Electroconvulsive stimulations prevent stress-induced morphological changes in the hippocampus.

Stress can precipitate major depression and other disorders linked to hippocampal shrinkage. It is hypothesized but not established that treatment of these disorders reverses and prevents the hippocampal changes. Dendritic retraction of individual neurons might in concert with other pathophysiological events contribute to the shrinkage phenomenon. Animal studies have shown that various stress paradigms can induce dendritic retraction in the CA3 pyramidal neurons of the hippocampus. Since electroconvulsive treatment is the most effective treatment in humans with major depression, we investigated whether repeated electroconvulsive stimulations (ECSs) could influence such changes in stressed rats. Furthermore, we investigated whether ECSs per se could influence neuronal branching and total length of the CA3 hippocampal neuronal dendritic tree in normal rats. Rats were stressed using the 21-day 6 h daily restraint stress paradigm. The study shows that stress caused remodelling of the pyramidal neurons by significantly reducing the number of dendritic branch points and total length of the apical dendritic tree. Concomitant administration of ECSs prevented these effects. ECSs had no effect on pyramidal neuron dendrites in normal rats.