ABSTRACT
Ascorbic acid depletion served as a useful measure of the pituitary-adrenal axis until the 1960s with the advent of the acid fluorescence technique for measuring adrenal steroids. Although melatonin formation is associated with the pineal gland and its function is more closely associated with circadian rhythms, its ability to act as a potent, ubiquitous hydroxyl and peroxyl radical scavenger has recently been demonstrated. Hypertrophy of the adrenal and ascorbate depletion can occur when the stimulus or stress is too prolonged. Release of ascorbic acid occurs throughout the entire gland, both cortex and medulla. In situations of continuous stress, death can ensue, indicating a need for ascorbate in adrenal function. Replenishing vitamin C by infusion enhances cortisol production activated by adrenocorti-cotrophic hormone. Melatonin has been shown to affect the hypothalamic-pituitary-adrenal axis in several ways. Melatonin exerts many of its known effects by signaling through G-protein-coupled receptors, all of which thus far are known to inhibit cAMP formation.
