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Menopause

20 July 2018

Why am I getting hot flushes?

Science delves deeper into solving the issue of menopausal hot flushes.

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Researchers report that stimulating particular brain cells triggers hot flushes in mice – a discovery they hope will lead to better therapies for women going through menopause.

Controlling the flushes

Humans also have these brain cells, known as Kiss1 neurons, and the new study suggests they perform similar functions in humans, according to the University of Washington researchers.

And the neurons' activity is dependent on sex hormones, including oestrogen – which drops in a woman's body during menopause.

Findings in mice often do not pan out in people, but the researchers noted that a human trial underway in Europe is testing a drug that blocks a protein present in Kiss1 neurons, called NkB.

This latest finding gives added support to that approach, said researcher Christopher Johnson, a neuroscience graduate student at the university.

They might also lead to even more specific treatments, said Stephanie Padilla, a postdoctoral researcher who also worked on the study.

Now, Padilla explained, researchers can continue to look at what happens "downstream" from there, and possibly find targets for drugs that get at the heart of hot flushes.

New options welcome

More refined drugs are needed. Right now, the most common treatment for hot flushes is hormone replacement therapy. But, Johnson pointed out, oestrogen also has widespread effects on the body.

Hormone therapy does effectively ease hot flushes, but new options would be welcome and "practice-changing", said Dr JoAnn Pinkerton, executive director of the North American Menopause Society.

That's particularly true, she said, for women who cannot use hormone therapy – including those who've had oestrogen-sensitive breast and uterine cancers.

"Relief of hot flashes is an important, unmet need for these women," Pinkerton said. "Other non-hormone therapies, such as low-dose antidepressants or gabapentin, have not been as effective as hormone therapy."

For the study, the UW researchers used genetically engineered mice to see what happened when they manipulated Kiss1 neurons. They found that activating the cells triggered a rise in the animals' skin temperature, followed by an increase in core body temperature.

The effect was most pronounced in female mice whose ovaries were removed to deplete their sex hormone levels.

Additional physiological mechanism

Other research has shown that when oestrogen levels are low, Kiss1 neurons fire at a heightened rate. And that, the researchers suspect, might make women more vulnerable to developing hot flushes in response to some external trigger – such as heat, spicy food or a change in altitude.

According to Padilla, it all raises interesting questions about why these oestrogen-sensitive neurons would be involved in body temperature at all.

One possibility, the researchers speculate, is that during pregnancy, it might be advantageous for women to have an additional physiologic mechanism that helps regulate core body temperature.

The study was published in the journal Cell Reports. 

Image credit: iStock