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The free radical theory of graying
An article published in the July, 2006 issue of the Federation of American Societies for Experimental Biology (FASEB) journal submitted the hypothesis of researchers at Humboldt University in Berlin that the destruction of pigment cells called melanocytes that leads to the production of white hair by the hair follicles is due to free radical damage caused mainly by the generation of the pigment melanin, which results in significant oxidative stress.
The researchers studied hair follicles obtained from graying donors and found an increase in melanocyte apoptosis (programmed cell self-destruction) and oxidative stress. A mitochondrial DNA deletion that is a marker for accumulating oxidative stress damage was found primarily in graying hair follicles compared to pigmented follicles. Additionally, when cultured pigmented hair follicles were exposed to a chemical that generates oxidative stress they were found to have an increase in hair bulb melanocyte apoptosis. Interestingly, unpigmented hair follicles were demonstrated to have a better capacity to grow in culture than pigmented follicles, which the authors suggest could be due in part to lower overall oxidative stress caused by the reduction in melanocytes.
In addition to oxidative stress generated within the body, the authors suggest that exogenous oxidative stress caused by ultraviolet light and other factors could also be at fault in graying hair, and note that smokers have a greater incidence of premature graying.
"The graying hair follicle therefore offers a unique model-system to study oxidative stress effects and aging and to test antioxidants and other antiaging therapeutics in their ability to slow down or even stop this process," the authors write. They suggest that clinical trials monitor hair follicle melanocytes as a measure of oxidative stress-tissue damage and the effectiveness of antiaging and antioxidant therapeutics.
An article published in the July, 2006 issue of the Federation of American Societies for Experimental Biology (FASEB) journal submitted the hypothesis of researchers at Humboldt University in Berlin that the destruction of pigment cells called melanocytes that leads to the production of white hair by the hair follicles is due to free radical damage caused mainly by the generation of the pigment melanin, which results in significant oxidative stress.
The researchers studied hair follicles obtained from graying donors and found an increase in melanocyte apoptosis (programmed cell self-destruction) and oxidative stress. A mitochondrial DNA deletion that is a marker for accumulating oxidative stress damage was found primarily in graying hair follicles compared to pigmented follicles. Additionally, when cultured pigmented hair follicles were exposed to a chemical that generates oxidative stress they were found to have an increase in hair bulb melanocyte apoptosis. Interestingly, unpigmented hair follicles were demonstrated to have a better capacity to grow in culture than pigmented follicles, which the authors suggest could be due in part to lower overall oxidative stress caused by the reduction in melanocytes.
In addition to oxidative stress generated within the body, the authors suggest that exogenous oxidative stress caused by ultraviolet light and other factors could also be at fault in graying hair, and note that smokers have a greater incidence of premature graying.
"The graying hair follicle therefore offers a unique model-system to study oxidative stress effects and aging and to test antioxidants and other antiaging therapeutics in their ability to slow down or even stop this process," the authors write. They suggest that clinical trials monitor hair follicle melanocytes as a measure of oxidative stress-tissue damage and the effectiveness of antiaging and antioxidant therapeutics.
