Fat yet muscular mouse provides clues to improving cardiovascular health

November 22, 2010

A fat yet muscular mouse is helping researchers learn whether more muscle improves the cardiovascular health of obese individuals.

"We are looking for ways to counteract the unhealthy effects of fat," said Dr. David Stepp, vascular biologist at the Medical College of Georgia Vascular Biology Center and co-director of MCG's Diabetes & Obesity Discovery Institute.

Obesity increases the risk for cardiovascular disease as well as diabetes, which essentially doubles the cardiovascular risk. But Stepp's laboratory research indicates more muscle could reduce that risk - a theory bolstered by people who appear "fit and fat." He recently received a $450,000 exploratory grant from the National Institutes of Health to further explore the possibilities.

The fact is that people - and mice - with more muscle have more blood vessels, use more oxygen and energy and eliminate more glucose even sitting still than their flabbier counterparts. "Fat does not consume a lot of energy and it's not very vascular," Stepp said. "Muscle and nerves, on the other hand, generate electricity, which is one of the most energetically expensive things we do." The heart and blood vessels also thrive with increased blood flow and diabetes risk is reduced by muscles' glucose disposal capabilities.

"The question is, if nothing else changes, if you are still fat and inactive, does having big muscles improve metabolic and cardiovascular function," Stepp said.

If the answer is "yes," myostatin inhibitors, already under study for muscle wasting diseases such as muscular dystrophy, could help break the unhealthy vicious cycle of inactivity promoting obesity and obesity impeding exercise. "Giving someone myostatin inhibitors is not going to magically fix their problems, but it may give them a little bit of a performance edge that gets them up and moving," Stepp said, particularly the heaviest individuals.

The hormone myostatin - which means "muscle stop" - is found at low levels during development but increases in adulthood when growth is supposed to stop. "If you express myostatin, your muscles stop growing at some point," he said. Exercise can help reduce myostatin levels and build muscle.

Stepp is studying a mouse that is a cross between "mighty mouse," a muscular rodent that lacks myostatin, and one that gets fat because of a diminished fullness sensation. The resulting mouse is literally quite a handful, said Stepp, noting that, unlike humans, mice tend not to overeat unless changes are made to food centers in the brain.

He wants to see whether the fat but muscular mouse has better cardiovascular function than its purely fat counterparts. That means looking at various related factors such as the ability to dilate blood vessels, which improves blood flow; production of antioxidants that promote inflammation and cardiovascular damage; and the heart's ability to pump blood.

These pursuits can help determine how muscle and exercise benefit the cardiovascular system as they target one of obesity's most debilitating and deadly risks.

"Even if you don't lose weight, exercise does good things. It limits metabolic damage, it limits cardiovascular damage," Stepp noted. "If we could get people over the hump where they could be stronger, they can be more active and hopefully lose some weight."
-end-


Medical College of Georgia at Augusta University

Related Diabetes Articles from Brightsurf:

New diabetes medication reduced heart event risk in those with diabetes and kidney disease
Sotagliflozin - a type of medication known as an SGLT2 inhibitor primarily prescribed for Type 2 diabetes - reduces the risk of adverse cardiovascular events for patients with diabetes and kidney disease.

Diabetes drug boosts survival in patients with type 2 diabetes and COVID-19 pneumonia
Sitagliptin, a drug to lower blood sugar in type 2 diabetes, also improves survival in diabetic patients hospitalized with COVID-19, suggests a multicenter observational study in Italy.

Making sense of diabetes
Throughout her 38-year nursing career, Laurel Despins has progressed from a bedside nurse to a clinical nurse specialist and has worked in medical, surgical and cardiac intensive care units.

Helping teens with type 1 diabetes improve diabetes control with MyDiaText
Adolescence is a difficult period of development, made more complex for those with Type 1 diabetes mellitus (T1DM).

Diabetes-in-a-dish model uncovers new insights into the cause of type 2 diabetes
Researchers have developed a novel 'disease-in-a-dish' model to study the basic molecular factors that lead to the development of type 2 diabetes, uncovering the potential existence of major signaling defects both inside and outside of the classical insulin signaling cascade, and providing new perspectives on the mechanisms behind insulin resistance in type 2 diabetes and possibly opportunities for the development of novel therapeutics for the disease.

Tele-diabetes to manage new-onset diabetes during COVID-19 pandemic
Two new case studies highlight the use of tele-diabetes to manage new-onset type 1 diabetes in an adult and an infant during the COVID-19 pandemic.

Genetic profile may predict type 2 diabetes risk among women with gestational diabetes
Women who go on to develop type 2 diabetes after having gestational, or pregnancy-related, diabetes are more likely to have particular genetic profiles, suggests an analysis by researchers at the National Institutes of Health and other institutions.

Maternal gestational diabetes linked to diabetes in children
Children and youth of mothers who had gestational diabetes during pregnancy are at increased risk of diabetes themselves, according to new research published in CMAJ (Canadian Medical Association Journal).

Two diabetes medications don't slow progression of type 2 diabetes in youth
In youth with impaired glucose tolerance or recent-onset type 2 diabetes, neither initial treatment with long-acting insulin followed by the drug metformin, nor metformin alone preserved the body's ability to make insulin, according to results published online June 25 in Diabetes Care.

People with diabetes visit the dentist less frequently despite link between diabetes, oral health
Adults with diabetes are less likely to visit the dentist than people with prediabetes or without diabetes, finds a new study led by researchers at NYU Rory Meyers College of Nursing and East Carolina University's Brody School of Medicine.

Read More: Diabetes News and Diabetes Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.