The GABA(A)ρ receptors in hippocampal spontaneous activity and their distribution in hippocampus, amygdala and visual cortex

A bicuculline-resistant and TPMPA-sensitive GABAergic component was identified in hippocampal neurons in culture and in acute isolated brain slices. In both preparations, total GABAergic activity showed two inactivation kinetics: fast and slow. RT-PCR, in situ hybridization (ISH) and immunohistochemistry detected expression of GABAρ subunits. Immunogold and electron microscopy indicated that the receptors are mostly extrasynaptic. In addition, by RT-PCR and immunofluorescence we found GABAρ present in amygdala and visual cortex.

► In mouse hippocampus a spontaneous activity was not blocked with TTX, CNQX, and bicuculline.
► This component was TPMPA-sensitive, attributed to the GABAρ expression.
► By RT-PCR, ISH, immunohistochemistry and immunogold; we detected GABAρ distribution.
► Additionally, we described the GABAρ localization in amygdala, and secondary visual cortex mediomedial area.