Presynaptic GABAB receptors differentially modulate GABA release from cholecystokinin and parvalbumin interneurons onto CA1 pyramidal neurons: A cell type-specific labeling and activating study

Combining cell type-specific optogenetics and whole cell recordings on mouse acute hippocampal slices, we compared GABA release from cholecystokinin-expressing (CCK) and parvalbumin-expressing (PV) interneurons onto CA1 pyramidal neurons. Baclofen, a selective GABAB receptor agonist, inhibited GABAergic synaptic transmission greater from CCK terminals, compared to that from PV terminals. The N-type calcium channels on CCK and P/Q-type calcium channels on PV terminals contributed to the GABAB receptor-mediated inhibition, respectively. Our data thus provide direct evidence that GABAB receptors differentially modulate GABA release from CCK and PV interneurons, adding to an increasing list of differences between these two interneuron subtypes in modulating hippocampal pyramidal neurons.