(A–C) Effect of pre- and postsynaptic overexpression of αNrxn1 and Nlgn3Δ, respectively, on unitary inhibitory synaptic transmission in organotypic slice cultures prepared from VGT3/NrxnTKO/RFP mice. (A) Configuration of triple whole-cell recording (left top), superimposed fluorescent, and Nomarski images (right top). (Bottom) Individual fluorescence and Nomarski images of TdTomato (left) and tag-blue fluorescent protein (tag-BFP; right). (B) Averaged sample unitary inhibitory postsynaptic current (uIPSC) traces. Nrxns and Nlgn3Δ were transfected in TdTomato-positive and CA1 pyramidal neurons, respectively, by electroporation. (C, D, and E) Summary of uIPSC amplitude (C), paired-pulse ratio (D), and connectivity (E). Numbers of cell pairs: αNrxn1+AS4, αNrxn1-AS4, and BFP at VGT3+ synapses (seven pairs/three mice, 9/4 and 9/4). The number of tested slice cultures is the same as that of cell pairs. Mann–Whitney U-test.