Chronic Exposure to Low Doses of Mercury Impairs Sperm Quality and Induces Oxidative Stress in Rats

Abstract

Mercury (Hg) is a widespread environmental pollutant that adversely affects the male reproductive system. The precise mechanisms underlying mercuric chloride (HgCl2)-induced toxicity are not fully understood; however, evidence indicates that oxidative stress may be involved in this process. Although the adverse effects of high levels of inorganic Hg on the male reproductive system have been investigated, the effects of low levels of exposure are unknown. Therefore, the aim of this study was to investigate the effects of chronic exposure to low concentrations of HgCl2 on sperm parameters, lipid peroxidation, and antioxidant activity of male rats. Three-month-old male Wistar rats were treated for 30 d and divided into groups: control (saline, i.m.) and HgCl2 group (i.m., first dose 4.6 μg/kg, subsequent doses 0.07 μg/kg/d). Sperm parameters (count, motility and morphology) and biomarkers of oxidative stress in testis, epididymis, prostate, and vas deferens were analyzed. Mercury treatment produced a reduction in sperm quantity (testis and epididymis) and daily sperm production, following by decrease in sperm motility and increase on head and tail morphologic abnormalities. HgCl2 exposure was correlated with enhanced oxidative stress in reproductive organs, represented not only by augmented lipid peroxidation but also by changes in antioxidant enzymes activity superoxide dismutase (SOD) and catalase (CAT) and nonprotein thiol levels. In conclusion, chronic exposure to low doses of Hg impaired sperm quality and adversely affected male reproductive functions, which may be due, at least in part, to enhanced oxidative stress.

Comparative Cytotoxicity and Sperm Motility Using a Computer-Aided Sperm Analysis System (CASA) for Isomers of Phthalic Acid, a Common Final Metabolite of Phthalates

“…Data suggest that CASA parameters may serve as a more sensitive marker of reproductive toxicity than semen parameters (Perreault and Cancel, 2001). One mechanism by which sperm motion or testes may be impaired includes oxidative stress, the production of reactive oxygen species (ROS), and subsequent lipid peroxidation of sperm plasma membrane although the probable mechanisms may depend on type of chemicals (Storey, 1997;Armstrong et al, 1999;Martinez et al, 2014;Almášiová et al, 2014). Ono et al (1999) examined the association between toluene levels and epididymal sperm counts, sperm motility, and sperm quality.…”

A brain proteome profile in rats exposed to methylmercury or thimerosal (ethylmercury)

“…In general, exposure to toxic elements induces a defense mechanism in the organism that includes changes in protein production in an attempt to maintain homeostasis, protecting tissues and organs from damage and simultaneously defending against adverse conditions (Ginsberg et al, 2014;Grotto et al, 2009;Martinez et al, 2014;Morimoto and Santoro, 1998). In this sense, proteomic research has become a useful and powerful technology that may provide information on protein modifications following toxicant exposure, thus contributing to the understanding of the mechanisms associated with toxicity (Miller et al, 2014).…”

Aluminum exposure for 60 days at human dietary levels impairs spermatogenesis and sperm quality in rats

“…Under a light microscope (20X magnification, Binocular, Olympus CX31, Tokyo, Japan), 100 spermatozoa were analyzed and classified as type A: motile with progressive movement, type B: motile without progressive movement and type C: immotile. Sperm motility was expressed as % of total sperm [29].…”