The influence of 5,7-dihydroxytryptamine lesions of the rat fornix-fimbria and cingulum bundles on spontaneous activity in an aversive maze

D. A. F. Robertson, J. E. Beattie, I. C. Reid, D. J. K. Balfour

Research output: Contribution to journalArticle


Exposure to aversive environmental stimuli stimulates the serotonergic neurones that project to the forebrain and inhibit spontaneous activity when studied in a simple maze. This study explored the putative role of the principal 5-hydroxytryptamine (5-HT) neurones that project to the hippocampus from the median raphe nucleus in this response to an aversive environment by lesioning the 5-HT fibres that project through the fornix/fimbria and cingulum bundles. The effects of the lesions were investigated in independent groups of animals tested in an enclosed four-arm maze and a more aversive elevated maze of the same dimensions composed entirely of four open arms. The rats were significantly less active in the open maze, the principal effect of maze design being observed during the first 5 min sub-trial of a 15 min trial. This response to the more aversive environment was totally abolished by the lesion. It is concluded that exposure to an explicitly aversive environment elicits a brief stimulation of the 5-HT neurones that project to the hippocampus from the median raphe nucleus and that this stimulation inhibits the initial burst of exploratory activity that is observed in animals placed in a less aversive novel environment.
Original languageEnglish
Pages (from-to)285-289
Number of pages5
JournalJournal of Psychopharmacology
Issue number3
Early online date21 Jan 2008
Publication statusPublished - May 2008



  • hippocampus
  • 5-HT
  • locomotor activity
  • 5,7-dihydroxytryptamine

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