Nitric oxide mediated effects on reproductive toxicity caused by carbon disulfide in male rats

How to Differentiate General Toxicity-Related Endocrine Effects from Endocrine Disruption: Systematic Review of Carbon Disulfide Data

This review provides an overview of the assessment of the endocrine disrupting (ED) properties of carbon disulfide (CS₂), following the methodology used at the European level to identify endocrine disruptors. Relevant in vitro, in vivo studies and human data are analyzed. The assessment presented here focuses on one endocrine activity, i.e., thyroid disruption, and two main adverse effects, neurotoxicity and cardiotoxicity. The data available on the different ED or non-ED modes of action (MoA), known to trigger these adverse effects, are described and the strength of evidence of the different MoA is weighted. We conclude that the adverse effects could be due to systemic toxicity rather than endocrine-mediated toxicity. This assessment illustrates the scientific and regulatory challenges in differentiating a specific endocrine disruption from an indirect endocrine effect resulting from a non-ED mediated systemic toxicity. This issue of evaluating the ED properties of highly toxic and reactive substances has been insufficiently developed by European guidance so far and needs to be further addressed. Finally, this example also raises questions about the capacity of the technics available in toxicology to address such a complex issue with certainty.

An approach to classifying occupational exposures to endocrine disrupting chemicals by sex hormone function using an expert judgment process

Endocrine disrupting chemicals (EDCs) are exogenous substances that interfere with the endocrine system and cause adverse effects. We aimed to classify the effects of 24 known EDCs, prevalent in certain occupations, according to four modes of action (estrogenic, antiestrogenic, androgenic, and/or antiandrogenic). A literature search, stratified into four types of literature was conducted (namely: national and international agency reports; review articles; primary studies; ToxCast^TM). The state of the evidence of each EDC on sex hormone function was summarized and reviewed by an expert panel. For each mode of action, the experts evaluated the likelihood of endocrine disruption in five categories: "No", "Unlikely", "Possibly", "Probably", and "Yes". Seven agents were categorized as "Yes," or having strong evidence for their effects on sex hormone function (antiandrogenic: lead, arsenic, butylbenzyl phthalate, dibutyl phthalate, dicyclohexyl phthalate; estrogenic: nonylphenol, bisphenol A). Nine agents were categorized as "Probable," or having probable evidence (antiandrogenic: bis(2-ethylhexyl)phthalate, nonylphenol, toluene, bisphenol A, diisononyl phthalate; androgenic: cadmium; estrogenic: copper, cadmium and; anti-estrogenic: lead). Two agents (arsenic, polychlorinated biphenyls) had opposing conclusions supporting both "probably" estrogenic and antiestrogenic effects. This synthesis will allow researchers to evaluate the health effects of selected EDCs with an added level of precision related to the mode of action.

Mitochondrion-mediated apoptosis is involved in reproductive damage caused by BPA in male rats

Bisphenol A (BPA) is a widely used environmental endocrine disruptor. Many studies have reported that BPA exposure shows reproductive toxicity and causes apoptosis in spermatogenic cells. However, few studies have investigated the relationship between the mitochondrial pathway and BPA-induced apoptosis. This study investigated the role of the mitochondrial pathway in apoptosis induced by BPA, which resulted in compromised male rat spermatogenesis and reproductive damage. Rats were exposed to various BPA concentrations (0, 50, 100, or 200mg of BPA/kg body weight per day), and factors in the mitochondrial signal transduction pathway and the apoptosis indices of spermatogenic cells were measured and sperm characteristics were analyzed. Our data revealed that BPA exposure increased the protein and mRNA levels of cytochrome C, apoptosis-inducing factor, caspase-3/9, and Bax; caspase-3 and caspase-9 activities; and the apoptosis indices of spermatogenic cells. In addition, abnormal structure of mitochondria and decreased protein and gene levels of Bcl-2 were observed following BPA exposure. These results suggest that apoptosis in the mitochondrial pathway mediates compromised reproductive system function caused by BPA exposure.