Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2024 Sep;29(9):2753-2764.
doi: 10.1038/s41380-024-02531-7. Epub 2024 Apr 2.

Pharmacological fingerprint of antipsychotic drugs at the serotonin 5-HT2A receptor

Affiliations

Pharmacological fingerprint of antipsychotic drugs at the serotonin 5-HT2A receptor

Supriya A Gaitonde et al. Mol Psychiatry. 2024 Sep.

Abstract

The intricate involvement of the serotonin 5-HT2A receptor (5-HT2AR) both in schizophrenia and in the activity of antipsychotic drugs is widely acknowledged. The currently marketed antipsychotic drugs, although effective in managing the symptoms of schizophrenia to a certain extent, are not without their repertoire of serious side effects. There is a need for better therapeutics to treat schizophrenia for which understanding the mechanism of action of the current antipsychotic drugs is imperative. With bioluminescence resonance energy transfer (BRET) assays, we trace the signaling signature of six antipsychotic drugs belonging to three generations at the 5-HT2AR for the entire spectrum of signaling pathways activated by serotonin (5-HT). The antipsychotic drugs display previously unidentified pathway preference at the level of the individual Gα subunits and β-arrestins. In particular, risperidone, clozapine, olanzapine and haloperidol showed G protein-selective inverse agonist activity. In addition, G protein-selective partial agonism was found for aripiprazole and cariprazine. Pathway-specific apparent dissociation constants determined from functional analyses revealed distinct coupling-modulating capacities of the tested antipsychotics at the different 5-HT-activated pathways. Computational analyses of the pharmacological and structural fingerprints support a mechanistically based clustering that recapitulate the clinical classification (typical/first generation, atypical/second generation, third generation) of the antipsychotic drugs. The study provides a new framework to functionally classify antipsychotics that should represent a useful tool for the identification of better and safer neuropsychiatric drugs and allows formulating hypotheses on the links between specific signaling cascades and in the clinical outcomes of the existing drugs.

PubMed Disclaimer

Conflict of interest statement

MB is the chair of the scientific advisory board of Domain Therapeutics, a biotech company to which some of the biosensors used in this study were licensed for commercial use. MdlFR is the owner of GONOGO solutions LLC. JG-M has as sponsor research contract with Terran Biosciences. None of the other authors declare competing interests.

Figures

Fig. 1
Fig. 1. The complete signaling profile of 5-HT at the 5-HT2AR in HEK293 cells.
a The complete G protein-activation profile of 5-HT (1 µM; 15 min) in HEK293 cells heterologously expressing the untagged 5-HT2AR and the biosensor (RlucII-Gγ5/GRK2-D110A-GFP10, Gβ1 and the respective Gα subunits). Results are expressed as BRET ratio (GFP10/RlucII) as % of mock condition (in the absence of heterologously expressed Gα subunit) (mean ± SEM; n = 3; one-way ANOVA followed by Dunnett’s post hoc: **p = 0.0029, ***p = 0.0009, and ****p < 0.0001 compared to the mock condition). Concentration response curves showing the activation of the Gαq family (b), Gαi/o/z family (c), Gα12 (d), Gα13 (e), Gαs (f), as well as the recruitment of β-arrestin1 (g) or β-arrestin2 (h) using the ebBRET-based EMTA biosensor in HEK293 cells heterologously expressing the untagged 5-HT2AR, the following biosensors (rGFP-CAAX along with p63-RlucII for Gαq, Rap1GAP-RlucII for Gαi/o/z, PDZ-RlucII for Gα12 and Gα13, Gαs67-RlucII for Gαs, β-arrestin1-RlucII or β-arrestin2-RlucII for β-arrestins), the respective Gα subunits (Gαq family, Gαi/o/z family, Gα12/13), Gβ1 and Gγ1 (Gαs) or WT-GRK2 (β-arrestins). The HA-TPα receptor (U46619) was used as the positive control for Gα12/13 while the 5-HT7A receptor (5-HT) was used as the positive control for Gαs. Results are expressed as BRET ratio (rGFP/RlucII), as % over vehicle (mean ± SEM; n = 3).
Fig. 2
Fig. 2. Differential agonist and inverse agonist activities of the antipsychotic drugs at the G protein pathways and for recruitment of β-arrestins.
a Concentration response curves depicting the inverse agonist activities of risperidone, clozapine, olanzapine and haloperidol using the ebBRET-based EMTA biosensors in HEK293 cells heterologously expressing the untagged 5-HT2AR, the biosensor (rGFP-CAAX along with p63-RlucII for the Gαq family and Rap1GAP-RlucII for Gαi1/z) and the respective Gα subunits. b Heatmap illustrating the potency (logEC50) of inverse agonist activity shown by risperidone, clozapine, olanzapine and haloperidol from the concentration response curves. The empty cell with a cross indicates no inverse agonist activity. c Concentration response curves depicting the partial agonist activities of aripiprazole and cariprazine at the Gαq family using the ebBRET-based EMTA biosensors in HEK293 cells heterologously expressing the untagged 5-HT2AR, the biosensor (rGFP-CAAX along with p63-RlucII for the Gαq family). d Curves of the six antipsychotic drugs at pathways where there was no activation when tested in the agonist mode using the ebBRET-based EMTA biosensors in HEK293 cells overexpressing the untagged 5-HT2AR, the biosensors (rGFP-CAAX along with p63-RlucII for the Gαq family, Rap1GAP-RlucII for Gαi/o/z family, β-arrestin-RlucII/WT-GRK2 for β-arrestins) and the respective Gα subunits (for Gαq and Gαi/o/z families). Results are expressed as ΔBRET (ligand-promoted BRET) (mean ± SEM; n = 3).
Fig. 3
Fig. 3. Comparison of the activities of aripiprazole and cariprazine with 5-HT in the agonist mode.
Graphs comparing the maximal response of aripiprazole and cariprazine with that of 5-HT at Gαq (a), Gα11 (b), Gα14 (c) and Gα15 (d) (mean ± SEM; n = 3; one-way ANOVA followed by Dunnett’s post hoc test). **p = 0.0046 for aripiprazole and **p = 0.0047 for cariprazine in a, **p = 0.0023 in b, *p = 0.0169, and ***p = 0.0007 for c and ****p < 0.0001 for d, compared to the maximal response by 5-HT at the respective pathways.
Fig. 4
Fig. 4. Pathway-specific antagonistic activity of the six antipsychotic drugs tested.
a-i Concentration response curves with the activity of the six antipsychotics tested in the antagonist mode (i.e; in the presence of an EC80 concentration of 5-HT) using the ebBRET-based EMTA biosensors in HEK293 cells heterologously expressing the untagged 5-HT2AR and the biosensor (rGFP-CAAX along with p63-RlucII for Gαq family, Rap1GAP-RlucII for Gαi/o/z, and the respective Gα subunits, as well as β-arrestin1-RlucII or β-arrestin2-RlucII and WT-GRK2 for recruitment of β-arrestins). Results are expressed as % response of 5-HT (EC80) at the respective pathways (normalized with respect to the response of 5-HT (EC80)) (mean ± SEM; n = 3–5). j Heatmap depicting the equilibrium dissociation constant (Kb) of the antipsychotics calculated based on the modified Cheng-Prusoff equation as described in the methods section along with the pKi values reported in the literature (a [66]; b [67]; c [68]; d [69]; e [70]; f [28]; g [56]; h [71]). The empty cells with a cross indicate no activity in the antagonist mode whereas cells colored blue indicate IC50 > 10 µM.
Fig. 5
Fig. 5. Pharmacological and binding properties of the six antipsychotic drugs tested.
a Web representation of the potency (logIC50) and efficacy (% inhibition) of the six antipsychotics tested in the antagonist mode. b Principal component analysis of the antagonist mode (potency and efficacy) depicting the hierarchical clustering of the antipsychotics into three distinct groups. c Binding modes of the six antipsychotics at the 5-HT2AR.

References

    1. Freedman R. Schizophrenia. N Engl J Med. 2003;349:1738–49. - PubMed
    1. Meltzer HY. Update on typical and atypical antipsychotic drugs. Annu Rev Med. 2013;64:393–406. - PubMed
    1. Meltzer HY, Matsubara S, Lee JC. Classification of typical and atypical antipsychotic drugs on the basis of dopamine D-1, D-2 and serotonin2 pKi values. J Pharmacol Exp Ther. 1989;251:238–46. - PubMed
    1. Schotte A, Janssen PF, Megens AA, Leysen JE. Occupancy of central neurotransmitter receptors by risperidone, clozapine and haloperidol, measured ex vivo by quantitative autoradiography. Brain Res. 1993;631:191–202. - PubMed
    1. Leysen JE, Janssen PM, Megens AA, Schotte A. Risperidone: a novel antipsychotic with balanced serotonin-dopamine antagonism, receptor occupancy profile, and pharmacologic activity. J Clin Psychiatry. 1994;55:5–12. - PubMed

MeSH terms

LinkOut - more resources