(1)
Department of Anaesthesia, Royal Free Hospital, London, UK
Serotonin is a transmitter found in the central nervous system. It is involved with nociception at the peripheral and spinal cord level. The receptors contribute to peripheral sensitisation and hyperalgesia. The receptors are divided into 7 classes with 15 subtypes. All subtypes act through modulation of cAMP except 5HT3 receptor which is a gated calcium channel.
14.1 5HT1a Receptors
5HT1a receptors are G-protein-coupled receptors that are present in nucleus raphe magnus and the dorsal horn. Antidepressants exert their effect by blocking 5HT1a autoreceptor-mediated control of serotonin. It also exerts inhibitory effect on NMDA receptor-mediated currents.
14.2 5HT1b/5HT1d Receptors
5HT1b receptors are more in number than 5HT1d and are present in superficial laminae of the dorsal horn of the spinal cord. Activation of 5HT1b receptors leads to the release of glutamate, substance P and calcitonin gene-related peptide in the spinal cord.