A new study conducted by researchers from the Massachusetts General Hospital are theorizing that people with red hair have a higher pain threshold than blondes or brunettes.
Lack of tanning abilities explains higher pain threshold
The cells that are responsible for giving us our hair colour—called melanocytes—could possibly have a link with tolerance to pain in humans as it was observed in mice during experiments. According to the study, redheads exhibit a genetic mutation in which their melanocytes have a faulty key receptor that prevents their skin to produce the dark pigment that allows for the process of tanning to occur—instead, they often burn under the sun.
Now, researchers believe that this same imbalance could also have an effect on hormones causing an enhanced effect on the pain-stopping opioid receptors. To come to this hypothesis, scientists studied mice with red-coloured fur as their skin cells are similar to those in humans. Dr. Fischer, lead author of the study, said:
These findings describe the mechanistic basis behind earlier evidence suggesting varied pain thresholds in different pigmentation backgrounds. Understanding this mechanism provides validation of this earlier evidence and a valuable recognition for medical personnel when caring for patients whose pain sensitivities may vary.
Testing on humans next
In addition to not being able to tan like other mice could, the faulty melanocyte receptor altered the production of a chemical called POMC that led to an imbalance between pain-inhibiting and pain-enhancing receptors. Ultimately, the lack of POMC produced in red-furred mice generated a boost in pain-killing opioid receptors.
And although the findings were only conclusive in mice, similar research is now being conducted to look for similarities in humans. Co-lead author Lajos V. Kemény added:
Our ongoing work is focused on elucidating how additional skin-derived signals regulate pain and opioid signalling. Understanding these pathways in depth may lead to the identification of novel pain-modulating strategies.