Male reproductive system and antioxidants in oxidative stress induced by hypobaric hypoxia

Abstract

In Chile, due to the intensive activity developed in confining areas of the Andes Mountains ranging in altitude over 4000 asl, there has been an increasing intermittent movement of human resources to high altitude conditions. This unusual condition, defined as hypobaric hypoxia, affects notoriously in any living organism and there shows a series of physiological responses. Studies performed in rats under chronic hypobaric hypoxia and intermittent hypobaric hypoxia have registered changes in testicular morphology together with loss of spermatogenic cells in all stages of spermatogenic cycle. Furthermore, recent tests reinforced the existence of an oxidative metabolism in epididymis of rats subjected to hypobaric hypoxia due to the increase in the regulator enzyme expression of reactive oxygen species (ROS), This increase in the production of ROS induced a rise in apoptosis at germinal cell level, leading to a state of hypo-spermatogenesis that may jeopardise masculine fertility. Therefore, the eventual development of oxidative stress in spermatogenic cells and consequently the spermatozoids of workers subjected to high altitude, either chronic or intermittent, turns out to be critical when it poses as an imminent risk to the viability and quality of the reproductive cells of workers subjected to intermittent hypobaric hypoxia.

Immigrant reproductive dysfunction facilitates ecological speciation

“…In amphibians, it has been suggested that local adaptation of egg coats to pH has a role in adaptive divergence (Shu et al 2015). Terrestrial examples include the yellow dung-fly (Scathophaga stercoraria) (temperature effects on eggs, Blanckenhorn et al 2014), and mammals (hypoxia and/or altitude effects on spermatogenesis and ovarian function, Vitzthum and Wiley 2003;Gonzalo Farias et al 2008;Parraguez et al 2014;Zepeda et al 2014)). Terrestrial examples include the yellow dung-fly (Scathophaga stercoraria) (temperature effects on eggs, Blanckenhorn et al 2014), and mammals (hypoxia and/or altitude effects on spermatogenesis and ovarian function, Vitzthum and Wiley 2003;Gonzalo Farias et al 2008;Parraguez et al 2014;Zepeda et al 2014)).…”

“…Other examples are temperature, which affects for example sperm performance in the mosquitofish Gambusia holbrooki (Adriaenssens et al 2012), and aquatic hypoxia, which for example reduces sperm motility and fertilization success in carp (Cyprinus carpio) (Wu 2009). Terrestrial examples include the yellow dung-fly (Scathophaga stercoraria) (temperature effects on eggs, Blanckenhorn et al 2014), and mammals (hypoxia and/or altitude effects on spermatogenesis and ovarian function, Vitzthum and Wiley 2003;Gonzalo Farias et al 2008;Parraguez et al 2014;Zepeda et al 2014)). In humans, this is only the case for immigrants, prompting Vitzhum and Wiley (2003) to suggest that the reproduction of humans is locally adapted to high altitudes.…”

Sperm forward motility is negatively affected by short-term exposure to altitude hypoxia

“…Normal fertility in male results from a complex of physiological processes that determine the production, transport and ejaculation of an adequate number of spermatozoa with normal motility and fertilising capacity (Pescetto et al ., ). The pathophysiological role of hypoxia in male fertility is an intriguing issue that has been investigated in several experimental animal models (Zepeda et al ., , ) in which the exposure to altitude induces several reproductive changes including altered production of pituitary hormones and, in general, sexual hormones. Only few studies investigated the effects of acute hypoxia in human fertility (Okumura et al ., ) so that we have only few and contradictory data about the changes in male reproductive hormones or in seminal parameters in response to acute hypoxic exposure (Zepeda et al., , ) and, even less data, about the response to acute hypoxia combined with exercise.…”

The influence of environmental factors on male fertility and its research progress

“…Study 14 showed that male sperm concentration tended to decrease in the high altitude hypoxia environment. Hypoxia can result in an increase of [15] in the level of germ cell apoptosis by oxidative stress, leading to lower levels of testosterone and related hormones, testicular tissue damage, which leads to reduced spermatogenesis and impaired testicular tissue.…”