What a Preclinical Study Suggests About How It May Work
Highlights:
- In a mouse model of inflammatory pain, Class 3B laser photobiomodulation (PBM) reduced pain sensitivity in a dose-dependent way.
- The pain-relief effect appeared to involve natural pain-modulating pathways linked to:
- Opioid receptors
- Cannabinoid receptors
- Adenosine receptors
- When researchers blocked these receptors, the PBM pain-relief effect disappeared.
- This supports a receptor-mediated explanation, not just a simple “warming” effect.
- The findings add to the scientific rationale for studying Class 3B laser PBM in pain-related applications.
Why this matters
Pain is not only a “signal” — it’s also shaped by chemical messengers and receptors in the nervous system. If a therapy can influence these pathways, it may help explain why some non-invasive approaches are being explored for pain support.
This study focused on a key question: Is PBM’s pain relief mainly due to heat, or does it trigger specific biological pathways?
What the researchers studied
Researchers created localized inflammatory pain in mice and measured pain sensitivity using a standard method (the von Frey test, which evaluates sensitivity to light mechanical pressure).
Then they applied Class 3B laser PBM to see if it reduced pain sensitivity — and whether that effect depended on specific receptors.
How the therapy was applied
PBM was delivered using a Class 3B laser with:
- 808 nm light (200 mW)
- 637 nm light (300 mW)
- Energy density: 8 J/cm²
To test the mechanism, mice were given “blockers” (antagonists) before PBM that temporarily prevent certain receptors from working:
- Naloxone (opioid receptor blocker)
- AM281 (CB1 cannabinoid receptor blocker)
- AM630 (CB2 cannabinoid receptor blocker)
- Caffeine and DPCPX (adenosine receptor blockers)
Key findings;
PBM reduced inflammatory pain sensitivity in the mice.
- When opioid, cannabinoid, or adenosine receptors were blocked, PBM no longer reduced pain sensitivity.
- This suggests PBM’s pain-relief effect in this model is linked to specific receptor-driven pathways, not only a nonspecific thermal effect.
Takeaway
This preclinical study suggests that Class 3B laser PBM may support pain relief in inflammatory conditions by engaging the body’s own pain-modulating receptor systems—opioid, cannabinoid, and adenosine pathways. That kind of mechanism-based evidence helps explain why PBM is being actively researched as a non-invasive approach for pain support.
Reference: Cidral-Filho FJ, Bonotto NA, Oliveira BH, Dutra AR, Nazário J, Martins DF. Experimental Neuroscience Laboratory (LaNEx), Postgraduate Program in Health Sciences, University of Southern Santa Catarina, Brazil.
Laser system: Avant Wellness LZ30 Pro Z