Perfluorododecanoic Acid Blocks Rat Leydig Cell Development during Prepuberty

Deoxynivalenol Inhibits Progenitor Leydig Cell Development by Stimulating Mitochondrial Fission in Rats

Deoxynivalenol (DON) is a common food contaminant that can impair male reproductive function. This study investigated the effects and mechanisms of DON exposure on progenitor Leydig cell (PLC) development in prepubertal male rats. Rats were orally administrated DON (0-4 mg/kg) from postnatal days 21-28. DON increased PLC proliferation but inhibited PLC maturation and function, including reducing testosterone levels and downregulating biomarkers like HSD11B1 and INSL3 at ≥2 mg/kg. DON also stimulated mitochondrial fission via upregulating DRP1 and FIS1 protein levels and increased oxidative stress by reducing antioxidant capacity (including NRF2, SOD1, SOD2, and CAT) in PLCs in vivo. In vitro, DON (2-4 μM) inhibited PLC androgen biosynthesis, increased reactive oxygen species production and protein levels of DRP1, FIS1, MFF, and pAMPK, decreased mitochondrial membrane potential and MFN1 protein levels, and caused mitochondrial fragmentation. The mitochondrial fission inhibitor mdivi-1 attenuated DON-induced impairments in PLCs. DON inhibited PLC steroidogenesis, increased oxidative stress, perturbed mitochondrial homeostasis, and impaired maturation. In conclusion, DON disrupts PLC development in prepubertal rats by stimulating mitochondrial fission.

Threats of per- and poly-fluoroalkyl pollutants to susceptible populations

Environmental exposure to per- and poly-fluoroalkyl substances (PFAS) has raised significant global health concerns due to potential hazards in healthy adults. However, the impact of PFAS on susceptible populations, including pregnant individuals, newborns, the older people, and those with underlying health conditions, has been overlooked. These susceptible groups often have physiological changes that make them less resilient to the same exposures. Consequently, there is an urgent need for a comprehensive understanding of the health risks posed by PFAS exposure to these populations. In this review, we delve into the potential health risks of PFAS exposure in these susceptible populations. Equally important, we also examine and discuss the molecular mechanisms that underlie this susceptibility. These mechanisms include the induction of oxidative stress, disruption of the immune system, impairment of cellular metabolism, and alterations in gut microbiota, all of which contribute to the enhanced toxicity of PFAS in susceptible populations. Finally, we address the primary research challenges and unresolved issues that require further investigation. This discussion aims to foster research for a better understanding of how PFAS affect susceptible populations and to pave the way for strategies to minimize their adverse effects.

Perfluorooctanoic acid inhibits androgen biosynthesis in rat immature Leydig cells

Perfluorooctanoic acid (PFOA) is a commonly used short-chain synthetic perfluoroalkyl agent. Immature Leydig cells (ILCs) are localized in the testis and responsible for androgen biosynthesis and metabolism. Although PFOA shows toxicity in the reproductive system, it is not clear if it disrupts the function of ILCs. In the present study, primary ILCs were isolated from 35-day-old rats and exposed to a range of PFOA concentrations (0, 0.01, 0.1, or 1 μM). It was determined that 0.1 or 1 μM PFOA reduced total androgen biosynthesis in ILCs. Specifically, 22R-hydroxycholesterol (22R), and pregnenolone (P5) mediated androgen biosynthesis were reduced by 0.1 μM PFOA. PFOA also selectively downregulated mRNA and protein expressions of steroidogenic enzymes including LHCGR, CYP11A1, 3β-HSD1, and NR5A1 at 0.01, 0.1, or 1 μM. Further analysis revealed that 0.1 μM PFOA inhibited CYP11A1 and 3β-HSD1 enzyme activities. However, PFOA did not significantly affect androgen metabolism and turnover under any of the conditions tested. And PFOA gavaging to 35-day-old rats at 5 or 10 mg/kg for 7 or 14 days also reduced serum androgen levels secreted by ILCs. Moreover, PFOA gavaging also downregulated the mRNA and protein expression levels of LHCGR, CYP11A1, 3β-HSD1, and NR5A1 in vivo. Taken together, these findings suggest that PFOA inhibits androgen biosynthesis in ILCs by selectively targeting key enzymes in the synthesis pathway.

Effects of perfluorododecanoic acid on testicular function in mice

Perfluorodecanoic acid (PFDoA) is a widely distributed environmental pollutant that can affect the functions of many organs. However, systematic evaluations of the effects of PFDoA on testicular functions are lacking. The aim of this study was to investigate the effects of PFDoA on mouse testicular functions, including spermatogenesis, testosterone synthesis, and stem Leydig cells (SLCs) in the interstitial tissue of the testis. PFDoA (0, 2, 5, 10 mg/kg/d) was administered via gavage to 2-month-old mice for 4 weeks. Serum hormone levels and sperm quality were assayed. Furthermore, to investigate the mechanisms by which PFDoA affects testosterone synthesis and spermatogenesis in vivo, the expression of StAR and P450scc in testicular tissue was measured by immunofluorescence staining and quantitative real-time PCR. In addition, the levels of SLC markers, including nestin and CD51, were studied. PFDoA decreased the luteinizing hormone concentration and sperm quality. Although the difference was not statistically significant, mean testosterone levels showed a downward trend. The expression of StAR, P450scc, CD51, and nestin was also suppressed in the PFDoA-treated groups compared with the control group. Our study suggested that PFDoA exposure can decrease testosterone biosynthesis, and even reduce the number of SLCs. These results indicated that PFDoA suppressed the main functions of testis, and further researches are required to identify strategies for preventing or reducing the effect of PFDoA on testicular function.

Leydig cell development in pubertal male rats is blocked by perfluorotetradecanoic acid through decreasing AMPK-mTOR-autophagy pathway

Perfluorotetradecanoic acid (PFTeDA) is a type of perfluoroalkyl acid that has been linked to various health effects in animals and humans. The study aimed to investigate the potential impact of PFTeDA exposure on Leydig cell development in rats during puberty. Understanding the effects of PFTeDA on Leydig cells is crucial as these cells play a significant role in male reproductive function. Male Sprague-Dawley rats were gavaged with PFTeDA at doses of 0, 1, 5, and 10mg/kg/day from postnatal day 35 to 56. The serum hormone levels were measured and testicular transcriptome changes were analyzed by RNA-seq and verified by qPCR, and the levels of steroidogenesis-related proteins and energy regulators were measured. PFTeDA significantly reduced serum testosterone levels while slightly increasing LH levels. RNA-seq and qPCR analysis showed that genes responsive to oxidative phosphorylation (Naufa1 and Ndufs6) and steroidogenesis (Ldlr, Star, Cyp11a1) were markedly downregulated at ≥5mg/kg, while those related to ferroptosis (Alox15) and cell senescence (Map2k3 and RT1-CE3) were significantly upregulated. PFTeDA markedly reduced SIRT1 (silent information regulator 1) /PGC-1α (peroxisome proliferator-activated receptor gamma coactivator-1α) and AMPKA (AMP activated kinase A), LC3B and Beclin1 (biomarkers for autophagy) levels while increasing phosphorylated mTOR. In vitro treatment of PFTeDA at 5 μM significantly reduced androgen output of Leydig cells from 35-day-old male rats while ferrostatin 1 (10 μM) reversed PFTeDA-mediated inhibition. In conclusion, the inhibitory effects of PFTeDA on pubertal rat Leydig cell development are possibly regulated by inducing ferroptosis thereby downregulating SIRT1/AMPKA/ autophagy pathways, eventually resulting in reduced steroidogenesis.

Effects of Bushen Yiyuan recipe on testosterone synthesis in Leydig cells of rats with exercise-induced low serum testosterone levels

CONTEXT

Bushen Yiyuan recipe (BYR) is an effective Chinese prescription with antifatigue and antioxidation effects.

OBJECTIVE

The effects of BYR on testosterone synthesis in rat Leydig cells with exercise-induced low serum testosterone levels (EILST) are assessed.

MATERIALS AND METHODS

Thirty-two Sprague-Dawley rats were chronically trained for 6 weeks to establish an EILST model. EILST rats were divided into model (physiological saline), EFE (700 mg/kg ethanol extract of Epimedii folium, the dried leaves of Epimedium brevicornu Maxim [Berberidaceae]), and BYR groups (350 and 700 mg/kg) for 6 weeks. Expression of HMG-CoA, LDL-R, SR-BI, STAR and CYP11A1 were quantified by RT qPCR and Western blots.

RESULTS

Compared with the model group (115.52 ± 13.05 μg/dL; 67.83 ± 14.29; 0.32 ± 0.04; 0.33 ± 0.02; 0.38 ± 0.01), serum testosterone, testosterone/cortisol ratio, HMG-CoA, STAR and CYP11A1 relative protein expression significantly increased in low-dose BYR (210.60 ± 5.08 μg/dL; 119.38 ± 13.02; 0.47 ± 0.01; 0.46 ± 0.03; 0.46 ± 0.02), high-dose BYR (220.57 ± 14.71 μg/dL; 124.26 ± 14.79; 0.49 ± 0.02; 0.42 ± 0.03; 0.51 ± 0.02), and EFE groups (206.83 ± 5.54 μg/dL; 119.53 ± 25.04; 0.45 ± 0.02; 0.42 ± 0.02; 0.41 ± 0.02) (all p < 0.01, except for CYP11A1 in EFE group). HMG-CoA, STAR and CYP11A1 mRNA relative expression significantly increased in low-dose and high-dose BYR group compared to model group (all p < 0.01).

CONCLUSIONS

BYR affects endogenous cholesterol synthesis and testosterone synthesis to prevent and treat EILST levels in rats. It can improve the body's sports ability.

Effects of bis (2-butoxyethyl) phthalate on adrenocortical function in male rats in puberty partially via down-regulating NR5A1/NR4A1/NR4A2 pathways

Phthalates may interfere with the biosynthesis of steroid hormones in the adrenal cortex. Bis (2-butoxyethyl) phthalate (BBOP) is a phthalate containing oxygen atoms in the alcohol moiety. In this study, 35-day-old male Sprague-Dawley rats were daily gavaged with BBOP (0, 10, 100, 250, and 500 mg/kg body weight) for 21 days. BBOP did not affect the weight of body and adrenal glands. BBOP significantly reduced serum corticosterone levels at 250 and 500 mg/kg, and lowered aldosterone level at 500 mg/kg without affecting adrenocorticotropic hormone. BBOP did not alter the thickness of the adrenal cortex. BBOP significantly down-regulated the expression of steroidogenesis-related genes (Scarb1, Star, Cyp11a1, Cyp21, Cyp11b1, Cyp11b2, Nr5a1, Nr4a1, and Nr4a2) and proteins, and antioxidant enzymes (Sod1, Sod2, Gpx1, and Cat) and their proteins, while up-regulating the expression of Mc2r and Agtr1a at various doses. BBOP reduced the phosphorylation of AKT1, AKT2, and ERK1/2, as well as the levels of SIRT1 and PGC1α without affecting the phosphorylation of AMPK. BBOP significantly induced the production of reactive oxygen species and apoptosis rate in H295R cells at 100 μM and higher after 24 h of treatment. In conclusion, male rats exposed to BBOP in puberty have significant reduction of steroid biosynthesis with a potential mechanism that is involved in the decrease in the phosphorylation of AKT1, AKT2, ERK1/2, as well as SIRT1 and PGC1α and increase in ROS.

Dimethylbisphenol A inhibits the differentiation of stem Leydig cells in adult male rats by androgen receptor (NR3C4) antagonism

Dimethylbisphenol A (DMBPA) is a novel alternative to bisphenol A. Whether short-term exposure to DMBPA affects Leydig cell regeneration remains unknown. The Leydig cell regeneration model was generated by intraperitoneal injection of 75 mg/kg ethane dimethane sulfonate (EDS) to adult male Sprague-Dawley rats. Leydig cell regeneration began on day 14 after EDS. Rats were gavaged with 0, 10, 50, or 200 mg/kg DMBPA from days 14-28 post-EDS, and Leydig cell regeneration was assessed on days 28 and 56 post-EDS. DMBPA significantly reduced serum testosterone levels on days 28 and 56 at 10 mg/kg and higher doses and sperm count in the caudal epididymis on day 56 at 200 mg/kg, without affecting estradiol, luteinizing hormone, and follicle-stimulating hormone. DMBPA had no effect on Leydig cell number but significantly down-regulated Scarb1 expression at ≥ 10 mg/kg on day 28, Cyp17a1 expression on day 28 at 200 mg/kg and on day 56 at ≥ 10 mg/kg. DMBPA markedly upregulated Srd5a1 expression at doses of 50 and 200 mg/kg on day 56 after EDS. DMBPA significantly down-regulated the expression of Sod1 and Nr3c4 at a dose of 200 mg/kg on day 28. Further semi-quantitative immunohistochemistry showed that DMBPA reduced NR3C4 levels in Leydig and Sertoli cells at 50 and 200 mg/kg. In vitro DMBPA treatment of immature Leydig cells for 24 h showed that it significantly reduced testosterone production at 10 and 50 μM, and further mechanistic studies showed that an NR3C4 agonist 7α-methyl-19-nortestosterone significantly reversed DMBPA-mediated suppression on testosterone output, but the estrogen receptor antagonist ICI 182,780 and G-coupled estrogen receptor 1 agonist G15 had no effect. In conclusion, DMBPA delays Leydig cell regeneration after short-term exposure during early Leydig cell regeneration via NR3C4 antagonism.

Exposure to perfluorooctane sulfonate reduced cell viability and insulin release capacity of β cells

Per- and polyfluoroalkyl substances (PFAS) are found to have multiple adverse outcomes on human health. Recently, epidemiological and toxicological studies showed that exposure to PFAS had adverse impacts on pancreas and showed association with insulin abnormalities. To explore how PFAS may contribute to diabetes, we studied impacts of perfluorooctane sulfonate (PFOS) on cell viability and insulin release capacity of pancreatic β cells by using in vivo and in vitro methods. We found that 28-day administration with PFOS (10 mg/(kg body weight•day)) caused reductions of pancreas weight and islet size in male mice. PFOS administration also led to lower serum insulin level both in fasting state and after glucose infusion among male mice. For cell-based in vitro bioassay, we used mouse β-TC-6 cancer cells and found 48-hr exposure to PFOS decreased the cell viability at 50 μmol/L. By measuring insulin content in supernatant, 48-hr pretreatment of PFOS (100 μmol/L) decreased the insulin release capacity of β-TC-6 cells after glucose stimulation. Although these concentrations were higher than the environmental concentration of PFOS, it might be reasonable for high concentration of PFOS to exert observable toxic effects in mice considering mice had a faster removal efficiency of PFOS than human. PFOS exposure (50 μmol/L) to β-TC-6 cells induced intracellular accumulation of reactive oxidative specie (ROS). Excessive ROS induced the reactive toxicity of cells, which eventually invoke apoptosis and necrosis. Results in this study provide evidence for the possible causal link of exposure to PFOS and diabetes risk.

Oncostatin M stimulates immature Leydig cell proliferation but inhibits its maturation and function in rats through JAK1/STAT3 signaling and induction of oxidative stress in vitro

BACKGROUND

Oncostatin M (OSM) is a member of the interleukin-6 group of cytokines, which can regulate cell proliferation, growth, and function. Immature Leydig cells have the ability to proliferate and differentiate, and adult Leydig cells have the function of testosterone synthesis. However, the role and underlying mechanisms of OSM on the proliferation and function of Leydig cells remain unclear.

METHODS

The effects of OSM on the proliferation, apoptosis, and function of immature Leydig cells isolated from 35-day-old rats and the function of adult Leydig cells isolated from 63-day-old rats in vitro.

RESULTS

OSM stimulated immature Leydig cell proliferation after up-regulating the expression of Ccnd1 and Cdk4 to drive the transition of G1 phase to M2 phase in the cell cycle at 10 and 100 ng/ml. OSM did not affect the apoptosis of immature Leydig cells up to 100 ng/ml. OSM inhibited testosterone production in immature and adult Leydig cells by down-regulating the expression of Lhcgr, Star, Cyp11a1, Hsd3b1, and Cyp17a1 at 1-100 ng/ml. OSM induced reactive oxygen species and down-regulated the expression of antioxidant genes and lowered mitochondrial membrane potential at 10 and 100 ng/ml in both Leydig cells. Janus kinase 1 (JAK1) antagonist filgotinib and signal transducer and activator of transcription 3 (STAT3) antagonist S3I-201 reversed the effect of OSM, indicating that it acts on JAK1/STAT3 signaling.

CONCLUSION

Oncostatin M stimulates immature Leydig cell proliferation while inhibiting the function of immature and adult Leydig cells.

Perfluorotridecanoic Acid Inhibits Leydig Cell Maturation in Male Rats in Late Puberty via Changing Testicular Lipid Component

Perfluorotridecanoic acid (PFTrDA) is a long-chain (C13) perfluoroalkyl carboxylic acid. Here, we report the influence of PFTrDA exposure on the maturation of rat Leydig cells in late puberty in vivo. Male Sprague-Dawley rats were administered PFTrDA by gavage of 0, 1, 5, and 10 mg/kg/day from 35 days to 56 days postpartum. PFTrDA had no effect on body weight, testis weight, and epididymis weight. It significantly decreased the serum testosterone level after 5 and 10 mg/kg exposure, while it did not alter the serum estradiol level. The serum luteinizing hormone level was markedly reduced after 10 mg/kg PFTrDA exposure, while the follicle-stimulating hormone level was unchanged. Star, Cyp11a1, Cyp17a1, Hsd3b1, and Insl3 transcript levels in the testis were markedly lowered in the 1-5 mg/kg PFTrDA group and the Lhb transcript level in the pituitary in the 10 mg/kg group. CYP11A1 and HSD11B1-positive Leydig cell numbers were markedly reduced after 10 mg/kg PFTrDA exposure. Testicular triglyceride and free fatty acid (palmitic acid, oleic acid, and linoleic acid) levels were significantly reduced by PFTrDA, while Mgll (up-regulation) and Scarb1 and Elovl5 (down-regulation) expression were altered. AKT1 and AMPK phosphorylation was stimulated after 10 PFTrDA mg/kg exposure. In conclusion, PFTrDA delays the maturation of Leydig cells in late puberty mainly by altering the free fatty acid profile.

Parental plasma concentrations of perfluoroalkyl substances and In Vitro fertilization outcomes

Perfluoroalkyl substances (PFAS) are known to be endocrine-disrupting compounds, but are nevertheless widely used in consumer and industrial products and have been detected globally in human and wildlife. Data from animal and epidemiological studies suggest that PFAS may affect human fertility. This led us to consider whether maternal or paternal plasma PFAS had effects on in vitro fertilization (IVF) outcomes. The study population consisted of 96 couples who underwent IVF treatment in 2017 due to tubal factor infertility. The concentrations of 10 PFAS in blood samples from both male and female partners were measured. Poisson regression with log link was performed to evaluate the association between the tertiles of PFAS concentrations and numbers of retrieved oocytes, mature oocytes, two-pronuclei (2 PN) zygotes, and good-quality embryos, while multiple linear regression models were used to investigate the correlation between plasma PFAS and semen parameters. Multivariable logistic regression was used to evaluate the association between the tertiles of PFAS concentrations and clinical outcomes. It was found that maternal plasma concentrations of perfluorooctanoic acid (PFOA) were negatively associated with the numbers of retrieved oocytes (p_trend = 0.023), mature oocytes (p_trend = 0.015), 2 PN zygotes (p_trend = 0.014), and good-quality embryos (p_trend = 0.012). Higher paternal plasma PFOA concentrations were found to be significantly associated with reduced numbers of 2 PN zygotes (p_trend = 0.047). None of the maternal or paternal PFAS were significantly associated with the probability of implantation, clinical pregnancy, or live birth. To our knowledge, the present study is the first to assess the association between parental exposure to PFAS and IVF outcomes. Our results suggest the potential reproductive effects of PFAS on both men and women, and that exposure to PFAS may negatively affect IVF outcomes. Future studies, particularly with large sample size cohorts, are needed to confirm these findings.

Perfluoroheptanoic acid induces Leydig cell hyperplasia but inhibits spermatogenesis in rats after pubertal exposure

Perfluoroheptanoic acid (PFHpA) is a short-chain alternative to long-chain perfluoroalkyl substances, which have been reported to possess reproductive toxicity. However, it is unclear whether PFHpA affects Leydig cell development during puberty. The 35-day-old Sprague Dawley male rats were exposed to PFHpA by gavage with 0 (corn oil), 10, 50, and 100 mg/kg/day for 21 days. PFHpA did not affect the body weight of rats, but it reduced testis weight, relative testis weight, and epididymis weight at 100 mg/kg. It significantly increased serum testosterone, luteinizing hormone, and follicle-stimulating hormone levels at a dose of 100 mg/kg without affecting serum estradiol levels. PFHpA suppressed sperm production at a dose of 100 mg/kg. PFHpA induced Leydig cell hyperplasia (increased number of CYP11A1-positive Leydig cells) at a dose of 100 mg/kg, but down-regulated the expression of Cyp11a1, Hsd3b1, and Cyp17a1 in individual Leydig cell pe se and up-regulated the expression of Fshr in the Sertoli cell pe se. PFHpA did not affect the number of HSD11B1 (a biomarker for more mature Leydig cells) positive Leydig cells and SOX9 positive Sertoli cells. PFHpA increased BCL2, and the phosphorylation of AKT1, AKT2, ERK1/2, and JNK, but decreased BAX levels. However, it had no effect on SIRT1 and PGC-1α levels. In conclusion, PFHpA induces Leydig cell hyperplasia due to the increase in the secretion of luteinizing hormone through negative feedback after down-regulating the expression of steroidogenic enzymes and inhibiting testosterone production in individual Leydig cells. This proliferation may be mediated by increasing BCL2 and phosphorylation of AKT, ERK1/2, and JNK, and decreasing BAX level.

Risk to human health related to the presence of perfluoroalkyl substances in food

The European Commission asked EFSA for a scientific evaluation on the risks to human health related to the presence of perfluoroalkyl substances (PFASs) in food. Based on several similar effects in animals, toxicokinetics and observed concentrations in human blood, the CONTAM Panel decided to perform the assessment for the sum of four PFASs: PFOA, PFNA, PFHxS and PFOS. These made up half of the lower bound (LB) exposure to those PFASs with available occurrence data, the remaining contribution being primarily from PFASs with short half-lives. Equal potencies were assumed for the four PFASs included in the assessment. The mean LB exposure in adolescents and adult age groups ranged from 3 to 22, the 95th percentile from 9 to 70 ng/kg body weight (bw) per week. Toddlers and 'other children' showed a twofold higher exposure. Upper bound exposure was 4- to 49-fold higher than LB levels, but the latter were considered more reliable. 'Fish meat', 'Fruit and fruit products' and 'Eggs and egg products' contributed most to the exposure. Based on available studies in animals and humans, effects on the immune system were considered the most critical for the risk assessment. From a human study, a lowest BMDL 10 of 17.5 ng/mL for the sum of the four PFASs in serum was identified for 1-year-old children. Using PBPK modelling, this serum level of 17.5 ng/mL in children was estimated to correspond to long-term maternal exposure of 0.63 ng/kg bw per day. Since accumulation over time is important, a tolerable weekly intake (TWI) of 4.4 ng/kg bw per week was established. This TWI also protects against other potential adverse effects observed in humans. Based on the estimated LB exposure, but also reported serum levels, the CONTAM Panel concluded that parts of the European population exceed this TWI, which is of concern.

Perfluoroalkyl substances cause Leydig cell dysfunction as endocrine disruptors

Perfluoroalkyl substances (PFASs) are a group of man-made organic substances. Some of PFASs have been classified as persistent organic pollutants and endocrine disruptors. They might interfere with the male sex endocrine system, causing the abnormal development of the male reproductive tract and failure of pubertal onset and infertility. The present review discusses the development and function of two generations of Leydig cells in rodents and the effects of PFASs on Leydig cell development after their exposure in gestational and postnatal periods. We also discuss human epidemiological data for the effects of PFASs on male sex hormone levels. The structure-activity relationship of PFASs on Leydig cell steroidogenesis and enzyme activities are also discussed.