Scientists Get Closer to Origins of Hot Flashes
Researchers report that stimulating particular brain cells triggers hot flashes in mice -- a discovery they hope will lead to better therapies for women going through menopause.
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 estrogen -- 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 flashes.
More refined drugs are needed: Right now, the most common treatment for hot flashes is hormone replacement therapy. But, Johnson pointed out, estrogen also has widespread effects on the body.
Hormone therapy does effectively ease hot flashes, 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 estrogen-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.
Other research has shown that when estrogen levels are low, Kiss1 neurons fire at a heightened rate. And that, the researchers suspect, might make women more vulnerable to developing hot flashes 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 estrogen-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, published July 10 in the journal Cell Reports, was funded by the U.S. National Institutes of Health.
The U.S. National Institutes on Aging has more on hot flashes.
SOURCES: Christopher Johnson, graduate student, neuroscience, University of Washington, Seattle; Stephanie Padilla, Ph.D., postdoctoral researcher, University of Washington; JoAnn Pinkerton, M.D., executive director, North American Menopause Society, Pepper Pike, Ohio, and professor, obstetrics and gynecology, University of Virginia Health System, Charlottesville, Va.; July 10, 2018, Cell Reports, online
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