LIGHT THERAPY

Researchers discover mechanism behind how bright light can protect against heart attacks



Researchers at the University of Colorado Anschutz Medical Campus have discovered that bright light amplifies a specific gene that strengthens blood vessels and provides protection against heart attacks.

We already knew that intense light can protect against heart attacks, but now we have found the mechanism behind it. “

Lead study author, Tobias Eckle, MD, PhD, professor of anesthesiology, University of Colorado School of Medicine

The study was published recently in the journal Cell reports.

Scientists have found that harboring mice in bright light conditions for a week “dramatically improves cardio protection”, which has resulted in a dramatic reduction in damage to heart tissue after a heart attack. They also found that humans could potentially benefit from a similar light exposure strategy.

In an effort to find out why, they developed a strategy to protect the heart by using intense light to target and manipulate the function of the PER2 gene, which expresses itself in a circadian pattern in the part of the brain that controls circadian rhythms.

By amplifying this gene with light, they discovered that it protects cardiovascular tissue from low oxygen conditions like myocardial ischemia, caused by reduced oxygen flow to the heart.

They also discovered that light increases heart adenosine, a chemical that plays a role in regulating blood flow.

Blind mice, however, had no cardio protection indicating a need for visual light perception.

Next, they studied whether the intense light had similar effects on healthy human volunteers. The subjects were exposed to 30 minutes of intense light measured in lumens. In this case, the volunteers were exposed to 10,000 LUX, or lumens, for five consecutive days. The researchers also took serial blood samples.

Light therapy increased PER2 levels as it did in mice. Plasma triglycerides, a substitute for insulin sensitivity and carbohydrate metabolism, have decreased significantly. Overall, the therapy improved the metabolism.

Eckle has long known that light plays an essential role in cardiovascular health and the regulation of biological processes. He pointed out that previous studies have shown an increase in myocardial infarctions during the darker winter months in all of the US states, including in sunnier places like Arizona, Hawaii and California. The duration of the light is not as important as the intensity, he said.

“The most dramatic event in Earth’s history was the arrival of the sun,” said Eckle. “Sunlight caused the big oxygen event. With sunlight, billions of algae could now produce oxygen, transforming the entire planet.”

Eckle said the study shows, at the molecular level, that intensive light therapy offers a promising strategy in the treatment or prevention of low oxygen conditions like myocardial ischemia.

He said that if therapy is given before high-risk cardiac and non-cardiac surgery, it could offer protection against life-threatening injuries to the heart muscle.

“Giving patients light therapy a week before surgery could increase cardio protection,” he said. “Drugs could also be developed that offer similar protections based on these results. However, future studies in humans will be needed to understand the impact of intense light therapy and its potential for cardio protection.”

Source:

Journal reference:

Oyama, Y. et al. (2019) Intense light mediated circadian cardioprotection by transcriptional reprogramming of the endothelium. Cell reports. doi.org/10.1016/j.celrep.2019.07.020.

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