Researchers found that people suffering from depression are less able to store information because their brains are less plastic and adaptable. The experiment, conducted by the Ssientists at Karolinska Institute has shown that D-serine, a substance synthesized by astrocytes, may improve memory function.
According to Mia Lindskog, biologist and Assistant Professor at Karolinska Institutet’s Department of Neuroscience, the research team was able to heal memory-related disorders by administering D-serine. The experiment was conducted on FSL rats, bred with a special predisposition to depression. First of all, the animals were tested to see if they present symptoms of human depression. In the first test, the rats were shown different objects which they had to recognize.
With the second test, scientists traced other depression symptoms like apathy: the rats were placed in a container with water and observed whether they are trying to jump out of the container or simply swim around. In both cases, the tests were positive, regarding memory and apathy when compared with normal mice. After these two tests, the researchers injected D-serine to the rats. Memory improved significantly, but this substance had no effect on apathy.
Dr Lindskog pointed out the experiment revealed that the two symptoms may be influenced independently of one anothers. Furthermore, researchers have studied the synaptic activity in the hippocampus of the rats, a very important region of the brain involved in the memory process. What they found was that in depressed mice there was a more intense activity at this level than in normal counterparts. However, when researchers tried to increase synaptic transmission, they found that the brain of depressed rats was unresponsive, unlike normal mice; when D-serine was administered, memory function significantly improved.
D-serine is a substance secreted by astrocytes, glial cells that are star-shaped . Astrocytes have many roles in the normal functioning of the brain, one of which is biochemical support of endothelial cells forming the blood-brain barrier. Also, astrocytes play a key role in repairing nervous tissue after tratumatic injury as well in maintaining ion balance. In the brain, D-serine is synthesized from L-serine, and serves as a neurotransmitter by activating NMDA receptors.
Brain Changes Seen In People With Depression
A scientist at the University of Mississippi Medical Center has demonstrated for the first time that two types of brain cells are abnormal in the brains of people who suffered from clinical depression and most of whom committed suicide.
Dr. Grazyna Rajkowska, associate professor of psychiatry and human behavior, looked at the region of the brain known as the prefrontal cortex. This “gray matter” – located just behind the forehead – is responsible for higher intellectual functions and regulation of emotional and motivational behavior.
The results of Rajkowska’s work appear in the lead article in the May issue of the journal, Biological Psychiatry.
Earlier work that scanned the same region of the brain in living subjects indicated that this region of the brain was smaller in those who suffered from depression than in the brains of those who did not.
“The decrease in volume was an indication to me that something was unusual in the cell architecture and that there might be cellular changes in that area,” she said.
The changes Rajkowska noted were in neurons and glial cells. The neurons are the basic unit of the brain, transmitting and receiving signals and processing information. Glial cells form the “support system” for the neurons. They don’t transmit impulses, but they control the nutrients the neurons get from the blood, are active in the immune response and generally facilitate the work of the neurons. While other scientists pinpointed changes in glial cells in one region of the cerebral cortex in individuals with depression, Rajkowska’s work at the same time found changes in both types of cells in three different regions of the cerebral cortex.
Dr Lindskog hopes that these experiments will lead to the discovery of new therapies for depression. Although D-serine does not have a good permeability regarding the blood-brain barrier, the mechanism that was identified can be used for other therapeutic strategies in order to enhance plasticity of the brain and improve memory.
What happens inside people’s brains when they’re depressed? How brains reshape during mood disorders
There have been studies showing a change in brain activity when mood shifts, but there is now also research showing a change in brain shape that appears to be associated with severe mood disorders. The brain shrinks, or rather, certain parts of it do. One of those parts is called the hippocampus. This part is associated with making and being able to recall memories. If mood symptoms are severe or go on very long, the hippocampus shrinks. This chapter shows you the evidence that this shrinkage really occurs. The same process appears also to be occurring in frontal lobes as well, though not elsewhere in the brain. This brain shrinkage, called “atrophy”, has long been associated with Alzheimer’s dementia; but lately it has also been associated with obesity, and even with back pain – perhaps through some common mechanism with depression?
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How Mood Changes Affect the Brain
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BY CIAPA DAN