title: Testosterone conversion blockade increases breathing stability in healthy men during NREM sleep.
abstract: OBJECTIVE
  Gender differences in the prevalence of sleep apnea/hypopnea syndrome may be mediated via male sex hormones. Our objective was to determine the exact pathway for a testosterone-mediated increased propensity for central sleep apnea via blockade of the 5α-reductase pathway of testosterone conversion by finasteride.
  
  
  METHODS
  Randomization to oral finasteride vs. sham, single-center study.
  
  
  METHODS
  Sleep research laboratory.
  
  
  METHODS
  Fourteen healthy young males without sleep apnea.
  
  
  METHODS
  Hypocapnia was induced via brief nasal noninvasive positive pressure ventilation during stable NREM sleep. Cessation of mechanical ventilation resulted in hypocapnic central apnea or hypopnea.
  
  
  RESULTS
  The apnea threshold (AT) was defined as the end-tidal CO₂(P(ET)CO₂) that demarcated the central apnea closest to the eupneic P(ET)CO₂. The CO₂ reserve was defined as the difference in P(ET)CO₂ between eupnea and AT. The apneic threshold and CO₂ reserve were measured at baseline and repeated after at a minimum of 1 month. Administration of finasteride resulted in decreased serum dihydrotestosterone. In the finasteride group, the eupneic ventilatory parameters were unchanged; however, the AT was decreased (38.9 ± 0.6 mm Hg vs.37.7 ± 0.9 mm Hg, P = 0.02) and the CO₂ reserve was increased (-2.5 ± 0.3 mm Hg vs. -3.8 ± 0.5 mm Hg, P = 0.003) at follow-up, with a significantly lower hypocapnic ventilatory response, thus indicating increased breathing stability during sleep. No significant changes were noted in the sham group on follow-up study.
  
  
  CONCLUSIONS
  Inhibition of testosterone action via the 5α-reductase pathway may be effective in alleviating breathing instability during sleep, presenting an opportunity for novel therapy for central sleep apnea in selected populations.
authors.affiliation: Medical Service, Sleep Medicine Section, John D. Dingell Veterans Affairs Medical Center, Detroit, MI ; Division of Pulmonary/Critical Care and Sleep Medicine, Department of Medicine, Wayne State University School of Medicine, Detroit, MI.
authors.forename: Susmita
authors.initials: S
authors.lastname: Chowdhuri
authors.forename: Amy
authors.initials: A
authors.lastname: Bascom
authors.forename: David
authors.initials: D
authors.lastname: Mohan
authors.forename: Michael P
authors.initials: MP
authors.lastname: Diamond
authors.forename: M Safwan
authors.initials: MS
authors.lastname: Badr
mesh_terms: D058891:5-alpha Reductase Inhibitors / Q000627:therapeutic use*; D000328:Adult; D018120:Finasteride / Q000627:therapeutic use*; D006801:Humans; D016857:Hypocapnia / Q000188:drug therapy; D008297:Male; D011175:Positive-Pressure Respiration; D012119:Respiration / Q000187:drug effects*; D012890:Sleep / Q000187:drug effects* / Q000502:physiology; D020182:Sleep Apnea, Central / Q000188:drug therapy; D013739:Testosterone / Q000037:antagonists & inhibitors*; D055815:Young Adult
chemical_list: D058891:5-alpha Reductase Inhibitors; D013739:Testosterone; D018120:Finasteride
keywords: 5α-reductase blockade; Apneic threshold; CO2 reserve; central sleep apnea; chemoresponsiveness; dihydrotestosterone; finasteride; testosterone