Urinary excretion of cortisol, norepinephrine, testosterone, and melatonin in panic disorder.

Nocturnal urinary cortisol, norepinephrine, epinephrine, testosterone, and melatonin secretion patterns were studied in male patients with DSM IV/ICD-10 panic disorder (n = 16) over two series of 5 consecutive nights each. Night-time urinary excretion of cortisol, norepinephrine, and epinephrine was significantly elevated in drug-free patients compared to normal individuals (n = 13). Measurements were repeated after 4 weeks, and the same differences were found again. There were high correlations between the first and the second series of measurements. Testosterone and melatonin levels did not differ between panic patients and controls.

No evidence for a physiological coupling between melatonin and glucocorticoids.

Much has been speculated about the existence of a physiological coupling between melatonin and glucocorticoid secretion and about a possible anti-stress action of melatonin. We examined the relationship between melatonin and glucocorticoid secretion under close-to-physiological conditions, when the plasma concentration of either melatonin or glucocorticoids was elevated acutely or chronically in both rats and humans. Tryptophan administration caused a massive rise of plasma melatonin, but had no effect on corticosterone levels in rats or on cortisol levels in humans. The acute and long-lasting exposure of rats to uncontrollable stress resulted in a significant rise of adrenal corticosterone secretion, but had no effect on circulating melatonin levels. Orchectomy caused an initial increase in circulating corticosterone (when melatonin was unaffected) and a delayed rise in circulating melatonin (when corticosterone levels were normalized). In humans, no correlation was found between the nocturnal urinary excretion of melatonin and cortisol, either among healthy subjects, or among patients suffering from panic disorder (with an increased urinary excretion of cortisol) or among insomnia patients (with a high incidence of low melatonin secretion). Furthermore, no evidence was found for a suppressive action of melatonin on dexamethasone-mediated thymus regression in rats and on dexamethasone-mediated suppression of lymphocyte proliferation in vitro. Taken together, the results of this study provide no evidence for the existence of mutual influences between melatonin and glucocorticoid secretion, nor do they support the proposed attenuation of glucocorticoid-mediated effects on target cells or tissues by melatonin under physiological conditions.