It has a small effect on dopamine and they think noreopinephrine as well, but the primary effects are on serotonin release. Although this does bring up a weird contradiction. Ectasy is supposed to make you feel very sexual. But elevated serotonin has the exact opposite effect. This is why SSRIs can kill the desire for love or sex. Low serotonin levels on the other hand make a person extremely hypersexual. So there is clearly more to the story that has not been discovered yet. Such as maybe the serotonin is being released, but being blocked from activating serotonin receptors.