MDMA blocks the reuptake of 5-HT similarly to SSRI (serotonin specific reuptake inhibiting) anti-depressants such as fluoxitine (Prozac). Unlike those drugs however MDMA appears to enter the neurone, though this point is still argued by some (Rattray 1991), either by passive diffusion or through the reuptake transporter, causing the release of cytoplasmic 5-HT. This 5-HT release is calcium independent and therefore independent of neuronal firing.  MDMA is thus considered to act on 5-HT in much the same way that amphetamines act on dopamine.

It is thought that the action of the 5-HT released by MDMA is central to it’s neuropharmacology. MDMA does however have micromolar potency for the serotonin 5-HT2, muscarinic M1, alpha-2 adrenergic and histamine H1 receptors (Rattray 1991).  Agonist properties at the 5-HT2 receptor have been found to be almost universally associated with classic psychedelic compounds such as LSD, psilocybin and mescaline (Cooper, Bloom and Roth 1991).  It would seem likely that the alpha-2 adrenergic receptor is associated with the cardiovascular effects of MDMA.  There is also evidence of less pronounced effects at the    5-HT1 and dopamine D2 receptors though the significance of this is not clear. (Battaglia et al 1988)