Connection Discovered between Gray Hair, Stress

US Senator John McCain. Photo: Reuters
US Senator John McCain. Photo: Reuters
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Connection Discovered between Gray Hair, Stress

US Senator John McCain. Photo: Reuters
US Senator John McCain. Photo: Reuters

When Marie Antoinette was captured during the French Revolution, her hair reportedly turned white overnight. In more recent history, John McCain experienced severe injuries as a prisoner during the Vietnam War and lost his hair color.

These incidents urged scientists to connect stressful experiences with the phenomenon of hair graying. However, the reasons remained a mystery until recently.

Harvard University scientists have discovered how the process plays out, and published their findings in the Nature Journal.

A team of researchers led by Dr. Ya-Chieh Hsu, an associate professor of Stem Cell and Regenerative Biology at Harvard, found that stress activates nerves that are part of the fight-or-flight response, which in turn causes permanent damage to pigment-regenerating stem cells in hair follicles.

Researchers first had to narrow down which body system was responsible for connecting stress to hair color, including the possibility of a link between the gray hair and Cortisol, as stress always elevates the levels of the hormone.

They believed that cortisol might play a role, however, as they removed the adrenal gland from the mice so that they couldn't produce cortisol-like hormones, their hair still turned gray under stress.

After systematically eliminating different possibilities, researchers honed in on the sympathetic nerve system, which is responsible for the body's fight-or-flight response.

Sympathetic nerves branch out into each hair follicle on the skin. The researchers found that stress causes these nerves to release the chemical norepinephrine, which gets taken up by nearby pigment-regenerating stem cells.

In a report released by Harvard's website, Hsu said: "When we started to study this, I expected that stress was bad for the body, but the detrimental impact of stress that we discovered was beyond what I imagined. After just a few days, all of the pigment-regenerating stem cells were lost. Once they're gone, you can't regenerate pigment anymore. The damage is permanent".



First Radioactive Rhino Horns to Curb Poaching in South Africa

A sedated rhinoceros lies unconscious as professor James Larkin (R) from the University of the Witwatersrand's Radiation and Health Physics Unit (RHPU) uses a can of identification spray (DataDot) after carefully implanting dosed and calculated radioisotopes into its horns along with other Rhisotope Project members at an undisclosed location in the Waterbury UNESCO biosphere in Mokopane on June 25, 2024. (Photo by EMMANUEL CROSET / AFP)
A sedated rhinoceros lies unconscious as professor James Larkin (R) from the University of the Witwatersrand's Radiation and Health Physics Unit (RHPU) uses a can of identification spray (DataDot) after carefully implanting dosed and calculated radioisotopes into its horns along with other Rhisotope Project members at an undisclosed location in the Waterbury UNESCO biosphere in Mokopane on June 25, 2024. (Photo by EMMANUEL CROSET / AFP)
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First Radioactive Rhino Horns to Curb Poaching in South Africa

A sedated rhinoceros lies unconscious as professor James Larkin (R) from the University of the Witwatersrand's Radiation and Health Physics Unit (RHPU) uses a can of identification spray (DataDot) after carefully implanting dosed and calculated radioisotopes into its horns along with other Rhisotope Project members at an undisclosed location in the Waterbury UNESCO biosphere in Mokopane on June 25, 2024. (Photo by EMMANUEL CROSET / AFP)
A sedated rhinoceros lies unconscious as professor James Larkin (R) from the University of the Witwatersrand's Radiation and Health Physics Unit (RHPU) uses a can of identification spray (DataDot) after carefully implanting dosed and calculated radioisotopes into its horns along with other Rhisotope Project members at an undisclosed location in the Waterbury UNESCO biosphere in Mokopane on June 25, 2024. (Photo by EMMANUEL CROSET / AFP)

South African scientists on Tuesday injected radioactive material into live rhino horns to make them easier to detect at border posts in a pioneering project aimed at curbing poaching.

The country is home to a large majority of the world's rhinos and as such is a hotspot for poaching driven by demand from Asia, where horns are used in traditional medicine for their supposed therapeutic effect.

At the Limpopo rhino orphanage in the Waterberg area, in the country's northeast, a few of the thick-skinned herbivores grazed in the low savannah.

James Larkin, director of the University of the Witwatersrand's radiation and health physics unit who spearheaded the initiative, told AFP he had put "two tiny little radioactive chips in the horn" as he administered the radioisotopes on one of the large animals' horns.

The radioactive material would "render the horn useless... essentially poisonous for human consumption" added Nithaya Chetty, professor and dean of science at the same university.

The dusty rhino, put to sleep and crouched on the ground, did not feel any pain, Larkin said.

The radioactive material's dose was so low it would not impact the animal's health or the environment in any way, he said.

In February the environment ministry said that, despite government efforts to tackle the illicit trade, 499 of the giant mammals were killed in 2023, mostly in state-run parks. This represents an 11 percent increase over the 2022 figures.

Twenty live rhinos in total would be part of the pilot Rhisotope project whereby they would be administered a dose "strong enough to set off detectors that are installed globally" at international border posts originally installed "to prevent nuclear terrorism", a pleased Larkin said, sporting a green hat and a khaki shirt.

Border agents often have handheld radiation detectors which can detect contraband in addition to thousands of radiation detectors installed at ports and airports, the scientists said.