Early-life inflammation diminished presynaptic GABA_B receptor activity in adult mice. A, Top, Diagram showing synaptic cleft in presence of the GABA_B receptor agonist baclofen in a vehicle-treated adult pyramidal cell; normal GABA_B receptor activity maintains low presynaptic glutamate release and low postsynaptic spontaneous EPSC frequency (f). Bottom, Diagram illustrates that baclofen acting on GABA_B receptors is less effective (dotted line) to decrease presynaptic glutamate release and postsynaptic spontaneous EPSC f in adult neonatally inflamed pyramidal cells. B, Representative scaled traces of paired pulse recording (with/without baclofen) of CA1 pyramidal cells evoked by stimulation of afferent fibers in the Schaffer collateral pathway from adult female (left) and male (right) mice exposed in early life to Veh (dark traces) or LPS (green/blue traces). Calibration: 200 pA, 20 ms. C, D, Scatter graphs on left show PPR of individual cells (with/without baclofen) and violin graphs on right show the comparison of the percentage of change among groups in females (C) and males (D). E, F, Pearson correlation coefficients between the baclofen-induced decrease in eEPSC amplitude and baclofen-induced increase in PPR from control and inflamed CA1 pyramidal neurons of female (E) and male mice (F). n = 10–11 cells, 4–5 mice/group. **p < 0.01, ***p < 0.001, ****p < 0.0001.