Neuroimmune interactions in stress

Stress has long been recognized as a putative modulator of immunity. Several clinical and experimental reports point to a role of physical and psychological stressors on progression or resistance to disease. Nonetheless, literature in this field is sometimes controversial due to the wide variety of stressors employed and parameters of immunity analyzed. This variation should not be considered a consequence of methodological inaccuracy. The stress response, although theoretically stereotyped in nature, may lead to slightly different outcomes according to several modifiers. Our group has compared the effects of several stressors over different parameters of brain activity, behavior, immunity and glucocorticoid levels. These data show altogether that while increased turnover of noradrenaline in the hypothalamus, along with anxiety-like behaviors and increase in serum corticosterone are present very often, the magnitude of changes in immunity may vary considerably. Thus, we review data from our group generated over the past decade to support that effects of stressors on immunity and behavior highly depend on their specifics, animal model, frequency, duration, intensity, perception, and coping by the stressed animal.