Re-structuring of synapses 24 hours after induction of long-term potentiation in the dentate gyrus of the rat hippocampus in vivo

M. G. Stewart, E. Harrison, D. A. Rusakov, G. Richter-Levin, M. Maroun

Research output: Contribution to journalArticlepeer-review


In male rats, long-term potentiation was induced unilaterally in the dentate gyrus, either by high frequency (200Hz) or theta rhythm stimulation. Structural synaptic changes were examined 24h after induction using quantitative electron microscopy. A disector technique was employed in order to estimate the density of synapses (using 70-80-nm sections) and of granule cell nuclei (using 2-μm sections) in the middle, and inner molecular layer in both hemispheres. Synaptic height and total lateral areas of synaptic active zones per unit tissue volume were assessed via assumption-free stereological techniques coupled with image analysis. The results obtained indicated that both synaptic density and number (corrected per neuron) of axo-spinous, but not axo-dendritic, synapses were ~40% higher in the middle, but not inner molecular layer of the potentiated hemisphere compared to the contralateral (control hemisphere). No significant inter-hemispheric difference was found in the volume densities of lateral areas of active zones.These data suggest that 24h after long-term potentiation induction, active zones of existing axo-spinous synapses either split forming separate contacts, or decrease in size while new synapses are formed. Copyright (C) 2000 IBRO.

Original languageEnglish
Pages (from-to)221-227
Number of pages7
Issue number2
StatePublished - 14 Sep 2000

Bibliographical note

Funding Information:
The study was funded by BBSRC Grant S02085 and by the Wellcome Trust.We are grateful to. T.V.P Bliss of the National Institute for Medical Research, Mill Hill, London for helpful discussions on this work.


  • Axo-spinous
  • Dentate
  • Morphology
  • Potentiation
  • Synapse restructuring

ASJC Scopus subject areas

  • General Neuroscience


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