How do mice handle stress? - briefly
Mice activate the hypothalamic‑pituitary‑adrenal axis, releasing corticosterone to mobilize energy reserves. They also display behavioral adjustments, including heightened grooming, diminished exploration, and avoidance of threatening cues.
How do mice handle stress? - in detail
Mice react to stressful stimuli through a cascade that begins with the perception of threat by sensory pathways and ends with physiological and behavioral adjustments aimed at restoring equilibrium. The central component is activation of the hypothalamic‑pituitary‑adrenal (HPA) axis: the hypothalamus releases corticotropin‑releasing hormone, the pituitary secretes adrenocorticotropic hormone, and the adrenal cortex produces corticosterone. Elevated corticosterone binds glucocorticoid receptors throughout the brain, modulating gene expression and influencing memory, motivation, and immune function.
Simultaneously, the sympathetic nervous system increases catecholamine release, raising heart rate, blood pressure, and glucose availability. These endocrine and autonomic changes prepare the animal for either confrontation or escape.
Behavioral coping strategies fall into two principal categories:
- Active responses – escape attempts, vigorous locomotion, and exploratory rearing.
- Passive responses – freezing, reduced movement, and increased grooming.
The choice between active and passive tactics depends on the nature of the stressor, the animal’s previous experience, and sex‑specific neurochemical profiles. For example, male mice often display heightened aggression in social defeat, whereas females may exhibit more pronounced passive coping.
Experimental paradigms that elicit stress in laboratory settings include:
- Restraint in a narrow tube for 30 minutes.
- Forced swim in water at 25 °C for 6 minutes.
- Exposure to predator odor (e.g., 2,4,5‑trimethylthiazoline) for 10 minutes.
- Chronic mild stress involving unpredictable light‑dark cycles, cage tilting, and social isolation over several weeks.
Each model produces a characteristic pattern of HPA activation and behavioral output, allowing researchers to dissect the contributions of specific brain regions such as the amygdala, prefrontal cortex, and hippocampus. Genetic manipulation (e.g., knockout of glucocorticoid receptors) and pharmacological interventions (e.g., beta‑adrenergic antagonists) reveal that stress resilience can be enhanced by reducing corticosterone signaling or by increasing neurotrophic factors like BDNF.
Environmental enrichment—providing nesting material, running wheels, and social companions—diminishes baseline corticosterone levels and shifts coping toward active strategies. Repeated exposure to mild stressors leads to habituation, evident as a blunted hormonal surge and quicker return to baseline activity.
In summary, the mouse stress response integrates endocrine, autonomic, and behavioral mechanisms that are modifiable by genetics, sex, prior experience, and housing conditions. Detailed knowledge of these pathways supports translational research on anxiety, depression, and resilience.