Differential effects of GABAA receptor activation in the prelimbic and orbitofrontal cortices on anxiety

Trudy A. Green, Sarah Baracz, Nick Everett, Katherine J. Robinson, Jennifer L. Cornish*

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    13 Citations (Scopus)
    29 Downloads (Pure)

    Abstract

    Rationale: The development of effective anxiety treatments has been hindered by limited understanding of the neurobiological mechanisms involved in anxiety regulation. Whilst gamma-aminobutyric acid (GABA) neurotransmission in the prefrontal cortex (PFC) is one mechanism consistently implicated in anxiety regulation, PFC subregions may contribute uniquely. Objectives: The present study examined the effects of inactivating the PFC subregions of the prelimbic cortex (PrL) or orbitofrontal cortex (OFC) through GABAA receptor (GABAAR) activation, on anxiety behaviours in male Wistar rats. Methods: Sixty-six male Wistar rats were surgically implanted with bilateral cannulae into the PrL (n = 33) or the OFC (n = 33). Rats then received a microinjection of either the GABAA receptor agonist muscimol or vehicle prior to each experiment, conducted 1 week apart. Measures of anxiety were examined using the elevated plus maze (EPM) and the emergence test (ET). The effect on locomotor activity (baseline or methamphetamine-induced) was also tested. Results: Differential effects of brain region inactivation on anxiety-like behaviour were shown by measures in the EPM and ET; muscimol infused into the PrL-reduced anxiety-like behaviour, yet had no significant effect when infused into the OFC, compared with control treated rats. No effects on locomotor activity at baseline or following methamphetamine treatment were found. Conclusions: This study highlights that activation of GABAARs specifically within the PrL, but not OFC, reduces anxiety behaviours in male rats. This suggests that activity of the PrL plays a more important role than the OFC in the neurobiological mechanisms of unconditioned anxiety and should be targeted for future therapies.

    Original languageEnglish
    Pages (from-to)3237-3247
    Number of pages11
    JournalPsychopharmacology
    Volume237
    Issue number11
    Early online date14 Jul 2020
    DOIs
    Publication statusPublished - Nov 2020

    Keywords

    • anxiety
    • GABA
    • GABA(A) receptors
    • orbitofrontal cortex
    • prelimbic cortex

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