Wednesday, May 18, 2011

Sugar fuels growth of insulin-making cells

A spoonful of sugar may be a remedy for diabetes. The more glucose that insulin-producing cells in the pancreas use, the faster those cells reproduce, a new study in mice shows. Giving animals more food to eat or bathing cells with glucose — the type of sugar that cells burn for energy — can increase the amount of insulin-producing pancreatic cells known as beta cells. But exactly how the sugar increases the number of beta cells has not been clear.

In the new study, researchers led by Yuval Dor and Benjamin Glaser of the Hebrew University of Jerusalem used genetic techniques to wipe out about 80 percent of the beta cells in the pancreases of mice. The mice became unable to produce enough insulin and thus diabetic, but between a month and six weeks later, the mice’s blood sugar levels dropped to normal. The researchers discovered that some of the beta cells had grown back.

He and his colleagues wanted to know whether that slow growth was fueled by the mice’s high blood sugar or by other factors. To find out, the researchers again killed about 80 percent of beta cells in another group of mice, but this time transplanted insulin-producing cells elsewhere in the mice to keep their blood sugar at normal levels. That meant the surviving beta cells in the pancreas didn’t have to work as hard. The cells’ regeneration rate dropped along with their work load, the team found. The result convinced researchers that glucose really was involved in the cells’ regrowth.

To confirm the finding the team removed an enzyme called glucokinase from the mice’s beta cells. Glucokinase is a key enzyme in the conversion of glucose to energy. Without glucokinase “the beta cell replication dropped nearly to zero.
The result also suggested that drugs that boost activity of glucokinase might increase beta cell growth. Such drugs might boost beta cell growth while still lowering circulating blood sugar levels.
People with mutations that increase glucokinase activity also have more beta cells in their pancreases.


Shih-Wei Kuo - 42621209

No comments: