Atypical Leydig cell hyperplasia in adult rats with low T and high LH induced by prenatal Di(n-butyl) phthalate exposure

GATA-1 mutation alters the spermatogonial phase and steroidogenesis in adult mouse testis

GATA-1 is a transcription factor from the GATA family, which features zinc fingers for DNA binding. This protein was initially identified as a crucial regulator of blood cell differentiation, but it is currently known that the Gata-1 gene expression is not limited to this system. Although the testis is also a site of significant GATA-1 expression, its role in testicular cells remains considerably unexplored. In the present study, we evaluated the testicular morphophysiology of adult ΔdblGATA mice with a mutation in the GATA-1 protein. Regarding testicular histology, GATA-1 mutant mice exhibited few changes in the seminiferous tubules, particularly in germ cells. A high proportion of differentiated spermatogonia, an increased number of apoptotic pre-leptotene spermatocytes (Caspase-3-positive), and a high frequency of sperm head defects were observed in ΔdblGATA mice. The main differences were observed in the intertubular compartment, as ΔdblGATA mice showed several morphofunctional changes in Leydig cells. Reduced volume, increased number and down-regulation of steroidogenic enzymes were observed in ΔdblGATA Leydig cells. Moreover, the mutant animal showed lower serum testosterone concentration and high LH levels. These results are consistent with the phenotypic and biometric data of mutant mice, i.e., shorter anogenital index and reduced accessory sexual gland weight. In conclusion, our findings suggest that GATA-1 protein is an important factor for germ cell differentiation as well as for the steroidogenic activity in the testis.

Prenatal exposure to di(n-butyl) phthalate delays the spermatogenic cycle in rats: Investigation using a BrdU-injection method

Di(n-butyl) phthalate (DBP) esters are plasticizers that are used to provide transparency and flexibility in household plastic products but can easily leach out to contaminate organisms and the environment. We investigated whether prenatal DBP exposure affects spermatogenesis in rats. Pregnant Sprague-Dawley rats were injected with DBP 10, 50, and 100 mg/kg, or vehicle, administered intragastrically, on gestation days 12-21. At 9 or 17 weeks, 5-bromodeoxyuridine (BrdU) 50 mg/kg was injected intraperitoneally, and one testis was removed 3 h later. The remaining testis was excised 12.95 days + 3 h after the BrdU injection. Immunohistochemical analysis of BrdU was performed with periodic acid-Schiff and hematoxylin counterstaining for a quantitative analysis of the delay in one cycle of spermatogenesis. The DBP 100 mg group showed that the ratio of the appearance of seminiferous tubules in stages VII and VIII were significantly decreased, but those of stages IX and X were significantly increased compared to the Vehicle group. The reference value for the duration of spermatogenesis per cycle was set at 310.8 h. The DBP 100 mg group showed a significant delay in the duration of one cycle of spermatogenesis (16.95 h at puberty and 19.01 h at adulthood) compared with the Vehicle group. This study determined that F1-generation rats with prenatal DBP 100 mg exposure revealed significant accumulation of spermatogenic cells at stages IX to X in the second and third cycles, and the significant delay in the duration of spermatogenesis was more prominent at adulthood than in puberty.

Combined Effects of Different Endocrine-Disrupting Chemicals (EDCs) on Prostate Gland

Endocrine-disrupting chemicals (EDCs) belong to a heterogeneous class of environmental pollutants widely diffused in different aquatic and terrestrial habitats. This implies that humans and animals are continuously exposed to EDCs from different matrices and sources. Moreover, pollution derived from anthropic and industrial activities leads to combined exposure to substances with multiple mechanisms of action on the endocrine system and correlated cell and tissue targets. For this reason, specific organs, such as the prostate gland, which physiologically are under the control of hormones like androgens and estrogens, are particularly sensitive to EDC stimulation. It is now well known that an imbalance in hormonal regulation can cause the onset of various prostate diseases, from benign prostate hyperplasia to prostate cancer. In this review, starting with the description of normal prostate gland anatomy and embryology, we summarize recent studies reporting on how the multiple and simultaneous exposure to estrogenic and anti-androgenic compounds belonging to EDCs are responsible for an increase in prostate disease incidence in the human population.

A strategy to validate a selection of human effect biomarkers using adverse outcome pathways: Proof of concept for phthalates and reproductive effects

Human biomonitoring measures the concentrations of environmental chemicals or their metabolites in body fluids or tissues. Complementing exposure biomarkers with mechanistically based effect biomarkers may further elucidate causal pathways between chemical exposure and adverse health outcomes. We combined information on effect biomarkers previously implemented in human observational studies with mechanisms of action reported in experimental studies and with information from published Adverse Outcome Pathways (AOPs), focusing on adverse reproductive effects of phthalate exposure. Phthalates constitute a group of chemicals that are ubiquitous in consumer products and have been related to a wide range of adverse health effects. As a result of a comprehensive literature search, we present an overview of effect biomarkers for reproductive toxicity that are substantiated by mechanistic information. The activation of several receptors, such as PPARα, PPARγ, and GR, may initiate events leading to impaired male and female fertility as well as other adverse effects of phthalate exposure. Therefore, these receptors appear as promising targets for the development of novel effect biomarkers. The proposed strategy connects the fields of epidemiology and toxicology and may strengthen the weight of evidence in observational studies that link chemical exposures to health outcomes.

The effects of flutamide on cell-cell junctions in the testis, epididymis, and prostate

In this review, we summarize recent findings on the effect of the anti-androgen flutamide on cell-cell junctions in the male reproductive system. We outline developmental aspects of flutamide action on the testis, epididymis, and prostate, and describe changes in junction protein expression and organization of junctional complexes in the adult boar following prenatal and postnatal exposure. We also discuss findings on the mechanisms by which flutamide induces alterations in cell-cell junctions in reproductive tissues of adult males, with special emphasis on cytoplasmic effects. Based on the results from in vivo and in vitro studies in the rat, we propose that flutamide affects the expression of junction proteins and junction complex structure not only by inhibiting androgen receptor activity, but equally important by modulating protein kinase-dependent signaling in testicular cells. Additionally, results from studies on prostate cancer cell lines point to a role for the cellular molecular outfit in response to flutamide.

Interference of dibutylphthalate on human prostate cell viability

Dibutylphthalate (DBP) is an environmental pollutant widely used as plasticizer in a variety of industrial applications worldwide. This agent can be found in personal-care products, children's toy, pharmaceuticals, food products. Exposure to DBP can occur via ingestion and inhalation as well as intravenous or skin contact. DBP belongs to the family of endocrine disrupting chemicals (EDCs) and its effects on reproductive system were demonstrated both in vivo and in vitro. In the present study we evaluated the effects of DBP on human prostate adenocarcinoma epithelial cells (LNCaP) in order to highlight xenoestrogens influence on human prostate. Moreover, we have compared DBP effects with 17β-estradiol action in order to investigate possible mimetical behaviour. We have assessed the effects of both compounds on the cell viability. After then, we have evaluated the expression of genes and proteins involved in cell cycle regulation. Furthermore, we have observed the expression and the cell localization of estrogen (ERs) and androgen (AR) receptors. In conclusion, we have demonstrated that DBP interacts with estrogen hormonal receptor pathway but differently from E2. DBP alters the normal gland physiology and it is involved in the deregulation of prostate cell cycle.

In utero-exposed di(n-butyl) phthalate induce dose dependent, age-related changes of morphology and testosterone-biosynthesis enzymes/associated proteins of Leydig cell mitochondria in rats

Female pregnant Sprague-Dawley rats were intragastrically (ig) administered di(n-butyl) phthalate (DBP) at four doses (0, 10, 50 and 100 mg/kg) during gestation days (GD) 12-21 (n = 5 per group). The age-related morphological changes of Leydig cell mitochondrion (LC-Mt) and testosterone biosynthesis enzymes/associated genes/proteins expression levels were investigated. As compared to the control (no DBP), the 10 mg, and 50 mg DBP dose groups, the 100 mg DBP dose group at weeks 5 and 7 showed a significant amount of small LC-Mt. Thereafter, from weeks 9 to 17, the LC-Mt size and quantity in the 100 mg DBP dose group increased and became statistically similar to the other dose groups; hence, dose and time-dependent LC-Mt changes were observed. Throughout the study, the 100 mg DBP dose group had significantly lower testosterone levels. In addition, the 100 mg DBP dose group displayed lower StAR (StAR, steroidogenic acute regulatory protein) and P450scc (CYP11a1, cholesterol side-chain cleavage enzyme) levels at weeks 5 and 7, but they became statistically similar to all other dose groups at weeks 9 to 17; in contrast, the SR-B1 (Sarb1, scavenger receptor class B member 1) levels were similar for all DBP dose groups. The rats in utero 100 mg DBP /kg/day (GD 12-21) exposure results from this study indicate a dose-dependent, age-related morphological change in LC-Mt which are linked to reductions in testosterone biosynthesis genes / proteins expression, specifically StAR and P450scc.

Smad2/3 Upregulates the Expression of Vimentin and Affects Its Distribution in DBP-Exposed Sertoli Cells

Sertoli cells (SCs) in the testes provide physical and nutritional support to germ cells. The vimentin cytoskeleton in SCs is disrupted by dibutyl phthalate (DBP), which leads to SCs dysfunction. In a previous study, we found that peroxisome proliferator-activated receptor alpha (PPARα) influenced the distribution of vimentin by affecting its phosphorylation in DBP-exposed SCs. In the present study, we investigated the role of Smad2/3 in regulating the expression of vimentin in DBP-exposed SCs. We hypothesized that Smad2/3 affects the distribution of vimentin by regulating its expression and that there is cross talk between Smad2/3 and PPARα. The real-time PCR and ChIP-qPCR results showed that SB431542 (an inhibitor of Smad2/3) could significantly attenuate the expression of vimentin induced by DBP in SCs. Phosphorylated and soluble vimentin were both downregulated by SB431542 pretreatment. WY14643 (an agonist of PPARα) pretreatment stimulated, while GW6471 (an antagonist of PPARα) inhibited, the activity of Smad2/3; SB431542 pretreatment also inhibited the activity of PPARα, but it did not rescue the DBP-induced collapse in vimentin. Our results suggest that, in addition to promoting the phosphorylation of vimentin, DBP also stimulates the expression of vimentin by activating Smad2/3 in SCs and thereby induces irregular vimentin distribution.

Effects of local testicular heat treatment on Leydig cell hyperplasia and testosterone biosynthesis in rat testes

Cryptorchidism or local testicular heat treatment induces reversible oligospermia or azoospermia in rodents and humans via increased germ cell apoptosis. Research in this field has concentrated on the impact of heat on spermatogenesis, with rather little attention paid to the molecular effects of heat treatment on Leydig cell function. In the present study, we investigated the effects of exposure to heat stress on the proliferative activity and testosterone biosynthesis of Leydig cells. We subjected adult rats to a single local testicular heat treatment of water at 43°C for 30min. The expression of Leydig cell-specific markers, such as cholesterol side-chain cleavage (P450SCC) and 3?-hydroxysteroid dehydrogenase, was evaluated by immunohistochemistry and western blot analysis. The proliferative activity of Leydig cells was detected by immunostaining with proliferation-associated markers, including Ki67, bromodeoxyuridine and phosphohistone-H3 (pHH3). The mRNA and protein levels of cell cycle proteins and testosterone synthesis-related enzymes were measured by real-time polymerase chain reaction and western blot analysis, respectively. The testes of heat-treated rats contained 50% more Leydig cells than those of control rats, indicating induction of Leydig cell hyperplasia by testicular heat treatment. Increased proliferative activity in Leydig cells, evidenced by enhanced expression of cell cycle proteins, was the main cause of Leydig cell hyperplasia. In addition, heat treatment reduced serum and testicular testosterone concentrations. Consistent with this finding, heat stress downregulated two enzymes required for testosterone biosynthesis, namely cytochrome P450, family 17 (CYP17) and steroidogenic acute regulatory protein, in Leydig cells. Together, the results suggest that testicular heat leads to Leydig cell hyperplasia and a reduction in testosterone biosynthesis in adult rat testes.

Effects of in utero exposure to di(n-butyl) phthalate for estrogen receptors α, β, and androgen receptor of Leydig cell on rats

Estrogens and androgens affect male and female reproductive systems. Recently, we reported that prenatal di(n-butyl) phthalate (DBP) exposure induced atypical Leydig cells (LCs) hyperplasia during adulthood. The present study investigated the expression of estrogen receptor α (ERα), estrogen receptor β (ERβ), and androgen receptor (AR) in LCs of 5-, 7-, 9-, 14-, and 17-week-old Sprague-Dawley (srl) rats whose dams had been administered DBP intragastrically at 100 mg/kg/day or the vehicle (corn oil) from days 12 to 21 postconception. Immunohistochemical, Western blotting, and reverse transcription polymerase chain reaction analyses revealed that the expressions of ERα, ERβ, and AR proteins and mRNAs in the DBP group were similar to those of the vehicle group at 5 and 7 weeks, but significantly higher ERα and lower ERβ and AR levels were observed in the DBP group at 9 to 17 weeks. The rats prenatally exposed to DBP had seminiferous tubule degeneration and atypical hyperplasia of LCs during adulthood, which was associated with an increase in expression of ERα and a decrease of ERβ and AR in the testis.

Nuclear Morphometric Analysis of Leydig Cells of Male Pubertal Rats Exposed In Utero to Di(n-butyl) Phthalate

We recently reported that prenatal rat exposure to di(n-butyl) phthalate (DBP) induced Leydig cell (LC) hyperplasia after nine weeks (wks) of age, yet the number of LCs was similar to that of the vehicle group until seven weeks. Nuclear pleomorphism of hyperplastic LCs is common and is considered to be continuous progressive degeneration. Thus, computer-assisted image cell nuclear analysis of LCs was performed on 5- and 7-wk-old Sprague-Dawley (SD) rats whose dams had been administered DBP (i.g.) at 100 mg/kg/day or vehicle (corn oil) on gestation day 12 to 21. The results of the 5-wk-old DBP group were similar to those of the vehicle group; LC nuclei of the 7-wk-old DBP group showed normal ploidy and similar amounts of DNA. However, the size, elongation and peripheral chromatin aggregation parameters were significantly higher, and the reticular chromatin distribution and isolated chromatin aggregation parameters were significantly lower compared with the vehicle group. The present study quantitatively demonstrated nuclear morphological alterations in rat LCs at 7 wks old (puberty) due to the prenatal DBP administration before apparent LC hyperplasia developed.