Skinny mice defy obesity 瘦老鼠挑戰肥胖

Lean mouse: Hope for the clinically obese

精瘦的老鼠：肥胖癥的希望

Genetically engineered mice which never put on weight could hold the key to a fat- free future for humans, say scientists.

Researchers at Smith Kline Beecham and Cambridge University, UK, have developed mice that eat far more than normal but remain leaner and lighter.

The lab rodents over-produce a human protein which ensures food is turned into heat, rather than stored as fat.

Reporting in the journal Nature, Dr John Clapham and colleagues say their mice make large amounts of Uncoupling Protein 3 (UCP-3) in the mitochondria of their muscle cells.

Mitochondria are often described as the tiny internal combustion engines of cells. They unlock the energy contained in food to make a chemical fuel called adenosine triphosphate (ATP).

But extra UCP-3 causes the mice to burn off energy without making ATP - their bodies produce more heat instead. This process makes the metabolic rate of the transgenic mice step up a gear. As a result, they are able to eat large amounts of food yet weigh less than normal mice.

科學家們說，從不增重的轉基因老鼠是人類將來擺脫肥胖的鑰匙。

Smith Kline Beecham和英國劍橋大學的研究人員培養出一些老鼠，它們超量進食卻能保持身體輕瘦。

這些實驗室里的嚙齒動物超量產生一種人體蛋白質，這種蛋白質保證食物轉化成熱量而不是以脂肪形式儲存。

在《自然》雜志上，約翰－克拉彭博士和他的同事們說，他們培養的這些老鼠在肌肉細胞的線粒體中產生大量解藕連蛋白質3（UCP-3）。

線粒體通常被形容成細胞的微型內燃機。它們將食物中的能量轉化成一種叫做三磷酸缐苷(ATP)的化學燃料。

但多余的UCP-3使這些老鼠將能量耗光而不產生ATP－它們的身體產生的是更多的熱量。這一過程使這些轉基因老鼠新陳代謝加快。結果就是，它們吃大量食物，卻比正常老鼠要輕。