Repeated electroconvulsive seizures increase the total number of synapses in adult male rat hippocampus.

The underlying mechanism of the therapeutic effect of electroconvulsive therapy (ECT) is still unclear. Here we investigated whether repeated electroconvulsive seizures (ECS), an animal model of ECT, in rats induce neuroplastic changes in the subregions of the hippocampus. ECS or sham treatment was given daily for 10 days to adult male rats. Stereological principles were employed to quantify volumes and the number of neurons and synapses. Volumes of granule cell layer (GCL) and Hilus in Dentate Gyrus of the hippocampus were significantly larger in the ECS treatment group. The neuron numbers in GCL, synapse numbers (including total synapses, spine synapses, and both perforated and nonperforated spine synapse subtypes) and synapse height in CA1 were significantly increased in the ECS treatment group. Our results indicated that repeated ECS induces neurogenesis, synaptogenesis and remodelling of synapses in rat hippocampus. This could provide a potential mechanism to explain the therapeutic effect of ECS.