Peptidase enzymes rapidly degrade endogenous opioid peptides in the spinal cord, preventing mu-opioid receptor internalization — when peptidases are blocked, endogenous opioids become potent enough to activate their receptors.
Natural brake removedWhen peptidases were blocked, endogenous opioids activated spinal receptors powerfully — the body has enough natural painkillers if they're protected from destruction
What the researchers found
Multiple peptidase inhibition in rat spinal cord slices allowed endogenous opioid peptides to accumulate and trigger mu-opioid receptor internalization, revealing that rapid enzymatic degradation normally prevents full endogenous opioid receptor activation.
Why it matters
Boosting endogenous opioids by blocking their degradation could provide pain relief without the addiction risk of external opioid drugs — using the body's own painkillers more effectively.
How the study worked
In-vitro rat spinal cord slice study. Peptidase inhibitor cocktail applied. Mu-opioid receptor internalization measured as a marker of receptor activation by endogenous opioids released by electrical stimulation.
What this study cannot tell us
In-vitro spinal cord slices. The degree of pain relief achievable in vivo through peptidase inhibition needs determination.
How to read the evidence
Moderate in-vitro evidence with clear receptor activation data from endogenous opioid accumulation.
When this study was published
Published in 2003. Dual enkephalinase inhibitors (DENKI) are now in clinical development for pain, validating this concept.
The bigger picture
The body produces enough opioid peptides for significant pain relief — but enzymes destroy them too fast. Peptidase inhibitors could be the key to non-addictive opioid analgesia using the body's own molecules.
Questions still open
- Could peptidase inhibitor drugs provide significant analgesia?
- Is the endogenous opioid amount sufficient for clinical pain relief when protected?
- Would chronic peptidase inhibition cause tolerance?
Common questions
Can the body's own painkillers be made stronger?
Would this be addictive?
Read the original research
Peptidases prevent mu-opioid receptor internalization in dorsal horn neurons by endogenously released opioids.
The Journal of neuroscience : the official journal of the Society for Neuroscience, 23(5), 1847-58
Citation
Song, Bingbing; Marvizón, Juan Carlos G. (2003). Peptidases prevent mu-opioid receptor internalization in dorsal horn neurons by endogenously released opioids.. The Journal of neuroscience : the official journal of the Society for Neuroscience, 23(5), 1847-58.