GENE RESPONSIBLE FOR TRAITS INVOLVED IN DIABETES DISCOVERED

A collaborative research team led by Medical College of Wisconsin (MCW) scientists has identified a new gene associated with fasting glucose and insulin levels in rats, mice and in humans. The findings are published in the September issue of Genetics.

Leah Solberg Woods, Ph.D., associate professor of pediatrics at MCW and a researcher in the Children's Hospital of Wisconsin Research Institute, led the study and is the corresponding author of the paper.

The authors of the paper identified a gene called Tpcn2 in which a variant was associated with fasting glucose levels in a rat model. Studies in Tpcn2 knockout mice also demonstrated the difference in fasting glucose levels as well as insulin response between the knockout animals and regular mice. Finally, Dr. Woods' team identified variants within Tpcn2 associated with fasting insulin in humans. Tpcn2 is a lysosomal calcium channel that likely plays a role in insulin signaling. Glucose tolerance, insulin resistance and beta cell dysfunction are key underlying causes of type 2 diabetes.

"Genome-wide association studies in humans have identified 60+ genes linked to type 2 diabetes; however, these genes explain only a small portion of heritability in diabetes studies. As we continue to identify genes and variants of interest, we will evaluate them in multiple models to understand the mechanism of disease," said Dr. Solberg Woods.

According to the American Diabetes Association, 29 million Americans have diabetes -- more than nine percent of the total population. It is the 7th leading cause of death, and experts estimate diabetes is an underreported cause of death because of the comorbidities and complications associated with the disease.

EATING BREAKFAST INCREASES BRAIN CHEMICAL INVOLVED IN REGULATING FOOD INTAKE CRAVINGS

According to the Centers for Disease Control and Prevention (CDC), many teens skip breakfast, which increases their likelihood of overeating and eventual weight gain. Statistics show that the number of adolescents struggling with obesity, which elevates the risk for chronic health problems, has quadrupled in the past three decades. Now, MU researchers have found that eating breakfast, particularly meals rich in protein, increases young adults' levels of a brain chemical associated with feelings of reward, which may reduce food cravings and overeating later in the day. Understanding the brain chemical and its role in food cravings could lead to improvements in obesity prevention and treatment.

"Our research showed that people experience a dramatic decline in cravings for sweet foods when they eat breakfast," said Heather Leidy, an assistant professor of nutrition and exercise physiology. "However, breakfasts that are high in protein also reduced cravings for savory -- or high-fat -- foods. On the other hand, if breakfast is skipped, these cravings continue to rise throughout the day."

Leidy studied the effects of different breakfasts on participants' levels of dopamine, a brain chemical involved in moderating impulses and reward, including food cravings. Dopamine levels were determined by measuring homovanillic acid (HVA), the main dopamine metabolite. Eating initiates a release of dopamine, which stimulates feelings of food reward. The reward response is an important part of eating because it helps to regulate food intake, Leidy said.

"Dopamine levels are blunted in individuals who are overweight or obese, which means that it takes much more stimulation -- or food -- to elicit feelings of reward; we saw similar responses within breakfast-skippers," Leidy said. "To counteract the tendencies to overeat and to prevent weight gain that occurs as a result of overeating, we tried to identify dietary behaviors that provide these feelings of reward while reducing cravings for high-fat foods. Eating breakfast, particularly a breakfast high in protein, seems to do that."

Participants in the study were young women with an average age of 19; however, Leidy said the findings may be generalized to a larger population of adults.

"In the U.S., people are skipping breakfast more frequently, which is associated with food cravings, overeating and obesity," Leidy said. "It used to be that nearly 100 percent of American adults, kids and teens were eating breakfast, but over the last 50 years, we have seen a decrease in eating frequency and an increase in obesity."

Leidy's research was published in the Nutrition Journal.