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Needles may not seem like the best tool for treating stress, but acupuncture could be tapping into basic biological systems that keep stress under control.

Reporting in the Journal of Endocrinology, researchers led by Ladan Eshkevari, assistant program director of the nurse anesthesia program at Georgetown University School of Nursing and Health Studies, mimicked chronic stress in a rat model and documented how stimulating certain body points with acupuncture can alter stress hormones.

The body’s stress response is triggered by two main pathways, one of which involves the HPA axis, or hypothalamus-pituitary-adrenal axis, in which these areas of the brain are activated to release peptides and proteins such as corticotropin-releasing hormone (CRH). They, in turn, launch the production of other hormones such as cortisol and norepinephrine that rev up the anxiety meter. Once activated, the system causes the heart to beat faster and the senses to go on alert. It also diverts the body’s energy away from background operations such as digestion to prime and fuel the muscles into a state of readiness.

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All of this is normal and necessary for protecting mammals, including us, from potential threats. But when stress becomes chronic, beating us down hour after hour and day after day, it’s no longer helpful and can become harmful. “People under chronic stress don’t handle acute stress very well,” says Eshkevari. “In chronic stress, the cortisol levels are elevated and never come back down to baseline, so people end up with insomnia or depressed or anxious because of the constant ramping up of this system.”

When Eshkevari, who is a nurse anesthetist, noticed that many of her patients who used acupuncture to treat pain reported sleeping better and feeling better able to cope with their pain, even if the needling did not relieve the pain itself, she wondered whether acupuncture might help to reduce stress.

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There weren’t many studies documenting how acupuncture could affect physiologic stress pathways, however, so she designed one using rats to investigate how the relationship might work. To create chronic stress in the animals, she exposed them to an ice bath for one hour a day over 10 days. One group of animals was just exposed to the ice bath, while another was treated beforehand with four days of electroacupuncture in a known active site in the stomach. And another group of rats was treated with a sham version of the acupuncture in a non-essential point 5 mm away. Eshkevari used an electric-based acupuncture in order deliver standard amounts of stimulation to the animals and avoid any confounding effects of inconsistent activation of the stomach site.

To monitor levels of the stress hormones and their precursors, she and her colleagues also collected blood from the animals on the first day and again on day seven and 14 of the study. These levels were compared to those of control animals that were not treated to the ice bath.

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As expected, the animals that were only treated to the cold-stress showed higher levels of CRH and other stress hormones after their exposure. And the sham animals showed similar levels of activated stress hormones. But those that were pre-treated with acupuncture showed no such spike in these hormones. In fact, their CRH levels were similar to those of the controls who hadn’t been exposed to the ice bath at all.

“The acupuncture seemed to help recalibrate, or normalize the [stress] hormone levels, at least in this model using the rat,” says Eshkevari.

So instead of keeping the animals in a constant state of anxiety, the acupuncture seemed to dial down the heightened stress response and return it toward normal levels.

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Whether that also occurs in people isn’t clear yet, but since the HPA axis works in similar ways among mammals, it’s possible the results could improve understanding of how to manage stress in people as well.

As far as why the needling at the stomach-point in the rat seemed to be so effective in tapping into the stress response, Eshkevari says there is evidence for a strong brain-gut connection, both in western and Chinese medicine. It may explain why, for example, we tend to eat when we feel stressed, or develop digestive disorders like constipation or diarrhea when we become especially anxious.

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Eshkevari is currently repeating the experiment in animals who have already been stressed by the exposure to the ice bath. The goal is to determine if acupuncture can function not just as prevention but as a treatment as well. Even if acupuncture doesn’t prove to be a magic bullet, it may lead to better understanding of the HPA system and other ways to break the cycle of chronic stress.