Multiple receptor subtypes of serotonin neurotransmitters with multiple physiologic functions have been recognized. The 5-HT-2 receptors mediate many of the central and peripheral physiologic functions of serotonin. Cardiovascular effects include contraction of blood vessels and shape changes in platelets; central nervous system effects include neuronal sensitization to tactile stimuli and mediation of hallucinogenic effects of phenylisopropylamine hallucinogens.[supplied by OMIM].