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Black Cohosh May Reduce Hot Flashes By Targeting Brain's Thermostat
9/7/2003

Source: American Chemical Society


Black cohosh, a medicinal herb increasingly used by women as an
alternative to estrogen replacement therapy, may reduce hot flashes by
targeting serotonin receptors — some of the same receptors used by the
brain to help regulate body temperature — according to a team of
researchers from the University of Illinois at Chicago. The finding, the
first to demonstrate a possible mechanism of action for the herb other
than estrogen, increases the likelihood that the herb is safe to use,
they say.

The study was described today during a press briefing on hormone
replacement therapy at the 226th national meeting of the American
Chemical Society, the world's largest scientific society. The study also
will appear in the Sept. 10 print issue of the Society's Journal of
Agricultural and Food Chemistry.

Until now, many scientists thought that black cohosh (koh-hawsh) worked
by targeting receptors for estrogen, the same hormone used in commercial
hormone replacement medicine that has recently been associated with
adverse side effects, including breast cancer and stroke.

"This study shows that black cohosh does not appear to be estrogenic
whatsoever and, as a result, is less likely to pose some of the dangers
associated with traditional estrogen replacement therapy," says study
leader Judy L. Bolton, Ph.D., a professor at the university's College of
Pharmacy. "We now have new clues to how it might work in the body."

Although preliminary evidence of the herb's efficacy in relieving hot
flashes, night sweats and other symptoms of menopause is encouraging,
further studies are still needed before it can be recommended, Bolton
says. Long-term safety data on black cohosh is also needed, she adds.

To determine whether black cohosh is estrogenic, the researchers used a
group of rats whose ovaries had been removed. The rats were divided into
different groups and each group was fed a different concentration of
cohosh extract daily for two weeks. Extracts of the herb, either alone
or in combination with synthetic estrogen, did not produce any changes
in uterine weight or ******l cell differentiation in the animals. This
indicates that the herb has no estrogenic effects, the researchers say.

In accompanying lab studies, the researchers also demonstrated that the
black cohosh extract is capable of binding to human serotonin receptors,
including those that help regulate body temperature. Previous studies
have shown that these receptors may play a role in regulating hot
flashes. Antidepressant medications, which some people believe may help
reduce hot flashes, also bind to the same receptors. The current study
may help provide an explanation for this effect, Bolton says.

Researchers still do not know the specific chemical or chemicals in
black cohosh that target the serotonin receptors. Nor do they know if
the herb may target hot flashes via additional mechanisms. Further
studies are underway to find answers to these questions, they say.

A Phase II clinical trial involving women with a high frequency of hot
flashes is now underway at the university to determine whether black
cohosh actually reduces the frequency and intensity of hot flashes and
other menopausal symptoms. The women will either receive black cohosh,
red clover, a placebo or estrogen replacement during the one-year trial,
which is one of the largest and longest of its kind, according to
Bolton. The trial is funded by the National Institutes of Health. Black
cohosh is indigenous to North America and is used by many women to treat
menopausal problems. Native Americans originally used it to treat a
variety of ailments, including gynecological disorders and even
depression. Interest in the herb has soared following the recent
findings of the Women's Health Initiative study, which showed that the
health risks of estrogen replacement therapy, including breast cancer
and stroke, might outweigh its benefits for some women.

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Michael Bernstein
212-542-1703 or 212-333-6356 American Chemical Society

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