ABSTRACT
Glucocorticosteroids, or glucocorticoids as they are often known, are adrenal steroid hormones with diverse physiological effects that can be anti-inÀ ammatory, immunosuppressive, and metabolic in nature. They also affect central nervous system function and the activity of other endogenous hormones. Glucocorticoids are regulated by a negative feedback loop involving the hypothalamic-pituitary-adrenal (HPA) axis ( Figure 16.1 ). Cortisol is the main hormone secreted from the adrenal cortex following the activation of the HPA axis; it is released during stressful situations, such as when encountering emotional stress, infection, trauma, and exercise. In addition to responding to stress stimuli, endogenous cortisol is released in an hourly pulsatile manner; it exhibits a circadian rhythm with peak concentrations occurring at the onset of the daily activity period (Young et al . 2004 ; Son et al . 2011 ).
