Beer belly or curvy hips: the reason is in gene expression
Scientists at the University of Texas, working under the guidance of Dr. Deborah Clegg, have received an answer to a question that has long been troubling people's minds: why do men and women get fat differently? Experiments on mice have shown that the reason for this lies in the peculiarities of gene expression. The results of the work are published in the International Journal of Obesity in the article "A microarray analysis of sexual dimorphism of adipose tissues in high-fat-diet-induced obese mice".
It is known that men get fat mainly in the abdominal area, whereas the problematic (typo, it should be read "attractive" – ed.) areas of women of childbearing age are the buttocks and thighs. Adipose tissue in the abdominal area is located mainly not under the skin, but around the internal organs (visceral fat), and male-type obesity is associated with a number of diseases, including diabetes and diseases of the cardiovascular system. Women are generally protected from these diseases, at least until the onset of menopause, when the level of ovarian hormones drops and the accumulation of adipose tissue shifts to the abdominal area.
The authors analyzed gene expression in subcutaneous and visceral fat fat cells of mice showing similar to human fat tissue distribution profiles. In addition to normal females and males, the study used females with removed ovaries, acting as a model of menopause.
The researchers expected a difference, but not so striking: it turned out that in the fat cells of representatives of different sexes, the same expression is characteristic of only 138 out of 40,000 genes. In addition, additional experiments showed that when kept on a fat-rich diet for 12 weeks, male mice gained significantly more weight than females. At the same time, the adipose tissue of males, especially visceral fat, acquired a pronounced inflammatory status, whereas in the fat cells of females, much lower expression of genes associated with inflammation was observed. Females with removed ovaries gained weight in the same way as males, while their adipose tissue was deposited mainly in the abdominal area and also began to acquire signs of inflammation at the epigenetic level. However, estrogen replacement therapy suppressed the inflammation of the adipose tissue of such females and normalized the distribution of adipose tissue.
The results indicate that ovarian hormones play a key role in regulating the distribution of adipose tissue in the body. The authors plan to study the mechanisms of the effect of these hormones on adipose tissue cells in order to develop methods of hormone replacement therapy that could protect menopausal women from the accumulation of visceral fat and associated diseases.
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru Based on ScienceDaily: Belly Fat or Hip Fat: It Really Is All in Your Genes, Says Researcher.
18.05.2010