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Friday, Dec. 14, 2012
Researchers in Tohoku shed light on mechanism that causes obesity
SENDAI — A research team that includes Tetsuya Yamada, associate professor at Tohoku University, has shed light on a bodily mechanism that causes obesity in mice.
When mice ingest high-calorie food, their brains curb the activity of energy-consuming brown fat cells, making it easier to store nutrients in their bodies, the team said in an article published in a recent issue of the U.S. journal Cell Metabolism.
Animals "may have a system to store excess calories they have ingested, in order to prepare for starvation," Yamada said, adding that his team is believed to be the world's first to discover a nutrient-storing mechanism inherent in animal bodies.
In their experiments on mice, the group focused on glucokinase, an enzyme in the liver that enhances sugar metabolism. In mice fed with high-calorie food containing a lot of sugar and fat, glucokinase rose. Their brains responded by curbing sympathetic nerve activity to reduce energy consumption by brown fat cells.
But there was no change in brown fat activity in mice fed with high-calorie food whose nerves between the brain and the liver had been cut, according to the article.
The team also compared mice that are inclined to become fat and mice that are not. In the obesity risk group, mice consumed more energy if an increase in their glucokinase was curbed.
A team comprising researchers from the University of Tokyo and Kyushu University said in a recent edition of British journal Nature Communications that they have developed a way to synthesize ammonia at ordinary temperatures and pressures with a low-cost iron-compound catalyst.
Fertilizer made from ammonia is necessary to produce food for some 7 billion people in the world. But the industrial synthesis of ammonia takes a huge amount of energy.
The breakthrough is expected to lead to energy-saving technologies as well as an increase in applications for ammonia.
Currently, synthesized ammonia accounts for almost the same amount of ammonia produced in the natural world. The existing method, which involves hydrogen reacting with nitrogen gas under high temperature and pressure, was invented some 100 years ago.