serotonergic agonist 5-HT agonist 5-hydroxytryptamine agonist An agent that has an affinity for serotonin receptors and is able to mimic the effects of serotonin by stimulating the physiologic activity at the cell receptors. Serotonin agonists are used as antidepressants, anxiolytics, and in the treatment of migraine disorders. CHEBI:35941 chebi_ontology serotonergic agonists serotonin agonist serotonin agonists serotonergic drug