Reproductive dysfunction after mercury exposure at low levels: evidence for a role of glutathione peroxidase (GPx) 1 and GPx4 in male rats.

Mercury is a ubiquitous environmental pollutant and mercury contamination and toxicity are serious hazards to human health. Some studies have shown that mercury impairs male reproductive function, but less is known about its effects following exposure at low doses and the possible mechanisms underlying its toxicity. Herein we show that exposure of rats to mercury chloride for 30 days (first dose 4.6µgkg-1, subsequent doses 0.07µgkg-1day-1) resulted in mean (±s.e.m.) blood mercury concentrations of 6.8±0.3ngmL-1, similar to that found in human blood after occupational exposure or released from removal of amalgam fillings. Even at these low concentrations, mercury was deposited in reproductive organs (testis, epididymis and prostate), impaired sperm membrane integrity, reduced the number of mature spermatozoa and, in the testes, promoted disorganisation, empty spaces and loss of germinal epithelium. Mercury increased levels of reactive oxygen species and the expression of glutathione peroxidase (GPx) 1 and GPx4. These results suggest that the toxic effects of mercury on the male reproductive system are due to its accumulation in reproductive organs and that the glutathione system is its potential target. The data also suggest, for the first time, a possible role of the selenoproteins GPx1 and GPx4 in the reproductive toxicity of mercury chloride.

Women with greater pelvic floor muscle strength have better sexual function.

OBJECTIVE: To investigate the relation between pelvic floor muscle strength and sexual function among women with higher and lower pelvic floor muscle strength. DESIGN: A cross-sectional study was performed among employees and students of the University. SETTING: Urogynecology department, Federal University of Pampa, Brazil, carried out between January and July of 2012. POPULATION: Forty women, aged 20-28 years. METHODS: Forty-nine women were screened and nine were excluded. Baseline information of the participants was obtained. The Female Sexual Function Index questionnaire was applied and pelvic floor muscle strength was randomly measured by transvaginal palpation according to the Ortiz scale, and by perineometry. Women were allocated into two groups according to muscle strength. MAIN OUTCOME MEASURES: Index of sexual function and pelvic floor muscle strength RESULTS: Women with stronger pelvic floor muscles scored higher in the following domains: desire, excitement, orgasm and general score of the questionnaire (4.9 ± 0.73 vs. 3.8 ± 0.58; 5.0 ± 0.35 vs. 4.3 ± 0.82; 5.8 ± 0.21 vs. 4.0 ± 1.00 and 32.4 ± 0.77 vs. 27.6 ± 3.29, p < 0.001). There was a moderate correlation between pelvic floor muscle pressure and both sexual satisfaction (r = 0.47, p = 0.03) and lubrication (r = -0.69, p = 0.001) as well as the manual evaluation of pelvic floor muscle strength, graded by the Ortiz and perineometry, which were interrelated (r = 0.65, p = 0.001). CONCLUSION: Our findings suggest that women with stronger pelvic floor muscles have better sexual function.

Chronic exposure to low doses of mercury impairs sperm quality and induces oxidative stress in rats.

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.

Aluminum Exposure at Human Dietary Levels for 60 Days Reaches a Threshold Sufficient to Promote Memory Impairment in Rats.

Aluminum (Al) is a significant environmental contaminant. While a good deal of research has been conducted on the acute neurotoxic effects of Al, little is known about the effects of longer-term exposure at human dietary Al levels. Therefore, the purpose of this study was to investigate the effects of 60-day Al exposure at low doses for comparison with a model of exposure known to produce neurotoxicity in rats. Three-month-old male Wistar rats were divided into two major groups: (1) low aluminum levels, and (2) a high aluminum level. Group 1 rats were treated orally by drinking water for 60 days as follows: (a) control-received ultrapure drinking water; (b) aluminum at 1.5 mg/kg b.w., and (c) aluminum at 8.3 mg/kg b.w. Group 2 rats were treated through oral gavages for 42 days as follows: (a) control-received ultrapure water; (b) aluminum at 100 mg/kg b.w. We analyzed cognitive parameters, biomarkers of oxidative stress and acetylcholinesterase (AChE) activity in hippocampus and prefrontal cortex. Al treatment even at low doses promoted recognition memory impairment seen in object recognition memory testing. Moreover, Al increased hippocampal reactive oxygen species and lipid peroxidation, reduced antioxidant capacity, and decreased AChE activity. Our data demonstrate that 60-day subchronic exposure to low doses of Al from feed and added to the water, which reflect human dietary Al intake, reaches a threshold sufficient to promote memory impairment and neurotoxicity. The elevation of oxidative stress and cholinergic dysfunction highlight pathways of toxic actions for this metal.

60-Day chronic exposure to low concentrations of HgCl2 impairs sperm quality: hormonal imbalance and oxidative stress as potential routes for reproductive dysfunction in rats.

Mercury is a toxic and bio-accumulative heavy metal of global concern. While good deals of research have been conducted on the toxic effects of mercury, little is known about the mechanisms involved in the pathogenesis of male reproductive dysfunction induced by mercury. Therefore, the purpose of this study was to assess the effects and underlying mechanisms of chronic mercury exposure at low levels on male reproductive system of rats. Three-month-old male Wistar rats were divided into two groups and treated for 60 days with saline (i.m., Control) and HgCl2 (i.m. 1st dose: 4.6 µg/kg, subsequent doses 0.07 µg/kg/day). We analyzed sperm parameters, hormonal levels and biomarkers of oxidative stress in testis, epididymis, prostate and vas deferens. Mercury treatment decreased daily sperm production, count and motility and increased head and tail morphologic abnormalities. Moreover, mercury treatment decreased luteinizing hormone levels, increased lipid peroxidation on testis and decreased antioxidant enzymes activities (superoxide dismutase and catalase) on reproductive organs. Our data demonstrate that 60-day chronic exposure to low concentrations of HgCl2 impairs sperm quality and promotes hormonal imbalance. The raised oxidative stress seems to be a potential mechanism involved on male reproductive toxicity by mercury.