Inactivation of the medial prefrontal cortex with the GABAA receptor agonist muscimol increases open-arm activity in the elevated plus-maze and attenuates shock-probe burying in rats.

This study examined the effects of infusions of a direct GABA(A) receptor agonist, muscimol, into the medial prefrontal cortex (MPFC), on fear behavior measured in the elevated plus-maze and shock-probe burying tests. Bilateral infusions of either a 0.175 or 4 nmol/0.5 microl dose of muscimol increased the percentage of entries and time spent in the open arms, and attenuated shock-probe burying. These findings indicate that intra-MPFC infusions of muscimol induce anxiolysis, and suggest that the direct stimulation of MPFC GABA(A) receptors attenuates fear-related behavior.