Unraveling the Link Between Genes and Environment

MONDAY, May 5 (HealthDay News) -- New studies in the field of epigenetics -- which looks at how environmental factors can change gene function without altering DNA sequence -- are identifying new molecular targets that may lead to improved drug treatment of depression, scientists report.

Epigenetics plays a major role in depression and the actions of antidepressants.

"The mechanisms that precipitate depression, such as stress, are incompletely understood," Dr. Eric Nestler, of the University of Texas Southwestern Medical School in Dallas, said in a prepared statement. "One mystery of the disease is its long-lasting nature and delayed response to antidepressant treatment. This persistence is thought to be influenced by slowly developing but stable adaptations, which might include epigenetic regulation."

Nestler held a symposium Monday on epigenetics at the American Psychiatric Association annual meeting, in Washington, D.C. A number of scientists outlined their research on epigenetics and depression. The symposium was sponsored by the U.S. National Institute of Mental Health.

Epigenetic changes aren't the same as genetic mutations, which are variations in the sequences of building blocks that make up the DNA in a gene. In epigenetic changes, genes remain stable, but environmental factors such as diet, stress and a mother's care act on the supporting structures of DNA, such as chromatin, molecules that package genes into chromosomes, according to background information in a news release about the symposium.

Certain chemical reactions can unravel the chromatin, which can affect a gene's DNA code and turn a gene on or off. As a result, a gene may produce more or less protein than normal which, in turn, can affect physical and behavioral traits. This change in protein production can be passed on from one cell to another as they multiply and can also be passed from parents to children.

Research conducted by Nestler and colleagues found that chronic social stress can cause chromatin changes in genes in the brain's nucleus accumbens and hippocampus.