Opioids are among the most widely used and extensively studied drugs in the world. A continuous application of relatively low opioid doses is thought to be necessary to maintain synaptic depression in pain pathways. Drdla-Schutting et al. found that a single opioid application could produce lasting reversal of synaptic long-term potentiation in pain pathways. Chronic pain is often associated with synaptic potentiation in nociceptive pathways. A brief, high-dose application of opioids depotentiated long-term potentiation in spinal pain pathways. The same dose also reversed hyperalgesia in behaving animals. Thus, opioids not only attenuate pain but may also eradicate a significant cause for chronic pain.
R. Drdla-Schutting, J. Benrath, G. Wunderbaldinger, J. Sandkühler, Erasure of a spinal memory trace of pain by a brief, high-dose opioid administration. Science 335, 235–238 (2012). [Abstract] [Full Text]