Orchiectomy exacerbates sleep-disordered breathing induced by intermittent hypoxia in mice

We tested the hypothesis that low testosterone levels alter the regulation of breathing in mice exposed to intermittent hypoxia (IH). We used orchiectomized (ORX) or control (Sham-operated) mice exposed to normoxia or IH (12 h/day, 10 cycles/h, 6% O-2) for 14 days. Breathing was measured by whole-body plethysmography to asses the stability of the breathing pattern (frequency distribution of total cycle time - Ttot) and the frequency and duration of spontaneous and post-sigh apneas (PSA). We characterized sighs as inducing one (S1) or more (S2) apnea and determined the sigh parameters (volume, peak inspiratory and expiratory flows, cycle times) associated with PSA. IH increased the frequency and duration of PSA and the proportion of S1 and S2 sighs. The PSA frequency was mostly related to the sigh expiratory time. The effects of IH on PSA frequency were amplified in ORX-IH mice. Our experiments using ORX support the hypothesis that testosterone is involved in the regulation of breathing in mice following IH.

Automated summary

We aimed to investigate the impact of low testosterone levels on breathing regulation in mice exposed to intermittent hypoxia (IH). We used orchiectomized (ORX) or control (Sham-operated) mice and exposed them to normoxia or IH. After measuring breathing stability and the frequency and duration of apneas, we found that IH increased the occurrence of apneas and the proportion of certain types of sighs. The effects were more pronounced in ORX-IH mice, suggesting that testosterone plays a role in breathing regulation following IH.