Robert Warren Gould, a graduate student in the laboratory of Michael A. Nader, Ph.D., presented the study results Sunday at Experimental Biology 2008 in San Diego. The presentation was part of the scientific program of the American Society for Pharmacology and Experimental Therapeutics (ASPET).
Male cynomolgus monkeys live in a complex social structure in which the social hierarchy is established by physical aggression and maintained by clear signals. A monkey that has established his dominance over another monkey can elicit a subordinate response with no more than a meaningful look.
The researchers exposed four dominant and four subordinate monkeys to a socially stressful situation in which an individual monkey was taken out of his home cage and placed in an unfamiliar cage surrounded by four unfamiliar animals. The monkey was physically safe, but he could see and hear the animals around him engaging in aggressive behavior.
The study was performed twice, in order to ask two different types of questions. The first concerned brain activity caused by the stressful situation. Before being placed in the unfamiliar cage, each monkey had been injected with radioactively labeled glucose. After 40 minutes, each was given a PET brain imaging examination to see which parts of the brain were most active, as determined by which parts were using the most glucose. This type of brain imaging has been used frequently in humans to determine brain activity during various activities and situations. The scan of the individual monkey’s brain during the stressful situation was compared to earlier scans made when the animal had spent time simply sitting in his own familiar home cage without stress.
The brains of dominant monkeys and subordinate monkeys responded differently in both situations. In the normal situation of sitting in their home cage, subordinate monkeys displayed less activity than did the dominant monkeys in areas of the brain involved in stress and anxiety (the amygdala and hippocampus) and also in areas of the brain involved with emotional and social processing (anterior cingulate cortex).
Gould and Nader say these findings suggest monkeys that have to cope with constant, ongoing social stressors may have developed a lower level of brain activity even at rest. In the abnormal situation of being placed in an unfamiliar cage surrounded by unfamiliar and aggressively behaving monkeys, however, the subordinate monkeys showed pronounced decreased brain activity in areas of the brain involved with stress, anxiety, reward, and emotion, whereas the dominant monkeys showed increases in reward-related areas after the same situation.
In a separate part of the study, researchers looked at the effect of the stressful situation on the likelihood that monkeys would use cocaine. After the 40 minutes in the unfamiliar cage surrounded by other monkeys, each monkey could choose between pressing a lever that they knew delivered cocaine or one that they knew delivered a food reward. The subordinate monkey was more likely to choose cocaine while the dominant monkey was less likely to choose cocaine after this encounter, compared to their respective typical choices during the days preceding this encounter.
These differences in both brain activity and the likelihood of using cocaine between animals of different social rank offer clues to the social context of drug use and addiction in humans, say the researchers. Nader said, “We believe this type of research can be used to identify better treatment strategies, including providing environmental enrichment, that may affect the likelihood of abusing drugs.”
It’s also important, he said, to understand distinct patters of neurobiological activity occurring after acute social stress that may increase the attraction to cocaine in vulnerable individuals. Understanding the brain changes associated with stress also is critical in developing treatment and prevention strategies for disorders such as anxiety and depression that can result from chronic stress.
Karen Richardson | EurekAlert!
The Great Unknown: Risk-Taking Behavior in Adolescents
19.01.2017 | Max-Planck-Institut für Bildungsforschung
A sudden drop in outdoor temperature increases the risk of respiratory infections
11.01.2017 | University of Gothenburg
An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...
Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
19.01.2017 | Event News
10.01.2017 | Event News
09.01.2017 | Event News
20.01.2017 | Awards Funding
20.01.2017 | Materials Sciences
20.01.2017 | Life Sciences