New! Sign up for our free email newsletter.
Science News
from research organizations

'Second-hand' psychological stress can lead to depression in mice, finds study

September 22, 2021
Tokyo University of Science
Few studies have explored the effect of psychological stressors on behavior, and neurogenesis, in the context of depression. With the elucidation of a vicarious social defeat stress mouse model, scientists have successfully endeavored in connecting the dots between psychological stress and depression.

Depression is a serious medical condition that plagues modern society. Several theories have been proposed to explain the physiological basis of depression, of which the "neurogenic hypothesis of depression" has garnered much attention. The theory follows that deterioration in brain regions, like hippocampus, can result in depression. This deterioration can be caused by physical and psychological stress. While the depressive effects of physical stress have been well studied, little is known about psychological stress in this regard.

Recent research has explained how vicarious social defeat can cause psychological stress in mice. This involves the mouse being made to experience defeat of another mouse in an experimental social setting. Using this model, a group of scientists from Japan attempted to establish a link between depressive symptoms and hippocampal neurogenesis.

Prof. Akiyoshi Saitoh from Tokyo University of Science, one of the lead authors of the study, further explains the motivation behind this research, "The number of individuals suffering from depression has been on the rise the world over. However, the detailed pathophysiology of depression still remains to be elucidated. So, we decided to focus on the possible mechanism of psychological stress in adult hippocampal neurogenesis, to understand its role in depressive disorders." The study was published in the journal Behavioural Brain Research.

After exposing the mice to chronic vicarious social defeat stress, Prof. Saitoh and the team, including Mr. Toshinori Yoshioka and Dr. Daisuke Yamada from Tokyo University of Science, analyzed their behavior and brains in close detail. Aside from behavioral deficits like social withdrawal, the stressed mice also showed a significant decrease in the survival rate of new-born neurons in the dentate gyrus, a region in the hippocampus responsible for sensory perception and memory, compared to the non-stressed controls. This condition persisted for up to four weeks, after "stressing" the mice. However, cell growth, differentiation, and maturation did not differ between the groups of mice during the period of observation. Notably, the cell survival rate was restored in the stressed mice after treatment with a chronic antidepressant called fluoxetine.

Regarding the results, Mr. Toshinori Yoshioka adds, "We have found out that chronic mental stress affects the neurogenesis of the hippocampal dentate gyrus. Also, we believe that this animal model will play an important role in elucidating the pathophysiology of depression, and in the development of corresponding novel drug."

Overall, this study has provided important insights into the pathophysiology of depression. Also, it goes without saying how this study paves the way for future research into the role of psychological stress in depression.

Story Source:

Materials provided by Tokyo University of Science. Note: Content may be edited for style and length.

Journal Reference:

  1. Toshinori Yoshioka, Daisuke Yamada, Riho Kobayashi, Eri Segi-Nishida, Akiyoshi Saitoh. Chronic vicarious social defeat stress attenuates new-born neuronal cell survival in mouse hippocampus. Behavioural Brain Research, 2022; 416: 113536 DOI: 10.1016/j.bbr.2021.113536

Cite This Page:

Tokyo University of Science. "'Second-hand' psychological stress can lead to depression in mice, finds study." ScienceDaily. ScienceDaily, 22 September 2021. <>.
Tokyo University of Science. (2021, September 22). 'Second-hand' psychological stress can lead to depression in mice, finds study. ScienceDaily. Retrieved December 3, 2023 from
Tokyo University of Science. "'Second-hand' psychological stress can lead to depression in mice, finds study." ScienceDaily. (accessed December 3, 2023).

Explore More
from ScienceDaily