Dual Modulation of 5-HT_2A Receptors and SERT by α-Ethyltryptamine and Its Optical Isomers

Area of Science:

• Neuropharmacology
• Psychopharmacology
• Medicinal Chemistry

Background:

• α-Ethyltryptamine (AET), a synthetic tryptamine, is regaining interest due to its similarity to serotonergic psychedelics and entactogens.
• Understanding the pharmacological profile of AET and its isomers is crucial for evaluating their therapeutic potential.

Purpose of the Study:

• To characterize the pharmacological properties of racemic AET and its optical isomers, R(-)-AET and S(+)-AET.
• To investigate the interactions of AET isomers with the serotonin 5-HT2A receptor (5-HT2A R) and serotonin transporter (SERT).

Main Methods:

• In vitro receptor binding and functional assays (calcium mobilization) to assess affinity and activity at 5-HT2A R.
• In vivo head-twitch response (HTR) studies in mice to evaluate behavioral effects.
• Pharmacological manipulations using 5-HT2A R antagonist (volinanserin) and SERT inhibitor (fluoxetine) to elucidate mechanisms.

Main Results:

• All AET forms exhibited micromolar affinity for 5-HT2A R; S(+)-AET showed weak partial agonist activity.
• AET isomers induced dose-dependent HTR in mice, confirming 5-HT2A R involvement.
• Fluoxetine pretreatment blocked AET-induced HTR, indicating a role for SERT-mediated serotonin release.

Conclusions:

• AET's behavioral effects result from a dual mechanism: direct 5-HT2A R activation and indirect SERT-mediated potentiation.
• This dual pharmacology differentiates AET from classical psychedelics and aligns it with MDMA-like agents.
• AET isomers hold potential for modulating mood and cognition, warranting further neuropsychiatric research.