Questão 882562

1 The same nerves involved in the fight-or-flight

response can cause permanent damage to the cells

responsible for producing hair color in mice, scientists

4 have found. There is some truth to the longstanding

anecdote that your locks can lose color when you’re

stressed.

7 A team of researchers has found that in mice,

stressful events damage the stem cells that are responsible

for producing pigment in hair. These stem cells, found near

10 the base of each hair follicle, differentiate to form more

specialized cells called melanocytes, which generate the

brown, black, red and yellow hues in hair and skin. Stress

13 makes the stem cells differentiate faster, exhausting their

number and resulting in strands that are more likely to be

transparent — gray.

16 The study also found that the sympathetic nervous

system, which prepares the body to respond to threats,

plays a major role in the graying process. “Normally, the

19 sympathetic nervous system is an emergency system for

fight or flight, and it is supposed to be very beneficial or, at

the very least, its effects are supposed to be transient and

22 reversible,” said Ya-Chieh Hsu.

Stress affects the whole body, so the researchers

had to do some investigation to figure out which

25 physiological system was conveying its effects to hair

follicles. The findings provide the first scientific link

between stress and hair graying. The new study is an

28 important step toward understanding the role of stress on

various tissues.

Internet: <www.nytimes.com> (adapted).

Concerning the text above, judge the items below.

The effects of the sympathetic nervous system are permanent regarding the fight-or-flight response, but not regarding the graying process.