What is the primary action of capsaicin?

The primary action of capsaicin is related to its effect on sensory neurons, particularly its ability to cause depolarization of these neurons. Capsaicin works by binding to the TRPV1 receptor, which is primarily found on nociceptive sensory neurons. This binding leads to the influx of calcium ions into the neuron, triggering an action potential and resulting in the sensation of heat or pain.

Over time, with repeated exposure to capsaicin, there is a depletion of substance P, a neuropeptide involved in transmitting pain signals. This can lead to a desensitization effect where the neurons become less responsive to painful stimuli. While this mechanism does involve aspects of inhibition, the prime action is primarily the initial depolarization and activation of sensory neurons.

Understanding this mechanism is crucial for the use of capsaicin in pain management therapies, particularly in conditions like neuropathic pain or arthritis, where it can provide significant relief by reducing the overall sensitivity of pain pathways.