每日英语听力

当前播放

战或逃神经让老鼠毛发变白

This is Scientific American's 60-second Science. I'm Karen Hopkin. They say that Marie Antoinette's hair turned white the night before she lost her head to the guillotine.

But can stress really have such a dramatic effect on hair color? A new study in mice concludes that it can and credits overactive nerves with stripping the color from the animals' locks-and possibly ours.

Researchers at Harvard's Stem Cell Institute were interested in the stress and hair color issue. So they decided to take a closer look at those stem cells that give rise to melanocytes-the cells that pump pigments into each hair follicle.

The stem cells were an obvious target. "Because changes in the stem cell population translate to changes in hair color, which are very visible and easy to identify."

Ya-Chieh Hsu, the study's senior author. To start, she and her colleagues subjected mice to some rodent-sized stressors-

like having their cage tilted, their bedding dampened or their lights left on all night. "So what did we find? We found that stress indeed leads to premature hair graying in mice.

But it took a long time for us to actually narrow down how it occurs." First, they thought it could be the immune system attacking the melanocyte stem cell population.

"However, mice lacking immune cells still show premature hair graying under stress." Then they thought the key factor could be cortisol, the quintessential stress hormone.

"But when we removed the adrenal glands from the mice so they cannot produce cortisol-like hormones, their hair still turned gray under stress." That's when they turned their attention to the sympathetic nervous system, which orchestrates the body's overall reaction to stress,

including the classic fight-or-flight response. Those nerves reach out to our muscles, organs and, yes, even our hair.

下载全新《每日英语听力》客户端,查看完整内容
点击播放