Rat Spermatogenesis Damage in Intermittent Hypobaric Hypoxia and the Protective Role of Melatonin: I Cauda Epididymal Spermatozoa

Abstract

At present it is not clear if male fertility is affected by intermittent hypobaric hypoxia (IHH). This is an important issue since a large human population works over 3000 masl. This study analyzes epididymal sperm, in adult Sprague Dawley rats after five cycles of IHH (7 days exposure to 4200 masl in a hypobaric chamber / 7 days at 500 masl). The animals were separated into groups of 8, one group was exposed to hypoxia (7 days), and the others to IHH for one to five cycles. Controls (500 masl) were examined at the beginning and at the end of the 70 experimental days. A duplicate set of rats treated with melatonin (supposedly protecting from hypoxia) was also examined, as were their controls, injected with 0,03% ethanol (melatonin solvent). Epididymal sperm parameters, were evaluated. Damage caused by IHH increases with time. Sperm counts drop, while sperm chromatin swelling, DNA instability (metachromasia with acridine orange epifluorescence) and comet (+) tests increase. Melatonin counteracts all this damage, possibly due to its high efficiency as a reactive oxygen species scavenger. In conclusion, IHH exposure damages sperm quality and therefore male reproductive function.

Melatonin Protects the Heart, Lungs and Kidneys from Oxidative Stress under Intermittent Hypobaric Hypoxia in Rats

“…However, in the aforementioned studies melatonin did not have any effect with the doses used in contrary to other reports where melatonin had a protective role in testis and spermatogenesis of rats subjected to intermittent hypobaric hypoxia (Hartley et al, 2009;Bustos-Obregón et al, 2010;Vargas et al, 2011);Ahmad & Haldar (2010) as well as hamsters and rats, where melatonin seems to act directly on Leydig cells to suppress testosterone release in vitro. When administered orally at 10 mg/kg bodyweight, melatonin has been described as a counteracting substance for testis and spermatogenesis damage in rats subjected to intermittent hypobaric hypoxia (Vargas et al, 2011).…”

“…for 5 days caused an increase in lipid peroxidation in the plasma of rats (Kumar et al, 1999). It has been previously shown that melatonin can also protect tissues from oxidative damage (e.g: testicles) under intermittent hypobaric hypoxia conditions (Bustos-Obregón et al, 2010;Hartley et al, 2009). The aim of this study was to evaluate the protective effect of melatonin in several organs, such as heart, lung, kidney, and reproductive system as testis and epididymis in animals exposed to IHH and therefore exposed to oxidative stress.…”

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

“…In addition, it was found that the expression of glutathione reductase enzyme was lower in both organs with respect to control, but in epididymis, the expression and GR activity was greater (Farias et al, 2010). It have been also described that melatonin (10 mg kg À1 body weight) counteracted the testis and spermatogenesis damage in rats subjected to intermittent hypobaric hypoxia (Hartley et al, 2009;Bustos-Obregon et al, 2010). However, our results showed that melatonin had no protective effect in testis and epididymis damaged (Farias et al, 2012).…”

Chronic hypobaric hypoxia diminishes the expression of base excision repair OGG1 enzymes in spermatozoa

“…Spermatozoa are cells particularly susceptible to oxidative stress given their limited content of antioxidants (Aitken & Curry, 2011), and several models of hypoxia exposure have shown to produce DNA damage in sperm cells (Hartley, Castro-Sanchez, Ramos-Gonzalez, & Bustos-Obregon, 2009). Our results showing reduced expression of OGG1 enzymes in CHH suggest that attenuation of DNA repair mechanisms may contribute to the DNA damage observed.…”