Repeated restraint stress facilitates fear conditioning independently of causing hippocampal CA3 dendritic atrophy

Behav Neurosci. 1999 Oct;113(5):902-13. doi: 10.1037//0735-7044.113.5.902.

Abstract

This study investigated whether 21 days of restraint stress (6 hr/day) and the subsequent hippocampal dendritic atrophy would affect fear conditioning, a memory task with hippocampal-dependent and hippocampal-independent components. Restraint-stressed rats were injected daily (21 days) with tianeptine (10 mg/kg; to prevent hippocampal atrophy) or vehicle then tested on fear conditioning (Days 23-25, with 2 tone-shock pairings) and open field (Day 25). Restraint stress enhanced freezing to context (hippocampal-dependent behavior) and tone (hippocampal-independent) and decreased open-field exploration, irrespective of whether tianeptine was given. Results confirmed that stress produced CA3 dendritic atrophy and tianeptine prevented it. Moreover, CA3 dendritic atrophy was not permanent but reversed to control levels by 10 days after the cessation of restraint stress. These data argue that different neural substrates underlie spatial recognition memory and fear conditioning.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Antidepressive Agents, Tricyclic / pharmacology
  • Cell Size / drug effects
  • Cell Size / physiology
  • Conditioning, Psychological / drug effects
  • Conditioning, Psychological / physiology*
  • Dendrites / drug effects
  • Dendrites / physiology*
  • Exploratory Behavior / drug effects
  • Exploratory Behavior / physiology
  • Fear / drug effects
  • Fear / physiology*
  • Hippocampus / cytology
  • Hippocampus / drug effects
  • Hippocampus / physiology
  • Male
  • Pyramidal Cells / cytology
  • Pyramidal Cells / drug effects
  • Pyramidal Cells / physiology*
  • Rats
  • Rats, Sprague-Dawley
  • Restraint, Physical
  • Stress, Physiological / physiopathology*
  • Thiazepines / pharmacology

Substances

  • Antidepressive Agents, Tricyclic
  • Thiazepines
  • tianeptine