By: Judy Zhao, Class of 2029
Figure 1. A woman’s skin under the sun
As one of the most vital organs of the human body, the skin serves as a protective barrier against environmental stressors. Research conducted under Dr. Lajos Kemény at Semmelweis University investigated neural pathways that link skin and hair color with the central nervous system (CNS). This link, referred to as the skin-brain axis, involves many shared hormones that originate between melanocytes in the skin and neurons in the brain. Both of these cell types are susceptible to influence by mechanisms that control melanin production or pigmentation, and could have an effect on neurological processes, behavior, and disease vulnerability.
The process of pigmentation begins in melanocytes from the skin, which produce two primary pigments: eumelanin and pheomelanin. While both pigments provide protection from ultraviolet radiation (UVR), pheomelanin offers reduced protection and is responsible for lighter pigmentations. Under UVR exposure, damage done to the skin’s DNA triggers pigment production, as well as production of β-endorphin, an opioid-like peptide. Once β-endorphin enters your circulation, there are several interlinked pathways through which it can influence the CNS, such as increasing neuromelanin production.
Neuromelanin, which is usually found in the substantia nigra of the midbrain, is very commonly present in dopaminergic neurons. It initially forms from dopamine oxidation, and by accumulating in the substantia nigra, it can protect neurons. While it usually does this by sequestering toxic molecules and metals, its dysfunction has been linked to neurodegenerative diseases. This helps explain why previous studies show that individuals with lighter pigmentation, and therefore more β-endorphin production, have an increased risk of developing diseases susceptible to UVR such as Parkinson’s.
The study’s researchers believe that these findings demonstrate how pigmentation in humans can represent not only a cosmetic trait, but also a biological connection between environmental exposure and neuronal function. By investigating the skin-brain axis more deeply, we could potentially provide more insight into other neurological disorders, and potentially look into novel therapeutic approaches to screen for conditions such as Parkinson’s disease.
Work’s Cited:
[1] Ascsillán, A. A., & Kemény, L. V. (2024). The Skin-Brain Axis: From UV and Pigmentation to Behaviour Modulation. International journal of molecular sciences, 25(11), 6199. https://doi.org/10.3390/ijms25116199
[2] Image retrieved from: https://unsplash.com/photos/woman-in-white-tank-top-w4Dj3MshHQ0
