Effects of varenicline and varenicline plus nicotine on mIPSCs in MS/DB neurons.A. Representative traces from a MS/DB pyramidal neuron featuring varenicline’s increase in GABA release and nicotine’s further enhancement of GABA release measured as mIPSC frequency. B. Cumulative probability plots of varenicline and nicotine’s effects on GABAAR mIPSC IEI from MS/DB neurons (n = 11–13 cells; number of events over 3 min: baseline = 3267, varenicline = 3864, varenicline + nicotine = 3659). C. Cumulative probability plots of varenicline and nicotine’s effects on GABAAR mIPSC amplitude from MS/DB neurons. (inset) Image of a basal forebrain slice featuring a bi-polar medial septum neuron with attached patch pipette, scale bar = 10 μm. D. Histograms and Gaussian curves of mIPSC amplitudes (10 pA bins). Color code: baseline = blue, varenicline = purple, nicotine plus varenicline = green.