Stress transmission in social groups of mice: unveiling physiological responses, behavioral patterns, and immune dynamics

In modern societies, stress is pervasive, requiring sophisticated physiological mechanisms for stability and survival, primarily through the sympatho-adrenal medullary (SAM) and hypothalamo-pituitary adrenal (HPA) axes. Chronic stress is linked to a range of mental and physical health problems and has been shown to affect immune function. In this study, a paradigm for social stress transmission in groups of mice was established, based on a restraint stress model to study how stress spreads among individuals. Mice exposed to indirect stress exhibited HPA-axis activation, elevated corticosterone (CORT) levels, enlarged adrenal glands, and anxiety-like behaviors in light-dark-box tests. Notably, female mice were more susceptible to stress transmission. While stress transmission enhanced innate immune responses, it did not affect adaptive immunity following vaccination with a poly(lactic-co-glycolic acid) (PLGA)-based vaccine. In contrast, direct stress impaired both immune responses and the effectiveness of immunotherapy in a melanoma model.