Layer-specific potentiation of evoked IPSCs in rat hippocampal CA1 pyramidal cells by lanthanum

Lanthanum (La3+) potentiates or depresses GABAA receptors (GABAAR) in a subunit-dependent manner. Such differential modulators may help to discriminate between-layer-specific inhibitory synaptic inputs to individual neurons, which use different molecular GABAAR isoforms. Here, we show that inhibitory postsynaptic currents (IPSCs) in CA1 pyramidal cells are potentiated by La3+ (100 microM) when they are evoked by stimulation in stratum oriens. In contrast, stimulation in stratum radiatum yields IPSCs which are not sensitive towards La3+. These data point towards an input-specific molecular and functional diversity of inhibitory synapses at CA1 pyramidal cells.