PhD Scientific Days 2026

Poster Session 3.N - Neurosciences

IPAP vs. β-PEA Activity at TAAR1

Name of the presenter

Chalabiani, Yashar

Institute/workplace of the presenter

Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary

Authors

Yashar Chalabiani¹, Brachyahu Meir Kestecher², Sayam Ghosal², Aliz Judit Ernyey¹, László Gábor Hársing Jr¹, Xabier Osteikoetxea², Ildikó Miklya¹
1: Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary
2: Institute of Genetics, Cell- and Immunobiology, Semmelweis University, Budapest, Hungary

Text of the abstract

Introduction
Trace amine–associated receptor 1 (TAAR1) is an intracellular, pleiotropic G protein–coupled receptor (GPCR) activated by endogenous trace amines such as β phenethylamine (β-PEA) and tryptamine (TRP), and it is also engaged by monoamine-releasing agents (MRAs) including amphetamine and methamphetamine. At low concentrations, β-PEA and TRP can act as monoaminergic activity enhancers (MAEs), preferentially facilitating vesicular neurotransmitter release, whereas MRAs trigger both vesicular release and non-vesicular, transporter-mediated monoamine efflux.  

Aims
We aimed to investigate the MOA of the synthetic MAE compound (−)-IPAP at TAAR1 by measuring receptor-mediated cAMP accumulation in rat-TAAR1-expressing Expi293F suspension cells.

Methods
Dose–response curves (10⁻¹⁰–10⁻⁴ M) were generated for β-phenethylamine (β-PEA; Sigma-Aldrich) and 1-(indol-3-yl)-2-propylaminopentane ((−)-IPAP; Fujimoto Pharmaceutical Corp) using seven-point serial dilutions prepared in assay buffer and applied to rTAAR1-expressing Expi293F cells to quantify TAAR1-mediated cAMP accumulation.
rTAAR1 cDNA (rTAAR1; GeneWiz) was cloned into the pcDNA3 mammalian expression vector with a CMV promoter. The plasmid was transformed into DH5α and grown using ampicillin selection. Plasmids were isolated and purified using a plasmid preparation kit, and sequenced prior to use. Expi293F suspension cells were transiently transfected using polyethyleneimine. After 48–72 h, receptor expression was confirmed by PCR, and cells were harvested immediately before the assay. cAMP accumulation was measured using the Revvity cAMP-Gs Dynamic homogeneous time-resolved fluorescence (HTRF) assay, a competitive immunoassay based on HTRF. Fluorescence ratios (665 nm/620 nm) were plotted against a compound concentration, signals were inversely proportional to intracellular cAMP levels. EC₅₀ values were determined using 4-parameter logistic (4PL) non-linear regression.

Result
In rTAAR1-expressing Expi293F cells, cAMP responses were normalised to the maximal response evoked by β-PEA; 100%. (−)-IPAP produced a robust, concentration-dependent increase in cAMP with slightly reduced maximal efficacy, reaching ~90% of the β-PEA Emax.

Conclusion
This profile supports (−)-IPAP as a TAAR1 agonist consistent with an MAE-like pharmacological signature rather than an MRA-like pattern.

Funding
SE250+