Hidden Health Science

Posts Tagged ‘Chronic stress’

from Environmental Health News via IAOMT

A study raises concern about children’s exposure to mercury through fish eating, tying it for the first time to hormone changes that increase chronic stress and associated immune system dysfunction.

The mercury levels measured in the children were well below the levels considered a health risk by the U.S. Environmental Protection Agency.

This new study from Oswego County, New York, finds that higher mercury levels measured in the children’s blood are significantly associated with lower cortisol levels. The hormone cortisol is released in response to stress and is important for metabolism, immune responses and blood pressure. Its levels naturally fluctuate during the day – levels are higher in the morning and lower in the afternoon.

Even lower cortisol levels and responses can result in chronic stress even though stress increases the hormone’s level. The study’s results suggest that mercury exposure at levels commonly seen in fish eating populations may do this. It may act as a chronic stressor and disrupt the stress response. Chronic stress means the body doesn’t relax – cells continually function in high gear and do not return to a normal state. Long-term stress can have many negative health effects such as increased heart disease, more metabolic disorders and lowered immunity.

The findings are in line with prior studies in people and fish. The toxic metal increased inflammation in miners exposed to mercury. Animal studies find reduced cortisol levels in mercury-contaminated fish after capture stress.

Fish consumption is a major source both of beneficial omega-3 fatty acids and toxic mercury. Omega-3s benefit health by protecting against heart disease. Mercury is potentially harmful because it affects the brain and nervous system in children. Although there are fish advisories in many states, it is still uncertain whether the benefit of eating fish outweighs the potential harm in children.

To address the pros and cons of fish eating in children, the researchers examined 100 children from 9 to 11 years old in New York State. Parents reported children’s fish consumption, which was categorized as eating or not in the analysis. Blood mercury levels, blood lipids, cortisol in saliva and inflammation markers were measured. Blood lipids indicate future heart disease risk; cortisol reflects changes of stress response; and inflammation markers indicate immune response differences.

Fish eaters had higher HDL – or so called good cholesterol – related to lower heart disease risk, than non-fish eaters. However, the fish eaters also had much higher – almost three times higher – mercury levels than non-fish eaters (1.1 and 0.4 microgram per liter, respectively).

Mercury levels were related to lower cortisol levels at all time points in the study. The highest mercury levels had about 20-25 percent lower cortisol in saliva samples compared with lowest mercury levels. At the same time, children with higher mercury also had higher inflammatory markers in their blood.

The study is limited by its design as a one-time survey, not a follow-up study. More work is still needed to examine whether the association is robust in larger studies with a follow-up design.

Image via Wikipedia

Acupuncture significantly reduces levels of a protein in rats linked to chronic stress, researchers at Georgetown University Medical Center (GUMC) have found. They say their animal study may help explain the sense of wellbeing that many people receive from this ancient Chinese therapy.

Published online in December in Experimental Biology and Medicine, the researchers say that if their findings are replicated in human studies, acupuncture would offer a proven therapy for stress, which is often difficult to treat.

“It has long been thought that acupuncture can reduce stress, but this is the first study to show molecular proof of this benefit,” says the study’s lead author, Ladan Eshkevari, Ph.D., an assistant professor at Georgetown’s School of Nursing & Health Studies, a part of GUMC.

Eshkevari, who is also a nurse anesthetist as well as a certified acupuncturist, says she conducted the study because many of the patients she treats with acupuncture in the pain clinic reported a “better overall sense of wellbeing — and they often remarked that they felt less stress.”

While traditional Chinese acupuncture has been thought to relieve stress —in fact, the World Health Organization states that acupuncture is useful as adjunct therapy in more than 50 disorders, including chronic stress — Eshkevari says that no one has biological proof that it does so.

So she designed a study to test the effect of acupuncture on blood levels of neuropeptide Y (NPY), a peptide that is secreted by the sympathetic nervous system in rodents and humans. This system is involved in the “flight or fight” response to acute stress, resulting in constriction of blood flow to all parts of the body except to the heart, lungs, and brain (the organs most needed to react to danger). Chronic stress, however, can cause elevated blood pressure and cardiac disease.

Eshkevari used rats in this study because these animals are often used to research the biological determinants of stress. They mount a stress response when exposed to winter-like cold temperatures for an hour a day.

Eshkevari allowed the rats to become familiar with her, and encouraged them to rest by crawling into a small sock that exposed their legs. She very gently conditioned them to become comfortable with the kind of stimulation used in electroacupuncture — an acupuncture needle that delivers a painless small electrical charge. This form of acupuncture is a little more intense than manual acupuncture and is often used for pain management, she says, adding “I used electroacupuncture because I could make sure that every rat was getting the same treatment dose.”

She then selected a single acupuncture spot to test: Zuslanli (ST 36 on the stomach meridian), which is said to help relieve a variety of conditions including stress. As with the rats, that acupuncture point for humans is on the leg below the knee.

The study utilized four groups of rats for a 14-day experiment: a control group that was not stressed and received no acupuncture; a group that was stressed for an hour a day and did not receive acupuncture; a group that was stressed and received “sham” acupuncture near the tail; and the experimental group that were stressed and received acupuncture to the Zuslanli spot on the leg.

She found NPY levels in the experimental group came down almost to the level of the control group, while the rats that were stressed and not treated with Zuslanli acupuncture had high levels of the protein.

In a second experiment, Eshkevari stopped acupuncture in the experimental group but continued to stress the rats for an additional four days, and found NPY levels remained low. “We were surprised to find what looks to be a protective effect against stress,” she says.

Eshkevari is continuing to study the effect of acupuncture with her rat models by testing another critical stress pathway. Preliminary results look promising, she says.