"We found that out of about 40,000 mouse genes, only 138 are commonly found in both male and female fat cells," said Dr. Deborah Clegg, assistant professor of internal medicine at UT Southwestern Medical Center and senior author of the study appearing in the International Journal of Obesity. "This was completely unexpected. We expected the exact opposite – that 138 would be different and the rest would be the same between the sexes."
The study involved mice, which distribute their fat in a sexually dimorphic pattern similar to humans.
"Given the difference in gene expression profiles, a female fat tissue won't behave anything like a male fat tissue and vice versa," Dr. Clegg said. "The notion that fat cells between males and females are alike is inconsistent with our findings."
In humans, men are more likely to carry extra weight around their guts while pre-menopausal women store it in their butts, thighs and hips. The bad news for men is that belly, or visceral, fat has been associated with numerous obesity-related diseases including diabetes and heart disease. Women, on the other hand, are generally protected from these obesity-related disorders until menopause, when their ovarian hormone levels drop and fat storage tends to shift from their rear ends to their waists.
"Although our new findings don't explain why women begin storing fat in their bellies after menopause, the results do bring us a step closer to understanding the mechanisms behind the unwanted shift," Dr. Clegg said.
For this study, researchers used a microarray analysis to determine whether male fat cells and female fat cells were different between the waist and hips and if they were different based on gender at a genetic level.
Because the fat distribution patterns of male and female mice are similar to those of humans, the researchers used the animals to compare genes from the belly and hip fat pads of male mice, female mice and female mice whose ovaries had been removed – a condition that closely mimics human menopause. Waist and hip fat (subcutaneous fat) generally accumulates outside the muscle wall, whereas belly fat (visceral fat), a major health concern in men and postmenopausal women, develops around the internal organs.
In addition to the genetic differences among fat tissues, the researchers found that male mice that consumed a high-fat diet for 12 weeks gained more weight than female mice on the same diet. The males' fat tissue, particularly their belly fat, became highly inflamed, while the females had lower levels of genes associated with inflammation. The female mice whose ovaries had been removed, however, gained weight on the high-fat diet more like the males and deposited this fat in their bellies, also like the males.
"The fat of the female mice whose ovaries had been removed was inflamed and was starting to look like the unhealthy male fat," Dr. Clegg said. "However, estrogen replacement therapy in the mice reduced the inflammation and returned their fat distribution to that of mice with their ovaries intact."
Dr. Clegg said the results suggest that hormones made by the ovaries may be critical in determining where fat is deposited. Her overall goal is to determine how fat tissue is affected by sex hormones and whether it would be possible to develop a "designer" hormone replacement therapy that protected postmenopausal women from belly fat and related diseases such as metabolic syndrome.
Researchers from Oregon Health and Science University, Boston University School of Medicine and the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University also contributed to the study. The study was supported by the Society for Women's Health Research.
Visit http://www.utsouthwestern.org/nutrition to learn more about clinical services in nutrition at UT Southwestern, including treatments for diabetes, kidney disease and obesity.
This news release is available on our World Wide Web home page at www.utsouthwestern.edu/home/news/index.html
To automatically receive news releases from UT Southwestern via e-mail, subscribe at www.utsouthwestern.edu/receivenews
Kristen Holland Shear | EurekAlert!
Nanobot pumps destroy nerve agents
21.08.2018 | American Chemical Society
How do muscles know what time it is?
21.08.2018 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt
There are currently great hopes for solid-state batteries. They contain no liquid parts that could leak or catch fire. For this reason, they do not require cooling and are considered to be much safer, more reliable, and longer lasting than traditional lithium-ion batteries. Jülich scientists have now introduced a new concept that allows currents up to ten times greater during charging and discharging than previously described in the literature. The improvement was achieved by a “clever” choice of materials with a focus on consistently good compatibility. All components were made from phosphate compounds, which are well matched both chemically and mechanically.
The low current is considered one of the biggest hurdles in the development of solid-state batteries. It is the reason why the batteries take a relatively long...
New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference
Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...
Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...
Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.
When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...
Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.
Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....
17.08.2018 | Event News
08.08.2018 | Event News
27.07.2018 | Event News
21.08.2018 | Medical Engineering
21.08.2018 | Physics and Astronomy
21.08.2018 | Power and Electrical Engineering