Design of Small Non-Peptidic Ligands That Alter Heteromerization between Cannabinoid CB and Serotonin 5HT Receptors.

Activation of cannabinoid CB receptors (CBR) by agonists induces analgesia but also induces cognitive impairment through the heteromer formed between CBR and the serotonin 5HT receptor (5HTR). This side effect poses a serious drawback in the therapeutic use of cannabis for pain alleviation. Peptides designed from the transmembrane helices of CBR, which are predicted to bind 5HTR and alter the stability of the CBR-5HTR heteromer, have been shown to avert CBR agonist-induced cognitive impairment while preserving analgesia. Using these peptides as templates, we have now designed nonpeptidic small molecules that prevent CBR-5HTR heteromerization in bimolecular fluorescence complementation assays and the heteromerization-dependent allosteric modulations in cell signaling experiments. These results provide proof-of-principle for the design of optimized ligand-based disruptors of the CBR-5HTR heteromer, opening new perspectives for studies.