Nociceptin

Where it comes from

Made in

Widely through the brain, spinal cord, and immune cells

Sent out by

Stress, pain and inflammation

Acts on

• Supraspinal pain circuits (anti-opioid)
• Spinal cord (analgesic)
• Amygdala (anxiety)
• Reward circuits (anti-reward)
• Airway and vessels

What it does

• In the brain it opposes opioid analgesia and lowers pain thresholds; in the spinal cord it relieves pain ¹
• Lowers anxiety, reduces the reward of drugs and alcohol, and suppresses cough
• Its name reflects the first finding (lower pain threshold), which proved to be half the story ¹

In medicine

• No medicine yet. Cebranopadol, which activates NOP and mu receptors together, relieved acute pain in two phase 3 trials in 2025 and is not approved anywhere ²
• In healthy volunteers cebranopadol depressed breathing less than oxycodone at doses giving comparable pain relief, which is the claim its development rests on ³

Beyond the body’s own use

• NOP agonists are in trials for alcohol use disorder, anxiety and cough, and NOP blockers for depression and Parkinson’s disease; no approved medicine stands behind any of them ²
• Nothing containing nociceptin is approved or obtainable outside the laboratory: it is broken down in blood and does not enter the brain in useful amounts ¹
• The open question is which end of the cord a drug reaches. The same peptide relieves pain given into the spinal cord and worsens it given into the brain, so anything taken systemically has to favour one over the other ¹