Depressed Patients Less Able To Store Information, According To New Study
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.
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.