Social Downsizing Stress (SDS): A novel paradigm for studying social transitions in mice.
4 affiliations
- 1Department of Psychiatry, Kawasaki Medical School, Kurashiki, 701-0192, Japan.
- 2Department of Medical Technology, Kawasaki University of Medical Welfare, Okayama, 701-0193, Japan.
- 3Department of Neuropsychiatry, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, 700-8558, Japan.
- 4Department of Medical Technology, Graduate School of Health Sciences, Okayama University, Okayama, 700-8558, Japan.
Abstract
Shrinking social networks and the transition to nuclear families represent significant structural changes in modern society. While traditional animal models have focused on total social isolation or defeat, the behavioral consequences of a dynamic reduction in group size remain poorly understood. We established a novel "Social Downsizing Stress (SDS)" model to investigate how a transition from high-density to low-density housing affects behavioral phenotypes and whether these effects are reversible through resocialization. Mice were assigned to four groups: Stable-6 (S6), Stable-3 (S3), SDS (6-3 mice at 8 weeks), and Resocialization (ReSDS; 6-3 at 8 weeks, followed by 3-6 at 11 weeks). Behavioral batteries were conducted at 10 weeks (acute phase) and 13-14 weeks (chronic/recovery phase). At 10 weeks, the SDS group exhibited a unique hyper-reactive phenotype distinct from the S3 group, characterized by significantly increased locomotor activity in the open field, increased entries in the light/dark transition test, and reduced social resting time. Both the S3 and SDS groups showed impaired spatial working memory in the Y-maze. By 13-14 weeks, resocialization (ReSDS) successfully restored social resting behavior and cognitive performance to control levels. However, SDS-induced hyperactivity in the open field persisted in both the SDS and ReSDS groups, regardless of the subsequent return to a higher-density environment. Furthermore, the ReSDS group exhibited significantly lower immobility in the tail suspension and forced swim tests compared to the S3 group. Social downsizing induces a distinct behavioral phenotype that differs from chronic low-density housing. While social interaction and cognitive functions retain high plasticity, hyperactivity persisted throughout the tested period (up to 13-14 weeks) despite resocialization, suggesting a long-lasting, though not yet confirmed irreversible, consequence of losing social density. This model provides a new framework for investigating the enduring neurobehavioral impacts of shrinking social environments on mental health.
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BibTeX
@article{tanaka2026social,
title = {{Social Downsizing Stress (SDS): A novel paradigm for studying social transitions in mice.}},
author = {Yoshihiro Tanaka and Hiroshi Ueno and Eriko Kitano and Yu Takahashi and Sachiko Mori and Shinji Murakami and Kenta Wani and Yosuke Matsumoto and Motoi Okamoto and Takeshi Ishihara},
journal = {IBRO neuroscience reports},
year = {2026},
month = oct,
doi = {10.1016/j.ibneur.2026.10.003},
url = {https://europepmc.org/article/MED/42997489},
note = {CC BY},
}
RIS
TY - JOUR
TI - Social Downsizing Stress (SDS): A novel paradigm for studying social transitions in mice.
AU - Yoshihiro Tanaka
AU - Hiroshi Ueno
AU - Eriko Kitano
AU - Yu Takahashi
AU - Sachiko Mori
AU - Shinji Murakami
AU - Kenta Wani
AU - Yosuke Matsumoto
AU - Motoi Okamoto
AU - Takeshi Ishihara
PY - 2026
DA - 2026/10/25
JO - IBRO neuroscience reports
DO - 10.1016/j.ibneur.2026.10.003
UR - https://europepmc.org/article/MED/42997489
AB - Shrinking social networks and the transition to nuclear families represent significant structural changes in modern society. While traditional animal models have focused on total social isolation or defeat, the behavioral consequences of a dynamic reduction in group size remain poorly understood. We established a novel "Social Downsizing Stress (SDS)" model to investigate how a transition from high-density to low-density housing affects behavioral phenotypes and whether these effects are reversible through resocialization. Mice were assigned to four groups: Stable-6 (S6), Stable-3 (S3), SDS (6-3 mice at 8 weeks), and Resocialization (ReSDS; 6-3 at 8 weeks, followed by 3-6 at 11 weeks). Behavioral batteries were conducted at 10 weeks (acute phase) and 13-14 weeks (chronic/recovery phase). At 10 weeks, the SDS group exhibited a unique hyper-reactive phenotype distinct from the S3 group, characterized by significantly increased locomotor activity in the open field, increased entries in the light/dark transition test, and reduced social resting time. Both the S3 and SDS groups showed impaired spatial working memory in the Y-maze. By 13-14 weeks, resocialization (ReSDS) successfully restored social resting behavior and cognitive performance to control levels. However, SDS-induced hyperactivity in the open field persisted in both the SDS and ReSDS groups, regardless of the subsequent return to a higher-density environment. Furthermore, the ReSDS group exhibited significantly lower immobility in the tail suspension and forced swim tests compared to the S3 group. Social downsizing induces a distinct behavioral phenotype that differs from chronic low-density housing. While social interaction and cognitive functions retain high plasticity, hyperactivity persisted throughout the tested period (up to 13-14 weeks) despite resocialization, suggesting a long-lasting, though not yet confirmed irreversible, consequence of losing social density. This model provides a new framework for investigating the enduring neurobehavioral impacts of shrinking social environments on mental health.
SN - 2667-2421
ER -