Serotonin agonists

A serotonin receptor agonist is a compound that activates serotonin receptors, mimicking the effect of the neurotransmitter serotonin.

There are various serotonin receptors

5-HT1A receptor
Buspirone, a 5-HT1A receptor agonist that is an anxiolytic medication.

5-HT1D receptor
Triptans are 5-HT1D receptor agonists that are used to abort migraine attacks.

5-HT2A receptor
Hallucinogens like LSD, mescaline and psilocybin act as 5-HT2A agonists, and action at this receptor is thought to be primarily responsible for their hallucinogenic effects (although the 5-HT1A and 5-HT2C receptors are also involved to a lesser extent)

5-HT4 receptor
Cisapride is a 5-HT4 receptor agonist that has been used to treat disorders of gastrointestinal motility.