Testicular and epididymal toxicity induced by benzo(a)pyrene, alcohol, and their combination in Wistar rats

The antioxidant/anti-inflammatory protective effects of rutin against ethanol-induced testicular perturbation in rats: Involvement of the immunosuppressive indoleamine 2,3-dioxygenase

This study investigated the influence of rutin against EtOH-induced testicular impairment in rats and the involvement of the indole-aminergic pathway. Four groups of eight rats each were orally exposed to drinking water (Group 1), EtOH (5 g/kg bwt, Group 2), R (5 g/kg bwt, Group 3), and EtOH + R (5 g/kg bwt + 50 mg/kg bwt, Group 4) via gavage for 15 days. Results showed that exposure to EtOH significantly (p < 0.0001) reduced the testicular antioxidant system and increased lipid peroxidation (LPO) relative to control. We observed a significant (p < 0.0001) increase in the inflammatory biomarkers, with attendant disruption in the testicular histological structure and concomitant elevation in the activities of indoleamine 2,3-dioxygenase (IDO), in comparison with control and no noticeable effects in tryptophan 2,3-dioxygenase (TDO) activity across the groups. Rutin-only exposed group did not show any alteration in the measured parameters when compared with the control. Rutin co-exposure augmented the antioxidant system, prevented histological damage, reduced LPO and inflammation, and thus, lowered EtOH-mediated increase in IDO activity, compared with control. Overall, these findings reveal the involvement of the indole-aminergic pathway in rutin's protective influence against EtOH-induced testicular impairment in rats.

Energy drinks and alcohol in a binge drinking protocol in Wistar rats: Male and female behavioral and reproductive effects

The consumption of energy drinks is common among adolescents and young adults. The possible effects (mainly behavioral and reproductive) of ingestion in this population remain unknown. For this reason, this study aimed to evaluate the behavioral and reproductive effects of energy drinks and their main constituents (caffeine and taurine), as well as their combinations with alcohol, via a binge drinking protocol in male and female Wistar rats during puberty. In this study, 100 male and 100 female rats were treated with a binge drinking protocol 3 days a week over 4 weeks from postnatal day (PND) 28 to PND 60, which included 10 mL/kg by oral gavage of distilled water, energy drink, caffeine (3.2 mg/kg), taurine (40 mg/kg), and their combinations with alcohol (2 g/kg). The animals were evaluated by behavioral tests from PND 56 to PND 60 (open field, plus maze and object recognition) and reproductive parameters (estrous cycle regularity, weight of sexual organs, oocyte quality, spermatid and sperm count, sperm morphology and testosterone level). Locomotor activity was increased in females in the groups combined with alcohol (except alcohol + caffeine) and in the caffeine group. Long-term memory was increased in males in the caffeine and taurine groups even when combined with alcohol. The combination of energy drinks and alcohol did not have significant effects on the reproductive parameters of either sex of rats during puberty. We concluded that energy drinks (and their main constituents) and alcohol combinations did not cause alterations in reproductive profiles, and locomotor activity and long-term memory were increased in females and males, respectively.

Benzo[a]pyrene inhibits testosterone biosynthesis via NDUFA10-mediated mitochondrial compromise in mouse Leydig cells: Integrating experimental and in silico toxicological approaches

Benzo[a]pyrene (B[a]P), a representative of polycyclic aromatic hydrocarbons (PAHs), is ubiquitously spread in the environment and showing deleterious impacts on male steroidogenesis, including testosterone synthesis disorder. However, the precise mechanisms involved in B[a]P-induced steroidogenesis perturbation remains obscure. In the present study, we integrated in vivo tests, transcriptome profiling, in vitro assays, and conjoint in silico toxicological approaches to delineate the detailed mechanisms. In mouse models, we observed that B[a]P administration remarkably inhibited testosterone synthesis accompanied by ultrastructural impairments of mitochondria and mitophagosome formation in mouse Leydig cells. Transcriptome profiling showed that B[a]P down-regulated the expression of Ndufa9, Ndufa6, Ndufa10, and Ndufa5 in mouse testes, which are identified as critical genes involved in the assembly and functionality of mitochondrial complex I. In the in vitro tests, the bioactive B[a]P metabolite BPDE induced perturbation of testosterone synthesis by NDUFA10-mediated mitochondrial impairment, which was further exacerbated by mitophagy in TM3 Leydig cells. The findings of in silico toxicological analyses were highly consistent with the experimental observations and further unveiled that B[a]P/BPDE-involved PPARα activation could serve as a molecular initiating event to trigger the decline in Ndufa10 expression and testosterone synthesis. Overall, we have shown the first evidence that mitochondrial compromise in Leydig cells is the extremely crucial target in B[a]P-induced steroidogenesis perturbation.

Integration of in silico methods to determine endocrine-disrupting tobacco pollutants binding potency with steroidogenic genes: comprehensive QSAR modeling and ensemble docking strategies

A myriad of tobacco-associated chemicals may have possibilities to developmental/reproductive axis and endocrine-disruption impacts. Mostly they breach the biotransformation of cholesterol in mitochondria by interfering with steroidogenic pathway genes, prompting to adverse effects in steroid biosynthesis; however, studies are scanty. The quantitative structure-activity relationship (QSAR) modeling and comparative docking strategies were used to understand structural features of dataset compounds that influence developmental/reproductive toxicity and estrogen and androgen receptor-binding abilities, and to predict binding levels of toxicants with steroidogenic acute regulatory protein (StAR) and cholesterol side-chain cleavage enzyme (CYP11A1) active sites. Developed QSAR models presented good robustness and predictive ability that were determined from the applicability domain and, clustering and classification of chemicals by performing self-organizing maps. Accordingly, the exorbitant amount of polycyclic aromatic hydrocarbons (PAHs) and a limited number of other chemicals including N-nitrosamines and nicotine was represented as potential developmental/reproductive toxicants as well as estrogen and androgen receptor binders. From the docking analysis, hydrogen bonding, nonpolar, atomic π-stacking, and π-cation interactions were found between PAHs (bay and fjord structural pockets) and functional hotspot residues of StAR and CYP11A1, which strengthened the subtle structural changes at domains. These govern barrier effects to cholesterol binding and/or locking cholesterol to complicate its ejection from the Ω1 loop of StAR, and further mitigates steroid biosynthesis through cholesterol by CYP11A1; therefore, they are presumably considered as block-cluster mechanisms. These outcomes are significant to be hopeful to estimate developmental/reproductive toxicity and endocrine-disruption activities of other environmental pollutants, and could be useful for further assessment to discover binding mechanisms of PAHs with other steroidogenesis pathway genes.

Abnormal methylation of spermatozoa induced by benzo(a)pyrene in rats

Epigenetic mutations caused by pollutants are possibly linked to many diseases. Benzo(a)pyrene (BaP) is one of the most representative air pollutants and has aroused wide concern because of its strong carcinogenicity. The reproductive toxicity induced by BaP has been identified, but little is known about the characteristics of the methylation changes induced by BaP. In this study, a methylated DNA immunoprecipitation sequencing method was used to detect the methylation of sperm DNA of rats exposed to BaP. Compared with the respective genes in normal rats, there were 3227 hypomethylated genes and 828 hypermethylated genes after BaP exposure. Gene ontology enrichment analysis reported that differentially methylated genes (DMGs) were enriched in the localization, single-multicellular organism process and plasma membrane. Kyoto Encyclopedia of Genes and Genomes pathway analysis showed that the DMGs were significantly enriched in the Ras signalling pathway, Rap1 signalling pathway, pancreatic secretion and neuroactive ligand-receptor interaction. DisGeNET disease spectrum analysis showed that DMGs were associated with infertility and certain genetic diseases. Further research needs to be done to explore whether these abnormal methylation are transgenerational.

Molecular activities and ligand-binding specificities of StAR-related lipid transfer domains: exploring integrated in silico methods and ensemble-docking approaches

In this study, cholesterol biotransformation gene-set of human steroidogenic acute regulatory protein-related lipid transfer (START) domains were evaluated from high-throughput gene screening approaches. It was shown that STARD1, STARD3 and STARD4 proteins are better effective transporters of cholesterol than STARD5 and STARD6 domains. Docking studies show a strong agreement with gene ontology enrichment data. According to both complementary strategies, it was found that only STARD1, STARD3 and STARD4 are potentially involved in cholesterol biotransformation in mitochondria through Ω1-loop of C-terminal α4-helical domain. Ensemble docking assessment for a set of selected chemicals of protein-chemical networks has shown possible binding probabilities with START domains. Among those, reproductive toxicity evoked drugs (mifepristone), insecticides (rotenone), tobacco pulmonary carcinogens (benzo(a)pyrene) and endocrine disruptor chemicals (EDCs) including perfluorooctanesulfonic acid (PFOS) and aflatoxin B₁ (AFB₁) potentially bound with novel hotspot residues of the α4-helical domain. Compound representation space and clustering approaches reveal that the START proteins show more sensitivity with these lead scaffolds, so they could provide probable barrier assets in cholesterol and steroidogenic acute regulatory (StAR) binding and leads adverse consequences in steroidogenesis. These findings indicate potential START domains and their binding levels with toxic chemicals; sorted viewpoints could be useful as a promising way to identify chemicals with related steroidogenisis impacts on human health.

Lead aggravates the diabetic-induced reproductive toxicity in male Wistar rats

Diabetes, an unresolved metabolic disorder, and lead contamination are prevalent problems in contemporary society. Previously, we have reported that either diabetes or lead exposure resulted in reproductive toxicity in male Wistar rats. The aim of this study was to evaluate whether diabetic rats exposed to lead demonstrate a higher degree of reproductive toxicity when compared with lead-exposed control rats. Diabetes was induced by injecting a single dose of streptozotocin (50 mg per kg body weight). Control and diabetic rats were exposed to lead at a concentration of 819 mg L-1 (0.15% lead acetate) through drinking water for a period of 30 days and assessed for reproductive and oxidative end points. The relative weights of the testes, epididymis, seminal vesicles, and the prostate gland were significantly decreased in diabetic rats. Daily sperm production, epididymal sperm count, motile, viable and HOS-tail swelled sperms, serum testosterone levels and testicular 3β- and 17β-hydroxysteroid dehydrogenase activity levels were significantly decreased in diabetic rats. Significant reductions in testicular and epididymal antioxidant enzyme activity levels and glutathione levels were observed in diabetic rats with an elevation in the levels of superoxide anions, hydrogen peroxides, and lipid peroxidation. A significant reduction in the number of implantations associated with elevated pre- and post-implantation losses was observed in females mated with diabetic males. Mild histopathological malformations were observed in the testis of the diabetic rats. Similar reproductive and oxidative toxicities were observed in lead-exposed control rats. Furthermore, lead exposed diabetic rats showed additional deterioration in reproductive end points and a noteworthy elevation in oxidative toxicity, suggesting that treatment with lead exacerbates reproductive toxicity in streptozotocin-induced diabetic rats.