Serotonin 5-HT3 receptors in the central nervous system

The 5-HT3 receptor is a ligand-gated ion channel activated by serotonin (5-HT). Although originally identified in the peripheral nervous system, the 5-HT3 receptor is also ubiquitously expressed in the central nervous system. Sites of expression include several brain stem nuclei and higher cortical areas such as the amygdala, hippocampus, and cortex. On the subcellular level, both presynaptic and postsynaptic 5-HT3 receptors can be found. Presynaptic 5-HT3 receptors are involved in mediating or modulating neurotransmitter release. Postsynaptic 5-HT3 receptors are preferentially expressed on interneurons. In view of this specific expression pattern and of the well-established role of 5-HT as a neurotransmitter shaping development, we speculate that 5-HT3 receptors play a role in the formation and function of cortical circuits.