The new method exploits a membrane-spanning protein called TRPV1, which is unique to pain-sensing neurons. TRPV1 forms a large channel, where molecules can enter and exit the cell. But a “gate” typically blocks this opening. The gate opens when cells are exposed to heat or the chili-pepper ingredient capsaicin. Thus, bathing pain-sensing neurons in capsaicin leaves these channels open, but non-pain sensing neurons are unaffected because they do not possess TRPV1.
“We’re optimistic that this method will eventually be applied to humans and change our experience during procedures ranging from knee surgery to tooth extractions,” adds Professor Clifford Woolf of Massachusetts General Hospital, who is senior author on the study
Despite enormous investments by industry, surgical pain management has changed little since the first successful demonstration of ether general anesthesia at MGH in 1846. General and local anesthetics work by interfering with the excitability of all neurons, not just pain-sensing ones. Thus, these drugs produce dramatic side effects, such as loss of consciousness in the case of general anesthetics or temporary paralysis for local anesthetics.
“We’re offering a targeted approach to pain management that avoids these problems,” says Woolf.
“Eventually this method could completely transform surgical and post-surgical analgesia, allowing patients to remain fully alert without experiencing pain or paralysis,” says Woolf.