Adrenocortical Responsiveness to Psychosocial Stress in Humans: Sources of Interindividual Differences
Among other physiological systems of the body, the hypothalamuspituitaryadrenal (HPA) axis responds rapidly and with comparatively high specificity to psychosocial stress. Whenever a situation (or stimulus) is perceived as novel, uncontrollable, or unpredictable, or if the individual anticipates negative organ-ismic or psychological consequences, the negative feedback signals from the hippocampus and other sites will be overridden. As a result, corticotropin releasing factor (CRH), adrenocorticotropin (ACTH), and cortisol are secreted in a sequential release pattern in an attempt to ensure proper functioning of the body in times of increased demand for energy, attention, emotionality, and so on. These demands are being partly met by the more immediate response of the parvocellular neurons in the periventricular nucleus (PVN) of the hypothalamus with a release of CRH into the portal blood and other parts of the brain. In contrast to CRH-related effects, the role of the final secretory product of the HPA axis, cortisol, in response to stress is thought to counterregulate the physiological and psychological alterations (Munck, Guyre, & Holbrook, 1984; Munck & Guyre, 1991). The adrenocortical response to stress (and other stimuli) appears to be a close correlate or
even a determining factor for the onset and course of certain diseases such as inflammatory processes in autoimmunity (Sternberg et al., 1989) or allergy in animals and humans (Buske-Kirschbaum et al., 1997; Rupprecht et al., 1995).