Microscopic comparative study of the exposure effects of testosterone cypionate and ethinylestradiol during prenatal life on the prostatic tissue of adult gerbils

BPS and BPF are as Carcinogenic as BPA and are Not Viable Alternatives for its Replacement

BACKGROUND

Plastic polymers are omnipresent, and life without them is virtually impossible. Despite the advantages provided by the material, conventional plastic also has harmful effects on the environment and human health. Plastics release microplastics and compounds, such as BPA, which is a xenoestrogen and once absorbed by the body, have an affinity for estrogen receptors α and β, acting as an agonist on human cells, being an endocrine disrupter able to cause various diseases and acting as a potential neoplastic inducer. BPS and BPF are BPA's analogs, a proposed solution to solve its harmful effects incorporated into the market. The analogs can be found in daily use products and are used in several industrial applications.

OBJECTIVES

In the present work, the researchers aimed to develop a revisional study of BPA's harmful effects on human health, focusing on its carcinogenic potential, discussing its mechanisms of action, as well as its analogs effects, and identifying if they are a viable alternative to BPA's substitution in plastic polymers' production.

METHODS

In this review, articles published in the last 15 years related to the different aspects of conventional plastics and BPA were analyzed and revised with precision. The subjects ranged from conventional plastics and the problems related to their large-scale production, BPA, its negative aspects, and the feasibility of using its analogs (BPS and BPF) to replace the compound. The articles were extensively reviewed and concisely discussed.

RESULTS

This study demonstrated that BPA has a high carcinogenic potential, with known mechanisms to trigger breast, ovarian, prostate, cervical, and lung cancers, thus elucidating that its analogs are also xenoestrogens, that they can exert similar effects to BPA and, therefore, cannot be considered viable alternatives for its replacement. Conclusion This study suggests that new research should be carried out to develop such alternatives, allowing the substitution of plastic materials containing BPA in their composition, such as developing economically viable and sustainable biodegradable bioplastics for socio-environmental well-being.

Prenatal and pubertal exposure to 17α-ethinylestradiol cause morphological changes in the prostate of old gerbils

This study evaluated such as exposure to ethinylestradiol during the prenatal (18th-22nd day) and pubertal (42nd-49th day) periods acts on the male ventral prostate and female prostate of 12-month old gerbils. We performed the analysis to serum hormone levels for estradiol and testosterone. The prostates were submitted to morphometric and immunohistochemical analyses. Exposure to ethinylestradiol during these developmental periods decreased the testosterone serum levels in males and increased the estradiol serum levels in females. Morphologically, prostate intraepithelial neoplasia and disorders in the arrangement of the fibrous components were observed in the prostate glands of both sexes of gerbil exposed to ethinylestradiol during development periods. In the male prostate, the ethinylestradiol promoted decreased in the frequency of positive epithelial cell for androgen receptor (AR) and increased the frequency of positive stromal cell for estrogen receptor α. However, in the female prostate, this synthetic estrogen caused AR upregulation and increased cell proliferation. This study shows that the exposure to ethinylestradiol during development phases alters the morphology and the hormonal signaling in the male and female prostates of old gerbils, confirming the action of ethinylestradiol as endocrine disruptor.

Telocytes are associated with tissue remodeling and angiogenesis during the postlactational involution of the mammary gland in gerbils

The postlactational involution of the mammary gland is a complex process. It involves the collapse of the alveoli and the remodeling of the extracellular matrix, which in turn implies a complex set of interrelations between the epithelial, stromal, and extracellular matrix elements. The telocytes, a new type of CD34-positive stromal cell that differs from fibroblasts in morphological terms and gene expression, were detected in the stroma of several tissues, including the mammary gland; however, their function remains elusive. The present study employed three-dimensional reconstructions and immunohistochemical, ultrastructural, and immunofluorescence techniques in histological sections of the mammary gland of the Mongolian gerbil during lactation and postlactational involution to evaluate the presence of telocytes and to investigate a possible function for these cells. By means of immunofluorescence assays for CD34 and c-kit, major markers of telocytes, and also through morphological and ultrastructural evidences, telocytes were observed to surround the mammary ducts and collapsing alveoli. It was also found that these cells are associated with matrix metalloproteinase 9, which indicates that telocytes can play a role in extracellular matrix digestion, as well as vascular endothelial growth factor, a factor that promotes angiogenesis. Together, these data indicate that telocytes are a distinct cell type in the mammary gland and, for the first time, show that these cells possibly play a role in tissue remodeling and angiogenesis during the postlactional involution of the mammary gland.

Prenatal exposure to finasteride promotes sex-specific changes in gerbil prostate development

Finasteride is a drug that is widely used in the treatment of benign prostatic hyperplasia, hair loss and even as a chemotherapeutic agent in the treatment of prostatic adenocarcinoma. However, its use is known to cause several side effects in adults and it can also cause changes in the embryonic development of the male prostate, which is a cause for concern given the possibility of the accumulation of finasteride in the environment. Nevertheless, no studies have investigated the effects of finasteride on the development of the prostate in females, which occurs in several species of mammals. To evaluate the effects of intrauterine exposure to finasteride (500μgkg-1 day-1) on postnatal prostate development in the Mongolian gerbil in the present study, we used immunohistochemistry, immunofluorescence, serological analysis and three-dimensional reconstruction techniques. Differences were observed in the effects of finasteride on periductal smooth muscle and cell proliferation between the sexes, as well as intersex differences in the presence of the androgen receptor, which was elevated in males, and the oestrogen receptor ERα, which was increased in females. Together, the data indicate that the female prostate has its own hormone dynamics and that there are sex-specific differences in the way in which the female prostate reacts to prenatal exposure to finasteride.

Postnatal exposure to finasteride causes different effects on the prostate of male and female gerbils

The development and maintenance of prostate function depend on a fine balance between oestrogen and androgen levels. Finasteride inhibits 5α-reductase, which is responsible for the conversion of testosterone into its most active form, dihydrotestosterone. Enzymes that metabolize these hormones have a highly relevant role in both the normal prostate metabolism and in the occurrence of pathological conditions. There are few studies on the impact of finasteride on male prostate development and fewer studies on the female prostate and possible intersexual differences. Therefore, we treated male and female gerbils from 7 to 14 days in postnatal life with a high dose of finasteride (500 μg/kg/day); the prostate complexes were then removed and submitted to immunohistochemistry, immunofluorescence and three-dimensional reconstruction. In addition, hormonal serum dosages were administered. Treatment with finasteride resulted in an increased thickness of the periductal smooth musculature in the prostate of both male and female gerbils, such as well as a reduction in the thickness of developing prostate alveoli in both sexes. In addition, intersexual differences were observed as increased epithelial proliferation and decreases in the number of developing alveoli in females. Together, the data indicate that postnatal exposure to finasteride causes greater changes in the female gerbil prostate than in the male.

Low-dose in utero exposure to finasteride promotes developmental changes in both male and female gerbil prostates

The prostate is an accessory reproductive gland that is sensitive to the action of exogenous compounds known as endocrine disrupters that alter normal hormonal function. Finasteride is a widely used chemical that acts to inhibit the conversion of testosterone in its most active form, dihydrotestosterone. It is known that intrauterine exposure to finasteride causes changes in the male prostate even at low dosages; however, it is not known whether these dosages are capable of causing changes in the female prostate, which is present in a large number of mammalian species, including humans. In the present study, histochemistry, immunohistochemistry, immunofluorescence, serological dosages, and three-dimensional reconstruction techniques were employed to evaluate the effects of intrauterine exposure to a low dose of finasteride (100 μg.BW/d) on postnatal prostate development in male and female Mongolian gerbils. The results indicate that the gerbil female prostate also undergoes alterations following intrauterine exposure to finasteride, exhibiting a thickening of periductal smooth muscle and increased stromal proliferation. There are also intersex differences in the impact of exposure on the expression of the androgen receptor, which was increased in males, and of the estrogen-α receptor, which was decreased in the male prostate but unchanged in females. Altogether, this study indicates there are sex differences in the effects of finasteride exposure even at low dosages.

Differences between male and female prostates in terms of physiology, sensitivity to chemicals and pathogenesis-A review in a rodent model

The prostate is a gland that is not exclusively present in males, being also found in females of several mammalian species, including humans. There is evidence that the prostate in both sexes is affected by the same pathologies such as prostatitis, benign alterations and even cancer. In view of the difficulties of manipulating the prostate gland, the Mongolian gerbil (Meriones unguiculatus), a rodent species with high incidence of functional prostates in females, is widely used in studies of the female prostate. However, despite knowing much about the similarities between the female and male prostate, little emphasis has been placed on the differences between them. This review investigates the intersex differences in prostate development, physiology and pathogenesis. The female prostate develops earlier than in males and studies indicate that it is more sensitive to oestrogens than the male prostate, as well as being more sensitive to exposure to xenoestrogens, such as Bisphenol A and methylparaben, with a higher susceptibility to benign lesions in the adult and senile prostate than in males. In addition, the female prostate is impacted by pregnancy and the oestrous cycle, and is also dependent on progesterone. The peculiarities of the female prostate raise concerns about the risk of it undergoing neglected changes as a result of environmental chemicals, since safe dosages are established exclusively for the male prostate.

Effects of gestational exposure to di-n-butyl phthalate and mineral oil on testis development of the Mongolian gerbil

Phthalate esters are endocrine disrupters that can affect the development of the testis in a species-specific manner. However, their interference in the male gonads of the Mongolian gerbil is unknown. The aim of the present study was to evaluate whether gestational exposure to di-n-butyl phthalate (DBP) interferes with the development of the gerbil testis during the first six weeks of life. Males were evaluated at 1, 7, 14, 28, 35 and 42 days of age in an untreated (control) group or groups exposed from 8 to 23 days gestation to DBP (100 mg kg−1 day−1 in mineral oil) or vehicle by maternal gavage. DBP exposure impaired cell proliferation within the seminiferous cords at birth, but increased proliferation at the end of the first week, when higher testosterone concentrations were observed. The vehicle (mineral oil) reduced the total number of gonocytes and attenuated the decrease in testosterone concentrations at 7 days. The vehicle also altered gonocyte relocation at 14 days and increased oestrogen concentrations at 28 days by approximately 112%. In summary, both DBP and oil interfered in gonadal development and testosterone plasma concentrations in the first week of postnatal life. However, the changes observed at the beginning of puberty were not seen after exposure to DBP, indicating a more harmful effect of mineral oil in this period.

Prenatal and pubertal testosterone exposure imprint permanent modifications in the prostate that predispose to the development of lesions in old Mongolian gerbils

The prostate is an accessory sex gland that develops under precise androgenic control. It is known that hormonal imbalance may disrupt its development predisposing this gland to develop diseases during aging. Although the hypothesis regarding earlier origins of prostate diseases was proposed many years ago, the mechanisms underlying this complex phenomenon are poorly understood. Therefore, the aim of this study was to evaluate the prostates of old male gerbils exposed to testosterone during intrauterine and postnatal life using morphological, biometrical, stereological, Kariometric, immunohistochemical, and immunofluorescence analyses. Our findings demonstrate that prenatal and pubertal exposure to testosterone increases the susceptibility to the development of prostate diseases during aging. The presence of a more proliferative gland associated with foci of adenomatous hyperplasia in animals exposed to testosterone during the prenatal and pubertal phase show that the utero life and the pubertal period are important phases for prostatic morphophysiology establishment, which is a determinant for the health of the gland during aging. Therefore, these findings reinforce the idea that prostate disease may result from hormonal disruptions in early events during prostate development, which imprint permanently on the gland predisposing it to develop lesions in later stages of life.

Pubertal exposure to ethinylestradiol promotes different effects on the morphology of the prostate of the male and female gerbil during aging

In rodents, the final growth and maturation of the prostate occur at puberty, a crucial period for prostate development. The present study is a serological, morphological, morphometric, and immunohistochemical analysis of the effects of exposure to ethinylestradiol (EE) (15 µg/kg/day) during puberty (EE/PUB group) on the male ventral and female prostate in senile gerbils. In the study, male and female gerbils (Meriones unguiculatus) (42 days) received by gavage 15 μg/kg/day of EE (a component of the contraceptive pill), diluted in 100 µL of Nujol® for 1 week (EE/PUB group). In the control group, males and females were not treated. Animals were killed (n = 5) after 12 months in the experimental groups. In the senile male in the EE/PUB group, we observed a reduction in testosterone levels and a decrease in the prostatic epithelial thickness, as well as in the thickness of the muscle layer. In addition, an increase in PIN multiplicity and prostatic inflammation was observed. In the senile female in the EE/PUB group, we observed increased testosterone and estradiol levels, an enhanced prostatic epithelial thickness and an increase in the thickness of the muscle layer. Immunohistochemical analysis revealed an increase in positive cells (%) for AR and PCNA in the male prostate and an increase in positive basal cells for p63 in the female prostate of the EE/PUB group. Exposure to EE during puberty resulted in an inhibitory action on the male ventral prostate and an anabolic effect on the female prostate in senile gerbils. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 477-489, 2017.

Acute exposure to bisphenol A and cadmium causes changes in the morphology of gerbil ventral prostates and promotes alterations in androgen-dependent proliferation and cell death

Bisphenol A (BPA) and cadmium (Cd) are environmental pollutants that are implicated in potential reproductive effects, including damage to the prostate gland. Their action during puberty requires analysis to determine the relationship of these compounds with the testosterone peak that occurs during this phase. This study evaluated whether exposure to BPA and Cd during puberty can cause changes in the morphology, proliferation and cell death and androgen receptor (AR) immunostaining of the ventral prostates of normal and castrated male gerbils (Meriones unguiculatus), considering an acute exposure to the chemicals and evaluation after short (52d) and long (120d) periods. Generally, morphometric-stereological results demonstrated that administration of BPA and Cd (individually or in combination) increased epithelial height, smooth muscle layer (SML) thickness and nuclear area and perimeter, and that these parameters were reduced in castrated animals. In addition, these groups showed important inflammatory processes but not prostate lesions. The proliferation/death rates of prostatic cells obtained by PCNA and TUNEL immunostaining demonstrated increased cell death in the 52d groups; in contrast, the gland acquired a more proliferative nature in the 120d groups. AR immunostaining showed that BPA and Cd compounds interact with ARs in different ways depending on the evaluated period and the hormonal profile of the animal. We conclude that BPA and cadmium are important agents in changing the morphology, proliferation and death of prostatic cells, in addition to interacting with ARs in different patterns. © 2015 Wiley Periodicals, Inc. Environ Toxicol 32: 48-61, 2017.

Neonatal exposure to ethinylestradiol increases ventral prostate growth and promotes epithelial hyperplasia and inflammation in adult male gerbils

The aim of this study was to analyse morphologically the ventral prostate of adult Mongolian gerbils exposed to ethinylestradiol (EE) during the first week of postnatal development. Lactating females received daily, by gavage, doses of 10 μg/kg of EE diluted in 100 μl of mineral oil from the 1st to 10th postnatal day of the pups (EE group). In the control group (C), the lactating females received only the vehicle. Upon completing 120 days of age, the male offspring were euthanized and the prostates collected for analyses. We employed morphological, stereological-morphometrical, immunohistochemical and ultrastructural methods. The results showed that the postnatal exposure to EE doubled the prostatic complex weight, increasing the epithelial and stromal compartments, in addition to the secretory activity of the ventral lobe of the prostate. All glands exposed to EE showed strong stromal remodelling, and some foci of epithelial hyperplasia and inflammatory infiltrate in both luminal and epithelial or stromal compartments. Cells positive for anti-AR and anti-PCNA reactions increased into the epithelial and stromal tissues. ERα-positive cells, which are normally found in the stromal compartment of intact prostates, were frequently observed in the prostatic epithelium of treated animals. This study demonstrated that the exposure to EE during postnatal development causes histophysiological alterations in this gland, predisposing to the development of prostatic lesions during life. These results are important for public health, considering that women worldwide have commonly used EE. Moreover, the bioaccumulation of this chemical has increased in different ecosystems.

Prenatal testosterone exposure as a model for the study of endocrine-disrupting chemicals on the gerbil prostate

The development of the prostate depends on a precise androgenic control, so sensible interferences may predispose this gland to develop prostatic diseases during life. These aspects are of interest and preoccupation, since human beings are exposed to a growing number of endocrine-disrupting chemicals with androgenic potential. Therefore, our aim was to evaluate the prostates of adult gerbils exposed to testosterone during intrauterine life. Serological, morphological, morphometric-stereologic, immunohistochemical and three-dimensional reconstruction analyses were used. We found that the testosterone effects were dose-dependent and more harmful to females, leading to the development of masculine characteristics, evidenced by an increased anogenital distance, and absence of vaginal opening and the ectopic development of prostatic tissue. Moreover, premalignant lesions, such as prostatic intraepithelial neoplasia, were observed in addition to inflammatory foci in the prostate. The results showed that the prenatal exposure to testosterone may affect the reproductive system, disrupting developmental processes and increasing susceptibility to the development of prostatic diseases in the Mongolian gerbil.

Postnatal development of Mongolian gerbil female prostate: An immunohistochemical and 3D modeling study

The development of the prostate in male rodents, which involves complex epithelial-mesenchymal interactions between the urogenital sinus epithelium (UGE) and the urogenital sinus mesenchyme (UGM), has been deeply studied. In females, however, this process is not very clear. In this study, the postnatal development of the prostate in female Mongolian gerbils employing three-dimensional (3D) reconstructions, histochemical, and immunohistochemical techniques was characterized. It was observed that prostatic branching and differentiation in females was induced by a single mesenchyme localized at a ventrolateral position, which was named as ventrolateral mesenchyme (VLM); furthermore, the canalization of solid buds began on the third postnatal day (P3) and the branching morphogenesis on P5. We observed secretions in the acini at the end of the first month, and, on P45, the acini were completely differentiated. The strong cell proliferation phase in the first week coincided with the mesenchymal expression of estrogen receptor 1 (ESR1). The expression of androgen receptor (AR) paralleled cell differentiation, and, on P30, immunolabelling with p63 was restricted to basal cells. This study serves as a baseline parameter for future research on disruptions that could affect the development of the female prostate.

Prenatal exposure to ethinylestradiol alters the morphologic patterns and increases the predisposition for prostatic lesions in male and female gerbils during ageing

Ethinylestradiol (EE) is an endocrine disruptor (ED) which acts as an oestrogen agonist; this compound is known as an oral contraceptive. Male and female rodents exposed to EE during critical time points of development, such as in the prenatal period, show alterations in their reproductive tract during adulthood. Few studies have placed an emphasis on the effects of EE during ageing. Thus, this study had as it's objective the analysis of the morphological and immunohistochemical effects of exposure to EE in the prenatal period on ventral male prostate and female prostate of gerbils (Meriones unguiculatus) during ageing. The animals were exposed to EE (15 μg/kg/day) during the 18-22th days of prenatal life (EE/PRE group), and the analyses were performed when the male and female reached 12 months of age. Our results showed an increase in the development of prostatic intraepithelial neoplasia (PIN), which was observed in the male and female prostate of EE/PRE groups. Immunohistochemistry showed a rise in prostatic epithelial and basal cells immunoreactivity, respectively, and to AR and p63 in the male EE/PRE. There were alterations in the morphological pattern of the prostatic glands and increase in predisposition to emergence of prostatic lesions of both sexes during ageing. Despite male and female having been exposed to the same doses of EE, the "exposure to EE promoted modifications" more accentuated in the male prostate. Thus the male gland is more sensitive to the action of this synthetic oestrogen than the female prostate.

Bisphenol-A promotes antiproliferative effects during neonatal prostate development in male and female gerbils

The aim of this study was to evaluate the development of male and female neonatal gerbil prostate under normal conditions and exposed to bisphenol-A (BPA). Normal postnatal development of the female gerbil prostate occurs earlier than and is morphologically distinct from that occurring in males. In BPA-exposed PND8 gerbils, we have not observed evidence of alterations in the ductal branching in either gender. However, the exposure to BPA alters the immunolabeling pattern of AR, ERα, and PCNA. In males, the exposure to high dosages of BPA resulted in a decrease in the proliferative status of the developing ventral prostate. In females, both high and low dosages were sufficient to decrease the proliferation of paraurethral buds in the branching process by more than 50%. Therefore, the obtained data indicate that BPA promotes antiproliferative effects during the neonatal development of the gerbil prostate, with more sensitivity to this endocrine disruptor in females.

Actions of oestradiol and progesterone on the prostate in female gerbils: reversal of the histological effects of castration

The female prostate is a functionally active gland in several mammalian species, including humans and rodents. Investigations of prostate morphophysiology during the phases of the oestrous cycle have shown that the female prostate is influenced by fluctuations in serum concentrations of oestradiol (E2) and progesterone (P4). The aim of the present study was to evaluate the effect of combined prolonged administration of E2 and P4 on the prostate in ovariectomised female gerbils. Ovariectomy caused atrophy and decreased glandular secretory activity. Administration of E2 and P4 (0.1mgkg(-1) diluted in 0.1mL of mineral oil, every 48h over 30 days) resulted in a recovery of overall prostate structure, as evidenced by increased epithelial height, mass and prostatic secretory activity, without leading the appearance of significant lesions. Evaluation of androgen receptor (AR) expression revealed increased immunoreactivity in the E2+P4-treated group. Immunostaining for oestrogen receptor (ER) α was decreased in the castrated groups, but increased in the group subjected to hormone treatment. There were no significant differences in ERβ immunoreactivity among the groups. Assessment of cell proliferation revealed greater immunoreactivity in the treated group. Together, the results indicate that the interaction between E2 and P4 may be responsible for maintaining female prostate gland histophysiology.

Budding process during the organogenesis of the ventral prostatic lobe in Mongolian gerbil

The prostate is a mammalian gland that shows a complex process of organogenesis. Here, a morphological study to characterize the organogenesis of the ventral prostate lobe in male gerbils was conducted. The urogenital sinus (UGS) was dissected out and processed for paraffin embedding. Histological sections were subjected to cytochemical, immunofluorescence, immunohistochemical, and three-dimensional reconstruction techniques. We found that the first ventral buds emerged from the ventral urethral epithelium between the days 20 and 21 of prenatal life, reaching the ventral mesenchymal pad and initiating the branching process on the first day of postnatal life. The buds presented a V-shaped elongation, suggesting that the smooth muscle layer (SML) plays an important role during budding events. Indeed, whereas the androgen receptor (AR) was preferentially found in the UGS mesenchyme (UGM), estrogen receptor alpha (ERα) was localized in both the UGM and in the emerging buds. This study characterized the morphological aspects of the budding process in a different rodent from rat and mice, serving as a new model for future studies on developmental biology of the prostate.