Disturbance in testosterone production in leydig cells by polycyclic aromatic hydevrepocarbons

Effects of polycyclic aromatic hydrocarbons on the gut-testis axis

Polycyclic aromatic hydrocarbons (PAHs) are a large group of organic compounds which are comprised of two or more fused benzene rings. As a typical environmental pollutant, PAHs are widely distributed in water, soil, atmosphere and food. Despite extensive researches on the mechanisms of health damage caused by PAHs, especially their carcinogenic and mutagenic toxicity, there is still a lack of comprehensive summarization and synthesis regarding the mechanisms of PAHs on the gut-testis axis, which represents an intricate interplay between the gastrointestinal and reproductive systems. Thus, this review primarily focuses on the potential forms of interaction between PAHs and the gut microbiota and summarizes their adverse outcomes that may lead to gut microbiota dysbiosis, then compiles the possible mechanistic pathways on dysbiosis of the gut microbiota impairing the male reproductive function, in order to provide valuable insights for future research and guide further exploration into the intricate mechanisms underlying the impact of gut microbiota dysbiosis caused by PAHs on male reproductive function.

Biological sex differences in hepatic response to in utero dimethylbenz(a)anthracene exposure

Fetal hepatic dimethylbenz(a)anthracene (DMBA) biotransformation is not defined, thus, this study investigated whether the fetal liver metabolizes DMBA and differs with biological sex. KK.Cg-a/a (lean; n = 20) or KK.Cg-Ay/J (obese; n = 20) pregnant mice were exposed to corn oil (CT) or DMBA (1 mg/kg bw/day) by intraperitoneal injection (n = 10/treatment) from gestation day 7-14. Postnatal day 2 male or female offspring livers were collected. Total RNA (n = 6) and protein (n = 6) were analyzed via a PCR-based array or LC-MS/MS, respectively. The level of Mgst3 was lower (P < 0.05) in livers of female compared to male offspring. Furthermore, in utero DMBA exposure increased (P < 0.1) Cyp2c29 and Gpx3 levels (P < 0.05) in female offspring. In male offspring, the abundance of Ahr, Comt (P < 0.1), Alox5, and Asna1 (P < 0.05) decreased due to DMBA exposure. Female and male offspring had 34 and 21 hepatic proteins altered (P < 0.05) by in utero DMBA exposure, respectively. Opposing patterns for hepatic CD81 and KRT78 occurred, being decreased in females but increased in males, while YWHAG was decreased by DMBA exposure in both. Functional KEGG pathway analysis identified enrichment of 26 and 13 hepatic metabolic proteins in male and female offspring, respectively, due to in utero DMBA exposure. In silico transcription factor analysis of differentially expressed proteins predicted involvement of female NRF1 but male AHR. Thus, hepatic biological sex differences and capacity to respond to toxicants in utero are supported.

Cordycepin mitigates spermatogenic and redox related expression in H2O2-exposed Leydig cells and regulates testicular oxidative apoptotic signalling in aged rats

CONTEXT

Cordycepin (COR), from Cordyceps militaris L., (Cordycipitaceae), is a valuable agent with immense health benefits.

OBJECTIVE

The protective effects of COR in ageing-associated oxidative and apoptosis events in vivo and hydrogen peroxide (H₂O₂)-exposed spermatogenesis gene alterations in TM3 Leydig cells was investigated.

MATERIALS AND METHODS

Male Sprague-Dawley rats were divided into young control (YC), aged control (AC) and COR treated (COR-20) aged groups. COR-20 group received daily doses of COR (20 mg/kg) for 6 months. Cell viability and hormone levels were analysed by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] and enzyme immunoassay kits with COR treated at 1, 5, and 10 μg/mL. Oxidative enzymes, spermatogenic, and apoptotic expression in testis tissues were evaluated by Western blotting and real-time RT-PCR.

RESULTS

COR treatment (1, 5, and 10 μg/mL) significantly (p < 0.05 ∼ p < 0.001) inhibited the H₂O₂-induced decrease in the percentage of viable cells (from 63.27% to 71.25%, 85.67% and 93.97%, respectively), and reduced the malondialdehyde (MDA) content (from 4.28 to 3.98, 3.14 and 1.78 nM MDA/mg protein, respectively). Further, the decreased antioxidant enzymes (glutathione-S-transferase mu5, glutathione peroxidase 4 and peroxiredoxin 3), spermatogenesis-related factors (nectin-2 and inhibin-α) and testosterone levels in H₂O₂-exposed TM3 cells were significantly (p < 0.05 ∼ p < 0.001) ameliorated by COR. In aged rats, COR (20 mg/kg) restored the altered enzymatic and non-enzymatic antioxidative status and attenuated the apoptotic p53 and Bax/Bcl-2 expression significantly (p < 0.05).

CONCLUSION

COR might be developed as a potential agent against ageing-associated and oxidative stress-induced male infertility.

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

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

Concerns with Male Infertility Induced by Exposure to Titanium Nanoparticles and the Supporting Impact of Pelargonium graveolens Essential Oil: Morphometric Records in Male-Wistar Rats

Background: Due to the increased use of titanium dioxide nanoparticles (TiO₂ NPs), the risks of their reprotoxic effect arise. This study anticipated examining the potential protective effects of GEO (geranium essential oil) components screened via GC/MS analysis against the reprotoxic impacts of TiO₂ NPs on male rats. Methods: Thirty-two adult male rats were randomly assigned to four groups: control, GEO (75 mg/kg bwt/orally/day/60 days), TiO₂ NPs (100 ppm/rat/IP/day/60 days), and TiO₂ NPs + GEO. After 60 days, hormonal assay, semen appraisal, lipid peroxidation, antioxidant enzymes, testis and prostate morphometry, and the steroidogenesis-related genes’ mRNA expressions were assessed. Results: The TEM and DLS results demonstrated that synthesized TiO₂ NPs are spherical with minimal aggregations polydispersed and varying in size from 50 to 100 nm. TiO₂ NPs IP injection-induced sperm abnormalities decreased the percent of motile sperms in the sperm count, reduced sex hormone levels, altered the testicular oxidant/antioxidant status and mRNA expression of steroid-related genes, and induced architectural alterations in testicular, epididymal, and prostate gland tissues. GEO significantly rescued the TiO₂ NPs-altered spermiogram, sex hormones, and antioxidant capacity, restored the tissue architectures, and enhanced steroidogenesis-related gene mRNA expression. Conclusions: These findings may significantly contribute to developing combinatorial treatments for infertility associated with various environmental and industrial xenobiotic exposures.

Long-term exposure to particulate matter and residential greenness in relation to androgen and progesterone levels among rural Chinese adults

BACKGROUND

Population-based studies on the associations of long-term exposure to particulate matter (PM) with androgen and progesterone are still scant. Residential greenness is benefits health by promoting physical activity, reducing air pollution, and improving mental health, but it remains unclear whether it is related to androgen and progesterone levels among humans.

AIMS

This study aimed to explore the individual and interactive effects of PM and residential greenness on serum testosterone and progesterone levels among rural Chinese adults.

METHODS

A total of 6017 subjects were recruited from the baseline of the Henan Rural Cohort Study in 2016. Serum testosterone and progesterone were measured with liquid chromatography-tandem mass spectrometry. Particulate matters (PM) (PM₁, PM_2.5, and PM₁₀) were assessed by machine learning algorithms. Residential greenness was assessed using the normalized difference vegetation index (NDVI) within 500-m, 1000-m, and 3000-m buffers around participants' residences. The effects of air pollutants and residential greenness and their interaction on serum testosterone and progesterone levels were assessed using linear mixed-effects models with township as a random intercept.

RESULTS

After adjusting for potential confounding factors, a 1 μg/m³ increase in PM_2.5 or PM₁₀ was associated with a 0.037 or 0.030 ng/ml increase in serum testosterone, respectively, in females and with a 0.111 or 0.182 ng/ml decrease in serum progesterone, respectively, in males. A 1 μg/m³ increase in PM₁, PM_2.5 or PM₁₀ was associated with a 0.222, 0.306, or 0.295 ng/ml decrease in serum progesterone, respectively, among females. Moreover, a 0.1-unit increase in NDVI was associated with a 0.310 ng/ml increase in serum testosterone and a 0.170 ng/ml increased in serum progesterone in males, as well as with a 0.143 ng/ml increase in serum progesterone in females. Interaction effects of PM and residential greenness on serum testosterone and progesterone levels were observed, indicating that the effects of residential greenness on serum testosterone and progesterone were modified by high levels of PM. In addition, physical activity significantly mediated 2.92% of the estimated association between greenness and testosterone levels.

CONCLUSIONS

Our study suggested that long-term exposure to PM was positively associated with serum testosterone in males but negatively associated with progesterone levels in both genderssin. In addition, positive associations of residential greenness with serum testosterone and progesterone levels were observed, but they were modified by high levels of PM. Furthermore, the estimated effects of residential greenness on testosterone levels were partly mediated by physical activity.

Levels of Follicle Stimulating Hormone (FSH), Luteinizing Hormone (LH), Testosterone and Prolactin at Moderate Altitude Inhabitant Male

BACKGROUND AND OBJECTIVE

Male fertility depends on the availability of the potent androgen called testosterone. Testosterone production is regulated by the hypothalamic anterior pituitary axis. Two anterior pituitary hormones Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH) are involved in spermatogenesis and testosterone production, respectively. Hypoxia, resulting from high altitude, may induce a change in these four hormones and may affect male fertility. This study was done to evaluate and compare the changes that occur in FSH, LH, testosterone and prolactin in males lived in moderate versus low altitude.

MATERIALS AND METHODS

This study was conducted on 300 individuals who were categorized based on the altitude of their habitat into two equal groups, namely: Inhabitants at moderate altitudes and inhabitants at low altitudes. A venous blood sample was collected from each individual to measure the levels of FSH, LH and prolactin.

RESULTS

Both LH and testosterone levels were significantly lower in high altitude inhabitants compared with low altitude inhabitants (p<0.01). The FSH level showed a significant statistical difference between two groups with a lower level in individuals living at high altitudes compared with low altitude inhabitants but on a value (p<0.05).

CONCLUSION

Moderate altitude hypoxia suppresses LH, FSH and testosterone levels as much as high altitude hypoxia does and these changes may depend on prolactin level.

Comparative effect of administration and discontinuation of sildenafil and/or clomipramine on the hepatic, cardiac and testicular tissues of male rats

In this study, we examined the adverse consequences of prolonged treatment with sildenafil and/or clomipramine (CLO) on the hepatic, cardiac and testicular tissues of rats. Additionally, we investigated the potential effects of treatment discontinuation. To this end, 60 adult male rats were randomly assigned into six groups and were orally treated with 4.5 mg sildenafil /kg BW (SLD) and 9 mg/ kg BW (SHD), 2.25 mg CLO/kg BW (CLO), 4.5 mg sildenafil/kg BW + 2.25 mg CLO/kg BW (SLD-CLO) and 9 mg sildenafil/kg BW + 2.25 mg CLO/kg BW (SHD-CLO) while the control rats received 0.5 ml distilled water for 8 weeks. Then, five rats from each group were sacrificed and the other five rats were left untreated for another four weeks to recover from the drug treatment. Long-term administration of sildenafil and/or CLO led to oxidative stress, inflammation and structural changes in the liver, heart and testis, reduction in sperm count and motility, an increase in abnormalities, and a reduction in serum testosterone, FSH and LH levels. All tested parameters returned to the normal state following the four-week discontinuation of sildenafil. Additionally, all the alterations caused by long-term administration of CLO, SLD-CLO and SHD-CLO were significantly improved during the recovery period.

Chronic intermittent hypoxia stimulates testosterone production in rat Leydig cells

AIMS

The hypoxia-stimulated response of the endocrine system depends on the kind and duration of hypoxia. Hypoxia has been reported to stimulate testosterone (T) production in rats, but the mechanisms remain to be investigated.

MATERIALS AND METHODS

Male rats were divided into two groups. The rats exposed to chronic intermittent hypoxia (CIH) at 8 h/day were housed in a hypoxic chamber (12% O₂) for 14 days. Normoxic rats were used as control animals. T was measured after challenging the rat Leydig cells (LCs) with different stimulators, including hCG (0.01 IU/ml), forskolin (10^-5 M), 8-bromo-cAMP (10^-4 M), A23187 (10^-5 M), cyclopiazonic acid (10^-4 M), and androstenedione (10^-8 M). Meanwhile, the LCs were incubated with trilostane (10^-5 M) and/or 25-OH-hydroxycholesterol (10^-5 M); thereafter the media were collected for pregnenolone assay.

KEY FINDINGS

In the CIH group, plasma T levels were increased, but the serum luteinizing hormone (LH) was decreased. Furthermore, at several time intervals after hCG injection, plasma T levels were higher in the CIH group. The evoked-release of T and pregnenolone were significantly increased in the CIH group. Compared with the normoxic group, the CIH group had higher mRNA and protein expression levels of the LH receptor and CYP11A1 but not StAR. The plasma and testicular microvasculature VEGF levels were increased in the CIH group. The testicular vessel distribution was more obvious in CIH rats.

SIGNIFICANCE

CIH-induced T secretion might be partially mediated by mechanisms involving the induction of LH receptor expression, testicular angiogenesis, CYP11A1 activity, 17β-HSD activity, and calcium-related pathway.

Transcriptome analysis reveals novel insights into the response of low-dose benzo(a)pyrene exposure in male tilapia

Despite a wide number of toxicological studies that describe benzo[a]pyrene (BaP) effects, the metabolic mechanisms that underlie these effects in fish are largely unknown. Of great concern is the presence of BaP in aquatic systems, especially those in close proximity to human activity leading to consumption of potentially contaminated foods. BaP is a known carcinogen and it has been reported to have adverse effects on the survival, development and reproduction of fish. The purpose of this study was to investigate if a low dose of BaP can alter genes and key metabolic pathways in the liver and testis in male adult tilapia, and whether these could be associated with biological endpoints disruption. We used both high-throughput RNA-Sequencing to assess whole genome gene expression following repeated intraperitoneal injections of 3 mg/kg of BaP (every 6 days for 26 days) and morphometric endpoints as indicators of general health. Condition factor (K) along with hepatosomatic and gonadosomatic indices (morphometric parameters) were significantly lower in BaP-treated fish than in controls. BaP exposure induced important changes in the gene expression pattern in liver and testis as revealed by both Pathway and Gene Ontology (GO) analyses. Alterations that were shared by both tissues included arachidonic acid metabolism, androgen receptor to prostate-specific antigen signaling, and insulin-associated effects on lipogenesis. The most salient liver-specific effects included: biological processes involved in detoxification, IL6-associated insulin resistance, mTOR hyperactivation, mitotic cytokinesis, spindle pole and microtubule binding. BaP effects that were confined to the testis included: immune system functions, inflammatory response, estrogen and androgen metabolic pathways. Taken together, gene expression and morphometric end point data indicate that the reproductive success of adult male tilapia could be compromised as a result of BaP exposure. These results constitute new insights on the mechanism of action of low dose BaP in a non-model organism (tilapia).

7,12-Dimethylbenz[α]anthracene increases cell proliferation and invasion through induction of Wnt/β-catenin signaling and EMT process

7,12-Dimethylbenz[α]anthracene (DMBA) is a hazardous component present in polluted environments. DMBA has been used as an experimental tool for in vivo tumor formation owing to its carcinogenic effects, but the detailed molecular mechanism of DMBA has not been fully established. To comprehend the carcinogenic mechanism of DMBA, we explored its effects in the breast cancer cell lines, MCF-7 and MDA-MB-231, and the cervical cancer cell line, HeLa. Cell viability assay and measurement of a proliferation marker showed that DMBA markedly increased cancer cell proliferation. Furthermore, morphological observations and wound healing assays in nontumorigenic MCF-10A cells and trans-well invasion assays in cancer cells following DMBA treatment revealed that DMBA induced cell migration and invasion. To reveal the molecular mechanism of DMBA, we investigated the effects of DMBA on the epithelial-mesenchymal transition (EMT) process and Wnt/β-catenin signaling, a critical pathway for cell proliferation that was reported to correlate with the EMT process, by using quantitative RT-PCR (qPCR), western blot analysis, and confocal microscopy. Consequently, we found that DMBA increased cancer cell proliferation and invasion through the promotion of EMT-inducing factors and β-catenin. Especially, it was revealed in promoter activity assay using mutated luciferase vectors on transcription factor-binding sites that TWIST1 is promoted by DMBA through induction of STAT3-mediated promoter activation. To further elucidate the detailed mechanism of DMBA, we aimed to identify the key regulator of its carcinogenic action. DMBA was shown to significantly upregulate the expression of specificity protein 1 (Sp1), a transcription factor, and the carcinogenic effects of DMBA were blocked via the suppression or interruption of Sp1 activity. In conclusion, our data suggested that DMBA induced carcinogenic effects through activation of Wnt/β-catenin signaling and the EMT process by upregulating Sp1 activity.

Fine particle matter disrupts the blood-testis barrier by activating TGF-β3/p38 MAPK pathway and decreasing testosterone secretion in rat

Fine particle matter (PM) is correlated with male reproductive dysfunction in animals and humans, but the underlying mechanisms remain unknown. To investigate the toxic mechanism of PM, 32 male Sprague-Dawley (SD) rats were exposed to saline or PM_2.5 with the doses of 1.8, 5.4, and 16.2 mg/kg.b.w. via intratracheal instillation, respectively, one time every 3 days, in total times for 30 days. Sperm concentration, hormone level, the expressions of BTB-associated protein and the mitogen-activated protein kinase (MAPK) pathway, tumor necrosis factor α and transforming growth factor β3 levels were detected. The results showed a decrease in sperm number, testosterone and luteinizing hormone levels and altered ultrastructure of BTB in testis of rat after exposure to PM_2.5 . The protein levels of N-Cadherin, Occludin, Claudin-11, and Connexin-43 were significantly decreased in the testes. TGF-β3 content in testes showed increase, with the p-p38/p38 MAPK ratio also increasing after PM_2.5 exposure. These results demonstrate that PM_2.5 restrained the expressions of BTB-associated proteins through activating TGF-β3/p38 MAPK pathway and decreasing testosterone secretion, and therefore lead to the damage of BTB resulting in the decrease of sperm quality, which might be the potential reasons for its negative effects on spermatogenesis and male reproduction.

Associations between urinary polycyclic aromatic hydrocarbon metabolites and serum testosterone in U.S. adult males: National Health and nutrition examination survey 2011-2012

Effects of environmental chemicals on human reproductive health and sex hormone levels have been reported for several years, but compared to other environmental chemicals, such as heavy metals, PCBs, triclosan, Phthalate, the links between polycyclic aromatic hydrocarbons (PAHs) and sex hormone levels have not been studied widely. Therefore, our purpose of research was to study the associations between urinary PAH metabolites and serum total testosterone (T) levels among men. The data was obtained from the independent cross-section wave (2011-2012) of the National Health and Nutrition Examination Survey (NHANES), including demographic, socioeconomic, dietary, health-related questions, examinations and laboratory test. All analyses were performed by R software (version 3.2.3), including one-way analysis of variance, multivariable linear regression, stratified analysis and heterogeneity test. Of 1102 American adults aged 20 and above included in the statistical analysis, we found that urinary 3-hydroxyfluorene and 2-hydroxyfluorene were significantly positively associated with serum T levels (β = 40.62, 95%CI = 21.78-59.46, P = 2.56 × 10^-5; β = 35.17, 95%CI = 13.18-57.15, P = 1.75 × 10^-3, respectively). The associations between urinary PAH metabolites and serum T levels signified a major public health problem over the world. Prospective work is needed to investigate the potential long-term health consequences of these findings.