Voltage-gated sodium (Nav) channels are central to electrical signaling in neurons and muscle, and are clinically validated targets for analgesics, antiepileptics, and local-anesthetics. Yet, the molecular logic governing state-selective inhibition remains incompletely understood. Our work has leveraged phytocannabinoids as mechanistic probes to uncover new dimensions of Nav channel pharmacology. We first defined the mechanism of cannabidiol (CBD) action, showing that it preferentially binds to and stabilizes inactivated-states of Nav channels, thereby suppressing high-frequency firing. Extending these insights, we compared CBD with structurally related cannabinoids such as cannabigerol (CBG) and cannabinol (CBN). These studies revealed divergent potency and state-dependent effects across the family, highlighting that subtle chemical differences translate into distinct kinetic and biophysical signatures. To rigorously dissect these interactions, we developed high-throughput automated patch-clamp methodologies, enabling parallel investigations across sensory neuron populations of different sizes. This platform allowed us to resolve how cannabinoids differentially modulate Nav currents in physiologically distinct neurons, bridging molecular pharmacology with systems-level excitability composed of different ensembles of Nav channels at varying stoichiometries. Unexpectedly, cannabinoids also illuminated a previously underappreciated ultra-hydrophobic pathway of access for local-anesthetic-type binding. This mechanistic discovery not only reshaped our understanding of how hydrophobic molecules engage Nav channels but also provided a conceptual framework to identify novel modulators. Applying these criteria, we discovered that amorolfine, a widely used antifungal, is a Nav inhibitor with distinctive state-dependence. Taken together, this progression from natural product pharmacology to methodological innovation and therapeutic discovery demonstrates how cannabinoids, beyond their own translational potential, can serve as a Rosetta stone for understanding the ultra-hydrophobic class of compounds that modulate Nav channel gating and inhibition. These findings highlight the power of biophysical approaches to bridge chemical biology with drug discovery and to uncover unifying principles of ion channel modulation.
Mohammad-Reza Ghovanloo (Sun,) studied this question.