Activation of mu-opioid receptors in the ventrolateral orbital cortex inhibits the GABAergic miniature inhibitory postsynaptic currents in rats.

•DAMGO reduced GABAergic mIPSCs frequency in the VLO slices.•DAMGO failed to alter GABAergic mIPSCs amplitude in the VLO slices.•Pretreatment with CTOP reversed DAMGO induced effects in the VLO slices.•Application of CTOP alone into the VLO slice did not produce any effect.•Mu-opioid receptors would presynaptically inhibit the GABA release in the VLO.