Intermittent Hypoxia Remedies Male Subfertility

Abstract

Progressive motility with high velocity that exhibits normal lateral head displacement is one of the most important characteristics of spermatozoa directly influencing their fertilizing capacity. A subfertile condition often depends more on sperm motility than count. Application of noninvasive methods of motility stimulation is an important treatment modality for male infertility. In this chapter, we demonstrate the efficacy of an intermittent hypoxic training (IHT) regimen on improving sperm motility in humans. The IHT consisted of 14 consecutive days having four repetitions of 5–7 min each of induced hypoxia interspersed with 5 min periods of ambient inspiration. Initial inspiration began with atmospheric air (20.9%) O2. During the procedure, inspired O2 fell to a value of 5–7%, with the final arterial O2 saturation typically at 84–85%. This IHT regimen produced a stimulatory effect on male reproductive function in the gametes, and this significant increase in the number of spermatozoa with high motility was coupled with a decrease of seminal plasma chemiluminescence (ChL), while sperm count and morphology did not change. Motility and free radical status are some of the most labile parameters when compared to other characteristics of male reproductive function, and their response to external influences is very rapid. Sperm count is more inert. Of course, sperm count also depends on spermatozoal survival. Lack of mitochondrial enzyme activity, high-energy phosphates, oxidative stress, or other stress factors can lead to decreased motility and eventually to apoptosis or necrosis. The increase we have found in motility after 2 weeks of IHT implies that experimenting with the parameters and regimens of the IHT might produce an increase in sperm count along with the motility increase. Our future investigations will include prolonged IHT duration in multiple protocols. We propose that the mechanism of sperm motility augmentation that occurred in our study is due to inhibition of free radical processes. Positive changes in free radical processes should lead to membrane stabilization and improvement of spermatozoal function. Decrease of free radical levels in blood and increase of erythrocyte superoxide dismutase activity could be two likely causes of decreased free radical oxidation in sperm leading to our improved motility results.