[Our] so-called “fight-or-flight” response served our ancestors well, but its continual activation in our modern-day lives comes with a cost. Scientists are starting to realize stress often exacerbates several diseases, including depression, diabetes, cardiovascular disease, HIV/AIDS and asthma. One theory is hoping to explain the link between stress and such widespread havoc by laying the blame on an unexpected source—the microscopic powerhouses inside each cell.
[R]ecent animal studies have shown chronic stress not only leads to mitochondrial damage in brain regions such as the hippocampus, hypothalamus and cortex, it also results in mitochondria releasing their DNA into the cell cytoplasm, and eventually into the blood.
The genetic cast-offs are not just inert cellular waste. “This circulating mitochondrial DNA acts like a hormone,” says [psychobiologist] Martin Picard.
These studies are all part of an emerging field of research on mitochondrial DNA, where scientists are recognizing that the tiny organelles have effects across a wide range of diseases. “Mitochondrial DNA is probably the most sensitive thing in your body,” says Douglas Wallace, director of the Center for Mitochondrial and Epigenomic Medicine at The Children’s Hospital of Philadelphia. “If your mitochondria are sensing a problem, then all the rest of you is in trouble, too.”
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