The rearrangement of filamentous actin in mossy fiber synapses in pentylenetetrazol-kindled C57BL/6 mice

• We examine the effect of PTZ on filamentous actin in mossy fiber synapses.
• F-actin is increased in the stratum lucidum of CA3 region.
• Synapsin I is up-regulated in the stratum lucidum of CA3 region.
• The rearrangement of F-actin contributes to the increased sensitivity of synapses during kindling.

SummaryChemical kindling, as an experimental model of epileptogenesis, is induced by repetitive administration of subconvulsive amount of excitatory drugs. Kindled mice do not typically display spontaneous recurrent seizures, but are instead characterized by enhanced seizure susceptibility to convulsive stimulations. In order to provide insights into the aberrant synaptic plasticity during kindling, this study investigated the effect of pentylenetetrazol (PTZ) kindling on filamentous actin (F-actin) in mossy fiber synapses in C57BL/6 mice. Phalloidin labeling of F-actin showed that F-actin puncta were increased in number in the stratum lucidum of CA3 region in the hippocampus after kindling. The rearrangement of F-actin seemed to occur presynaptically, since synapsin I, a specific marker for mossy fiber terminals, was also up-regulated. Such subtle structural modifications occurring in the synapses are thought to contribute to the long-lasting increased sensitivity in the PTZ-kindled C57BL/6 mice.