Endocrine Abstracts

The HPA axis has a massive dynamic response rate. At nadir periods (at night in man and during the day in nocturnal rodents) there is a low level of activity which increases up until the circadian peak. This circadian rhythm is made up of an underlying ultradian rhythm of pulsatile glucocorticoid section, with pulse amplitude increasing from the circadian nadir to the circadian peak. Superimposed on this underlying rhythm is, of course, the stress response which can result in ...