Different mechanisms for lead acetate, aluminum and cadmium sulfate in rat corpus cavernosum

Embryonic exposure to aluminum chloride blocks the onset of spermatogenesis through disturbing the dynamics of testicular tight junctions via upregulating Slc25a5 in offspring

Studies have revealed neurotoxicity, hepatotoxicity, and developmental and reproductive toxicity in mice exposed to aluminum. However, relatively few studies have been conducted to clarify the mechanism underlying the impact of embryonic exposure to aluminum on the development of the male reproductive system in offspring. Pregnant mice were administered aluminum chloride (AlCl3) by gavage from day 12.5 of gestation until birth. Our findings demonstrated that embryonic exposure to AlCl3 disrupted testicular development and spermatogenesis by impairing testicular architecture, reducing sperm count, and upregulating the expression of tight junction (TJ) protein between Sertoli cells (SCs). Further in vitro studies revealed that treatment with AlCl3 stabilized TJ proteins Occludin and ZO-1 expression by inhibiting ERK signaling pathway activation, thereby upregulating Slc25a5 expression which induced ATP production leading to disruption of cytoskeletal protein homeostasis. Therefore, the study provided a new mechanistic insight into how AlCl3 exposure interfered with testicular development and spermatogenesis while suggesting that Slc25a5 might be a target affected by AlCl3 influencing cell metabolism.

Erectile dysfunction in copper and cobalt miners: a cross-sectional study in the former Katanga province, Democratic Republic of the Congo

Background

The African Copperbelt is a site of intense artisanal and industrial mining and refining of copper and cobalt.

Aim

We aimed to investigate factors that are possibly associated with erectile dysfunction (ED) in metal miners in the former Katanga province of the Democratic Republic of the Congo.

Methods

In a cross-sectional study of 138 miners and 139 controls (bakers), we administered questionnaires to obtain sociodemographic and occupational data and to assess male sexual function (International Index of Erectile Function [IIEF]) and marital relation quality (Revised Dyadic Adjustment Scale). Furthermore, we measured trace metals in blood and urine, as well as testosterone and thyroid hormones in serum.

Outcomes

Outcomes included the prevalence of questionnaire-derived ED and the relation of ED with individual characteristics, serum testosterone, and environmental factors.

Results

Miners were on average 4 years older than bakers (mean ± SD, 37.5 ± 6.9 vs 33.3 ± 5.7 years). Miners had significantly lower scores than bakers on the IIEF (median [IQR], 66 [49-73] vs 73 [66-74]) and the 3 domains of the Revised Dyadic Adjustment Scale (consensus, satisfaction, cohesion). Free testosterone was significantly lower in miners than bakers (ng/dL; 8.11 [6.90-10.10] vs 10.52 [8.83-12.58]; P ˂ .001). In miners, sex hormone-binding globulin correlated positively with blood Pb and urinary Cd. In a multivariable analysis, mild to moderate ED or moderate ED (IIEF-erectile function score ≤18) was significantly associated with having a mining-related job (adjusted odds ratio [aOR], 2.6; 95% CI, 1.3-5.3), work seniority ˃5 years (aOR, 2.3; 95% CI, 1.1-4.6), alcohol consumption (aOR, 2.8; 95% CI, 1.2-6.7), and aphrodisiacs use (aOR, 4.2; 95% CI, 2.2-8.0). Mediation analysis showed that marital relationship partially mediated the relation between work seniority >5 years in mining and ED.

Clinical Implications

The high prevalence of ED found in artisanal mine workers indicates that work-related factors should be considered as possibly contributing, directly or indirectly, to sexual dysfunction in men.

Strengths and Limitations

Strengths include being the first epidemiologic study documenting ED with validated questionnaires and its possible determinants, including exposure to toxic metals, among young artisanal miners vs a suitable control group. Limitations are the cross-sectional design with convenience sampling and absence of objective confirmation of ED.

Conclusion

As compared with controls, miners reported poorer sexual function and lower quality of their marital relationship, and they had lower free testosterone levels, which may be due to their high exposure to trace metals.

Associations between exposure to different heavy metals and self-reported erectile dysfunction: a population-based study using data from the 2001-2004 National Health and Nutrition Examination Survey

Heavy metals are ubiquitous and nonbiodegradable pollutants that are widely distributed in the environment. Heavy metal exposure can damage various biological tissues and cause several diseases. This study aimed to investigate the association between blood and urinary cadmium, lead, and mercury levels and erectile dysfunction (ED) based on data from the 2001-2004 National Health and Nutrition Examination Survey. In total, 3681 participants were included in the analysis. Results showed that participants with ED had high blood cadmium, mercury, creatinine, urinary lead, cadmium levels, low blood lead, serum cotinine, and urinary mercury levels. Multivariate logistic regression analysis showed that only blood cadmium level was an independent risk factor of ED (tertile [T]2 vs T1: odds ratio = 1.495, 95% confidence interval: 1.181-1.892, p = 0.001; T3 vs T1: odds ratio = 2.089, 95% confidence interval: 1.554-2.809, p < 0.001). The dose-response curve showed a positive nonlinear association between blood cadmium and lead levels and ED and a negative nonlinear association between blood and urinary mercury levels and ED after propensity score matching. In conclusion, heavy metal exposure is closely correlated with the development of ED, and a high blood cadmium level is an independent risk factor of ED.

Lead acetate versus cadmium sulfate in the modulation of main physiological pathways controlling detrusor muscle contractility in rat

Heavy metals have a deleterious effect on lower urinary tract functions. Scant data has been reported about metals’ effect on altering detrusor muscle contractility. Rats were given lead acetate (3, 30 mg/kg), cadmium sulfate (0.1, 1 mg/kg) or ferrous sulfate-iron overload-(3, 30 mg/kg), in a subacute toxicity study (21 days, ip). In-vitro tension experiments were conducted using isolated rat detrusor muscle. Measurement of heavy metal concentrations in blood and tissue homogenates was performed, as well as histopathological examinations. Subacute toxicity induced by treatment with lead and cadmium was manifested as a decrease in EFS, ACh, and ATP-mediated contraction of isolated detrusor muscle. Iron overload only decreased E_MAX of EFS and ACh-mediated contraction. Lead (30 mg/kg) caused an upward shift in the dose response curve of isoprenaline-induced relaxation, with a significant decrease in E_MAX. Lead (30 mg/kg) or cadmium (1 mg/kg) inhibited adenosine (10⁻⁵ M)-induced relaxation. Comparisons to control tissues showed a selective accumulation of metals in the detrusor muscle. Histopathological examinations revealed edema and inflammation in the urinary bladder. Directly added lead (10 mM) inhibited detrusor muscle contraction in-vitro, and its effect was decreased in presence of atropine, and potentiated in presence of TEA, L-NAME, or MB. Cadmium's (0.1 mM) inhibitory effect was reduced in presence of nifedipine or trifluoperazine. In conclusion, lead, cadmium, or iron induce detrusor hypoactivity: The inhibitory effect of lead may be mediated by modulating muscarinic receptors but not the K⁺/NO/cGMP pathway, whereas cadmium inhibitory effect may be mediated by inhibiting the Ca²⁺/calmodulin pathway.

Aluminum reproductive toxicity: a summary and interpretation of scientific reports

Publications addressing aluminum (Al)-induced reproductive toxicity were reviewed. Key details were compiled in summary tables. Approximate systemic Al exposure, a measure of bioavailability, was calculated for each exposure, based on the Al percentage in the dosed Al species, Al bioavailability, and absorption time course reports for the exposure route. This was limited to laboratory animal studies because no controlled-exposure human studies were found. Intended Al exposure was compared to unintended dietary Al exposure. The considerable and variable Al content of laboratory animal diets creates uncertainty about reproductive function in the absence of Al. Aluminum-induced reproductive toxicity in female mice and rats was evident after exposure to ≥25-fold the amount of Al consumed in the diet. Generally, the additional daily Al systemic exposure of studies that reported statistically significant results was greater than 100-fold above the typical human daily Al dietary consumption equivalent. Male reproductive endpoints were significantly affected after exposure to lower levels of Al than females. Increased Al intake increased fetus, placenta, and testes Al concentrations, to a greater extent in the placenta than fetus, and, in some cases, more in the testes than placenta. An adverse outcome pathway (AOP) was constructed for males based on the results of the reviewed studies. The proposed AOP includes oxidative stress as the molecular initiating event and increased malondialdehyde, DNA and spermatozoal damage, and decreased blood testosterone and sperm count as subsequent key events. Recommendations for the design of future studies of reproductive outcomes following exposure to Al are provided.