In a study of mice, the researchers determined that weeks after experiencing a stressful event, animals that were more susceptible to stress exhibited enhanced neurogenesis – the birth of new nerve cells in the brain.
Specifically, the cells that these animals produced after a stressful event survived longer than new brain cells produced by mice that were more resilient.
In addition, when researchers prevented neurogenesis in both stress-susceptible and resilient mice, the animals previously susceptible to stress became more resilient.
"This work shows that there is a period of time during which it may be possible to alter memories relevant to a social situation by manipulating adult-generated nerve cells in the brain," said Dr. Amelia Eisch, associate professor of psychiatry at UT Southwestern and senior author of the study, available in the Proceedings of the National Academy of Sciences. "This could eventually lead to a better understanding of why, in humans, there is an enormous variety of responses to stressful situations."
Mice that are susceptible to stress exhibit long-lasting social avoidance and depressive-like behavior after experiencing a stressful event, such as being placed in a cage with a more aggressive mouse. Resilient mice behave more like unstressed control animals. This animal model is commonly used in studies of stress and depression, as understanding the changes in the brain and behavior of the mice can shed light on stress-induced changes in the human brain and in human behavior.
In the study, the brain cells of both groups of mice responded in similar ways after a stressful event. But weeks later, researchers found that mice displaying social avoidance had more nerve cells in a region of the brain called the hippocampus that survived the stressful event than mice that were more resilient.
The study is the first to link the memory of a social experience with neurogenesis in the hippocampus, Dr. Eisch said. Recently, Dr. Eisch and her team have linked adult neurogenesis with addiction. Previously, neurogenesis was primarily associated with spatial learning and memory.
In this study, Dr. Eisch and her colleagues exposed some mice to social defeat by having the animals live in the same cage as larger, aggressor mice for five minutes a day, and in the same cage but with a barrier in place the rest of the day. Researchers then tested the mice to see if they were susceptible to stress.
The researchers labeled the new cells of susceptible and unsusceptible mice so they could see how the cells divided. Both types of mice produced fewer dividing cells immediately after stress, but in the long run, mice susceptible to stress had more new adult cells than unsusceptible and control mice, who lived in cages with nonaggressor mice.
Dr. Eisch and her colleagues also used radiation to prevent hippocampal neurogenesis in all groups of mice. Mice susceptible to stress stopped producing new nerve cells and didn't display social avoidance in the long term.
Inhibiting social avoidance also had detrimental effects, however.
"Radiation in susceptible mice led to behavior that might be interpreted as harmful, such as approaching a potential aggressor mouse instead of avoiding it. We hypothesize that the survival of new nerve cells may be a compensatory event in the brain to allow the mouse to remember a socially relevant aggressor," Dr. Eisch said. "We are very eager to see if these results carry over to other models of stress in animals and to explore the mechanisms underlying these changes, as these are critical steps to understanding how adult-generated neurons might be modulated to help humans in stressful situations."
Future studies also will help determine which genes are involved with increased survival of new nerve cells in mice susceptible to stress, Dr. Eisch said.
Other UT Southwestern researchers participating in this study were Nathan DeCarolis, student research assistant in psychiatry and Shveta Malhotra, senior research associate in psychiatry. Others involved in the work were lead author Dr. Diane Lagace, former instructor of psychiatry, now at the University of Ottawa, as well as investigators from the University of Pennsylvania School of Medicine and Mount Sinai School of Medicine.
The study was supported by the National Institutes of Health, NASA, the National Alliance for Research on Schizophrenia and Depression, and the Canadian Institutes of Health Research.
Visit http://www.utsouthwestern.org/neurosciences to learn more about UT Southwestern's clinical services in neurosciences, including psychiatry.
This news release is available on our World Wide Web home page at http://www.utsouthwestern.edu/home/news/index.html
To automatically receive news releases from UT Southwestern via e-mail, subscribe at www.utsouthwestern.edu/receivenews
LaKisha Ladson | EurekAlert!
The balancing act: An enzyme that links endocytosis to membrane recycling
07.12.2016 | National Centre for Biological Sciences
Transforming plant cells from generalists to specialists
07.12.2016 | Duke University
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
07.12.2016 | Health and Medicine
07.12.2016 | Life Sciences
07.12.2016 | Health and Medicine