Researchers at the University of California, Davis, identified multiple functional open states in the TRPV1 pain receptor, challenging long-held assumptions about how the ion channel operates. Published in Proceedings of the National Academy of Sciences, the study could guide the design of selective non-opioid analgesics.
Challenging Assumptions About TRPV1 Open States
Scientists studying the transient receptor potential vanilloid type 1 receptor have long operated under a uniform rulebook. For years, the scientific consensus assumed that once this polymodal nociceptor opened, it adopted a single, identical conformation regardless of what triggered it.
A team at the University of California, Davis, put that premise to the test by measuring electrical currents through individual channel structures. Instead of finding a single response, the researchers observed distinct conductance levels when exposing the ion channel to various activating agents.
Researchers have generally assumed that once TRPV1 is activated, the channel enters essentially the same open state regardless of what stimulus triggered it. Our findings show that the receptor is more sophisticated than that. Different stimuli appear to stabilise different open states, each with distinct functional properties.
Bo Hyun Lee, first author of the study via Drugtargetreview
Measuring Electrical Currents Across Multiple Stimuli
The UC Davis research team exposed individual TRPV1 channels to a diverse panel of activators. The tested stimuli included capsaicin—the chemical compound responsible for the burning sensation associated with chilli peppers—alongside resiniferatoxin, acidic conditions, heat, and the chemical compound 2-APB.
By combining ion-permeation measurements, fluorescence-based experiments in living cells, and computational modelling, the team investigated whether those varying electrical readings correlated with physical alterations in the channel’s structure. The gathered evidence suggested changes in the configuration of the channel pore itself.
Applying two stimuli simultaneously slowed channel opening. This interference pattern demonstrated that different activation mechanisms can interfere with one another.
Targeting Pain Relief Without Disrupting Normal Temperature Regulation
The search for non-opioid pain medicines has repeatedly collided with a biological roadblock. While blocking TRPV1 offers a promising avenue for halting pain signals, the receptor also contributes to normal temperature regulation. Previous attempts to develop drugs that block TRPV1 have proved challenging because of concerns about unwanted side effects.
The new findings provide a mechanistic basis that could help bypass this hurdle. If pharmaceutical designers can figure out how to isolate specific conformations, future therapies might successfully affect pain-related activity while leaving other essential functions intact.
If different forms of activation produce different functional states, we may eventually be able to design therapies that selectively affect pain-related activity while leaving other essential functions intact.
Prof Vladimir Yarov-Yarovoy, co-author via Drugtargetreview
Investigators emphasize that further research is needed to determine whether individual receptor states can be selectively targeted by drugs. The discovery alters how scientists approach analgesic development.
