Exposures of male rats to environmental chemicals [bisphenol A and di (2-ethylhexyl) phthalate] affected expression of several proteins in the developing epididymis

Role of autonomic nervous system in BDE-209 maternal exposure induced immunotoxicity in female offspring

Decabrominated diphenyl ether (BDE-209) is a typical persistent organic pollutant that can cross the placental barrier, increasing the exposure risk for offspring. Norepinephrine (NE) from nerve terminals and acetylcholine (Ach) can bind to specific receptors on immune cells, inhibit the immune function of the body then cause immunotoxicity. However, whether maternal exposure to BDE-209 could lead to immunotoxicity in the offspring by acting on the sympathetic and parasympathetic nervous systems remains unclear. In view of this, the pregnancy and lactation rat BDE-209 exposure model was established and the results demonstrated that pregnancy and lactation BDE-209 exposure could induce immunotoxicity to female offspring via affecting immunopathology (hematological and biochemical parameters, organ indices, and spleen histopathological), decreasing humoral immunity (serum hemolysin, immunoglobulins, and cytokine productions), damaging cellular immunity (splenic lymphocytes and spleen cytokine productions), and restraining nonspecific immunity. Moreover, a dramatically significant correlation was observed between spleen nerve indices and immunity indices. Additionally, the mechanism revealed that maternal BDE-209 exposure caused offspring immunotoxicity through (1) activating MHC/PKCθ/NF-κB pathway; (2) promoting sympathetic nervous pathway, by upregulating the expression of β2AR protein, which in turn elevating cAMP, following activate PKA and phosphorylate CREB, ultimately leading to immunotoxicity;(3) activating parasympathetic nerve pathway by reducing the binding with Ach and α7nAchR, upregulating the expression of JAK2 and phosphorylating STAT3, induced immunotoxicity of female offspring.

Gonadal sex steroid hormone secretion after exposure of male rats to estrogenic chemicals and their combinations

Environmental chemicals can interfere with the endocrine axis hence they are classified as endocrine disrupting chemicals (EDCs). Bisphenol S (BPS) is used in the manufacture of consumer products because of its superior thermal stability and is thought to be a safe replacement chemical for its analog bisphenol A (BPA). However, the safety profile of these compounds alone or in the presence of other EDCs is yet to be fully investigated. Also, the estrogenic chemical 17α-ethinyl estradiol (EE2) and a constituent of female oral contraceptives for women, is present in water supplies. To simulate concurrent exposure of the population to chemical mixtures, we investigated the effects of BPA, BPS, EE2, and their combinations on sex steroid secretion in the growing male rat gonad. Prepubertal and pubertal male rats at 21 and 35 days of age were provided test chemicals in drinking water (parts per billion) for 14 days. At termination of exposure, some individual chemical effects were modified by exposure to chemical combinations. Single chemical exposures markedly decreased androgen secretion but their combination (e.g., BPA + BPS + EE2) caused the opposite effect, i.e., increased Leydig cell T secretion. Also, the test chemicals acting alone or in combination increased testicular and Leydig cell 17β-estradiol (E2) secretion. Chemical-induced changes in T and E2 secretion were associated with altered testicular expression of the cholesterol side-chain cleavage (Cyp11a1) and 17β-hydroxysteroid dehydrogenase (Hsd17β) enzyme protein. Additional studies are warranted to understand the mechanisms by which single and chemical combinations impact function of testicular cells and disrupt their paracrine regulation.

Combining in vivo pathohistological and redox status analysis with in silico toxicogenomic study to explore the phthalates and bisphenol A mixture-induced testicular toxicity

The aim of this study was to: (i) determine and compare the capacity of bis (2 -ethylhexyl) phthalate (DEHP), dibutyl phthalate (DBP), bisphenol A (BPA), and their mixture to produce testicular toxicity after the subacute exposure; (ii) explore the mechanisms behind the observed changes using in silico toxicogenomic approach. Male rats were randomly split into groups (n = 6): (1) Control (corn oil); (2) DEHP (50 mg/kg b.w./day); (3) DBP (50 mg/kg b.w./day); (4) BPA (25 mg/kg b.w./day); and (5) MIX (50 mg/kg b.w./day DEHP + 50 mg/kg b.w/day DBP + 25 mg/kg b.w./day BPA). Animals were sacrificed after 28 days of oral exposure, testes were extracted and prepared for histological assessments under the light microscope (haematoxylin and eosin staining) and redox status analysis. The Comparative Toxicogenomics Database (CTD; http://CTD.mdibl.org), Cytoscape software (https://cytoscape.org) and ToppGene Suite (https://toppgene.cchmc.org) were used for data-mining. Present pathohistological study has demonstrated more pronounced testicular toxicity of the MIX group (desquamated germinal epithelium cells, enlarged cells with hyperchromatic nuclei, multinucleated cell forms and intracytoplasmic vacuoles) in comparison with the single substances, while effects on redox status parameters were either more prominent, or present only in the MIX group. In silico investigation revealed 20 genes linked to male reproductive disorders, affected by all three investigated substances. Effects on metabolism, AhR pathway, apoptosis and oxidative stress could be singled out as the most probable mechanisms involved in the subacute DEHP, DBP and BPA mixture testicular toxicity, while the effect on oxidative stress parameters was confirmed by in vivo experiment.