Psychopharmacology

, Volume 123, Issue 4, pp 346–352 | Cite as

Increased 5-HT2C receptor responsiveness occurs on rearing rats in social isolation

  • K. C. F. Fone
  • K. Shalders
  • Z. D. Fox
  • R. Arthur
  • C. A. Marsden
Original Investigation

Abstract

To investigate whether isolation rearing alters 5-hydroxytryptamine2C (5-HT2C) receptors, the effect of the serotonin agonistm-chlorophenylpiperazine (mCPP) was examined on elevated plus-maze behaviour, plasma corticosterone and brain 5-HT2C receptor protein levels in rats. There was no distinction between behaviour or corticosterone levels in drug-free isolates or socially housed rats exposed to the elevated plus-maze. The anxiogenic response tomCPP (decrease in open arm entry and time and an increase in stretch attend postures) on the elevated plus-maze was greater in isolation than in socially reared controls without any concomitant difference in the hypolocomotor effect ofmCPP in the two groups.mCPP produced a greater elevation in plasma corticosterone in isolates than in group-housed controls. Hippocampal 5-HT2C receptor protein-like immunoreactive levels were significantly lower followingmCPP than saline only in rats reared in isolation. These results indicate that increased 5-HT2C receptor responsiveness accompanies isolation-rearing and may contribute to the enhanced response to stress and the increased neophobia seen in this animal model of trait anxiety/depression. In isolation reared rats, rapid down-regulation of supersensitive 5-HT2C receptors may occur in the hippocampus following 5-HT agonist challenge.

Key words

5-Hydroxytryptamine2C receptors Social isolation Elevated plus-maze Anxiety Corticosterone Serotonin 

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Copyright information

© Springer-Verlag 1996

Authors and Affiliations

  • K. C. F. Fone
    • 1
  • K. Shalders
    • 1
  • Z. D. Fox
    • 1
  • R. Arthur
    • 1
  • C. A. Marsden
    • 1
  1. 1.Department of Physiology and Pharmacology, Queen's Medical CentreNottingham UniversityNottinghamUK

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