title: Hypothalamic-pituitary-adrenal axis activity in obese men with and without sleep apnea: effects of continuous positive airway pressure therapy.
abstract: BACKGROUND
  Previous studies on the association between the hypothalamic-pituitary-adrenal axis activity and sleep apnea (SA) and obesity are inconsistent and/or limited.
  
  
  OBJECTIVE
  In this study, we evaluated the activity of the hypothalamic-pituitary-adrenal axis in nonpsychologically distressed obese subjects with and without SA and examined the impact of continuous positive airway pressure (CPAP) in SA patients.
  
  
  METHODS
  In study I, four-night sleep laboratory recordings and serial 24-h plasma measures of cortisol were obtained in 45 obese men with and without apnea and nonobese controls. Sleep apneic patients were reassessed after 3 months of CPAP use. In study II, 38 obese men with and without sleep apnea and nonobese controls were challenged with ovine CRH administration after four nights in the sleep laboratory.
  
  
  RESULTS
  The sleep patterns were similar between obese and nonobese controls. Twenty-four-hour plasma cortisol levels were highest in nonobese controls, intermediate in obese apneic patients, and lowest in obese controls (8.8 +/- 0.4 vs. 8.1 +/- 0.3 vs. 7.5 +/- 0.3 microg/dl, P < 0.05). CPAP tended to reduce cortisol levels in the apneic patients (difference -0.7 +/- .4 microg/dl, P = 0.1). CRH administration resulted in a higher ACTH response in both obese groups, compared with nonobese controls; the three groups were not different in cortisol response.
  
  
  CONCLUSIONS
  Nonpsychologically distressed, normally sleeping, obese men had low cortisol secretion. The cortisol secretion was slightly activated by SA and returned to low by CPAP use. The low cortisol secretion in obesity through its inferred hyposecretion of hypothalamic CRH might predispose the obese to sleep apnea.
authors.affiliation: Sleep Research and Treatment Center, Department of Psychiatry, H073, Penn State University College of Medicine, 500 University Drive, Hershey, Pennsylvania 17033, USA. avgontzas@psu.edu
authors.forename: A N
authors.initials: AN
authors.lastname: Vgontzas
authors.forename: S
authors.initials: S
authors.lastname: Pejovic
authors.forename: E
authors.initials: E
authors.lastname: Zoumakis
authors.forename: H-M
authors.initials: HM
authors.lastname: Lin
authors.forename: C M
authors.initials: CM
authors.lastname: Bentley
authors.forename: E O
authors.initials: EO
authors.lastname: Bixler
authors.forename: A
authors.initials: A
authors.lastname: Sarrigiannidis
authors.forename: M
authors.initials: M
authors.lastname: Basta
authors.forename: G P
authors.initials: GP
authors.lastname: Chrousos
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000097:blood; D000328:Adult; D000818:Animals; D045422:Continuous Positive Airway Pressure; D003346:Corticotropin-Releasing Hormone; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007030:Hypothalamo-Hypophyseal System / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000503:physiopathology* / Q000628:therapy*; D010913:Pituitary-Adrenal System / Q000503:physiopathology*; D017286:Polysomnography; D015656:Respiratory Mechanics / Q000502:physiology; D012756:Sheep; D012890:Sleep / Q000502:physiology; D012891:Sleep Apnea Syndromes / Q000188:drug therapy* / Q000503:physiopathology