Potent CaV3.2 channel inhibitors exert analgesic effects in acute and chronic pain models

Pain is the most common presenting physical symptom and a primary reason for seeking medical care, which chronically affects people's mental health and social life. Ca(V)3.2 channel plays an essential role in the peripheral processing maintenance of pain states. This study was designed to identify novel drug candidates targeting the Ca(V)3.2 channel. Whole-cell patch-clamp, cellular thermal shift assay, FlexStation, in vivo and in vitro Ca(V)3.2 knock-down, site-directed mutagenesis, and double-mutant cycle analysis were employed to explore the pain related receptors and ligand-receptor direct interaction. We found that toddaculin efficiently inhibits the Ca(V)3.2 channel and significantly reduced the excitability of dorsal root ganglion neurons and pain behaviors. The Carbonyl group of coumarins directly interacts with the pore domain of Ca(V)3.2 via van der Waals (VDW) force. Docking with binding pockets further led us to identify glycycoumarin, which exhibited more potent inhibition on the Ca(V)3.2 channel and better analgesic activity than the parent compound. Toddaculin and its analog showed beneficial therapeutic effects in pain models. Toddaculin binding pocket on Ca(V)3.2 might be a promising docking site for the design of drugs.

Automated summary

Pain is a common reason for seeking medical care, leading to negative impacts on mental health and social life. This study identifies toddaculin as a potential inhibitor of the Ca(V)3.2 channel, which reduces excitability of neurons and pain behaviors. The binding pocket of toddaculin on the Ca(V)3.2 channel may be a promising target for drug design.