Chronic pain is not merely a prolonged form of acute pain but rather results from plastic changes that occur along sensory transduction pathways from the peripheral to the central nervous system. Recent studies have revealed that “hyperalgesic priming,” the plastic changes of nociceptors, is essential for the transition from acute to chronic pain. Once challenged, nociceptors may elicit a signal switch to favor pain chronicity in response to future noxious stimuli. This article summarizes the recent progress in research into hyperalgesic priming in different chronic pain models and highlight how the plastic changes of the signal switch varies in different nociceptors. Also discussed is the involvement of proton-sensing receptors in pain chronicity associated with rheumatoid arthritis and fibromyalgia.
