Objectives: There has been increasing evidence that the γ-aminobutyric acid (GABA)ergic system is involved in the neurobiology of anxiety. The present study aimed to investigate the role of GABAergic systems in the modulation of anxiety in the medial prefrontal cortex (mPFC) of rats using the elevated plus maze test.
Methods: Rats were anaesthetised with a mixture of ketamine and xylazine, and then special cannulae were inserted stereotaxically into the mPFC. After 5-7 days of recovery, the effects of intra-mPFC administration of GABAergic agents were studied.
Results: Bilateral injection of the GABAA receptor agonist muscimol (0.25, 0.5 and 1 μg/rat) produces an anxiolytic-like effect, shown by significant increases in the percentage of open-arm time (%OAT) and percentage of open-arm entries (%OAE). Intra-mPFC administration of the GABAA receptor antagonist bicuculline (0.25, 0.5 and 1 μg/rat) produces significant anxiogenic-like behaviour. However, intra-mPFC injection of the GABAB receptor agonist baclofen (0.05, 0.1 and 0.2 μg/rat) and the GABAB receptor antagonist CGP35348 (5, 10 and 15 μg/rat) did not alter %OAT and %OAE significantly.
Conclusion: The results of the present study demonstrate that the GABAergic system of the mPFC modulates anxiety-related behaviours of rats through GABAA receptors.