Dual Antagonism of 910 nAChR and GABA_B Receptor-Coupled Ca_V2.2 Channels by an Analgesic O-Conotoxin Analogue

Pain severely affects the physical and mental health of patients. The need to develop nonopioid analgesic drugs to meet medical demands is urgent. In this study, we designed a truncated analogue of alpha O-conotoxin, named GeX-2, based on disulfide-bond deletion and sequence truncation. GeX-2 retained the potency of its parent peptide at the human alpha 9 alpha 10 nAChR and exhibited potent inhibitory activity at Ca(V)2.2 channels via activation of the GABA(B) receptor (GABA(B)R). Importantly, GeX-2 significantly alleviated pain in the rat model of chronic constriction injury. The dual inhibition of GeX-2 at both alpha 9 alpha 10 nAChRs and Ca(V)2.2 channels is speculated to synergistically mediate the potent analgesic effects. Results from site-directed mutagenesis assay and computational modeling suggest that GeX-2 preferentially interacts with the alpha 10(+)alpha 10(-) binding site of alpha 9 alpha 10 nAChR and favorably binds to the top region of the GABA(B)R2 subunit. The study offers vital insights into the molecular action mechanism of GeX-2, demonstrating its potential as a novel nonopioid analgesic.