New Insights Into Fat's Effect on the Body

Studies detail discovery of fat-burning gene, show how leptin controls glucose levels

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TUESDAY, Jan. 18, 2005 (HealthDayNews) -- Scientists have identified a gene called lipin that regulates how your body produces and uses fat.

The researchers say lipin may offer a new drug target for controlling obesity, diabetes and other weight-related health problems. Their research with mice appears in the January issue of Cell Metabolism.

"Lipin regulates how the body stores and burns fat. Our findings suggest that differences in lipin levels may play a role in why some people are more prone to weight gain than others who consume the same calories," lead investigator Karen Reue said in a prepared statement. She is a professor of medicine and human genetics at the David Geffen School of Medicine at UCLA and a researcher at the Veterans Affairs Greater Los Angeles Healthcare System.

She and her colleagues studied two groups of specially bred mice. One group had a genetic mutation that boosted lipin levels in their fat tissue and the other group had a mutation that increased lipin levels in their muscles. There was also a control group of normal mice.

All three groups of mice were fed a high-fat diet for six weeks. The mice with elevated lipin in their fat or muscles gained twice the amount of weight as normal mice.

In fat tissue, lipin influences the capacity of your cells to store fat. In muscle, lipin affects the rate at which your body burns fat, the researchers said.

"When we increased lipin in the muscle, the cells burned carbohydrates before fat. When lipin is absent, however, the cells burn fat before carbohydrates," Reue said.

"We saw a different effect when lipin acted on fat tissue. High levels of lipin promoted fat storage. Lipin deficiency prevented the cells from forming and storing fat," she explained.

In another study on body fat, Harvard researchers found the hormone leptin acts directly on a brain region called the hypothalamic arcuate nucleus (ARH) to control glucose and insulin levels in the blood. That report also appears in the current issue of Cell Metabolism.

The study found that leptin receptors in the ARH accounted for about 22 percent of leptin's effects on body weight.

These findings in mice offer new information about potential mechanisms underlying type 2 diabetes and may help in the development of new treatments, the study authors said.

Leptin plays an important role in maintaining normal body weight and glucose balance.

"As the incidence of obesity and diabetes continues to rise in industrialized countries, a clear understanding of the cellular and neuroanatomic pathways that control energy and glucose balance is critical to the discovery of new methods to prevent or treat these conditions," study co-author Joel Elmquist, of Beth Israel Deaconess Medical Center and Harvard Medical School, said in a prepared statement.

More information

The U.S. National Institute of Diabetes and Digestive and Kidney Diseases has more about obesity.

SOURCE: UCLA and Cell Press, news releases, Jan. 18, 2005


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