Schaffer collateral-CA1 paired-pulse facilitation (PPF) is enhanced in chronically Pb2+-exposed rat hippocampus, indicative of reduce transmitter release.
(A) Representative excitatory postsynaptic currents (EPSC) in field CA1 in response to Schaffer collateral paired-pulse stimuli at a 30 ms interstimulus interval (ISI) in a hippocampal slice from a control (black trace) versus a Pb2+-treated (red trace) rat. (B) Mean ± SEM ratio of P2/P1 (30ms ISI) at Schaffer collateral-CA1 synapses in slices from control (black, N = 13 slices) versus Pb2+-treated (red, N = 9 slices) rats, showing that PPF was significantly larger in Pb2+-treated rats (*, P<0.05, Student’s t-test). (C) Representative EPSCs evoked by the second of two Schaffer collateral stimuli in a CA1 pyramidal neuron, illustrating the ISI range of PPF. (D) Mean ± SEM EPSC PPF P2/P1 ratio as a function of ISI, where PPF was significantly enhanced for ISI 10–125 ms in slices from Pb2+-treated (red circles) versus control (black circles) rats (*, P<0.05, ANOVA for repeated measures and post-hoc Student’s t-test with Bonferroni correction).
