According to a 2016 survey conducted by the Cabinet Office, an estimated 15 people in the 39-54 age group in Japan who are in a "withdrawal" state who avoid social participation such as employment and schooling and stay at home for a long period of time. It is said to reach people.The most common withdrawal period is 1,000 years or more, which is about 7%.It is thought that one of the causes of this prolongation is that once isolated from society, anxiety is further increased and it becomes difficult to reintegrate into society.

Therefore, the research group tried to clarify this mechanism using mice and connect it to a solution.Specifically, we created a social isolation stress model mouse that was isolated from other mice and kept alone for a long period of time.In this way, we attempted to elucidate the mechanism of brain function in which anxiety is enhanced by social isolation.

As a result, in mice subjected to social isolation stress, neurotransmission from the lateral sciatic nucleus in the brain to the ventral tegmental area is suppressed and anxiety increases, and suppression of neurotransmission is caused by projection nerve cells. At the neuronal terminal, the protein "mDia" involved in the polymerization of the actin cytoskeleton, which is a fibrous structure in which a large number of actin molecules, which are one of the proteins that make up muscle in cells, are linked, is activated and contracts the presynaptic terminal. It was discovered that this is because it causes a decrease in synapse transmission efficiency.

The result of this research is a study using model mice, but it is expected that it will be useful in the future to elucidate the brain function mechanism involved in the enhancement of anxiety due to social isolation.