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Wikipedia hat geschrieben:Wirkungsweise

Der Botenstoff Histamin reguliert diverse Funktionen im Gehirn und löst zudem jene Beschwerden aus, die bei einer Allergie auftreten. Promethazin besetzt die Histamin-Bindungsstellen im Gehirn. Dadurch wirkt es beruhigend und schlaffördernd. Darüber hinaus bindet Promethazin auch an den muskarinischen Acetylcholinrezeptor sowie an die Rezeptoren für 5-HT2A, 5-HT2C, Dopamin-D2, den NMDA-Glutamatrezeptor und den α1-Adrenorezeptor.[6][7][8][9][10] Promethazin ist zudem ein potentes Antioxidans[11] und steigert die Glutamataufnahme in Gliazellen des Gehirns.[12]

Die neuroleptische Potenz von Promethazin wird in der Literatur mit 0,5 angegeben."

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Every study subject tried the task three times: once sober, once on LSD, and once after taking both LSD and a substance called ketanserin. This substance blocks LSD from interacting with a particular serotonin receptor in the brain, which researchers call "5-HT2."

Previous studies on animals had suggested that 5-HT2 played a key role in LSD's ability to mess with sense of self. The researchers suspected that blocking the receptor in humans might somewhat reduce the effect of LSD.

But it turned out to more than "somewhat" block the effect: There was no difference between the performance of subjects who took ketanserin and the placebo group.

"This was surprising to us, because LSD interacts with a lot of receptors [in the brain], not just 5-HT2," Preller said.

But LSD's most dramatic measurable effects entirely abated when subjects first took ketanserin.

That tentatively indicates that 5-HT2 plays an important role in regulating sense of self in the brain, Preller said. The next step, she added, is to work on drugs that target that receptor and see if they might alleviate some of the symptoms of severe psychiatric illnesses that affect the sense of self.