Serotonin

Serotonin (5-hydroxytryptamine [5-HT]) levels are unaltered in most brain regions of rats after administration of inhaled agents but may increase in specific brain structures (e.g., substantia nigra, nucleus raphe dorsalis).^[62] The inability of ondansetron, a 5-HT₃ receptor antagonist used to treat postoperative nausea, to alter the isoflurane MAC suggests that this particular subtype of serotonergic receptor is not involved in the surgical immobility produced by inhaled anesthetics.^[63]