Rhythms of pituitary-adrenal activity during sleep in patients with Cushing's disease

Previous studies have indicated a dependence of nocturnal pituitary-adrenal secretory activity on central nervous sleep processes in healthy humans: U nder normal physiological conditions the release of ACTH/cortisol is inhibi ted during early sleep and becomes entrained to periods of NonREM sleep dur ing late sleep. Here. we compared nocturnal dynamics in plasma concentratio ns of ACTH/cortisol in 7 patients with Gushing's disease with those of 7 he althy controls matched in age and sex with the patients. The patients in pa rt were repeatedly tested. The total of 13 nights is composed of 7 nights o f hyperpulsatile secretion pattern (5 patients) and 6 nights from hypopulsa tile secretion pattern (4 patients). After an adaptation night polysomnogra phic sleep recordings were obtained and blood was sampled every 15 min betw een 23.00 and 7.00 h. Controls displayed the typical minimum in ACTH/cortis ol concentrations during the early part of the night and maximum concentrat ions during the late part of the night, whereas ACTH/cortisol levels of Gus hing patients indicated a relatively constant elevated pituitaryadrennl act ivity throughout the night, lacking any circadian variation. Autocorrelatio n functions revealed the presence of cortisol secretory rhythms with a simi lar period length in healthy controls (155.6+/-17.4 min) and patients with a hyperpulsatile pattern (142.4+/-6.6 min). In patients displaying hypopuls atility, no significant rhythmicity was observed. However, regardless of th e type of secretory pulsatility, adrenal secretory activity started predomi nantly during periods of NonREM sleep (p<0.01) in healthy controls as well as in patients with Gushing's disease. This data indicates that the normal nocturnal circadian oscillation of pituitary-adrenal activity is absent in Gushing patients, whereas a link between pituitary-adrenal activity and ult radian rhythms of sleep appears to be preserved.