Effect of 5-hydroxytryptophane on behavior and hippocampal physiology in young and old rats

Y. Levkovitz, G. Richter-Levin, M. Segal

Research output: Contribution to journalArticlepeer-review


Spatial memory ability, tested in a water maze, was severely impaired in control, 24-month-old hooded rats. A daily injection of the serotonin precursor, 5-hydroxytryptophane (5-HTP), prior to training sessions, had no effect on the behavior of the young rats but improved considerably the performance of the old rats in the watermaze. In the same groups of young and aged rats, the response properties of the hippocampal dentate gyrus to perforant path stimulation was assessed before and after parenteral administration of 5-HTP. The dentate gyrus of aged rats produces a smaller EPSPs in response to perforant path stimulation but a larger population spike for a given EPSP than that produced in young rat brains. These differences are not affected by 5-HTP. In young brains, priming commissural stimulation suppresses subsequent reactivity to perforant path stimulation. This priming effect is nearly absent in aged rat hippocampus but reappears when the rat is injected with 5-HTP. It is suggested that the serotonergic innervation of the rat hippocampus plays a major role in regulation of the excitability of the hippocampus and in behavioral functions associated with this structure.

Original languageEnglish
Pages (from-to)635-641
Number of pages7
JournalNeurobiology of Aging
Issue number5
StatePublished - 1994
Externally publishedYes

Bibliographical note

Funding Information:
This research was supported by Grant No. 89/011 from the United States-Israel Binational Science Foundation (BSF), Jerusalem, Israel. We thank E. Schechter for statistical consultation.


  • Aging
  • Evoked potentials
  • Hippocampus
  • Rat
  • Serotonin
  • Spatial learning

ASJC Scopus subject areas

  • Neuroscience (all)
  • Aging
  • Clinical Neurology
  • Developmental Biology
  • Geriatrics and Gerontology


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