Transcriptional profile of ethylene glycol monomethyl ether-induced testicular toxicity in rats

Decoding the enigmatic estrogen paradox in pulmonary hypertension: delving into estrogen metabolites and metabolic enzymes

Pulmonary hypertension (PH) presents a puzzling sex bias, being more prevalent in women yet often less severe than in men, and the underlying reasons remain unclear. Studies using animal models, and limited clinical data have revealed a protective influence of exogenous estrogens, known as the estrogen paradox. Research suggests that beyond its receptor-mediated effects, estrogen acts through metabolites such as 2-ME2, 4-OHE2, and 16-OHE2, which are capable of exhibiting protective or detrimental effects in PH, prompting the need to explore their roles in PH to untangle sex differences and the estrogen paradox. Hypoxia disrupts the balance of estrogen metabolites by affecting the enzymes responsible for estrogen metabolism. Delving into the role of these metabolic enzymes not only illuminates the sex difference in PH but also provides a potential rationale for the estrogen paradox. This review delves into the intricate interplay between estrogen metabolites, metabolic enzymes, and PH, offering a deeper understanding of sex-specific differences and the perplexing estrogen paradox in the context of this condition.

The adverse role of endocrine disrupting chemicals in the reproductive system

Reproductive system diseases pose prominent threats to human physical and mental well-being. Besides being influenced by genetic material regulation and changes in lifestyle, the occurrence of these diseases is closely connected to exposure to harmful substances in the environment. Endocrine disrupting chemicals (EDCs), characterized by hormone-like effects, have a wide range of influences on the reproductive system. EDCs are ubiquitous in the natural environment and are present in a wide range of industrial and everyday products. Currently, thousands of chemicals have been reported to exhibit endocrine effects, and this number is likely to increase as the testing for potential EDCs has not been consistently required, and obtaining data has been limited, partly due to the long latency of many diseases. The ability to avoid exposure to EDCs, especially those of artificially synthesized origin, is increasingly challenging. While EDCs can be divided into persistent and non-persistent depending on their degree of degradation, due to the recent uptick in research studies in this area, we have chosen to focus on the research pertaining to the detrimental effects on reproductive health of exposure to several EDCs that are widely encountered in daily life over the past six years, specifically bisphenol A (BPA), phthalates (PAEs), polychlorinated biphenyls (PCBs), parabens, pesticides, heavy metals, and so on. By focusing on the impact of EDCs on the hypothalamic-pituitary-gonadal (HPG) axis, which leads to the occurrence and development of reproductive system diseases, this review aims to provide new insights into the molecular mechanisms of EDCs' damage to human health and to encourage further in-depth research to clarify the potentially harmful effects of EDC exposure through various other mechanisms. Ultimately, it offers a scientific basis to enhance EDCs risk management, an endeavor of significant scientific and societal importance for safeguarding reproductive health.

Syringic acid demonstrates an anti-inflammatory effect via modulation of the NF-κB-iNOS-COX-2 and JAK-STAT signaling pathways in methyl cellosolve-induced hepato-testicular inflammation in rats

Syringic acid (SACI) is an emerging nutraceutical and antioxidant used in modern Chinese medicine. It has potential neuroprotective, anti-hyperglycemic, and anti-angiogenic properties. Methyl cellosolve (MCEL) has been reported to induce tissue inflammation in the testis, kidney, liver, and lung. This study aimed to investigate the effect and probable mechanism of action of SACI on MCEL-induced hepatic and testicular inflammation in male rats. Compared to the control group, administration of MCEL to rats significantly increased the levels of IL-6, TNF-α, iNOS, COX-2, and NF-κB in the liver and testis. Additionally, the total mRNA expressions of JAK1 (in the liver only), STAT1, and SOCS1 were significantly increased in both the liver and testis, while testicular JAK1 total mRNA levels were significantly decreased. The expression of PIAS1 protein was significantly higher in the liver and testis. Treatments with SACI at 25 (except liver iNOS), 50, and 75 mg/kg significantly decreased the levels of IL-6, TNF-α, iNOS, COX-2, and NF-κB compared to the control group. Furthermore, the total mRNA expressions of JAK1 and SOCS1 in the liver were significantly reduced by all doses of SACI investigated, while the total mRNA levels of liver and testis STAT1 were significantly reduced by 25 and 50 mg/kg of SACI only. In the testis, the mRNA level of SOCS1 was significantly reduced by all doses of SACI compared to MCEL only. Additionally, SACI (at 75 mg/kg) significantly reduced PIAS1 protein expression in the liver, while in the testis, SACI at all investigated doses significantly reduced the expression of PIAS1. In conclusion, SACI demonstrated a hepatic and testicular anti-inflammatory effect by inhibiting the MCEL-induced activation of the NF-κB and JAK-STAT signaling pathways in rats.

Circulating microRNAs as promising testicular translatable safety biomarkers: current state and future perspectives

Drug-induced testicular injury (DITI) is one of the often-observed and challenging safety issues seen during drug development. Semen analysis and circulating hormones currently utilized have significant gaps in their ability to detect testicular damage accurately. In addition, no biomarkers enable a mechanistic understanding of the damage to the different regions of the testis, such as seminiferous tubules, Sertoli, and Leydig cells. MicroRNAs (miRNAs) are a class of non-coding RNAs that modulate gene expression post-transcriptionally and have been indicated to regulate a wide range of biological pathways. Circulating miRNAs can be measured in the body fluids due to tissue-specific cell injury/damage or toxicant exposure. Therefore, these circulating miRNAs have become attractive and promising non-invasive biomarkers for assessing drug-induced testicular injury, with several reports on their use as safety biomarkers for monitoring testicular damage in preclinical species. Leveraging emerging tools such as 'organs-on-chips' that can emulate the human organ's physiological environment and function is starting to enable biomarker discovery, validation, and clinical translation for regulatory qualification and implementation in drug development.

Environmental and occupational exposures associated with male infertility

The upsurge in male infertility over the last two decades, possibly due to environmental exposure, has raised significant interest, particularly boosted by reports from fertility clinics, which showed that chronic diseases and hereditary or other medical conditions might only partially explain current incidence of male infertility. Both environmental and occupational settings may have a significant role in exposure to complex mixtures of endocrine disruptors (ED), which play a major role in fertility disorders. The aim of this review is to give an insight into the current knowledge on exposure settings which may be associated with male infertility. Our study relied on a systematic search of PubMed, Scopus, and Web of Science for articles published between January 2000 and September 2020. It showed that some well documented factors associated with male infertility include smoking, and physiological disturbances or chronic diseases such as obesity and diabetes, which in turn, may also reflect lifestyle choices and environmental exposures, especially to EDs such as phthalates, bisphenols, pesticides, and flame retardants. However, the number of studies on the aetiology of male infertility is still too low in comparison with the size of affected population. Occupational health follow-ups and medical surveillance do not collect any data on male infertility, even though ED chemicals are part of many technological processes.

Integrated In Silico Models for the Prediction of No-Observed-(Adverse)-Effect Levels and Lowest-Observed-(Adverse)-Effect Levels in Rats for Sub-chronic Repeated-Dose Toxicity

Repeated-dose toxicity (RDT) is a critical endpoint for hazard characterization of chemicals and is assessed to derive safe levels of exposure for human health. Here we present the first attempt to model simultaneously no-observed-(adverse)-effect level (NO(A)EL) and lowest-observed-(adverse)-effect level (LO(A)EL). Classification and regression models were derived based on rat sub-chronic repeated dose toxicity data for 327 compounds from the Fraunhofer RepDose database. Multi-category classification models were built for both NO(A)EL and LO(A)EL though a consensus of statistics- and fragment-based algorithms, while regression models were based on quantitative relationships between the endpoints and SMILES-based attributes. NO(A)EL and LO(A)EL models were integrated, and predictions were compared to exclude inconsistent values. This strategy improved the performance of single models, leading to R² greater than 0.70, root-mean-square error (RMSE) lower than 0.60 (for regression models), and accuracy of 0.61-0.73 (for classification models) on the validation set, based on the endpoint and the threshold applied for selecting predictions. This study confirms the effectiveness of the modeling strategy presented here for assessing RDT of chemicals using in silico models.

Exploration of small RNA biomarkers for testicular injury in the serum exosomes of rats

Testicular injury is often observed in drug development. Serum hormones are usually used as noninvasive biomarkers for testicular injury; however, their sensitivities are low. Therefore, it is difficult to monitor testicular injury in drug development. In recent years, molecules in body fluid exosomes have attracted attention as biomarkers for diseases. In this study, small RNAs in serum exosomes were analyzed to identify noninvasive biomarkers of testicular injury in rats, which are often used in preclinical drug development. The rat models of testicular injury were prepared by a single oral administration of 2000 mg/kg ethylene glycol monomethyl ether, in which spermatocyte degeneration and Sertoli cell vacuolation were observed, or 400 mg/kg carbendazim, in which Sertoli cell vacuolation and seminiferous tubule dilation were observed. Serum exosomal small RNA-seq analysis of these models was performed. The analysis identified 3 small RNAs that fluctuated in common between the models, and miR-423-5p and miR-128-3p were selected as candidate markers. For evaluating these candidate markers in other testicular injury models, the models were prepared by a single oral administration of 60 mg/kg 1,3-dinitrobenzene or 500 mg/kg nitrofurazone, and spermatocyte degeneration and Sertoli cell vacuolation were observed. In qPCR analysis, these exosomal miRNAs were upregulated in all models except for the 1,3-dinitrobenzene model, in which severe hemolysis was observed. By contrast, these miRNAs in whole serum extracts did not significantly change in any of the models. In conclusion, we identified miR-423-5p and miR-128-3p in serum exosomes as noninvasive biomarkers for testicular injury in rats.

The signal transduction of xanthone as a protector on 2-methoxyethanol-induced cardiac cell damage in mice

This research aims at investigating the role of antioxidant of xanthone on 2-methoxyethanol (2-ME)-induced cardiac cell damage in mice. Forty mice were grouped into: (1) The control group (mice were given with distilled water), (2) the ME group (mice were given with 2-ME 200 mg/kg BW orally), and (3) the treatment group (mice were given of xanthone with doses 60 mg, 120 mg, 240 mg/kg BW orally and were also given 2-ME 200 mg/kg BW). Their blood samples were taken to measure the level of lactate dehydrogenase (LDH) and creatinine kinase-MB (CK-MB). Heart tissues were also taken to determine the malondialdehyde (MDA), histological findings of heart damage, and the immunohistochemical of the expression of superoxide dismutase (SOD) and glutathione peroxidase (GPx). The administration of 2-ME resulted in a significant increase level of the LDH, CK-MB, MDA, and a decrease in SOD and GPx expression were compared with the control group. The 2-ME also induced loss of the normal structure of heart cells and necrosis. However, treatment with the xanthone, only dose 240 mg/kg BW significantly decrease the level of LDH, CK-MB, MDA, and increase SOD, GPx expression. The xanthone 240 mg/kg BW also demonstrated significantly improved heart cell damage. From the results, it is concluded that the xanthone are a potent antioxidant in against 2-ME-induced cardiac toxicity in mice, through increasing SOD and GPx expression, and also inhibiting LDH, CK-MB and MDA.