Dynamic actin filaments are required for stable long-term potentiation (LTP) in area CA1 of the hippocampus

The hypothesis that dynamic actin filaments participate in specific aspects of synaptic plasticity was investigated at the Schaffer-collateral-CA1 pyr amidal cell synapse of mouse hippocampus. Low concentrations (0.01-1 mu M) of compounds that inhibit actin filament assembly were bath applied to hipp ocampal slices during extracellular recording of field excitatory postsynap tic potentials. Cytochalasin D. cytochalasin B, and latrunculin A all impai red the maintenance of LTP induced by brief high-frequency stimulation. Thi s effect on LTP maintenance was specific, because none of the compounds aff ected basal synaptic transmission, paired-pulse facilitation. LTP induction , or post-tetanic potentiation. The effect of cytochalasin B was reversible . The results are consistent with a model in which dynamic actin filaments play an essential role in the molecular mechanisms underlying the early mai ntenance phase of LTP, such as growth of new synaptic connections or conver sion of silent synapses.