and, were higher than dominants only, in entorhinal cortex. Subordinates' regional 5-HIAA/5-HT ratios were reliably higher than those of dominant or control animals in midbrain and spinal cord and reliably higher than dominants only, in hypothalamus. Dopamine (DA) and dihydroxyphenylacetic acid (DOPAC) levels and DA/DOPAC ratios were affected neither in hypothalamus nor midbrain. These findings suggest that a consistent increase of 5-HIAA levels in selected brain regions of subordinate rats may represent a biological substrate for a well-characterized pattern of alterations in defensive behaviors for these animals.

Original languageEnglish (US)
Pages (from-to)61-66
Number of pages6
JournalBrain Research
Volume568
Issue number1-2
DOIs
StatePublished - Dec 24 1991
Externally publishedYes

Keywords

  • 5-Hydroxyindoleacetic acid
  • Animal model
  • Depression
  • Serotonin
  • Subordination
  • defensive behavior

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology

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