Effects of lead exposure on sperm concentrations and testes weight in male rats: A meta-regression analysis

Department of Epidemiology and Biostatistics, School of Public Health, Nanjing Medical University, Nanjing, China.
Journal of Toxicology and Environmental Health Part A (Impact Factor: 1.83). 02/2008; 71(7):454-63. DOI: 10.1080/15287390701839331
Source: PubMed

ABSTRACT The correlation between exposure to lead (PB) and sperm concentrations and testes weight are important in risk assessment of metal toxicity to male reproductive functions. The authors carried out two systematic reviews and meta-analyses of rats. In addition, a meta-regression analysis was taken to explore a dose-response relationship between the mean difference of testes weight (MD(testes)) and available confounding factors. Data were obtained from computerized literature searches of several databases from their inception through December 2005. The reference lists of identified articles were examined further for relevant articles. The authors identified 6 and 12 studies, separated into 16 and 28 subgroups, in the two meta-analyses. The authors conducted random- or fixed-effect models toward the effect size. Heterogeneity between study results was explored through chi-square tests and meta-regression. Results showed that a decrease in sperm concentrations was found as low as mean difference of sperm concentrations (MD(sperm)) = 30.9 and 95%CI = (25.43-36.37) in a fixed-effect model or MD(sperm) = 35.47 and 95%CI = (15.27-55.68) in a random-effect model after Pb exposure. Similarly, a significantly lower testes weight was also evident: MD(testes) = 0.033 and 95%CI = (0.021-0.046) in a fixed-effect model or MD(testes) = 0.047 and 95%CI = (0.0044-0.089) in a random-effect model. In the meta-regression analysis, two confounders, age and body weight, explained part of the observed heterogeneity. The body weight after Pb exposure was inversely associated with MD(testes). These findings support the notion that Pb exposure produced decreased sperm concentrations and testes weight in rats.

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    • "In addition, a significant positive correlation was also observed between Pb in seminal plasma and the 8-hydroxy-2'-deoxyguanosine (8-OHdG) level (Xu et al., 2003). Pb is a testicular toxicant in experimental animals (Wang et al., 2008). The effects of Pb on spermatogenesis have been demonstrated in rat testes. "
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    ABSTRACT: Lead (Pb) is a testicular toxicant. In the present study, we investigated the effects of maternal Pb exposure during lactation on testicular development and steroidogenesis in male offspring. Maternal mice were exposed to different concentration of lead acetate (200 or 2000 ppm) through drinking water from postnatal day (PND) 0 to PND21. As expected, a high concentration of Pb was measured in the kidneys and liver of pups whose mothers were exposed to Pb during lactation. In addition, maternal Pb exposure during lactation elevated, to a less extent, Pb content in testes of weaning pups. Testis weight in weaning pups was significantly decreased when maternal mice were exposed to Pb during lactation. The level of serum and testicular T was reduced in Pb-exposed pups. The expression of P450scc, P450(17α) and 17β-HSD, key enzymes for T synthesis, was down-regulated in testes of weaning pups whose mothers were exposed to Pb during lactation. Interestingly, the level of serum and testicular T remained decreased in adult offspring whose mothers were exposed to Pb during lactation. Importantly, the number of spermatozoa was significantly reduced in Pb-exposed male offspring. Taken together, these results suggest that Pb could be transported from dams to pups through milk. Maternal Pb exposure during lactation persistently disrupts testicular development and steroidogenesis in male offspring. Copyright © 2012 John Wiley & Sons, Ltd.
    Journal of Applied Toxicology 12/2013; 33(12). DOI:10.1002/jat.2795 · 3.17 Impact Factor
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    • "In the animal model, lead has a primary toxic effect on the hypothalamic-pituitary unit, a primary effect on the testes and acts at all levels of the reproductive axis (Sokol et al., 2002). Male rats exposed to lead acetate have been reported to show a significant decrease in the weight of both the testes, epididymis (Wang et al., 2008; Smith et al., 2008) and pituitary (Cooper et al., 1986; Coffigny et al., 1994) and this weight reduction in sex glands and pituitary was accompanied by an alteration of the normal histological structure. There are reports that some metal such as lead, cadmium, arsenic and mercury can affect male reproductive functions including sperm counts (Chia et al., 1992), motility and morphology (Meeker et al., 2008) and spermatogenesis (Telisman et al., 2007). "
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    ABSTRACT: The current study evaluates the impact of low or moderate levels of lead acetate (PbAc) on sperm parameters, gonadotropins (FSH, LH) and testosterone. Adult albino wistar male rats were allocated to five groups and given 0%, 0.025%, 0.05%, 0.1% and 0.3% PbAc in distilled drinking water for 24 weeks. There was no change in body weight gain and in absolute or relative weight of testes, epididymides and seminal vesicles. The ventral prostate weight was decreased in groups exposed to 0.05%, 0.1% and 0.3% PbAc without statistically significant differences. Sperm velocity was decreased in all treated groups while reduction of sperm motility was observed in rats exposed to 0.05%, 0.1% and 0.3% PbAc without statistically significant differences compared to the control group. However, there was a significant increase greater than 100% in the total percentage of abnormal sperm in groups treated with 0.1% (p<0.01) and 0.3% PbAc (p<0.05).The frequency of dead sperm was significantly increased only in the 0.3% PbAc group (p<0.01). Significant increases in frequencies of amorphous head sperm (p<0.01) and abnormal tails (p<0.01) were found in the group exposed to 0.1% PbAc, while the frequency of neck abnormalities was increased in the high-lead-exposed group (p<0.01). The levels of LH and FSH were not significantly affected after lead treatment and significant increase in serum testosterone level was noted only in animals administered 0.05% PbAc (p<0.01). In conclusion, our results reveal that some sperm parameters were altered at low or moderate lead concentrations with no obvious alteration of hypothalamic-pituitary function. The increase of testosterone level observed suggests that lead may target testicular function.
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