Psychogenic, neurogenic, and systemic stressor effects on plasma corticosterone and behavior: mouse strain-dependent outcomes.

The effects of several stressors were assessed in inbred strains of mice, BALB/cByJ and C57BL/6ByJ, thought to be differentially reactive to stressors. Behavioral reactivity was greater in BALB/cByJ mice with respect to open-field emergence, step-down responding, response to a predator (rat) or to fox urine odor. Neurogenic insults (e.g., footshock, forced swim, restraint) and a systemic stressor (intraperitoneal interleukin-1beta treatment) likewise provoked a greater rise of plasma corticosterone in the BALB/cByJ mice. Psychogenic stressors (e.g., novel open-field exposure, acoustic startle stimuli) also enhanced plasma corticosterone to a greater extent in BALB/cByJ mice, but such an outcome was not apparent following predator-related cues. It appears that whereas stressor reactivity and adrenal glucocorticoid release may be exaggerated in BALB/cByJ mice, such effects may be dependent on the specific characteristic of the stressor situation.