title: Effects of inescapable stress on LTP in the amygdala versus the dentate gyrus of freely behaving rats.
abstract: Stress impairs hippocampal long-term potentiation (LTP), a model of synaptic plasticity that is assumed to underlie memory formation. In the amygdala, little is known about the effects of stress on LTP, or about its longevity. Here we assessed the ability of entorhinal cortex (EC) stimulation to induce LTP simultaneously in the basal amygdaloid nucleus (B) and in the dentate gyrus (DG) of freely behaving Wistar rats. We also tested whether LTP persists over days. Once established, we investigated the effects of acute vs. repeated inescapable stressful experiences on LTP in both structures. Results show that B, like DG, sustained LTP for 7 days. Furthermore, a single exposure to moderate stress facilitated LTP in B but did not affect DG LTP. Stress re-exposure inhibited LTP in DG but only long-lasting LTP (>3 days) in B. Behaviourally, animals exhibited a higher immobility when re-exposed to the stressor than with a single/first exposure. These data support a role for B in memory storage. Furthermore, they support a differential involvement of the amygdala and hippocampus in memory formation and storage depending on the emotional characteristics of the experience.
authors.affiliation: Department of Psychology, and the Brain and Behaviour Research Center, University of Haifa, 31905, Israel. rvouimba@chuma1.cas.usf.edu
authors.forename: Rose-Marie
authors.initials: RM
authors.lastname: Vouimba
authors.forename: Dan
authors.initials: D
authors.lastname: Yaniv
authors.forename: David
authors.initials: D
authors.lastname: Diamond
authors.forename: Gal
authors.initials: G
authors.lastname: Richter-Levin
mesh_terms: D000679:Amygdala / Q000502:physiology*; D000818:Animals; D001522:Behavior, Animal; D018891:Dentate Gyrus / Q000502:physiology*; D004558:Electric Stimulation / Q000379:methods; D018728:Entorhinal Cortex / Q000502:physiology / Q000528:radiation effects; D007103:Immobilization; D017774:Long-Term Potentiation / Q000502:physiology* / Q000528:radiation effects; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D013315:Stress, Psychological / Q000503:physiopathology*; D009435:Synaptic Transmission / Q000502:physiology; D013997:Time Factors; D014851:Wakefulness / Q000187:drug effects / Q000502:physiology*