Anatomical and Physiological Properties of GABAergic Neurotransmission in Organotypic Slice Cultures of Rat Hippocampus

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Abstract
The anatomical and physiological properties of GABAergic inhibitory neurotransmission were investigated in organotypic slice cultures of rat hippocampus. Interneurons and terminal‐like elements containing GABA‐like immunoreactivity were numerous in tissue kept for 13–26 days in culture and showed a similar morphology and distribution to those known from investigations on the hippocampal formation in situ. Furthermore, after 8–30 days in culture, spontaneous and evoked IPSPs were observed in all CA3 pyramidal cells tested, resulting from an increase in chloride conductance, and were shown to be mediated by activation of GABA receptors. No functional decrement in the efficacy of GABAergic inhibitory synaptic transmission following chronic isolation and long‐term maintenance in vitro was noticed. In particular, neither the magnitude of the synaptic conductance underlying the inhibitory postsynaptic currents nor its reversal potential varied with time in culture. Taken together, the present physiological and immunohistochemical data show that GABAergic inhibition is well expressed in organotypic hippocampal slice cultures and is maintained over periods of at least 4 weeks in vitro.