Vitamin E and vitamin C attenuate Di-(2-ethylhexyl) phthalate-induced blood-testis barrier disruption by p38 MAPK in immature SD rats

Di-(2-ethylhexyl) phthalate exposure induces premature testicular senescence by disrupting mitochondrial respiratory chain through STAT5B-mitoSTAT3 in Leydig cell

Di-(2-ethylhexyl) phthalate (DEHP), a prevalent plasticizer, is known to have endocrine-disrupting effects on males and cause reproductive toxicity. There were causal effects of DEHP on testosterone levels in the real world by Mendelian randomization analysis. Exposure to DEHP during the preadult stage might lead to premature testicular senescence, but the mechanisms responsible for this have yet to be determined. In this study, we administered DEHP (300 mg/kg/day) to male C57BL/6 mice from postnatal days 21 to 49. The mice were kept for 6 months without DEHP. RNA sequencing was conducted on testicular tissue at PNM6. The results indicated that DEHP hindered testicular development, lowered serum testosterone levels in male mice, and induced premature testicular senescence. TM3 Leydig cells were exposed to 300 μM of mono(2-ethylhexyl) phthalate (MEHP), the bioactive metabolite of DEHP, for 72 h. The results also found that DEHP/MEHP induced senescence in vivo and in vitro. The mitochondrial respiratory chain was disrupted in Leydig cells. The expression and stability of STAT5B were elevated by MEHP treatment in TM3 cells. Furthermore, p-ERK1/2 was significantly decreased by STAT5B, and mitochondria-STAT3 (p-STAT3 ser727) was significantly decreased due to the decrease of p-ERK1/2. Additionally, the senescence level of TM3 cells was decreased and treated with 5 mM NAC for 1 h after MEHP treatment. In conclusion, these findings provided a novel mechanistic understanding of Leydig cells by disrupting the mitochondrial respiratory chain through STAT5B-mitoSTAT3.

The effects of fine particulate matter on the blood-testis barrier and its potential mechanisms

With the rapid expansion of industrial scale, an increasing number of fine particulate matter (PM2.5) has bringing health concerns. Although exposure to PM2.5 has been clearly associated with male reproductive toxicity, the exact mechanisms are still unclear. Recent studies demonstrated that exposure to PM2.5 can disturb spermatogenesis through destroying the blood-testis barrier (BTB), consisting of different junction types, containing tight junctions (TJs), gap junctions (GJs), ectoplasmic specialization (ES) and desmosomes. The BTB is one of the tightest blood-tissue barriers among mammals, which isolating germ cells from hazardous substances and immune cell infiltration during spermatogenesis. Therefore, once the BTB is destroyed, hazardous substances and immune cells will enter seminiferous tubule and cause adversely reproductive effects. In addition, PM2.5 also has shown to cause cells and tissues injury via inducing autophagy, inflammation, sex hormones disorder, and oxidative stress. However, the exact mechanisms of the disruption of the BTB, induced by PM2.5, are still unclear. It is suggested that more research is required to identify the potential mechanisms. In this review, we aim to understand the adverse effects on the BTB after exposure to PM2.5 and explore its potential mechanisms, which provides novel insight into accounting for PM2.5-induced BTB injury.

Influence of Ascorbic Acid on Di-(2-Ethylhexyl) Phthalate-induced Ovarian Gene Alterations in Pubertal Female Wistar Rats

Background

Di-(2-ethylhexyl) phthalate (DEHP), a plasticizer compound affecting female reproduction, leads to scenarios, such as polycystic ovarian syndrome (PCOS) and infertility through oxidative stress (OS) mechanisms. Ascorbic acid (AA) is one of the antioxidants in infertility issues.

Objectives

The present study investigates the ameliorative effect of AA on DEHP-induced ovarian toxicity in pubertal female Wistar rats.

Materials and Methods

Thirty female Wistar rats of four weeks of age were stratified into five groups. Group I was treated with corn oil (Vehicle), groups II and III with low and high dose DEHP, and groups IV and V with low and high dose DEHP+AA were administered for 30 days.

Results

Increased body weight gain was noted in DEHP groups. Estradiol hormone was considerably reduced, whereas progesterone levels were increased in both low- and high-dose DEHP-treated groups. DEHP+AA groups have shown significant ( p < 0.005) protection of these hormone levels as equal to the control group. The high-dose DEHP group shows an increased, ovarian estrogen receptor (ER) alpha, ER-beta, and progesterone receptor gene expression, and DEHP+AA groups have significantly ( p < 0.005) showed expression similar to the control. OS was noted with decreased superoxide dismutase and increased malondialdehyde expression in Group III (GR III) compared to control, whereas the DEHP+AA treated group significantly protected OS by restoring the expression levels. DEHP-treated groups show elevated levels of both Bcl-2 and BAX which is specific to apoptotic expression and restored by AA treatment ( p < 0.005).

Conclusion

Evidence suggests that AA may protect against DEHP-induced ovarian toxicity by decreasing OS levels, improving folliculogenesis, and restoring the hormonal with receptor level alterations.

Kiwifruit (Actinidia deliciosa) aqueous extract improves hyperglycemia, testicular inflammation, apoptosis, and tissue structure induced by Streptozotocin via oxidative stress inhibition

Diabetes mellitus (DM) is a well-known hyperglycemic metabolic condition identified by oxidative stress and biological function disruption. Kiwifruit is a valuable source of polyphenols and vitamin C with great antioxidant, nutritional, and health-promoting effects. Therefore, this study was initiated to explore the antioxidant and anti-hyperglycemic effects of kiwifruit aqueous extract (KFE) against oxidative injury and testis dysfunction in rats with diabetes. Twenty-four male Wistar Albino rats (160-170 g) were divided into four groups: Group 1 served as the control, Group 2 supplemented orally with kiwifruit extract (KFE; 1 g/kg/day) for one month, Group 3 was treated with a single streptozotocin dose (STZ; 50 mg/kg ip), and Group 4 where the diabetic rats were administered with KFE, respectively. According to the results, the GC-MS analysis of KFE revealed several main components with strong antioxidant properties. In diabetic rats, lipid peroxidation and hyperglycemia were accompanied by perturbations in hormone levels and sperm characteristics. Antioxidant enzymes, glutathione content, aminotransferase, phosphatase activities, and protein content were decreased. Furthermore, histology, immunohistochemical PCNA expression, and histochemical analysis of collagen, DNA, RNA, and total protein. were altered in rat testis sections, supporting the changes in biochemistry. Furthermore, diabetic rats supplemented with KFE manifested considerable amendment in all the tested parameters besides improved tissue structure and gene expressions (NF-kB, p53, IL-1β, Bax, IL-10, and Bcl2) relative to the diabetic group. In conclusion, KFE has beneficial effects as it can improve glucose levels and testis function, so it might be used as a complementary therapy in DM.

Recent advances in toxicological research of di-(2-ethylhexyl)-phthalate: Focus on endoplasmic reticulum stress pathway

The plasticizer di-(2-ethylhexyl)-phthalate (DEHP) is the most significant phthalate in production, usage, and environmental occurrence. DEHP is found in products such as personal care products, furniture materials, cosmetics, and medical devices. DEHP is noncovalently bind with plastic therefore, repeated uses lead to leaching out of it. Exposure to DEHP plasticizers leads to toxicity in essential organs of the body through various mechanisms. The main objective of this review article is to focus on the DEHP-induced endoplasmic reticulum (ER) stress pathway implicated in the testis, brain, lungs, kidney, heart, liver, and other organs. Not only ER stress, PPAR-related pathways, oxidative stress and inflammation, Ca2+ homeostasis disturbances in mitochondria are also identified as the relative mechanisms. ER is involved in various critical functions of the cell such as Protein synthesis, protein folding, calcium homeostasis, and lipid peroxidation but, DEHP exposure leads to augmentation of misfolded/unfolded protein. This review complies with various recently reported DEHP-induced toxicity studies and some pharmacological interventions that have been shown to be effective through ER stress pathway. DEHP exposure does assess health risks and vulnerability to populations across the globe. This study offers possible targets and approaches for addressing various DEHP-induced toxicity.

Di-(2-ethylhexyl) phthalate induces ferroptosis in prepubertal mouse testes via the lipid metabolism pathway

Di-(2-ethylhexyl) phthalate (DEHP), a widely used plasticizer, has been shown to cause reproductive toxicity, but the precise mechanism remains unclear. This study aimed to investigate the possible molecular mechanism of DEHP-induced testicular damage. In vivo study, we administered different doses of DEHP (0, 250, and 500 mg/kg/day) to male C57BL/6 mice from 22 and 35 days after birth. We found that DEHP exposure induced histopathological alterations in prepubertal testes, and testicular lipidomics indicated notable alterations in lipid metabolism and significant enrichment of ferroptosis. Further tests showed that ferrous iron (Fe2+ ) and malondialdehyde (MDA) levels significantly increased after DEHP exposure. Western blotting revealed that DEHP exposure reduced glutathione peroxidase 4 (GPX4) expression, and elevated acyl coenzyme A synthetase long-chain member 4 (ACSL4) and lysophosphatidylcholine acyltransferase 3 (LPCAT3) expression. The in vitro results were consistent with the in vivo results. When Leydig cells and Sertoli cells were treated with ferrostatin-1 and monoethylhexyl phthalate (MEHP), MEHP-induced increases in Fe2+ and MDA levels, accumulation of lipid reactive oxygen species, downregulation of GPX4, and upregulation of ACSL4 and LPCAT3 were reversed. Collectively, our findings suggested that aberrant lipid metabolism and ferroptosis may be involved in prepubertal DEHP exposure-induced testicular damage.

Novel insights into DEHP-induced zebrafish spleen damage: Cellular apoptosis, mitochondrial dysfunction, and innate immunity

DEHP (Di(2-ethylhexyl) phthalate) is the most abundant phthalate component detected in environmental samples as it is widely used in the manufacturing of children's toys, medical devices and furniture. Due to its wide prevalence and propensity to accumulate in the food chain, significant concerns have risen about the safety profile of DEHP. Here, we used a zebrafish model to investigate the toxicity mechanisms of DEHP. Our results indicated that exposure to DEHP altered the ROS content in zebrafish spleen and inhibited the activities of antioxidant enzymes SOD and CAT, detoxification enzyme GSH-Px and induced histopathological damage. In addition, elucidated the mechanism of DEHP significantly promoted apoptosis and caused damage in spleen cells through the bax/bcl-2 pathway. Further genetic testing demonstrated significant alterations in mitochondrial biogenesis, fission, and fusion-related genes and suggested potential mechanistic pathways, including GM10532/m6A/FIS1 axis, the STAT3/POA1 axis, and the NFR1/TFAM axis. Serological and genomic analysis indicated that DEHP exposure activated the C3 complement cascade immune pathway and interfered with innate immune function. IBRv2 analysis proposes that innate immunity may serve as a signal indicator of early toxic responses to DEHP pollutants. This study provided comprehensive cellular and genetic data for DEHP toxicity studies and emphasized the need for future management and remediation of DEHP contamination. It also provides data to specifically support the health risk assessments of DEHP, as well as contributing to broader health and environmental research.

Alleviating 3-MCPD-induced male reproductive toxicity: Mechanistic insights and resveratrol intervention

3-Monochloropropane-1, 2-diol (3-MCPD), a food-borne contaminant, is widely regarded as the primary cause of male infertility. At present, identifying a method to improve/reduce the male reproductive toxicity caused by 3-MCPD is important. In our study, we explored the potential application of resveratrol (RSV) in mitigating the adverse effects of 3-MCPD. Using 7-week-old Sprague-Dawley (SD) rats as animal models, we investigated the impacts and underlying mechanisms of 3-MCPD and RSV on reproductive function. The administration of 3-MCPD led to significant reductions in testicular and epididymal weights, as well as disruptions in spermatogenesis and histological abnormalities. However, co-treatment with RSV and 3-MCPD mitigated these adverse effects. In vitro study, RSV exhibited the ability to reverse the decline in Leydig and Sertoli cell populations inflicted by 3-MCPD treatment. Mechanistically, RSV reduced endoplasmic reticulum stress (PARP), inflammasome activation (NLRP3), and autophagy-mediated lysosome dysfunction (p62 and LC3BII) induced by 3-MCPD. In addition, 3-MCPD treatment increased the expression level of steroidogenesis-related proteins, steroidogenic acute regulatory (StAR) and CYP11A1, but RSV normalized StAR expression. Moreover, 3-MCPD-induced pro-inflammatory responses were counteracted by RSV treatment, with the cytokine reduction and modulation of CD206 expression, a marker of macrophage activation. These findings indicate that RSV attenuates 3-MCPD-induced reproductive toxicity, highlighting its application potential as an adjuvant agent for male reproductive health.

Fluorene-9-bisphenol exposure damages the testis in mice through a novel mechanism of ferroptosis

Fluorene-9-bisphenol (BHPF) is an emerging global endocrine-disrupting chemical found in numerous household products as a substitute of bisphenol A. Many studies have reported various toxicities associated with BHPF. However, the effect of BHPF on male reproduction, particularly on the structural integrity of the blood testis barrier (BTB) in mice, has not yet been extensively studied. Ferroptosis, a newly identified form of cell death, occurs in the testicular tissue following exposure to BPA, affecting male fertility. We investigated whether ferroptosis plays a role in BHPF-induced testicular damage. The findings indicated that BHPF exposure led decreases in serum testosterone (T) concentration and sperm concentration and motility in mice. Furthermore, BHPF disrupted the BTB by interfering with key BTB-related proteins, including Cx43, β-catenin, and ZO-1. Moreover, BHPF induced ferroptosis through the induction of lipid peroxidation, iron overload, oxidative stress, and mitochondrial dysfunction in the testicular tissue. Inhibition of ferroptosis using Fer-1 mitigated the BHPF-induced damage to the BTB and ferroptosis in TM4 cells. Overall, our findings indicated the detrimental effects of BHPF on male reproductive function in mice, suggesting ferroptosis as a mechanism underlying testicular damage.

Protective effects of melatonin on DEHP-induced apoptosis and oxidative stress in prepubertal testes via the PI3K/AKT pathway

Di(2-ethylhexyl) phthalate (DEHP), an environmental endocrine disruptor, is one of the most common plasticizers and is widely used in various plastic products. DEHP induces apoptosis and oxidative stress and has been shown to have androgenic toxicity. However, the methods to combat DEHP-induced testicular damage and the mechanisms involved remain to be elucidated. In the present study, we used melatonin, which has strong antioxidant properties, to intervene in prepubertal mice and mouse Leydig cells (TM3) treated with DEHP or its metabolite mono(2-ethylhexyl) phthalate (MEHP). The results showed that melatonin protected against DEHP-induced testicular damage in prepubertal mice, mainly by protecting against DEHP-induced structural destruction of the germinal tubules and by attenuating the DEHP-induced decrease in testicular organ coefficients and testosterone levels. Transcriptomic analysis found that melatonin may attenuate DEHP-induced oxidative stress and apoptosis in prepubertal testes. In vitro studies further revealed that MEHP induces oxidative stress injury and increases apoptosis in TM3 cells, while melatonin reversed this damage. In vitro studies also found that MEHP exposure inhibited the expression levels of molecules related to the PI3K/AKT signaling pathway, and melatonin reversed this change. In conclusion, these findings suggest that melatonin protects against DEHP-induced prepubertal testicular injury via the PI3K/AKT signaling pathway, and provide a theoretical basis and experimental rationale for combating male reproductive dysfunction.

PM 2.5 juvenile exposure-induced spermatogenesis dysfunction by triggering testes ferroptosis and antioxidative vitamins intervention in adult male rats

PM2.5 derived from automobile exhaust can cause reproductive impairment in adult males, but the toxic effects of PM2.5 exposure on reproductive function in juvenile male rats and its relationship with ferroptosis have not been reported. In this paper, 30-day-old juvenile male Sprague-Dawley (SD) rats were divided into four groups (blank control, vitamin control, PM2.5, and PM2.5+Vitamin). The blank control group was fed normally, and the vitamin control group was given intragastric administration of vitamins in addition to normal feeding. PM2.5 was administered via tracheal intubation. When the rats were treated for 4 weeks until reaching the period of sexual maturity. A mating test was performed first, and then their testicular and epididymal tissues were studied. Compared with control rats, juvenile male rats exposed to PM2.5 showed a decreased sperm count and fertility rate, redox imbalance, damaged mitochondria, a metabolic disorder of intracellular iron ions, and a significant rise in ferroptosis during the period of sexual maturity. After antioxidative vitamins intervention, the redox imbalance, metabolic disorder of intracellular iron ions, and ferroptosis were all alleviated, leading to the following conclusions: after being exposed to PM2.5 from automobile exhaust, male juvenile rats during the period of sexual maturity have significantly decreased reproductive function. The reproductive toxicity of PM2.5 is closely related to oxidative stress and ferroptosis. In addition, ferroptosis decreases and reproductive function is recovered to some degree after antioxidative vitamins intervention.

Prenatal DEHP Exposure Induces Premature Testicular Aging by Promoting Leydig Cell Senescence through the MAPK Signaling Pathways

Previous studies show that prenatal di-(2-ethylhexyl) phthalate (DEHP) exposure induces premature testicular aging. However, the evidence is weak, and the underlying mechanisms remain unclear. p38/extracellular signal-regulated kinase (ERK)/c-Jun NH(2)-terminal kinase (JNK) MAPK pathways participate in aging. Leydig cell (LC) senescence results in testicular aging. Whether prenatal DEHP exposure induces premature testicular aging by promoting LC senescence warrants further study. Here, male mice undergo prenatal exposure to 500 mg per kg per day DEHP, and TM3 LCs are treated with 200 µm mono (2-ethylhexyl) phthalate (MEHP). MAPK pathways, testicular toxicity, and senescent phenotypes (β-gal activity, p21, p16, and cell cycle) of male mice and LCs are explored. Prenatal DEHP exposure induces premature testicular aging in middle-aged mice (poor genital development, reduced testosterone synthesis, poor semen quality, increased β-gal activity, and upregulated expression of p21 and p16). MEHP induces LCs senescence (cell cycle arrest, increased β-gal activity, and upregulated expression of p21). p38 and JNK pathways are activated, and the ERK pathway is inactivated. In conclusion, prenatal DEHP exposure induces premature testicular aging by promoting LC senescence through MAPK signaling pathways.

Transcriptomic Analysis of the Developing Testis and Spermatogenesis in Qianbei Ma Goats

Reproductive competence in male mammals depends on testicular function. Testicular development and spermatogenesis in goats involve highly complex physiological processes. In this study, six testes were, respectively, obtained from each age group, immature (1 month), sexually mature (6 months) and physically mature (12 months old) Qianbei Ma goats. RNA-Seq was performed to assess testicular mRNA expression in Qianbei Ma goats at different developmental stages. Totally, 18 libraries were constructed to screen genes and pathways involved in testis development and spermatogenesis. Totally, 9724 upregulated and 4153 downregulated DEGs were found between immature (I) and sexually mature (S) samples; 7 upregulated and 3 downregulated DEGs were found between sexually mature (S) and physically mature (P) samples, and about 4% of the DEGs underwent alternative splicing events between I and S. Select genes were assessed by qRT-PCR, corroborating RNA-Seq findings. The detected genes have key roles in multiple developmental stages of goat testicular development and spermatogenesis. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed to determine differentially expressed genes (DEGs). GO analysis revealed DEGs between S and P contributed to "reproduction process", "channel activity" and "cell periphery part" between I and S, and in "ion transport process", "channel activity" and "transporter complex part". KEGG analysis suggested the involvement of "glycerolipid metabolism", "steroid hormone biosynthesis" and "MAPK signaling pathway" in testis development and spermatogenesis. Genes including IGF1, TGFB1, TGFBR1 and EGFR may control the development of the testis from immature to sexually mature, which might be important candidate genes for the development of goat testis. The current study provides novel insights into goat testicular development and spermatogenesis.

Arsenic interferes with spermatogenesis involving Rictor/mTORC2-mediated blood-testis barrier disruption in mice

Ingestion of arsenic interferes with spermatogenesis and increases the risk of male infertility, but the underlying mechanism remines unclear. In this study, we investigated spermatogenic injury with a focus on blood-testis barrier (BTB) disruption by administrating 5 mg/L and 15 mg/L arsenic orally to adult male mice for 60 d. Our results showed that arsenic exposure reduced sperm quality, altered testicular architecture, and impaired Sertoli cell junctions at the BTB. Analysis of BTB junctional proteins revealed that arsenic intake downregulated Claudin-11 expression and increased protein levels of β-catenin, N-cadherin, and Connexin-43. Aberrant localization of these membrane proteins was also observed in arsenic-treated mice. Meanwhile, arsenic exposure altered the components of Rictor/mTORC2 pathway in mouse testis, including inhibition of Rictor expression, reduced phosphorylation of protein kinase Cα (PKCα) and protein kinase B (PKB), and elevated matrix metalloproteinase-9 (MMP-9) levels. Furthermore, arsenic also induced testicular lipid peroxidative damage, inhibited antioxidant enzyme (T-SOD) activity, and caused glutathione (GSH) depletion. Our findings suggest that disruption of BTB integrity is one of the main factors responsible for the decline in sperm quality caused by arsenic. PKCα-mediated rearrangement of actin filaments and PKB/MMP-9-increased barrier permeability jointly contribute to arsenic-induced BTB disruption.

Probiotic cultures as a potential protective strategy against the toxicity of environmentally relevant chemicals: State-of-the-art knowledge

Environmentally relevant toxic substances may affect human health, provoking numerous harmful effects on central nervous, respiratory, cardiovascular, endocrine and reproductive system, and even cause various types of carcinoma. These substances, to which general population is constantly and simultaneously exposed, enter human body via food and water, but also by inhalation and dermal contact, while accumulating evidence suggests that probiotic cultures are able to efficiently adsorb and/or degrade them. Cell wall of probiotic bacteria/fungi, which contains structures such as exopolysaccharide, teichoic acid, protein and peptidoglycan components, is considered the main place of toxic substances adsorption. Moreover, probiotics are able to induce metabolism and degradation of various toxic substances, making them less toxic and more suitable for elimination. Other probable in vivo protective effects have also been suggested, including decreased intestinal absorption and increased excretion of toxic substances, prevented gut microbial dysbiosis, increase in the intestinal mucus secretion, decreased production of reactive oxygen species, reduction of inflammation, etc. Having all of this in mind, this review aims to summarize the state-of-the-art knowledge regarding the potential protective effects of different probiotic strains against environmentally relevant toxic substances (mycotoxins, polycyclic aromatic hydrocarbons, pesticides, perfluoroalkyl and polyfluoroalkyl substances, phthalates, bisphenol A and toxic metals).

Adverse cardiovascular effects and potential molecular mechanisms of DEHP and its metabolites-A review

Currently, cardiovascular disease (CVD) is a health hazard that is associated with progressive deterioration upon exposure to environmental pollutants. Di(2-ethylhexyl) phthalate (DEHP) has been one of the focuses of emerging concern due to its ubiquitous nature and its toxicity to the cardiovascular (CV) system. DEHP has been noted as a causative risk factor or a risk indicator for the initiation and augment of CVDs. DEHP represents a precursor that contributes to the pathogenesis of CVDs through its active metabolites, which mainly include mono (2-ethylhexyl) phthalate (MEHP). Herein, we systematically presented the association between DEHP and its metabolites and adverse CV outcomes and discussed the corresponding effects, underlying mechanisms and possibly interventions. Epidemiological and experimental evidence has suggested that DEHP and its metabolites have significant impacts on processes and factors involved in CVD, such as cardiac developmental toxicity, cardiac injury and apoptosis, cardiac arrhythmogenesis, cardiac metabolic disorders, vascular structural damage, atherogenesis, coronary heart disease and hypertension. DNA methylation, PPAR-related pathways, oxidative stress and inflammation, Ca²⁺ homeostasis disturbance may pinpoint the relevant mechanisms. The preventive and therapeutic measures are potentially related with P-glycoprotein, heat-shock proteins, some antioxidants, curcumin, apigenin, β-thujaplicin, glucagon-like peptide-1 receptor agonists and Ang-converting enzyme inhibitors and so on. Promisingly, future investigations should aid in thoroughly assessing the causal relationship and molecular interactions between CVD and DEHP and its metabolites and explore feasible prevention and treatment measures accordingly.

Perfluorooctanoic acid alternatives hexafluoropropylene oxides exert male reproductive toxicity by disrupting blood-testis barrier

As alternatives to perfluorooctanoic acid (PFOA), hexafluoropropylene oxide (HFPO) homologues, including hexafluoropropylene oxide dimer acid (HFPO-DA), hexafluoropropylene oxide trimer acid (HFPO-TA), and hexafluoropropylene oxide tetramer acid (HFPO-TeA), have attracted widespread attention recently due to their environmental ubiquity and high potential for bioaccumulation and toxicity. In the present study, a set of in vivo mouse and in vitro mouse testicular Sertoli TM4 cell experiments were employed to explore the male reproductive toxicity and underlying mechanisms of HFPO homologues on blood-testis barrier. Tissue and permeability analyses of mice testes after 28-day treatment with 5 mg/kg/day HFPO-DA or PFOA, or 0.05 mg/kg/day HFPO-TA or HFPO-TeA indicated that there was an increase in the degradation of TJ protein occludin in mice with a disrupted blood-testis barrier (BTB). Following exposure to 100 μM HFPO-DA, HFPO-TA or 10 μM PFOA, HFPO-TeA, transepithelial electrical resistance measurements of TM4 cells also indicated BTB disruption. Additionally, as a result of the exposure, matrix metalloproteinase-9 expression was enhanced through activation of p38 MAPK, which promoted the degradation of occludin. On the whole, the results indicated HFPO homologues and PFOA induced BTB disruption through upregulation of p-p38/p38 MAPK/MMP-9 pathway, which promoted the degradation of TJ protein occludin and caused the disruption of TJ.

The inhibition of CFTR in the descended testis of SD rats with unilateral cryptorchidism induced by di-(2-ethylhexyl) phthalate (DEHP)

Di-(2-ethylhexyl) phthalate (DEHP) is a kind of environmental endocrine disruptors (EEDs), which has been confirmed to cause serious consequences, such as cryptorchidism. Patients with unilateral cryptorchidism still had oligospermia or infertility even if they received orchidopexy before puberty. Testicular dysgenesis syndrome (TDS) attributes this kind of problems to the abnormal testicular development during the embryonic period, and considers that the environmental exposure factors during pregnancy play a major role. Therefore, for unilateral cryptorchidism, even if one testicle has dropped to scrotum, it may be exposed to these substances and cause damage. Cystic fibrosis transmembrane conduction regulator (CFTR) is very important for the maturation of male reproductive system. Previously, cryptorchidism was thought to cause abnormal expression of heat sensitive protein CFTR in testis, but the expression of CFTR in healthy side (descended side) testis was not clear. In this study, we established SD rats with unilateral cryptorchidism by exposure to DEHP (500 mg/kg/day) during pregnancy, and detected the expression of CFTR and downstream signal NF-κB/COX-2/PGE2 in bilateral testis. Finally, we found that the expression of CFTR and downstream signal NF-κB/COX-2/PGE2 in the undescended testis was significantly abnormal, but the expression of them in the descended testis was also abnormal to some extent. Therefore, we speculate that in addition to high temperature will affect the expression of CFTR, there may be other factors that cause abnormal expression of CFTR induced by DEHP, and lead to abnormal male reproductive function eventually, but the specific mechanism needs to be further studied.

Polystyrene nanoparticles enhance the adverse effects of di-(2-ethylhexyl) phthalate on male reproductive system in mice

Coexposure of nanoplastics (NPs) with other pollutants adsorbed from the surroundings has received extensive attention. Currently, the combined effects of NPs and plasticizers remain unclear. Di-(2-ethylhexyl) phthalate (DEHP) is a commonly used plasticizer that has raised much concern owing to its ubiquitous pollution and endocrine-disrupting potential. This study aimed to investigate the toxic effects on the male reproductive system upon coexposure to NPs and DEHP. The C57BL/6J mice were orally administrated with polystyrene nanoparticles (PSNPs), DEHP or both for 35 days to evaluate their effects on sperm quality, histology of testes and epididymides, testicular transcriptomic characteristics as well as expression of some important genes in the epididymides. The low-dose PSNPs used here did not induce significant changes in sperm quality, while DEHP alone or cotreatment with DEHP and PSNPs caused notable impairment, mainly manifesting as decreased sperm quality and aberrant structure of the testis and epididymis. Moreover, enhanced toxic effects were found in the cotreatment group when compared with the individual DEHP treatment group, as manifested by more obvious alterations in the sperm parameters as well as histological changes in the testis and epididymis. Testicular transcriptomic analysis revealed differential regulation of genes involved in immune response, cytoplasmic pattern recognition receptor signaling pathways, protein ubiquitination, oxidative stress, necrotic cell death, ATP synthesis and the cellular respiratory chain. RT-qPCR verified that the expression patterns of Cenpb, Crisp1 and Mars were changed in testes, and genes relevant to epididymal function including Aqp9 and Octn2 were downregulated in epididymides, particularly in the cotreatment group. Collectively, our results emphasize that DEHP at an environmentally relevant dose can induce male reproductive toxicity, and PSNPs may aggravate the toxic effects.

N6-methyladenosine modification on Hmbox1 is related to telomere dysfunction in DEHP-induced male reproductive injury

AIMS

Di (2-ethylhexyl) phthalate (DEHP), as an environmental endocrine-disrupting chemical (EDC), can induce male reproductive injury. N6-methyladenosine (m6A) plays a vital role in environmental exposure-induced diseases by regulating gene expression. Therefore, we aim to investigate the role of m6A in DEHP-induced reproductive injury.

MAIN METHODS

We established an in vivo model of mice exposed to DEHP to explore the effect of DEHP on reproductive injury and m6A. To further explore the molecular mechanism of DEHP toxicity, we built a model of GC-2 cells exposed to mono-(2-ethylhexyl) phthalate (MEHP) in vitro and further silenced Mettl3 in GC-2cells. Besides, we also conducted MeRIP-qPCR and RIP assays to identify the target genes for m6A modification.

KEY FINDINGS

DEHP induced testicular injury and senescence. And telomeres shortening, reduced levels of telomere repeat-binding factor 1 (TRF1), TRF2, protection of telomeres 1 (POT1), and telomerase reverse transcriptase (TERT) can be observed in DEHP-treated testes. MEHP also induced GC-2 cellular senescence and telomere dysfunction. Besides, increased m6A mediated by METTL3 stabilized homeobox containing 1 (Hmbox1) in an m6A-dependent manner in MEHP-exposed GC-2 cells. Mettl3 knockdown led to lower m6A modification and reduced Hmbox1 stability, resulting in further shortening of telomere length.

SIGNIFICANCE

our work uncovered that DEHP led to male reproductive injury by telomere dysfunction and m6A modified Hmbox1 contributed to maintaining telomere homeostasis in this process, suggesting that accurate regulation of m6A modification level by drugs has potential value in the treatment of DEHP-induced male reproductive injury.

Probing the Potential Mechanism of Quercetin and Kaempferol against Heat Stress-Induced Sertoli Cell Injury: Through Integrating Network Pharmacology and Experimental Validation

Quercetin and kaempferol are flavonoids widely present in fruits, vegetables, and medicinal plants. They have attracted much attention due to their antioxidant, anti-inflammatory, anticancer, antibacterial, and neuroprotective properties. As the guarantee cells in direct contact with germ cells, Sertoli cells exert the role of support, nutrition, and protection in spermatogenesis. In the current study, network pharmacology was used to explore the targets and signaling pathways of quercetin and kaempferol in treating spermatogenic disorders. In vitro experiments were integrated to verify the results of quercetin and kaempferol against heat stress-induced Sertoli cell injury. The online platform was used to analyze the GO biological pathway and KEGG pathway. The results of the network pharmacology showed that quercetin and kaempferol intervention in spermatogenesis disorders were mostly targeting the oxidative response to oxidative stress, the ROS metabolic process and the NFκB pathway. The results of the cell experiment showed that Quercetin and kaempferol can prevent the decline of cell viability induced by heat stress, reduce the expression levels of HSP70 and ROS in Sertoli cells, reduce p-NF-κB-p65 and p-IκB levels, up-regulate the expression of occludin, vimentin and F-actin in Sertoli cells, and protect cell structure. Our research is the first to demonstrate that quercetin and kaempferol may exert effects in resisting the injury of cell viability and structure under heat stress.

Bibliometric and visual analysis of blood-testis barrier research

Background: Extensive research on the blood-testis barrier has been undertaken in recent years. However, no systematic bibliometric study has been conducted on this subject. Our research aimed to identify the hotspots and frontiers of blood-testis barrier research and to serve as a guide for future scientific research and decision-making in the field.

Methods: Studies on the blood-testis barrier were found in the Web of Science Core Collection. VOSviewer, CiteSpace, and Microsoft Excel were used to conduct the bibliometric and visual analyses.

Results: We found 942 blood-testis barrier studies published in English between 1992 and 2022. The number of annual publications and citations increased significantly between 2011 and 2022, notably in the United States. China and the United States, the US Population Council, Endocrinology, and Cheng C. Yan were the most productive countries, institution, journal, and author, respectively. The study keywords indicated that blood-testis barrier research involves a variety of compositional features (tight junctions, cytoskeleton, adherens junctions), cell types (Sertoli cells, germ cells, Leydig cells, stem cells), reproductive toxicity (cadmium, nanoparticles, bisphenol-a), and relevant mechanisms (spermatogenesis, apoptosis, oxidative stress, dynamics, inflammation, immune privilege).

Conclusion: The composition and molecular processes of the blood-testis barrier as well as the blood-testis barrier in male infertility patients are the primary research hotspots in this field. In addition, future research will likely focus on treatment and the development of novel medications that target signal pathways in oxidative stress and apoptosis to preserve the blood-testis barrier. Further studies must extend to clinical diagnosis and therapy.

DEHP induces ferroptosis in testes via p38α-lipid ROS circulation and destroys the BTB integrity

Exposure to Di (2-ethylhexyl) phthalate (DEHP) has been associated with toxic effects of the reproductive system. However, the exact mechanism remains to be elucidated. In this study we explored the testicular toxicity induced by DEHP, and the probable molecular mechanism in the process. In vivo, the results demonstrated that DEHP affected testosterone levels and blood-testosterone barrier (BTB) integrity and caused ferroptosis. We further demonstrated that DEHP up-regulated the expression of p38α, p-p38α, p53, p-p53, SAT1, ALOX15. This view has also been confirmed in TM4 cells. After pre-treatment with fer-1 or si-MAPK14, the expression of either p53, p-p53, SAT1 and ALOX15 up-regulated by MEHP was inhibited in vitro. Interestingly, p38α can prevent the accumulation of lipid ROS, and the production of lipid ROS in turn promoted the expression of p38α, thus forming a feedback loop during the ferroptosis. In this process, a vicious cycle consisting of p38α, p53, SAT1, ALOX15, lipid ROS was involved. This study provides new mechanistic insights into DEHP-induced toxicity of the reproductive system.

Di-(2-ethylhexyl) phthalate exposure leads to ferroptosis via the HIF-1α/HO-1 signaling pathway in mouse testes

Di-(2-ethylhexyl) phthalate (DEHP) is an extensively used plasticizer and has been shown to cause reproductive dysfunction in humans and model animals. However, the exact mechanisms of testicular injury induced by DEHP exposure have not been fully clarified. Using gas chromatography-mass spectrometry, we found that mono-2-ethylhexyl ester (MEHP, a major biometabolite of DEHP) and DEHP concentrations were elevated in mouse serum after DEHP exposure. Using RNA-seq, we found that ferroptosis and HIF-1 signaling pathways might be involved in testicular injury due to prepubertal DEHP exposure. Subsequent Western blotting, ferrous iron and MDA measurements, and immunofluorescence of testicular sections verified the RNA-seq findings. Consistently, based on the RNA-seq findings, we found that ferroptosis and HIF-1 signaling pathways might play crucial roles in Leydig and Sertoli cell injury due to MEHP exposure in vitro. Further experiments also confirmed ferroptosis in Leydig and Sertoli cells. Using Western blotting, cellular immunofluorescence and ChIP-qPCR, we found that MEHP exposure caused HIF-1α accumulation and stabilization, resulted in HIF-1α translocation into the nucleus, and induced HIF-1α/Hmox1 binding in Leydig and Sertoli cells. To clarify whether HIF-1α plays a pivotal role in MEHP-induced ferroptosis, we knocked out Hif-1α using the CRISPR/Cas9 technique. We found that Hif-1α knockout rescued MEHP-induced ferroptosis. In summary, our findings certified that prepubertal DEHP exposure led to ferroptosis in mouse testes via the HIF-1α/HO-1 signaling pathway.

Multiple transcriptomic profiling: potential novel metabolism-related genes predict prepubertal testis damage caused by DEHP exposure

The toxic effect of di(2-ethylhexyl) phthalate (DEHP) on prepubertal testes was examined in this study. We treated 3-week-old male mice with 4.8 mg/kg/day (milligram/kilogram/day) (no observed adverse effect level), 30 mg/kg/day (high exposure dose relative to humans), 100 mg/kg/day (level causing a reproductive system disorder), and 500 mg/kg/day (dose causing a multigenerational reproductive system disorder) of DEHP via gavage. Obvious abnormalities in the testicular organ coefficient, spermatogenic epithelium, and testosterone levels occurred in the 500 mg/kg DEHP group. Ribonucleic acid sequencing (RNA-seq) showed that differentially expressed genes (DEGs) in each group could enrich reproduction and reproductive process terms according to the gene ontology (GO) results, and coenrichment of metabolism pathway was observed by the Reactome pathway analysis. Through the analysis of common genes in the metabolism pathway, we discovered that DEHP exposure at 4.8 to 500 mg/kg or 100 mg/kg caused the same damages to the prepubertal testis. In general, we identified two key transcriptional biomarkers (fatty acid binding protein 3 (Fabp3) and carboxylesterase (Ces) 1d), which provided new insight into the gene regulatory mechanism associated with DEHP exposure and will contribute to the prediction and diagnosis of prepuberty testis injury caused by DEHP.

The relationship between exposure to phthalate metabolites and adult-onset hypogonadism

OBJECTIVE

Adult-onset hypogonadism (AOH) is a common disease for males >40 years old and is closely associated with age-related comorbidities. Phthalates are compounds widely used in a number of products with endocrine-disrupting effects. However, little is known about the association between exposure to phthalates and the risk of AOH. Thus, we conducted this study to explore the potential association using the 2013-2016 National Health and Nutrition Examination Survey (NHANES) data.

METHOD

Data on AOH and urinary phthalate metabolites were collected, and univariable and multivariable logistic regression analyses were adapted to evaluate the association. The concentrations of each metabolite were calculated and grouped according to their quartiles for the final analysis.

RESULT

Finally, we found that the odds ratio (OR) increased with increased concentrations of di-(2-ethylhexyl) phthalate (DEHP) metabolites, including mono(2-ethyl-5-carboxypentyl) phthalate (MECPP), mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) and mono(2-ethyl-5-oxohexyl) phthalate (MEOHP). Simultaneously, a significant dose-dependent effect was also observed. The OR for the fourth quartile was highest among all three groups. Specifically, the ORs for the third quartile and fourth quartile were 1.774 and 1.858, respectively, in the MECPP group. For the MEHHP group, the OR increased from 1.580 for the second quartile to 1.814 for the fourth quartile. Similarly, the OR for the higher three quartiles varied from 1.424 to 1.715 in the MEOHP group.

CONCLUSION

This study first revealed that there was a positive association between exposure to DEHP metabolites and the risk of AOH. These findings add limited evidence to study this topic, while further studies are needed to explain the potential molecular mechanisms.

Exposure to DEHP induces testis toxicity and injury through the ROS/mTOR/NLRP3 signaling pathway in immature rats

As the most abundantly used phthalate derivative, di-(2-ethylhexyl) phthalate (DEHP) leads to reproductive disorders, especially in males. Testicular injury can be triggered when the testis is exposed to DEHP during the immature stage. However, the potential mechanism is largely unclear. In the present study, Sprague-Dawley rats were exposed to 0, 250 and 500 mg/kg/day DEHP from postnatal day (PND) 20 to PND 30. The spermatogonia cell line GC-1 and spermatocyte cell line GC-2 were exposed to different doses of monoethylhexyl phthalate (MEHP), a metabolite of DEHP. Testicular injury was observed. Oxidative stress was evaluated both in vivo and in vitro. Our results showed that after DEHP exposure, the testicular structure was damaged and spermatogenesis was disturbed. We also found that oxidative stress was increased, as indicated by the upregulation of the important factors in the antioxidant pathway. Furthermore, the expression of autophagy-related proteins was significantly downregulated. Autophagy inhibition led to activation of the pyroptosis pathway. Nucleotide-binding and oligomerisation (NOD) domain-like receptor (NLR) family pyrin domain (PYD)-containing 3 (NLRP3), Caspase-1 and cytokine interleukin-1β (IL-1β) were significantly upregulated. Additionally, an imbalance in self-renewal and differentiation was observed in germ cells after DEHP exposure, causing the cessation of germ cell development. In summary, these data suggest that DEHP exposure enhances oxidative stress, downregulates autophagy, induces NLRP3 inflammasome activation and subsequently triggers pyroptosis in vivo and in vitro, which provides novel insight into DEHP-related injury in immature testes in the context of pyroptosis.

Weighted gene coexpression network analysis reveals ESR1, FLNA and Furin as hub genes for DEHP-induced prepubertal testicular injury

Di-(2-ethylhexyl) phthalate (DEHP) is an environmental endocrine disruptor that accumulates in organisms in various ways and induces male reproductive system disorders. In this study, we established a testicular injury model by gavage with different concentrations of DEHP. The testes were then collected for RNA sequencing (RNA-seq), and the results were analyzed by bioinformatics and verified by experiments. Our research results show that different concentrations of DEHP interfere with testicular development differently. Weighted gene coexpression network analysis (WGCNA) generated sixteen modules and identified the turquoise module as key. Then, estrogen receptor 1 (ESR1), filamin A (Flna) and Furin were identified as hub genes. qPCR and immunohistochemistry results revealed that all three hub genes were upregulated. We detected the locations of these genes by immunohistochemistry. ESR1 was mainly located in Leydig cells; Flna immunostaining is observed in the Leydig and some germ cells and Furin staining was seen in almost all types of testicular cells. Furthermore, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses showed enrichment mainly in MAPK signaling pathways, p53 signaling pathways, HIF-1 signaling pathways, protein processing in the endoplasmic reticulum, apoptosis, the cell cycle, RNA degradation, etc. This is the first study using WGCNA to investigate the mechanism of DEHP-induced injury in the prepubertal testis, providing new research angles to further understand the mechanism of DEHP-induced injury in the prepubertal testis.

Vitamin E Supplementation Enhances Lipid Oxidative Stability via Increasing Vitamin E Retention, Rather Than Gene Expression of MAPK-Nrf2 Signaling Pathway in Muscles of Broilers

Dietary vitamin E (VE) supplementation is a method to produce VE-enriched meat and improve meat lipid oxidative stability. We aimed to study the effect of the VE supplementation duration on meat lipid oxidative stability, VE retention, and antioxidant enzymes’ activity, and explore its relationship with the mitogen-activated protein kinases (MAPK)-nuclear factor-erythroid 2-related factor 2 (Nrf2) signaling pathway in broilers slaughtered after electrical stunning. A total of 240 male 18-day-old Arbor Acres Plus broilers were distributed to four treatments, with six replicates in each treatment, and ten broilers per replicate. Broilers were fed with a basal diet (no supplementation of VE) or VE diet (200 IU/kg VE, DL-α- tocopherol) for one (W1), two (W2), or three (W3) weeks before electrical stunning (130 mA, 60 Hz, for 1s) and slaughter. The VE retention was positively and linearly affected (p < 0.01) by the VE feeding duration at one to three weeks before slaughter, and negatively (all p < 0.01) related to the thiobarbituric acid reactive substance (TBARS) content in both breast and thigh muscles at d 0, d 2, and d 6 postmortem. The VE retention was negatively (p < 0.05) related to the gene expression of c-Jun N-terminal kinases 1 (JNK1) and 2 (JNK2), Nrf2 in breast muscles, and JNK1 and p38 MAPK in thigh muscles. In conclusion, dietary vitamin E supplementation at 200 IU/kg for three weeks before electrical stunning and slaughter improved lipid oxidative stability via increasing VE retention, rather than the regulation by gene expression of the MAPK-Nrf2 signaling pathway in skeletal muscles of broilers.

DEHP-induced testicular injury through gene methylation pathway and the protective effect of soybean isoflavones in Sprague-Dawley rats

As one of the most important members of Phthalate esters (PAEs), di-(2-ethylhexyl) phthalate (DEHP) is widely used in plastics and known as a male reproductive toxicant. Many studies have shown that soybean isoflavones (SI) can rescue the testicular injury caused by DEHP, but the underlying mechanism is unknown. Because methylation is one of the most important mechanisms for maintaining normal biological functions, we studied whether methylation is involved in testicular injury induced by DEHP and whether SI could counter testicular impairment in peripubertal male Sprague Dawley rats. Compared with the control group, we found that the mRNA levels of testicular Sod2, Gpx1, and Igf-1 significantly decreased in the 900 mg/kg DEHP group (DEHP' group) (P < 0.01); however, in the DEHP + SI group, the mRNA levels of the genes obviously increased compared with the DEHP' group (P < 0.01). Simultaneously, the methylation level changes of testicular Sod2, Gpx1, and Igf-1 were similar to the mRNA levels (P < 0.01). Therefore, DEHP may affect testis and leydig cells via inducing methylation of Sod2, Gpx1, and Igf-1, and SI may rescue the impairments at the methylation level. In summary, SI is supposed to be used in DEHP-induced testicular injury treatment.

circBTBD7 Promotes Immature Porcine Sertoli Cell Growth through Modulating miR-24-3p/MAPK7 Axis to Inactivate p38 MAPK Signaling Pathway

Sertoli cells are the crucial coordinators to guarantee normal spermatogenesis and male fertility. Although circular RNAs (circRNAs) exhibit developmental-stage-specific expression in porcine testicular tissues and have been thought of as potential regulatory molecules in spermatogenesis, their functions and mechanisms of action remain largely unknown, especially in domestic animals. A novel circBTBD7 was identified from immature porcine Sertoli cells using reverse transcription PCR, Sanger sequencing, and fluorescence in situ hybridization assays. Functional assays illustrated that circBTBD7 overexpression promoted cell cycle progression and cell proliferation, as well as inhibited cell apoptosis in immature porcine Sertoli cells. Mechanistically, circBTBD7 acted as a sponge for the miR-24-3p and further facilitated its target mitogen-activated protein kinase 7 (MAPK7) gene. Overexpression of miR-24-3p impeded cell proliferation and induced cell apoptosis, which further attenuated the effects of circBTBD7 overexpression. siRNA-induced MAPK7 deficiency resulted in a similar effect to miR-24-3p overexpression, and further offset the effects of miR-24-3p inhibition. Both miR-24-3p overexpression and MAPK7 knockdown upregulated the p38 phosphorylation activity. The SB202190 induced the inhibition of p38 MAPK pathway and caused an opposite effect to that of miR-24-3p overexpression and MAPK7 knockdown. Collectively, circBTBD7 promotes immature porcine Sertoli cell growth through modulating the miR-24-3p/MAPK7 axis to inactivate the p38 MAPK signaling pathway. This study expanded our knowledge of noncoding RNAs in porcine normal spermatogenesis through deciding the fate of Sertoli cells.

Protective effects of curcumin against methotrexate-induced testicular damage in rats by suppression of the p38-MAPK and nuclear factor-kappa B pathways

Objective

The present study aimed to investigate the possibility that curcumin (CMN) protects against methotrexate (MTX)-induced testicular damage by affecting the phospho-p38 (p-p38) mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-κB) signaling pathways.

Methods

Eighteen male Wistar albino rats were randomly divided into three groups. The control group was given an intragastric administration of dimethyl sulfoxide (DMSO) daily for 14 days, the MTX group was given a single intraperitoneal dose of MTX (20 mg/kg) on the 11th day, and the MTX+CMN group was given intragastric CMN (100 mg/kg/day, dissolved in DMSO) for 14 days and a single intraperitoneal dose of MTX (20 mg/kg) on the 11th day. At the end of the experiment, all animals were sacrificed and the testicular tissues were removed for morphometry, histology, and immunohistochemistry. Body and testicular weights were measured.

Results

Body weights, seminiferous tubule diameter, and germinal epithelium height significantly decreased in the MTX group compared to the control group. Whereas, the number of histologically damaged seminiferous tubules and interstitial space width significantly increased in the MTX group. In addition, the number of p-p38 MAPK immunopositive cells and the immunoreactivity of NF-κB also increased in the MTX group compared to the control group. CMN improved loss of body weight, morphometric values, and histological damage due to MTX. CMN also reduced the number of p-p38 MAPK immunopositive cells and the NF-κB immunoreactivity.

Conclusion

CMN may reduce MTX-induced testicular damage by suppressing the p38 MAPK and NF-κB signaling pathways.

Multiple transcriptomic profiling: p53 signaling pathway is involved in DEHP-induced prepubertal testicular injury via promoting cell apoptosis and inhibiting cell proliferation of Leydig cells

Di(2-ethylhexyl) phthalate (DEHP) is a widely-used plasticizer and has long been recognized as an endocrine-disrupting chemical with male reproductive toxicities. DEHP exposure at the prepubertal stage may lead to extensive testicular injury. However, the underlying mechanisms remain to be elucidated. In the present study, we gavaged male C57BL/6 mice with different concentrations of DEHP (0, 250, and 500 mg/kg-bw·d) from postnatal day 22-35, and exposed TM3 Leydig cells with 0, 100, 200, 300, and 400 μM of MEHP (bioactive metabolite of DEHP) for 12-48 h. RNA sequencing was performed both in testicular tissue and TM3 cells. The results showed that DEHP disrupts testicular development and reduces serum testosterone levels in male prepubertal mice. Bioinformatic analysis and experimental verification have revealed that DEHP/MEHP induces cell cycle arrest in TM3 cells and increases apoptosis both in vivo and in vitro. Furthermore, the p53 signaling pathway was found to be activated upon DEHP/MEHP treatment. The inhibition of p53 by pifithrin-α significantly reduced MEHP-induced injuries in TM3 cells. Cumulatively, these findings revealed the involvement of the p53 signaling pathway in DEHP-induced prepubertal testicular injury by promoting cell apoptosis and inhibiting cell proliferation of Leydig cells.

The role of different compounds on the integrity of blood-testis barrier: A concise review based on in vitro and in vivo studies

Sertoli cells are "nurturing cells'' in the seminiferous tubules of the testis which have essential roles in the development, proliferation and differentiation of germ cells. These cells also divide the seminiferous epithelium into a basal and an adluminal compartment and establish the blood-testis barrier (BTB). BTB shields haploid germ cells from recognition by the innate immune system. Moreover, after translocation of germ cells into the adluminal compartment their nutritional source is separated from the circulatory system being only supplied by the Sertoli cells. The integrity of BTB is influenced by several organic/ organometallic, hormonal and inflammatory substances. Moreover, several environmental contaminants such as BPA have hazardous effects on the integrity of BTB. In the current review, we summarize the results of studies that assessed the impact of these agents on the integrity of BTB. These studies have implications in understanding the molecular mechanism of male infertility and also in the male contraception.

Increased m6A modification of RNA methylation related to the inhibition of demethylase FTO contributes to MEHP-induced Leydig cell injury☆

N⁶-methyladenosine (m6A) modification, the most prevalent form of RNA methylation, modulates gene expression post-transcriptionally. Di-(2-ethylhexyl) phthalate (DEHP) is a common environmental endocrine disrupting chemical that induces testicular injury due to the inhibition of the demethylase fat mass and obesity-associated protein (FTO) and increases the m6A modification. How FTO-mediated m6A modification in testicular Leydig cell injury induced by DEHP remains unclear. Here, the TM3 Leydig cell line was treated with mono-(2-ethylhexyl) phthalate (MEHP), the main metabolite of DEHP in the body, as well as FB23-2, an inhibitor of FTO. Decreased levels of testosterone in the culture supernatant, significantly increased apoptosis, and a remarkable upregulation of global m6A modification were found in both TM3 cells treated with MEHP and FB23-2. Transcriptome sequencing showed that both treatments significantly induced apoptosis-associated gene expression. Methylated RNA immunoprecipitation sequencing showed that the Leydig cell injury induced by upregulated m6A modification could be associated with multiple physiological disorders, including histone acetylation, reactive oxygen species biosynthesis, MAPK signaling pathway, hormone secretion regulation, autophagy regulation, and male gonadal development. Overall, the inhibition of FTO-mediated up-regulation of m6A could be involved in MEHP-induced Leydig cell apoptosis.

Omega-3 polyunsaturated fatty acids alleviate hydrogen sulfide-induced blood-testis barrier disruption in the testes of adult mice

Hydrogen sulfide (H₂S), a gaseous intracellular signal transducer, participates in multiple physiological and pathological conditions, including reproductive conditions, and disrupts spermatogenesis. The blood-testis barrier (BTB) plays a vital role in spermatogenesis. However, the effect of H₂S on the BTB and the underlying mechanism remain unclear. Herein, we examined the effect of H₂S and omega-3 polyunsaturated fatty acids (ω-3 PUFAs) on the BTB and testicular functions. ICR male mice were randomly divided into the following groups: control, H₂S exposure, and H₂S exposure with ω-3 PUFAs intervention. The sperm parameters (sperm concentration and sperm motility) declined in the H₂S group and improved in the ω-3 intervention group. BTB integrity was severely disrupted by H₂S, and the BTB-related gene levels (ZO-1, Occludin, Claudin 11) decreased; ω-3 supplementation could alleviate BTB disruption by upregulating BTB-related genes, and TM4 Sertoli cells had a similar trend in vitro. p38 MAPK phosphorylation was upregulated in the Na₂S treatment group and downregulated after ω-3 cotreatment. These findings suggest that H₂S can impair the BTB and that ω-3 PUFAs supplementation can attenuate H₂S toxicity in the male reproductive system. Our study elucidated the relationship between a gasotransmitter (H₂S) and the BTB and identified the potential therapeutic effect of ω-3 PUFAs.

The gut-microbiota-testis axis mediated by the activation of the Nrf2 antioxidant pathway is related to prepuberal steroidogenesis disorders induced by di-(2-ethylhexyl) phthalate

Di-(2-ethylhexyl) phthalate (DEHP) is a common plasticizer, which is known to be an environmental endocrine-disrupting chemical that can jeopardize the male reproductive system. Prepuberal exposure to DEHP leads to steroidogenesis disorders. However, the specific mechanism remains ambiguous. Therefore, Sprague Dawley (SD) rats underwent prepuberal DEHP exposure at a dose of 500 mg/kg per day through gavage. Additionally, the resulting testicular injury was evaluated to confirm the disturbed steroidogenesis. Changes in testicular histology, significant reduction of serum testosterone (P < 0.01) and luteinizing hormone (P < 0.001), and significantly decreased expressions of steroidogenic acute regulatory protein (P < 0.01) and 3-beta-hydroxysteroid dehydrogenase (P < 0.05) were found in DEHP-treated rats. DEHP exposure resulted in obvious intestinal damage and oxidative stress imbalance, primarily in the jejunum. Both the activation of the nuclear factor-E2-related factor 2 (Nrf2) signaling pathway and alterations of microbiota profiles were observed in all three gut specimens, but were most notable in the jejunum. We hypothesize that the gut-microbiota-testis axis, which is mediated by the activation of the Nrf2 antioxidant pathway, could be involved in the dysfunction of prepuberal steroidogenesis induced by DEHP.

Maternal Exposure to Di-n-butyl Phthalate Promotes the Formation of Testicular Tight Junctions through Downregulation of NF-κB/COX-2/PGE2/MMP-2 in Mouse Offspring

Previous studies demonstrated that maternal exposure to di-n-butyl phthalate (DBP) resulted in developmental disorder of the male reproductive organ; however, the underlying mechanism has not been thoroughly elucidated to date. The present study was aimed to investigate the effects of maternal exposure to DBP on the formation of the Sertoli cell (SC)-based tight junctions (TJs) in the testes of male offspring mice and the underlying molecular mechanism. By observing the pathological structure and ultrastructure, permeability analysis of the testis of 22 day male offspring in vivo, and transepithelial electrical resistance measurement of inter-SCs in vitro, we found that the formation of TJs between SCs in offspring mice was accelerated, which was paralleled by the accumulation of TJ protein occludin at 50 mg/kg/day DBP exposure in utero and 0.1 mM monobutyl phthalate (MBP, the active metabolite of DBP) in vitro. Our in vitro results demonstrated that 0.1 mM MBP downregulated the expression of matrix metalloproteinase-2 (MMP-2) by inhibiting the activation of nuclear factor-κB (NF-κB)/cyclooxygenase-2 (COX-2)/prostaglandin E2 (PGE₂) cascades via attenuated binding of NF-κB to both the MMP-2 promoter and COX-2 promoter. Taken together, the data confirmed that maternal exposure to a relatively low dose of DBP promoted the formation of testicular TJs through downregulation of NF-κB/COX-2/PGE₂/MMP-2, which might promote the development of the testis during puberty. Our findings may provide new perspectives for prenatal DBP exposure, which is a potential environmental contributor, leading to earlier puberty in male offspring mice.

Increased m6A RNA modification is related to the inhibition of the Nrf2-mediated antioxidant response in di-(2-ethylhexyl) phthalate-induced prepubertal testicular injury

Di-(2-ethylhexyl) phthalate (DEHP) is a common environmental endocrine disrupting chemical that may induce male reproductive disorders. Exposure to DEHP at a prepubertal stage could lead to prepubertal testicular injury, but the underlying mechanisms remain unclear. In this study, we exposed Sprague-Dawley rats to 0, 250, and 500 mg DEHP per kg body weight per day at the prepuberty stage from postnatal day 22 (PND 22) to PND 35 by oral gavage. Testicular injury and oxidative stress were evaluated, and the levels of 6-methyladenosine (m6A) modification and expression of modulator genes for RNA methylation were measured in testes. Furthermore, m6A modification of the important antioxidant transcription factor Nrf2 was analyzed using methylated RNA immunoprecipitation qPCR. Our results show that DEHP worsened testicular histology, decreased testosterone concentrations, downregulated expression of spermatogenesis inducers, enhanced oxidative stress, inhibited the Nrf2-mediated antioxidant pathway, and increased apoptosis in testes. Additionally, DEHP increased global levels of m6A RNA modification and altered the expression of two important RNA methylation modulator genes, FTO and YTHDC2. Moreover, m6A modification of Nrf2 mRNA increased upon DEHP exposure. Overall, these findings link oxidative stress imbalance with epigenetic effects of DEHP toxicity and provide insight into the testicular toxicity of DEHP from the new perspective of m6A modification.

Automobile exhaust-derived PM2.5 induces blood-testis barrier damage through ROS-MAPK-Nrf2 pathway in sertoli cells of rats

Particulate matter with an aerodynamic diameter of less than 2.5 μm (PM_2.5) derived from automobile exhaust can lead to serious male spermatogenesis dysfunction, but its specific molecular mechanism is unclear. In this experiment, we focused on the blood-testis barriers (BTB) and explored the intracellular mechanisms underlying the fertility toxicity of PM_2.5 originating from automobile exhaust in the primary cultured Sertoli cells(SCs) of rats. After PM_2.5 exposure, excessive reactive oxygen species (ROS) and increased apoptosis of SCs were detected. The expression of the BTB related proteins including ZO-1, Occludin, N-cadherin and β-catenin were significantly decreased and the spatial arrangement of F-actin was completely disordered through Immunofluorescence and Western blots tests. The phosphorylation of Jun N-terminal kinase (JNK), extracellular signal regulatory kinase (ERK), p38 mitogen-activated protein kinase (MAPK) were upregulated and nuclear factor (erythroid-derived 2) -like 2-related factor (Nrf2) was downregulated respectively. However, combined utilization of vitamin C and E were observed to prevent the increase of ROS generation, reduce celluar apoptosis, increase the expression of BTB related proteins, reconstructed the spatial arrangement of F-actin as well as improved the Nrf2 expression and attenuated the phosphorylation of the MAPK kinases and cleaved caspase-3 levels. Furthermore, ERK inhibitor (SCH772984), JNK inhibitor (SP600125) and p38 MAPK inhibitor (SB203580) obviously up-regulated BTB-related proteins expression as well as activated Nrf2 expression at varying degrees, indicating that ROS-MAPKs-Nrf2 is involved in the signaling pathway that leads to PM_2.5-induced spermatogenesis dysfunction. These findings indicate that PM_2.5 derived from automobile exhaust causes oxidative stress, which in turn causes cellular apoptosis of SCs and damage of the blood-testis barrier, resulting male spermatogenesis dysfunction, in which ROS-MAPK-Nrf-2 pathways may play a key role.

Maternal energy insufficiency affects testicular development of the offspring in a swine model

We determined the effects of insufficient maternal energy on testicular development in offspring in a swine model. Thirty-six sows were divided into control (CON) and low-energy diet (LE) groups during gestation. We observed that the number of Sertoli, germ, and Leydig cells in the offspring of the CON group were significantly higher than those in the LE group at 28 and 120 d after birth. Furthermore, the percentage of apoptotic testis cells was significantly higher in the offspring of the LE group than in the CON group. Transcriptome analysis of differentially expressed mRNAs and long noncoding RNAs in offspring testes indicated that these RNAs were mainly involved in lipid metabolism, apoptosis, cell proliferation, and some pivotal regulatory pathways. Results revealed that AMPK-PI3K-mTOR, MAPK, and oxidative phosphorylation signaling pathways play an important role in mediating the programming effect of insufficient maternal energy on testicular development, and that this effect occurs mainly at an early stage in life. mRNA and protein expression analyses confirmed the importance of certain signaling pathways in the regulation of testicular development. This study provides insights into the influence and possible mechanism underlying the effect of inadequate maternal energy intake on testicular development in the offspring.

Protective effects of betaine on diabetic induced disruption of the male mice blood-testis barrier by regulating oxidative stress-mediated p38 MAPK pathways

BACKGROUND

Blood-testis barrier (BTB) impairments is one of the major secondary complications of diabetes. Betaine (BET) is the important active ingredients isolated from Lycium barbarum, which exhibits numerous pharmacological activities such as antioxidant, anti-diabetic, and anti-inflammatory effects. This study aimed to establish whether BET contributes to the recovery from BTB dysfunction in streptozotocin (STZ) induced diabetic mice.

METHODS

BET (200, 400, 800 mg/kg) was orally administered to diabetic mice for 8 weeks. Testis tissues were collected for histopathological and biochemical analysis, the reproductive organ weight was estimated. Antioxidant enzyme activity and BTB associated protein expressions were determined with their corresponding assay kits and western blot analysis. The results revealed that BET significantly improved the weight of the reproductive organs and testicular morphology in diabetic mice. Furthermore, reactive oxygen species (ROS) and malondialdehyde (MDA) levels were significantly reduced, and the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH), markedly increased in the testicular tissue after SAL treatment. In addition, our data also showed a marked down-regulated the expressions of p38 MAPK phosphorylation and up-regulation the protein expressions of ZO-1, Occludin, Claudin-11, N-cadherin, and Connexin-43 after BET administration compared with the diabetic group. In conclusion, these results demonstrated that BET exerts protective effects on diabetes-induced BTB dysfunction, which may be through regulating oxidative stress-mediated p38 MAPK pathways.

Multiple signaling pathways in Sertoli cells: recent findings in spermatogenesis

The functions of Sertoli cells in spermatogenesis have attracted much more attention recently. Normal spermatogenesis depends on Sertoli cells, mainly due to their influence on nutrient supply, maintenance of cell junctions, and support for germ cells' mitosis and meiosis. Accumulating evidence in the past decade has highlighted the dominant functions of the MAPK, AMPK, and TGF-β/Smad signaling pathways during spermatogenesis. Among these pathways, the MAPK signaling pathway regulates dynamics of tight junctions and adherens junctions, proliferation and meiosis of germ cells, proliferation and lactate production of Sertoli cells; the AMPK and the TGF-β/Smad signaling pathways both affect dynamics of tight junctions and adherens junctions, as well as the proliferation of Sertoli cells. The AMPK signaling pathway also regulates lactate supply. These signaling pathways combine to form a complex regulatory network for spermatogenesis. In testicular tumors or infertile patients, the activities of these signaling pathways in Sertoli cells are abnormal. Clarifying the mechanisms of signaling pathways in Sertoli cells on spermatogenesis provides new insights into the physiological functions of Sertoli cells in male reproduction, and also serves as a pre-requisite to identify potential therapeutic targets in abnormal spermatogenesis including testicular tumor and male infertility.