Local potentiation of excitatory synapses by serotonin and its alteration in rodent models of depression

The authors find that serotonin, acting through 5-HT1B receptors, potentiates temporoammonic pathway–to–CA1 cell excitatory synapses in the hippocampus. Chronic unpredictable stress increased the magnitude of this potentiation, and chronic treatment with fluoxetine restored normal levels of this potentiation, a process that was required for the behavioral effects of chronic fluoxetine.