title: Corticosterone-induced enhancement of memory and synaptic Arc protein in the medial prefrontal cortex.
abstract: Acute administration of the stress hormone corticosterone enhances memory consolidation in a manner that is dependent upon the modulatory effects of the basolateral complex of the amygdala (BLA). Posttraining administration of corticosterone increases expression of the activity-regulated cytoskeletal-associated protein (Arc) in hippocampal synaptic-enriched fractions. Interference with hippocampal Arc expression impairs memory, suggesting that the corticosterone-induced increase in hippocampal Arc plays a role in the memory enhancing effect of the hormone. Blockade of β-adrenoceptors in the BLA attenuates the corticosterone-induced increase in hippocampal Arc expression and blocks corticosterone-induced memory enhancement. To determine whether posttraining corticosterone treatment affects Arc protein expression in synapses of other areas of the brain that are involved in memory processing, a memory-enhancing dose of corticosterone was administered to rats immediately after inhibitory avoidance training. As seen in the hippocampus, Arc protein expression was increased in synaptic fractions taken from the prelimbic region of the medial prefrontal cortex (mPFC). Blockade of Arc protein expression significantly impaired memory, indicating that the protein is necessary in the mPFC for long-term memory formation. To test the hypothesis that blockade of β-adrenoceptors in the BLA would block the effect of systemic corticosterone on memory and attenuate mPFC Arc expression, as it does in the hippocampus, posttraining intra-BLA microinfusions of the β-adrenoceptor antagonist propranolol were given concurrently with the systemic corticosterone injection. Although this treatment blocked corticosterone-induced memory enhancement, it increased corticosterone-induced Arc protein expression in mPFC synaptic fractions. These findings suggest that the BLA mediates stress hormone effects on memory by participating in the negative or positive regulation of corticosterone-induced synaptic plasticity in efferent brain regions.
authors.affiliation: School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX 75080-3021, United States.
authors.forename: Jayme R
authors.initials: JR
authors.lastname: McReynolds
authors.affiliation: School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX 75080-3021, United States.
authors.forename: Crystal M
authors.initials: CM
authors.lastname: Holloway-Erickson
authors.affiliation: School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX 75080-3021, United States.
authors.forename: Tulja U
authors.initials: TU
authors.lastname: Parmar
authors.affiliation: School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX 75080-3021, United States. Electronic address: christa.mcintyre@utdallas.edu.
authors.forename: Christa K
authors.initials: CK
authors.lastname: McIntyre
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D066272:Basolateral Nuclear Complex / Q000187:drug effects / Q000378:metabolism*; D003345:Corticosterone / Q000494:pharmacology*; D003598:Cytoskeletal Proteins / Q000096:biosynthesis* / Q000187:drug effects; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008569:Memory Disorders / Q000139:chemically induced / Q000378:metabolism*; D057567:Memory, Long-Term / Q000187:drug effects / Q000502:physiology*; D009419:Nerve Tissue Proteins / Q000096:biosynthesis* / Q000187:drug effects; D009473:Neuronal Plasticity / Q000187:drug effects / Q000502:physiology; D017397:Prefrontal Cortex / Q000187:drug effects / Q000378:metabolism*; D011433:Propranolol / Q000008:administration & dosage / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013569:Synapses / Q000187:drug effects / Q000378:metabolism
chemical_list: D000319:Adrenergic beta-Antagonists; D003598:Cytoskeletal Proteins; D009419:Nerve Tissue Proteins; C092069:activity regulated cytoskeletal-associated protein; D011433:Propranolol; D003345:Corticosterone
keywords: Avoidance learning; BLA; Cortisol; Immediate early gene; Memory consolidation; Norepinephrine; Stress; Synaptic plasticity