Special Immune Cells Of Brain Drive Depression

by Karishma Abhishek on Jan 26 2021 9:06 AM

Special Immune Cells Of Brain Drive Depression
Negative mood experiences like feeling uneasy and depressed in correlation with inflammation or several neurological diseases are found to be driven by a special immune cell of the brain – microglia, as per a study at the Linköping University, //Sweden, published in the journal Immunity.
Earlier studies have shown the role of activated microglial cells in several neurological diseases, such as Alzheimer's disease, Parkinson's disease, and stroke. These conditions often induce a negative mood in the people affected.

Role of other inflammatory processes is also shown to play a role in the development of depression. This allowed the study team to explore the action of microglial cells in regulating mood during inflammation.

Microglial Cells in Negative Mood

"The study showed that animals feel sick and uneasy when we activate the microglial cells. We demonstrate that two signal molecules, interleukin-6, and prostaglandin E2, are particularly important in these processes. It's not surprising that these signal substances are central, but we were a bit surprised that it is the microglial cells that release these molecules", says David Engblom, a professor in the Department of Biomedical and Clinical Sciences (BKV) at Linköping University.

Using a specific technique called chemogenetics, scientists were able to activate the microglial cells when the mice models were being kept in a certain type of surroundings. Avoidance behavior was seen in the mice, showing that the animals disliked the experience.

Also, the mice demonstrated symptoms of negative mood where it became less interested in a sweet solution, which they normally find very tempting.

Inhibition of the microglial cells, that is, when the microglia were not available for activation, the mice did not feel poorly, even when they had inflammation. This depicts an important link between the immune system and mood, in the presence of microglia cells.

"Our results show that the activation of microglial cells is sufficient to create aversion and negative mood in mice. It's natural to suggest that similar processes take place in several human diseases. It's not unlikely that activated microglia contribute to the discomfort and depressed mood in people with inflammatory and neurological diseases", says, David Engblom.

However further research is needed to demonstrate the microglial biological mechanism in humans, that may aid in formulating ways to inhibit this pathway and reduce symptoms of depression.