Female Sex Hormones and Women's Obesity

Menopause makes women fat!

 
If a babe does not match your aesthetic principles, don't blame her for that, but put it on the play between her brain and her sexual hormones. And indeed, menopause can make women fat.

A new research managed to solve how hormonal change during menopause could provoke higher appetite and weight gain in aging women.

Animal lab tests revealed how estrogen receptors located in the hypothalamus control food intake, energy waste and body fat distribution. The impairment of these receptors makes animals start eating more, burn less energy and store large amounts of fat.

"This research seems to support a link between estrogen and regulation of obesity, especially the dangerous accumulation of abdominal fat linked to heart disease, diabetes, and cancer," said lead researcher Dr. Deborah J. Clegg, assistant professor of psychiatry at the University of Cincinnati Medical Center.

"The findings may also help scientists develop more targeted hormone replacement therapies, capable of stimulating estrogen receptors in one part of the brain or body while dampening it in the next," said Clegg.

Estrogen receptors are placed on cells throughout a woman's body. It was already known that one type of estrogen receptor, called estrogen receptor alpha (ER-alpha) is a main actor in regulating food intake and energy expenditure, but the location of the fat-regulating receptors and how they work was a puzzle.

To see how lower estrogen levels affect the brain, Clegg's team targeted two ER-alpha rich areas from the hypothalamus, a brain part controlling body temperature, hunger and thirst.

The first area, named the ventromedial nucleus (VMN) is crucial for energy regulation. Through RNA interference technique, the team turned off ER-alpha in the VMN. This plummeted the metabolism.

The mice females got an impaired tolerance to glucose and a significant weight gain, even when ingesting the same number of calories. Moreover, the excess of fat was deposited mostly in their visceral zone.

VMN ER-alpha appears to be crucial in balancing energy, body fat distribution and body weight.

The team is going to turn off ER-alpha in the arcuate nucleus region of the hypothalamus, which has two masses of neurons: one inhibiting and one activating hunger. Clegg forecasts that impaired ER-alpha in that area could boom the appetite and weight of the animals.

"The accumulation of abdominal fat puts both men and women at a heightened risk of cardiovascular disease, diabetes, and insulin resistance. Women are protected from these negative consequences as long as they carry their weight in their hips and saddlebags. But when they go through menopause and the body fat shifts to the abdomen, they have to start battling all of these medical complications. If we could target those critical regions and estrogen receptors associated with weight gain and energy expenditure, we could perhaps design therapies that help women sidestep many of the complications brought on by the onset of menopause," said Clegg.

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By    31 Aug 2007, 07:29 GMT