Stress and nerve cells survival in rats; finding may open widow for depression treatment

A single, socially stressful situation can kill off new nerve cells in the brain region that processes learning, memory, and emotion, and possibly contribute to depression, new animal research shows.

Researchers found that in young rats, the stress of encountering aggressive, older rats did not stop the generation of new nerve cells—the first step in the process of neurogenesis. But stress did prevent the cells, located in the hippocampus, from surviving, leaving fewer new neurons for processing feelings and emotions. The hippocampus is one of two regions of the brain that continues to develop new nerve cells throughout life, in both rats and humans. The reduction of neurogenesis could be one cause of depression, says senior author Daniel Peterson, PhD, of the Rosalind Franklin University of Medicine and Science, near Chicago. His team reports their findings in the March 14 issue of The Journal of Neuroscience.

"This is strong evidence that the effects of social stress on neurogenesis occur after a delay of 24 hours or more, providing a possible time window for treatment after acute episodes of stress," says Henriette van Praag, PhD, of the Salk Institute for Biological Studies.

When Peterson and his research team put a young rat in a cage with two older rats for 20 minutes, the resident rats quickly pinned down and, in many cases, bit the intruder. The team reported that intruder rats were fearful and acted depressed around the bigger, more mature animals and had stress hormone levels six times as high as young rats that didn't experience a stressful encounter.

Examining the rats' brains under a microscope, the scientists discovered that even with high levels of stress hormones, the young, stressed rats generated as many new cells as their unstressed counterparts. Previous research had led some to think that hormone levels played a role in blocking the generation of new cells or caused them to die early on. But a week after the encounter, the team found that only a third of the cells generated under stress had survived. Long-term survival of nerve cells was also compromised: When Peterson's team marked newborn cells in the hippocampus, subjected rats to stress a week later, then examined brain tissue at the end of a month, they counted a third fewer fully developed nerve cells.

"The next step is to understand how stress reduced this survival," says Peterson. "We want to determine if anti-depressant medications might be able to keep these vulnerable new neurons alive."

Source: Society for Neuroscience

Related stories:

Blood pressure response to daily stress provides clues for better hypertension treatment
How the body regulates blood pressure in response to daily stress is the focus of a study geared toward helping people whose pressure is out of control.
Research identifies brain cells related to fear
The National Institute of Mental Health estimates that in any given year, about
40 million adults (18 or older) will suffer from some form of anxiety disorder, including debilitating conditions such as phobias, panic disorders and post-traumatic stress disorder (PTSD). It is estimated that nearly 15 percent of U.S. soldiers returning from Iraq and Afghanistan develop PTSD, underscoring the urgency to develop better treatment strategies for anxiety disorders. These disorders can lead to myriad problems that hinder daily life – or ruin it altogether – such as drug abuse, alcoholism, marital problems, unemployment and suicide.
Coffee's aroma kick-starts genes in the brain
Drink coffee to send a wake-up call to the brain? Or just smell its rich, warm aroma? An international group of scientists is reporting some of the first evidence that simply inhaling coffee aroma alters the activity of genes in the brain.
Study shows how cocaine impairs fetal brain development
Exposure of the developing brain to cocaine can cause neurological and behavioral abnormalities in babies born to mothers who use the drug during pregnancy. In a study research published in this week's PLoS Medicine, Chun-Ting Lee and colleagues at the U.S. National Institutes of Heath— who note that cocaine use occurs in several hundred thousand pregnancies per year in the United States alone — investigated the mechanism of cocaine's effect on fetal brain development.
Researchers show how the brain can protect against cancer
Scientists have been aware for many years that if cancer patients are not able to deal with the stress associated with being sick, the cancer will progress faster than in calmer patients. To counteract this phenomenon, physicians encourage treatments that help cancer patients handle their stress. Scientists theorized that the stress relief may have come as a result of increased beta-endorphin peptide (BEP), the "feel good" hormones in the brain that are released during exercise, a good conversation, and many other aspects of life that give humans pleasure.
Flow of potassium ions in brain cells is key to sexual arousal
When it comes to sex, a female rat knows how to avoid a communication breakdown. To announce her sexual readiness, she will automatically arch her back, deflect her tail and stand rigid to allow an aroused male to mount. Now, Rockefeller University researchers have figured out the precise chemical and physical mechanism in a group of brain cells that controls this swayback posture, a reflex called lordosis that signals one of life’s most complex yet primitive instincts — the need for sex.
Scientists find seizure drug reverses cellular effects
In the new research, published in the May 28, 2008 edition of The Journal of Neuroscience, the scientists found that gabapentin normalizes the action of certain brain cells altered by chronic alcohol abuse in an area of the brain known as the central amygdala, which plays an important role in fear- and stress-related behaviors, as well as in regulating alcohol drinking. In the study, alcohol-dependent rodents receiving gabapentin drank less alcohol.
Where college students live can impact their weight, eating and exercise habits
Endometriosis is a poorly understood condition that incapacitates and affects the productivity and lifestyle of millions of women around the world. In the US, it affects approximately six million women and adolescents at a cost of some $1.6 billion per year. It is a chronic painful disease which occurs when endometrial tissue grows as lesions outside the uterus, mainly in the area of the ovaries and fallopian tubes, but can also affect the intestinal tract. The condition results in chronic pelvic pain, painful menstrual periods and pain during intercourse.

News discussion:

Medicine & Health news