Fertility Impairment after Trekking at High Altitude: A Proof of Mechanisms on Redox and Metabolic Seminal Changes

Abstract

Many authors described negative but reversible effects of high-altitude hypoxic exposure on animal and human fertility in terms of sperm concentration, function, and biochemical alterations. The aim of this study was to evaluate the acute and chronic effects of high-altitude exposure on classical sperm parameters, redox status, and membrane composition in a group of travellers. Five healthy Italian males, all lowlanders not accustomed to the altitude, were evaluated after 19 days-trekking through low, moderate, and high altitudes in the Himalayas. Sperm samples were collected before (Pre), 10 days after (Post), and 70 days after the end of the expedition (Follow-up). Sperm concentration, cholesterol and oxysterol membrane content, and redox status were measured. Hypoxic trek led to a significant reduction in sperm concentration (p < 0.001, η2p = 0.91), with a reduction from Pre to Post (71.33 ± 38.81 to 60.65 ± 34.63 × 106/mL) and a further reduction at Follow-up (to 37.13 ± 39.17 × 106/mL). The seminal volume was significantly affected by the hypoxic trek (p = 0.001, η2p = 0.75) with a significant reduction from Pre to Post (2.86 ± 0.75 to 1.68 ± 0.49 mL) and with partial recovery at Follow-up (to 2.46 ± 0.45 mL). Moreover, subjects had an increase in ROS production (+86%), and a decrease in antioxidant capacity (−37%) in the Post period with partial recovery at Follow-up. These results integrated the hormonal response on thyroid function, hypothalamus–pituitary–gonadal axis, and the prolactin/cortisol pathways previously reported. An uncontrolled ROS production, rather than a compromised antioxidant activity, was likely the cause of impaired sperm quality. The reduction in fertility status observed in this study may lie in an evolutionary Darwinian explanation, i.e., limiting reproduction due to the “adaptive disadvantage” offered by the combined stressors of high-altitude hypoxia and daily physical exercise.

Does Nanosilver Exposure Modulate Steroid Metabolism in the Testes?—A Possible Role of Redox Balance Disruption

“…The study conducted by Paciorek et al [42] reported that the production of primary products of cellular lipid oxidation (lipid hydroperoxides) was stimulated by AgNPs and subsequently transformed into secondary lipid end-products or glutathione peroxidase substrates [43]. Our study showed an increased level of 7-KCH as a consequence of uncontrolled lipid peroxidation in testicular cells and impaired redox balance [44]. The cytotoxic and pro-oxidant effects of nanoparticles disrupt steroid hormones metabolism [3,45].…”

Male reproductive system and simulated high-altitude environment: preliminary results in rats

“… 9 High-altitude environments negatively impact spermatogenesis, testis function, penile erection, and offspring production in rats, and high-altitude activities have been shown to damage reproductive parameters in men. 9 10 11 12 13 14 15 16 17 18 19 20 The reversibility of the effects of hypobaric hypoxia exposure on the male reproductive system remains controversial. Two studies in rhesus monkeys and rats showed that the sperm parameters and testis function of animals exposed to hypobaric hypoxia did not return to normal levels even long after the return to normal living conditions.…”

Asociación de parámetros espermáticos y la residencia en tres departamentos peruanos de distinta altura geográfica

“…Así mismo, el estudio realizado por Garcia-Hjarles encontró diferencias significativas en el volumen espermático de personas nativas a nivel del mar con el de nativos de altura, pero en contraste con nuestro estudio dicho estudio contó solo con 15 participantes expuestos a altura y 9 participantes a nivel del mar (15). Además, Verratti et al (31), halló en su estudio de exposición aguda a la altura en deportistas que realizan caminatas, y dicho resultado junto con el estudio realizado por Iwasaki et al (32), el cual correlacionó la formación de ROS con la calidad espermática; señalan que el volumen seminal y los niveles de especies reactivas de oxígeno presentan una correlación inversa, siendo así que la exposición a alturas elevadas lleva a una generación mayor de especies reactivas de oxígeno desencadenado por el sometimiento a hipoxia constante, radiación UV y otros estresores fisiológicos que llevan a la alteración del volumen seminal.…”

“…pág. 31 No Categoría de comparación Categoría de comparación Si 1,317 (0,001-24463,84) 0,307 (0,208-4,531) 0,390 IMC 0,966 (0,698-1,336) 0,836…”