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

The Mongolian Gerbil as a Useful Experimental Model in Reproductive Biology

Ultimately, the Mongolian gerbils (Meriones unguiculatus) have acquired a relevant role in biological and biomedical experiments alongside other rodents. The use of gerbils in research has been mainly oriented to physiological and pharmacological studies, with special attention to nervous, digestive, and auditory systems as well as microbiology and parasitology. Ultimately, gerbils have also been applied for studying carcinogenesis in different organs and systems, since these animals show a natural propensity to develop spontaneous proliferative lesions, especially in steroid-responsive organs. This characteristic shed light on the reproductive aspects of this rodent model regarding morphological features in male and female individuals. This review of literature summarizes the significance of this model as an alternative to the use of inbred mice and rats in reproductive experimental research, highlighting recent findings. Gerbils have contributed to the expansion of knowledge in prostate biology in male and female individuals, providing studies related to prostatic morphogenesis and neoplasia. In the testes, spermiogenesis occurs in 15 steps, differently from other experimental models. Also, the complete maturation of the testis-epididymal complex occurs between the second and third months. Mammary gland alterations related to the estrous cycle and pregnancy were described, as well as its modulation under endogenous and exogenous estrogenic compounds. The ovaries frequently present ovarian cysts. Furthermore, this organ shows predominantly interstitial steroidogenic glands in the stroma, especially at aging. Adrenal gland shows a large size compared to other animals, presenting three distinct zones with a remarkable role in steroidogenesis.

Stromal cell interplay in prostate development, physiology, and pathological conditions

Advances in prostatic stroma studies over the past few decades have demonstrated that the stroma not only supports and nourishes the gland's secretory epithelium but also participates in key aspects of morphogenesis, in the prostate's hormonal metabolism, and in the functionality of the secretory epithelium. Furthermore, the stroma is implicated in the onset and progression of prostate cancer through the formation of the so-called reactive stroma, which corresponds to a tumorigenesis-permissive microenvironment. Prostatic stromal cells are interconnected and exchange paracrine signals among themselves in a gland that is highly sensitive to endocrine hormones. There is a growing body of evidence that telocytes, recently detected interstitial cells that are also present in the prostate, are involved in stromal organization, so that their processes form a network of interconnections with both the epithelium and the other stromal cells. The present review provides an update on the different types of prostate stromal cells, their interrelationships and implications for prostate development, physiology and pathological conditions.

Inflammatory repercussions in female steroid responsive glands after perinatal exposure to bisphenol A and 17-β estradiol

The mammary gland (MG) and female prostate are plastic reproductive organs which are highly responsive to hormones. Thus, endocrine disruptors, such as bisphenol A (BPA) and exogenous estrogens, negatively affect glandular homeostasis. In addition to previously described alterations, changes in inflammatory markers expression also trigger the development of a microenvironment that contributes to tumor progression. The current work aimed to evaluate the inflammatory responses of the MG and prostate gland to BPA (50 µg/kg) and 17-β estradiol (35 µg/kg) exposure during the perinatal window of susceptibility. The results showed that at 6 months of age there was an increase in the number of phospho-STAT3 (P-STAT3) positive cells in the female prostate from animals perinatally exposed to 50 µg/kg BPA daily. In addition, the number of macrophages increased in these animals in comparison with nonexposed animals, as shown by the F4/80 marker. Despite an increase in the incidence of lobuloalveolar and intraductal hyperplasia, the MG did not show any difference in the expression of the four inflammatory markers evaluated: tumor necrosis factor-α, COX-2, P-STAT3, and F4/80. Analysis of both glands from the same animal led to the conclusion that exposure to endocrine disruptors during the perinatal window of susceptibility leads to different inflammatory responses in different reproductive organs. As the prostate is more susceptible to these inflammatory mechanisms, it is reasonable to affirm that possible neoplastic alterations in this organ are related to changes in the inflammatory pattern of the stroma, a characteristic that is not evident in the MG.

The Influence of Pregnancy on Female Prostate Morphophysiology in Gerbils (Meriones unguiculatus)

Morphophysiological changes of the female prostate during pregnancy are still little known. Considering that this gland is highly influenced by steroid hormones, the aim of this study was to evaluate the impact of the pregnancy on female prostate morphophysiology in gerbils. Pregnant females were timed, and the prostates were analyzed at pregnancy days 6 (P6), 12 (P12), 18 (P18), and 24 (P24). Virgin females were used as the control group (C). We observed a profound change in the hormonal profile during gestation, which was marked by a high oscillation of the progesterone (P4) hormone. P4 serum levels increased, peaking at the middle of gestation, and decreased to the end of the pregnancy. The morphology of the gland in pregnant females also changed, being marked by an increase of acini lumen, and a decrease in stroma. Indeed, the acinar changes during pregnancy were followed by a significant reduction of the epithelial height, besides a change of the smooth muscle cells' morphology that became more relaxed. The number of progesterone receptor (PR) and androgen receptor (AR)-positives cells decreased with the increase of progesterone serum levels, showing an inverse relationship. Finally, we observed a reduction of epithelial proliferation and a significant increase of gland PAS-positive secretion at the end of pregnancy. Altogether, these results showed, for the first time, that the female prostate morphophysioloy is profoundly influenced by the gestational period, suggesting that the fluctuation of the P4 serum levels is the main factor influencing the gland during this period.

Testosterone exposure in prenatal life disrupts epithelial nuclear morphology, smooth muscle layer pattern, and FGF10 and Shh expression in prostate

The aim of this study was to evaluate whether high levels of exogenous testosterone (T) interfere in prostate morphogenesis. Pregnant females were exposed to subcutaneous injections of T cypionate (500 μg/animal) at gestational days 20 and 22. Male and female pups were euthanized at postnatal days 1 and 15. 15-day-old males had only fibroblast growth factor 10 (FGF10) immunostaining and nuclear form factor altered by the treatment, whereas treated females (T1 and T15) had almost all analyzed parameters changed. T1 females showed an increased anogenital distance (AGD), whereas T15 females had both AGD and ovary weight increased. T1 females had a higher number of epithelial buds emerging from the urethral and vaginal epithelium. We observed ectopic prostatic tissue surrounding the vagina in both T1 and T15 females. Moreover, the ectopic acini of T15 females showed delayed luminal formation, and there was a thickening of the periacinar smooth muscle layer (SML). Finally, FGF10 immunostaining intensity decreased in both T15 male and female prostates. Indeed, Sonic hedgehog (Shh) was upregulated in T15 female prostates, whereas no difference was observed between the male groups. These data showed that exogenous T changed the nuclear morphology of prostate epithelial cells in both males and females. Surprisingly, smooth muscle hyperplasia was also observed in the ectopic female prostate. Moreover, T downregulated FGF10 in both male and female prostates. Interestingly, the results suggest that FGF10 downregulation is mediated by the upregulation of Shh in females. In conclusion, exogenous T disrupts prostate development, particularly, affecting, the female.

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.

Influence of postnatal prolactin modulation on the development and maturation of ventral prostate in young rats

Besides androgenic dependence, other hormones also influence the prostate biology. Prolactin has been described as an important hormone associated with maintenance of prostatic morphophysiology; however, there is a lack of information on the involvement of prolactin during prostate development and growth. This study aimed to evaluate whether perinatal prolactin modulation interferes with rat ventral prostate (VP) development and maturation. Therefore, prolactin or bromocriptine (an inhibitor of prolactin release from the pituitary) were administered to Sprague Dawley rats from postnatal Day (PND) 12 to PND 21 or 35. Animals were then killed and serum hormonal quantification, VP morphological-stereological and immunohistochemical analyses and western blotting reactions were employed. Our results demonstrate that prolactin blockage increased serum testosterone on PND 21, which reflected an increase in anogenital distance. Although prolactin modulation did not interfere with VP weight, it modified VP morphology by dilating the acinar lumen and reducing epithelial cell height. Prolactin activated the signal transducer and activator of transcription (STAT) downstream pathway, increased androgen receptor expression and epithelial proliferation. In addition, prolactin and bromocriptine also increased expression of cytokeratin 18, a marker of luminal-differentiated cells. In conclusion, the VP responds to prolactin modulation through a mechanism of increasing the epithelial proliferative response and dynamics of cell differentiation, especially in animals treated for a more prolonged period.