Cells in our brain usually send “stop eating” signal when we’ve had enough. But after mice ate fatty foods for just two weeks, their brains’ brake on overeating quieted down. That finding may help explain the complex link between food and appetite that can become disordered when people overeat.
Food is essential to life. Our brains have, therefore, evolved a series of systems to make sure we eat enough. Garret Stuber, a neuroscientist at the University of Washington, together with his team took aim at one brain area known to be involved in eating behaviors.
This lateral hypothalamus (下丘脑外侧区) contains many diverse cells Stuber’s group looked at the behaviors of genes in the cells here. And in one type—glutamatergic nerve (谷氨酸能神经) cells—big differences appear between fat mice and lean ones.
Earlier work by Stuber’s group had suggested that these cells act like a brake on eating. When the researchers prevented these cells from firing, mice suddenly overate. They also fattened up. But it wasn’t clear how the cells’ activity changed as the mice transitioned from slim to fat.
“Obesity doesn’t just happen overnight,” notes Stuber. To find out the secret, his group undertook a new study. They fed mice high-fat food. Now and again, they’d use a fancy microscope to look at how well the animals’ glutamatergic cells could fire off signals.
Two weeks into the high-fat food—even before the mice became round – the activity of these nerve cells had slowed. It continued as the animals grew larger over a 12-week period. “The cells’ activity was going down as a function of high-fat diet. The results suggest that the high-fat diet is removing the brake on eating and obesity,” explains Stuber.
It’s hard to say whether similar cells normally control people’s appetite. Brain-imaging tests have shown that the same brain region —the hypothalamus—plays a role when people shift between hunger and feeling full.
12. What happened after the mice ate fatty foods for two weeks?
A.Their appetite was getting worse. | B.Their brains became disordered. |
C.They refused to eat zero fat food. | D.They lacked a feeling of fullness. |
13. It can be learned from the text that glutamatergic nerve cells ________.
A.are easily found in lean mice | B.can prevent mice from overeating |
C.function well under any condition | D.are a main part of lateral hypothalamus |
14. Why did Stuber’s group undertake the new study?
A.To study the role of glutamatergic cells in mice’s fattening up. |
B.To find out the link between high-fat diets and obesity. |
C.To find out deciding factors in mice’s appetite. |
D.To study the eating habit of fat mice. |
15. What is the main idea of the text?
A.Obesity influences glutamatergic nerves’ function. |
B.Glutamatergic nerves decide people’s appetite. |
C.High-fat diets lead to overeating. |
D.Our brains control our food choices. |