Involvement of the insular cortex in regulating glucocorticoid effects on memory consolidation of inhibitory avoidance training

Raquel V. Fornari, Romy Wichmann, Erika Atucha, Tifany Desprez, Ellie Eggens-Meijer, Benno Roozendaal*

*Corresponding author for this work

    Research output: Contribution to journalArticleAcademicpeer-review

    21 Citations (Scopus)
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    Abstract

    Glucocorticoids are known to enhance the consolidation of memory of emotionally arousing experiences by acting upon a network of interconnected brain regions. Although animal studies typically do not consider the insular cortex (IC) to be part of this network, the present findings indicate that the IC is importantly involved in regulating glucocorticoid effects on memory consolidation of emotionally arousing inhibitory avoidance training. The specific glucocorticoid receptor (GR) agonist RU 28362 (3 or 10 ng in 0.5 mu l) infused bilaterally into the IC of male SpragueDawley rats immediately after one-trial inhibitory avoidance training dose-dependently enhanced 48 h retention performance. Moreover, training on the inhibitory avoidance task increased neuronal activity of the IC, as assessed by an increased number of cells expressing immunoreactivity for phosphorylated extracellular signal-regulated kinase 1/2 (pERK1/2). However, systemic administration of a memory-enhancing dose of corticosterone (1 mg/kg) after inhibitory avoidance training rapidly reduced the number of pERK1/2-positive cells in the IC, suggesting that glucocorticoid administration reduces overall neuronal activity of the IC. To investigate which components of the inhibitory avoidance training experience were influenced by the intra-IC glucocorticoid administration, in the last experiment rats were trained on a modified inhibitory avoidance task in which context exposure and footshock training occur on two sequential days. RU 28362 administration into the IC enhanced later retention when infused immediately after either the context or footshock training. Thus, these findings indicate that the IC mediates glucocorticoid effects on the consolidation of memory of different components of inhibitory avoidance training and suggest that the IC might be an important element of the rodent brain network involved in emotional regulation of learning and memory.

    Original languageEnglish
    Article number10
    Number of pages11
    JournalFrontiers in Behavioral Neuroscience
    Volume6
    DOIs
    Publication statusPublished - 15-Mar-2012

    Keywords

    • stress
    • emotional memory
    • corticosterone
    • pERK
    • insula
    • glucocorticoid receptor
    • CONDITIONED TASTE-AVERSION
    • OBJECT RECOGNITION MEMORY
    • RAT BASOLATERAL AMYGDALA
    • ACTIVATED PROTEIN-KINASE
    • MEDIAL PREFRONTAL CORTEX
    • EVENT-RELATED FMRI
    • LONG-TERM-MEMORY
    • EMOTIONAL MEMORIES
    • UNFAMILIAR TASTE
    • MAPK CASCADE

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