Orchidectomy induces a wave of apoptotic cell death in the epididymis

Emerging organoid models to study the epididymis in male reproductive toxicology

The importance of the epididymis on sperm maturation and consequently male fertility has been well documented. The pseudostratified epithelium of the epididymis is comprised of multiple cell types, including principal cells, which are the most abundant, and basal cells. The role of basal cells has been unclear and has been a source of discussion in the literature. However, the recent demonstration that these cells are multipotent or adult stem cells has opened new areas of research in epididymal biology. One such avenue is to understand the regulation of these stem cells, and to exploit their properties to develop tools for toxicological studies to elucidate the effects of chemicals on cell differentiation and epididymal function in vitro. Studies in both rat and mouse have shown that purified single epididymal basal cells cultured under 3D conditions can proliferate and differentiate to form organoids, or mini organs. Furthermore, these epididymal basal stem cells can self-renew and differentiate into other epididymal cell types. It is known that during epididymal development, basal cells are derived from undifferentiated columnar cells, which have been reported to share common properties to stem cells. Like basal cells, these undifferentiated columnar cells can also form organoids under 3D culture conditions and can differentiate into basal, principal and clear cells. Organoids derived from either basal cells or columnar cells offer unique models for toxicology studies and represent an exciting and emerging approach to understand the epididymis.

Cosmetic Appeal, HRQoL, and Effectiveness of Simple and Pseudotesticular Techniques of Orchidectomy in Prostate Cancer

INTRODUCTION

Orchidectomy is the most cost-effective means of hormonal therapy for locally advanced or metastatic prostate cancer (LAMP). However, cost-effectiveness should not detract from health-related quality of life (HRQoL) considerations. Bilateral simple orchidectomy (BSO) has been linked to negative psychometric deficits from an empty scrotum. This study compared the HRQoL, therapeutic efficacy, and cosmetic appeal of BSO with endogenous pseudotesticular techniques of bilateral subcapsular orchidectomy (BSCO) and bilateral-epididymal-sparing orchidectomy (BESO). Research Design. Nigerian patients with LAMP were randomised into three surgical arms: BSO, BSCO, and BESO. Expanded Prostate Cancer Index Composite-26 HRQoL and sociodemographic questionnaires were administered before and three months after orchidectomy. Serum testosterone and PSA were measured at 0, 1, 2, and 3 hours; 7 days; and 3 months postoperatively. Pseudotesticular volumes and cosmetic appeal were assessed at 3 months.

RESULT

Sixty-three patients were recruited (24 BSO, 21 BSCO, 18 BESO), 73% of whom were low-income earners. There was no significant difference in the procedure cost nor the PSA or testosterone nadirs achieved over the three-month follow-up period (11.3, 12.6, 15.2 ng/ml (p=0.667) and 0.44, 0.64, 0.79 nmol/l (p=0.603) respectively). Those with pseudotesticles (BSCO, BESO) felt less emasculated (p=0.010). BSCO produced the least sexual bother, highest sexual function, and largest pseudotesticular volumes. The cosmetic appeal scores were similar between groups (77.9 ± 22.8, 81 ± 13.9, and 81.9 ± 22.5, respectively, p=0.858).

CONCLUSION

Endogenous pseudotesticular techniques, when compared with BSO, reduce the negative psychological impact experienced by patients without increasing costs. BSCO produced the best pseudotesticular volumes and postoperative sexual function. This study is registered with the ClinicalTrials.gov of the National Institute of Health U.S. National Library of Medicine as TEPSO study, NCT03744494: Comparison of the Therapeutic Efficacy and Patient Satisfaction of Three Techniques of Bilateral Orchidectomy in Prostate Cancer Patients of a Nigerian Sub-population. Registration completed on 16th of November, 2018 (registered retrospectively) NCT03744494.

Morphological and morphometric changes and epithelial apoptosis are induced in the rat epididymis by long-term letrozole treatment

The epididymis is an organ that plays a key role in sperm maturation. The aim of this study was to examine the association between the chronic treatment of mature male rats with letrozole and morphological evaluation and morphometric values of epididymis as well as changes in the number of apoptotic cells in epididymal epithelium. Adult rats were treated with letrozole for 6 months and the epididymis weight, morphology, morphometric values and the number of apoptotic cells in  the epithelium were examined. Long-term aromatase inhibition resulted in presence of intraepithelial clear vacuoles, hyperplasia of clear cells and a hyperplastic alteration in the epithelium known as a cribriform change. Moreover, changes in diameters of the epididymal duct and the epididymal lumen and changes in the epididymal epithelium height were observed. The number of apoptotic epithelial cells was increased in letrozole-treated group. It can be indicated that chronic treatment with letrozole can affect morphology, morphometric values and apoptosis in the epididymis of adult male rats. Observed changes are similar to that observed in the aging processes and may also be important for patients treated with aromatase inhibitors.

Examination of testicular lumicrine regulation of activins and immunoregulatory genes in the epididymal caput

BACKGROUND

Immunoregulatory genes encoding activin A (Inhba) and B (Inhbb), and indolamine 2,3-dioxygenase-1 (Ido1) are highly expressed in the murine caput epididymidis, which also has a network of intraepithelial mononuclear phagocytes. This environment is postulated to promote immunological tolerance to epididymal sperm. The factors regulating the immunoregulatory agents in the epididymal caput are poorly understood.

OBJECTIVES

This study aimed to investigate the potential role of testicular lumicrine factors in regulating activin and other immune-related genes in the caput epididymidis.

MATERIALS AND METHODS

The efferent ducts in adult C57/Bl6 mice were exposed and ligated bilaterally. Serum and tissues were collected seven days later. Animals with bilateral sham ligation and animals with no ligations (collectively referred to as the "intact" group) were used as controls.

RESULTS

Pressure-induced seminiferous epithelial damage due to intratubular fluid accumulation was observed in all ligated testes. Testicular inhibin was significantly increased and testosterone was elevated in some animals following bilateral ligation, but serum testosterone, serum LH, and serum inhibin were normal. Ligation caused epithelial regression in the initial segment, with similar but less severe effects in other caput segments. Activin A staining by immunohistochemistry in the epithelium was reduced in bilateral ligation, particularly in the initial segment, with moderately reduced staining intensity in the rest of the caput. Inhba expression within the caput was not significantly affected by bilateral ligation, but Inhbb was reduced by more than 60%. Transcripts encoding the macrophage-specific receptor Cx3cr1 were significantly reduced following bilateral ligation, but other immune cell markers, Ido1, and inflammatory genes were unaffected.

CONCLUSION

These data indicate that testicular lumicrine secretion regulates several genes that are preferentially expressed in the initial segment, but has marginal effects on genes such as those encoding activin A and IDO1, which are expressed more widely in the caput.

Aquaporins Are Differentially Regulated in Canine Cryptorchid Efferent Ductules and Epididymis

Simple Summary

The distribution and expression of aquaporins (AQPs) in the testes and spermatozoa of several animal species play important roles in spermatogenesis and spermatozoon transit in this region. The aim of this study was to evaluate AQP7, AQP8, and AQP9 localization and expression in the efferent ductules and epididymal regions (the caput, corpus, and cauda) of normal and cryptorchid dogs. The results from immunohistochemistry, Western blotting, and real-time reverse transcription polymerase chain reaction (RT-PCR) show regional tissue distributions, particularly at the level of the epithelium of efferent ductules and both the regions caput and cauda of the canine cryptorchid epididymis. These findings support the hypothesis that these channel proteins respond differently to multiple stimuli that cause cryptorchidism (hormones, heat, osmolarity, etc.) and participate in the mechanisms of cell “resilience” or apoptosis taking place in the epididymis.

Abstract

The efferent ductules and the epididymis are parts of the male reproductive system where spermatozoa mature. Specialized epithelial cells in these ducts contribute to the transport of fluids produced by spermatozoa’s metabolic activity. Aquaporins (AQPs) have been demonstrated to be expressed in the spermatozoan membrane and testis epithelial cells, where they contribute to regulating spermatozoan volume and transit through environments of differing osmolality. Due to the lack of detailed literature regarding AQP expression in the canine male genital tract, the aim of this study was to investigate both the distribution and expression of AQP7, AQP8, and AQP9 in the efferent ductules and epididymal regions (caput, corpus, and cauda) from normal and cryptorchid dogs by using immunohistochemistry, Western blotting, and real-time reverse transcription polymerase chain reaction (RT-PCR). Our results show different patterns for the distribution and expression of the examined AQPs, with particular evidence of their upregulation in the caput and downregulation in the cauda region of the canine cryptorchid epididymis. These findings are associated with a modulation of Hsp70 and caspase-3 expression, suggesting the participation of AQPs in the luminal microenvironment modifications that are peculiar characteristics of this pathophysiological condition.

Castration causes an increase in lysosomal size and upregulation of cathepsin D expression in principal cells along with increased secretion of procathepsin D and prosaposin oligomers in adult rat epididymis

In the epididymis, lysosomal proteins of the epithelial cells are normally targeted from the Golgi apparatus to lysosomes for degradation, although their secretion into the epididymal lumen has been documented and associated with sperm maturation. In this study, cathepsin D (CatD) and prosaposin (PSAP) were examined in adult epididymis of control, and 2-day castrated rats without (Ct) and with testosterone replacement (Ct+T) to evaluate their expression and regulation within epididymal epithelial cells. By light microscope-immunocytochemistry, a quantitative increase in size of lysosomes in principal cells of Ct animals was noted from the distal initial segment to the proximal cauda. Androgen replacement did not restore the size of lysosomes to control levels. Western blot analysis revealed a significant increase in CatD expression in the epididymis of Ct animals, which suggested an upregulation of its expression in principal cells; androgens restored levels of CatD to that of controls. In contrast, PSAP expression in Ct animals was not altered from controls. Additionally, an increase in procathepsin D levels was noted from samples of the epididymal fluid of Ct compared to control animals, accompanied by an increased complex formation with PSAP. Moreover, an increased oligomerization of prosaposin was observed in the epididymal lumen of Ct rats, with changes reverted to controls in Ct+T animals. Taken together these data suggest castration causes an increased uptake of substrates that are acted upon by CatD in lysosomes of principal cells and in the lumen by procathepsin D. These substrates may be derived from apoptotic cells noted in the lumen of proximal regions and possibly by degenerating sperm in distal regions of the epididymis of Ct animals. Exploring the mechanisms by which lysosomal enzymes are synthesized and secreted by the epididymis may help resolve some of the issues originating from epididymal dysfunctions with relevance to sperm maturation.

Apoptosis in epididymis of sand rat Psammomys obesus, Cretzschmar, 1828: Effects of seasonal variations, castration and efferent duct ligation

The aim of this study was to visualize apoptosis throughout the reproductive cycle and after castration, castration then treatment with testosterone, and ligation of efferent ducts. The sand rat, Psammomysobesus, Cretzschmar 1828, is a diurnal rodent belonging to the family Gerbillidae. Its breeding cycle is seasonal with reproduction in autumn, winter and early spring and a short resting period from late spring to early summer. Five groups of males were studied: (1) animals captured during the breeding season; (2) animals captured during the resting season; (3) animals castrated and kept 30 days; (4) animals castrated, kept 30 days, and then treated with testosterone for 15 days; (5) animals subjected to the ligation of efferent ducts and kept 30 days. Epididymis were removed and the presence of apoptotic cells was explored using the "Apostain" immunohistochemical method. Histological results showed cell and tissue remodeling. During the breeding season, a positive apoptotic signal was observed mainly in smooth muscle cells of caput and cauda epididymis. This signal persisted throughout the resting season. The orchiectomy induced apoptosis in almost of epithelial and connective cells. However, this intense cell death was not reversed by treatment with testosterone. In animals that experienced efferent duct ligation, principal cells and smooth muscle cells showed a positive signal for apoptosis. Our results converge to qualify the sand rat epididymis as an excellent model for the study of apoptosis and argue for continued cell death, at least independent of circulating testosterone levels.

Pfaffia glomerata hydroalcoholic extract stimulates penile tissue in adult Swiss mice

ETHNOPHARMACOLOGICAL RELEVANCE

Roots of Pfaffia glomerata are used in traditional medicine as aphrodisiacs and sexual stimulants.

AIM OF THE STUDY

The aim of this study was to evaluate the action of the hydroalcoholic extract from the roots of Pfaffia glomerata on the Leydig cells, cavernous bodies and other penile constituents, as well as on serum testosterone and 17β-estradiol levels of adult mice.

MATERIALS AND METHODS

Mature male Swiss mice were divided into 6 groups: control (water), sildenafil citrate, 3 groups receiving daily doses of P. glomerata extract (100, 200 and 400 mg/kg) and one group receiving intermittent doses of P. glomerata (200 mg/kg/3-3d).

RESULTS

The proportions of blood vessels, lymphatic space and estradiol levels were increased. On the other hand, reduction of testosterone levels due to Leydig cells death was observed. As for penile parameters, volumetric proportions of cavernous bodies, collagen and nitric oxide were increased, while smooth muscle content was decreased.

CONCLUSIONS

Despite that the long term intake of P. glomerata extract was related to a stimulant action, reduction on Leydig cell viability induced decreased testosterone production.

Epididymal contribution to male infertility: An overlooked problem

The diagnosis and treatment of male infertility, excluding assisted conception, are limited because of, but not limited to, poor understanding of sperm post-testicular development and storage. Many may think that sperm dysfunction is only self-contained in the sperm cell itself as a result of defective spermatogenesis. However, it can also be a consequence of inadequate epididymal maturation following disorders of the epididymis. Improper epididymal functions can disturb semen parameters and sperm DNA integrity, result in high leucocyte concentrations and high numbers of immature germ cells and debris or even cause idiopathic infertility. To date, the data are limited regarding critical markers of sperm maturation and studies that can identify such markers for diagnosis and managing epididymal dysfunction are scarce. Therefore, this article aims to draw attention to recognise a disturbed epididymal environment as a potential cause of male infertility.

Androgens are essential for epithelial cell recovery after efferent duct ligation in the initial segment of the mouse epididymis†

Efferent duct ligation (EDL) induces epithelial cell degeneration followed by regeneration in the epididymal initial segment. We tested here the role of androgens in the recovery phase. EDL was performed at post-natal weeks (PNW) 3, 4, 5, 6, and 7, and apoptotic and proliferating epithelial cells were quantified 24 h, and at days 2 and 2.5 post-EDL, respectively. A progressive increase in the number of apoptotic basal cells (BCs) and principal cells (PCs) was detected from PNW3 to 6, 24 h after EDL. Two days after EDL, no increase in proliferating BCs and PCs was observed at PNW3 and 4, despite the induction of apoptosis by EDL. A progressive increase in the number of proliferating BCs was then observed from PNW5 to 6, while the number of proliferating PCs remained low. 2.5 days after EDL, the number of proliferating BCs and PCs remained low at PNW3, 4, and 5, but a marked increase in the number of proliferating PCs was observed at PNW6. Flutamide pretreatment for 3 weeks followed by EDL at PNW7 dramatically decreased the number of proliferating BCs on EDL day 2, and the number of proliferating PCs on EDL day 2.5, compared to controls. We conclude that (1) BCs are the first to show recovery after EDL, followed by PCs; (2) androgens are essential for BC and PC repair after injury in the postpubertal epididymis; and (3) the prepubertal epididymis lacks repair ability following injury.

Tissue regeneration and the epididymal stem cell

BACKGROUND

In most pseudostratified epithelia, basal cells represent a multipotent adult stem cell population. These cells generally remain in a quiescent state, until they are stimulated to respond to tissue damage by initiating epithelial regeneration. In the epididymis, cell proliferation occurs at a relatively slow rate under normal physiological conditions. Epididymal basal cells have been shown to share common properties with multipotent adult stem cells. The development of organoids from stem cells represents a novel approach for understanding cellular differentiation and characterization of stem cells.

OBJECTIVE

To review the literature on tissue regeneration in the epididymis and demonstrate the presence of an epididymal stem cell population.

METHODS

PubMed database was searched for studies reporting on cell proliferation, regeneration, and stem cells in the epididymis. Three-dimensional cell culture of epididymal cells was used to determine whether these can develop into organoids in a similar fashion to stem cells from other tissues.

RESULTS

The epididymal epithelium can rapidly regenerate following orchidectomy or efferent duct ligation, in order to maintain epithelial integrity. Studies have isolated a highly purified fraction of rat epididymal basal cells and reported that these cells displayed properties similar to those of multipotent adult stem cells. In two-dimensional cell culture conditions, these cells differentiated into cells which expressed connexin 26, a marker of columnar cells, and cytokeratin 8. Furthermore, three-dimensional cell culture of epididymal cells resulted in the formation of organoids, a phenomenon associated with the proliferation and differentiation of stem cells in vitro.

CONCLUSIONS

The rapid proliferation and tissue regeneration of the epididymal epithelium to preserve its integrity following tissue damage as well as the ability of cells to differentiate into organoids in vitro support the notion of a resident progenitor/stem cell population in the adult epididymis.

Seasonal variation of cell proliferation and apoptosis in the efferent ductules and epididymis of the Neotropical bat Artibeus lituratus (Chiroptera, Phyllostomidae)

The balance between cell proliferation and apoptosis is important for maintenance of male fertility, being influenced by a variety of stimuli including androgens and estrogens. However, studies concerning regulation of these processes along the male reproductive tract under physiological conditions are scarce. Therefore, in this study, we investigated the profile of cell proliferation and apoptosis in the efferent ductules and epididymis of the Neotropical bat Artibeus lituratus, a seasonal breeder that presents natural variation in components of the androgen and estrogen responsive systems along the circannual cycle. Low rates of cell proliferation and apoptosis were found in the efferent ductules and epididymis of A. lituratus during the reproductive period, as few epithelial cells were positive for MCM7 (proliferation marker) and cleaved caspase-3 or TUNEL (apoptosis markers). In contrast, during the regressive period, the rate of both proliferating and apoptotic cells was significantly higher in the epithelium lining the efferent ductules as well as throughout the epididymis. The increased proliferative activity at this phase was positively correlated with the expression of estrogen receptor alpha (ERα), whereas the variation in apoptosis appears to be unrelated to the local expression of androgen and estrogen receptors. Together, these data suggest that cell proliferation and apoptosis are differentially modulated in the efferent ductules and epididymis of A. lituratus during the annual reproductive cycle, and support the hypothesis that ERα may be important in preparing the male reproductive tract for sexual recrudescence.

Ethylene dimethane sulfonate (EDS) ablation of Leydig cells in adult rat depletes testosterone resulting in epididymal sperm granuloma: Testosterone replacement prevents granuloma formation

Sperm granuloma may develop in the epididymis following vasectomy or chemical insults. Inflammation due to sperm granuloma causes abdominal and scrotal pain. Prolonged and persistent inflammation in the epididymis due to sperm granuloma may lead to infertility. Extravasation of germ cells into the interstitium of epididymis following damage of the epididymal epithelium is one of the primary reasons for sperm granuloma-associated pathology. Since testosterone is vital for the maintenance of epididymal epithelium, we investigated the pathology of sperm granuloma and its relationship with testosterone. Adult rats were treated with a Leydig cell-specific toxicant ethylene dimethane sulfonate (EDS) to eliminate testosterone. At 7 days post-EDS, disrupted epididymal epithelium and sperm granuloma were observed in the caput epididymis. Sperm granuloma and caput were collagen-filled indicating fibrosis. Numerous round apoptotic cells were localized inside the caput lumen and dispersed through the sperm granuloma. Tnp1 (round spermatid marker) was significantly higher in the epididymis of the EDS-treated group compared to controls suggesting the apoptotic cells were round spermatids. Increases in CD68⁺ macrophages and T cells (CD4 and CD8) support an inflammatory immune infiltration in post-EDS epididymis. However, testosterone replacement following EDS prevented the sperm granuloma-associated pathology. We suggest that the immune response in the sperm granuloma may be due to the increased numbers of apoptotic round spermatids or other testicular tissue components that may be released, in addition to the regression of epididymal epithelium due to testosterone loss. Thus, testosterone replacement prevents EDS-induced sperm granuloma and ameliorates sperm granuloma-associated pathology.

Regulation of apical blebbing in the porcine epididymis

Apical blebbing, a non-classical secretion mechanism, occurs in the mature porcine epididymis as part of its normal function. Proteins secreted by this mechanism contribute to the modification of the sperm plasma membrane during epididymal transit and are thought to contribute to acquisition of fertilizing ability. However, little is known about the regulation of this secretion mechanism in an in vivo model. Previous work demonstrated apical blebbing in the epididymis developed pubertally, suggesting androgens, sperm or other luminal factors regulated this process. Hence, the objective was to evaluate the hypothesized regulation of apical blebbing in the epididymis of pubertal boars by androgens and luminal factors. Androgen receptor blockade (flutamide) and surgical interventions (efferent duct ligation, orchidectomy or transection of the caput epididymis) were used to alter signaling, and the subsequent effects on apical blebbing were evaluated histologically. Apical blebbing was not altered by androgen receptor blockade with flutamide, but was significantly reduced 24 h after efferent duct ligation and after orchidectomy, treatments that eliminated luminal flow from the testis (P < 0.05). Like efferent duct ligation, epididymal transection altered luminal flow without removing the androgen source and significantly reduced the appearance of apical blebbing (P < 0.05). In conclusion, apical blebbing in the porcine epididymis appears to be regulated by luminal factors.

Regulation of epithelial function, differentiation, and remodeling in the epididymis

The epididymis is a single convoluted tubule lined by a pseudostratified epithelium. Specialized epididymal epithelial cells, the so-called principal, basal, narrow, and clear cells, establish a unique luminal environment for the maturation and storage of spermatozoa. The epididymis is functionally and structurally divided into several segments and sub-segments that create regionally distinct luminal environments. This organ is immature at birth, and epithelial cells acquire their fully differentiated phenotype during an extended postnatal period, but the factors involved in this complex process remain incompletely characterized. In the adult epididymis, the establishment of an acidic luminal pH and low bicarbonate concentration in the epididymis contributes to preventing premature activation of spermatozoa during their maturation and storage. Clear cells are proton-secreting cells throughout the epididymis, but principal cells have distinct acid/base transport properties, depending on their localization within the epididymis. Basal cells are located in all epididymal segments, but they have a distinct morphology depending on the segment and species examined. How this structural plasticity of basal cells is regulated is discussed here. Also, the role of luminal factors and androgens in the regulation of epithelial cells is reviewed in relation to their respective localization in the proximal versus distal regions of the epididymis. Finally, we describe a novel role for CFTR in tubulogenesis and epithelial cell differentiation.

Epididymis of Viscacha (Lagostomus maximus maximus): A Morphological Comparative Study in Relation to Sexual Maturity

The morphological variations and the androgen receptor (AR) expression were studied in viscacha epididymis in relation to sexual maturity. The animals were divided into immature, pre-pubertal and adult, according to their corporal weight and testicular histology. The epididymides were studied by light microscopy, immunohistochemistry for AR and morphometric analysis. In pre-pubertal and adult animals, four well-differentiated segments (initial, caput, corpus and cauda) were observed, while in immature animals, three segments were identified (initial-caput segment, corpus and cauda). In each segment, the structural parameters and the relative cell distribution were different between the groups. The serum testosterone levels of pre-pubertal and adults showed a very significant increase related to sexual maturity. The AR expression in epithelial and fibromuscular stromal cells was different between the groups. In conclusion, the present work demonstrates that the morphological characteristics of the viscacha epididymis vary while sexual maturity is reached, the development of initial and caput is subsequent to corpus and cauda development and the androgens might play an important role during this process.

Apoptosis in the Epididymal Epithelium of Adult Male Golden Hamster Exposed to Diethylstilbestrol

Apoptosis in the testis and prostate exposed to disrupters of endocrine function, including diethylstilbestrol (DES), during neonatal or postnatal periods has repeatedly been demonstrated, but not in the mature epididymis. We investigated the effects of DES, a potent and synthetic estrogen, on apoptosis in the adult. Adult male golden hamsters received an SC injection of DES and were then sacrificed to collect epididymides after 1, 4, or 7 days of treatment. A significant decrease in epididymal weight and an increase in apoptotic cells were shown on the first day after DES injection. Flow cytometry showed that DES treatment (1 mg/kg) for 1, 4, or 7 days induced significant apoptosis both in the caput and the cauda epididymides. Greater numbers of apoptotic cells were detected in the caput than in the cauda at a fixed time after DES treatment. Serum levels of testosterone decreased markedly within 24 hr after DES administration, reaching undetectable levels of 0.1 ng/ml at 4 days and thereafter. These results indicate that DES administration can increase epididymal apoptosis with a decrease in serum testosterone levels. Because DES used to be injected into domestic animals, adult males also have a chance to take this substance through food. Our study indicates that exposure to DES in adults is as toxic as that in the perinatal period.

Development of apical blebbing in the boar epididymis

Microvesicles are of increasing interest in biology as part of normal function of numerous systems; from the immune system (T cell activation) to implantation of the embryo (invasion of the trophoblasts) and sperm maturation (protein transfer in the epididymis). Yet, the mechanisms involved in the appearance of apical blebbing from healthy cells as part of their normal function remain understudied. Microvesicles are produced via one of two pathways: exocytosis or apical blebbing also termed ectocytosis. This work quantifies the histological appearance of apical blebbing in the porcine epididymis during development and examines the role of endogenous estrogens in regulating this blebbing. Apical blebbing appears at puberty and increases in a linear manner into sexual maturity suggesting that this blebbing is a mature phenotype. Endogenous estrogen levels were reduced with an aromatase inhibitor but such a reduction did not affect apical blebbing in treated animals compared with their vehicle-treated littermates. Epididymal production of apical blebs is a secretion mechanism of functionally mature principal cells regulated by factors other than estradiol.

Dynamic changes in the spatio-temporal expression of the β-defensin SPAG11C in the developing rat epididymis and its regulation by androgens

Herein, we characterized the spatio-temporal expression, cellular distribution and regulation by androgens of the β-defensin SPAG11C, the rat ortholog of the human SPAG11B isoform C, in the developing epididymis by using RT-PCR, in situ hybridization and immunohistochemistry. We observed that Spag11c mRNA was ubiquitously expressed in rat fetuses, but preferentially detected in male reproductive tissues at adulthood. SPAG11C (mRNA and protein) was prenatally mainly detected in the mesenchyme of the Wolffian duct, switching gradually after birth to a predominant localization in the epididymis epithelium during postnatal development. In the adult epididymis, smooth muscle and interstitial cells were also identified as sources of SPAG11C. Furthermore, SPAG11C was differentially immunolocalized on spermatozoa surface during their transit from testis throughout caput and cauda epididymis. Developmental and surgical castration studies suggested that androgens contribute to the epididymal cell type- and region-specific modulation of SPAG11C mRNA levels and immunolocalization. Together our findings provide novel insights into the potential role of β-defensins in the epididymis.

Interpreting histopathology in the epididymis

While most of this Special Issue is devoted to the testis (which is where most drug and chemically induced toxicity of the male reproductive tract is identified), being able to recognize and understand the potential effects of toxicants on the epididymis is immensely important and an area that is often overlooked. The epididymis is the organ where the post-testicular sperm differentiation occurs, through a complex and still not completely understood sperm maturation process, allowing them to fertilize the oocyte. Also in the epididymis, sperm are stored until ejaculation, while being protected from immunogenic reaction by a blood-epididymis barrier. From a toxicologic perspective the epididymis is inherently complicated as its structure and function can be altered both indirectly and directly. In this review we will discuss the factors that must be considered when attempting to distinguish between indirect and direct epididymal toxicity and highlight what is currently known about mechanisms of epididymal toxicants, using the rat as a reference model. We identify 2 distinguishable signature lesions - one representing androgen deprivation (secondary to Leydig cell toxicity in the testis) and another representing a direct acting toxicant. Other commonly observed alterations will also be shown and discussed. Finally, we point out that many of the key functions of the epididymis can be altered in the absence of a detectable change in tissue structure. Collectively, we hope this will provide pathologists with increased confidence in identification of epididymal toxicity and enable more informed guidance as mechanism of action is considered.

Role of testicular luminal factors on Basal cell elongation and proliferation in the mouse epididymis

A subset of basal cells (BCs) in the initial segment (IS) of the mouse epididymis has a slender body projection between adjacent epithelial cells. We show here that these projections occasionally cross the apical tight junctions and are in contact with the luminal environment. Luminal testicular factors are critical for the establishment of the IS epithelium, and we investigated their role in the regulation of this luminal sensing property. Efferent duct ligation (EDL) was performed to block luminal flow from the testis without affecting blood flow. Cytokeratin 5 (KRT5) labeling showed a time-dependent reduction of the percentage of BCs with intercellular projections from 1 to 5 days after EDL, compared to controls. Double labeling for caspase-3 and KRT5 showed that a subset of BCs undergoes apoptosis 1 day after EDL. Ki67/KRT5 double labeling showed a low rate of BC proliferation under basal conditions. However, EDL induced a marked increase in the proliferation rate of a subset of BCs 2 days after EDL. A 2-wk treatment with the androgen receptor antagonist flutamide did not affect the number of BCs with intercellular projections, but reduced BC proliferation. Flutamide treatment also reduced the increase in BC proliferation induced 2 days after EDL. We conclude that, in the adult mouse IS, 1) luminal testicular factors play an important role in the ability of BCs to extend their body projection towards the lumen, and are essential for the survival of a subset of BCs; 2) androgens play an important role in the proliferation of some of the BCs that survive the initial insult induced by EDL; and 3) the formation and elongation of BC intercellular projections do not depend on androgens.

Microphysiological modeling of the reproductive tract: a fertile endeavor

Preclinical toxicity testing in animal models is a cornerstone of the drug development process, yet it is often unable to predict adverse effects and tolerability issues in human subjects. Species-specific responses to investigational drugs have led researchers to utilize human tissues and cells to better estimate human toxicity. Unfortunately, human cell-derived models are imperfect because toxicity is assessed in isolation, removed from the normal physiologic microenvironment. Microphysiological modeling often referred to as 'organ-on-a-chip' or 'human-on-a-chip' places human tissue into a microfluidic system that mimics the complexity of human in vivo physiology, thereby allowing for toxicity testing on several cell types, tissues, and organs within a more biologically relevant environment. Here we describe important concepts when developing a repro-on-a-chip model. The development of female and male reproductive microfluidic systems is critical to sex-based in vitro toxicity and drug testing. This review addresses the biological and physiological aspects of the male and female reproductive systems in vivo and what should be considered when designing a microphysiological human-on-a-chip model. Additionally, interactions between the reproductive tract and other systems are explored, focusing on the impact of factors and hormones produced by the reproductive tract and disease pathophysiology.

Mononuclear phagocytes rapidly clear apoptotic epithelial cells in the proximal epididymis

We have shown previously that a network of mononuclear phagocytes (MPs) expressing macrophage and dendritic cell markers such as CD11c, F4/80 and CX3CR1, lines the base of the epididymal tubule. However, in the initial segment (IS) and only in that particular segment, epididymal MPs establish extremely close interactions with the epithelium by projecting slender dendrites between most epithelial cells. We undertook the present study to determine how epididymal phagocytes respond to the transient wave of apoptosis initiated by unilateral efferent duct ligation (EDL) in the epididymal epithelium. We show profound morphological and phenotypical changes restricted to the MPs populating the proximal epididymis following EDL. Within 48 h, a large subset of IS epithelial cells had entered an apoptotic state, visualized by the terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL) assay and CD11c(+) and CX3CR1(+) MPs readily engulfed TUNEL-positive cells and other debris. Despite the high levels of apoptosis and the rapid clearance of apoptotic cells occurring after EDL, the epithelium preserved its overall architecture and maintained tight junctions of the blood-epididymis barrier (BEB). The discovery of a functional population of MPs in the epididymal epithelium responsible for maintaining the integrity of the BEB raises further questions regarding the role of these cells in clearing defective epithelial cells in the steady-state epididymis, as well as pathogens and abnormal spermatozoa in the lumen.

Recovery of lead-induced suppressed reproduction in male rats by testosterone

The objective of the present study was to investigate the effects of testosterone in recuperation of lead-induced suppressed reproduction in adult male rats. Lead acetate was administered orally to adult male rats (95 ± 5 days) at dosage level of 0.05 and 0.15% for 55 days through drinking water and injected intraperitoneally with either testoviron depot at a dose of 4.16 mg kg(-1) body weight or vehicle alone on days 1, 7 and 14 respectively. At the end of treatment, control and treated males were cohabited with untreated normal-cycling females. After cohabitation for 5 days, all the male rats were killed and weights of reproductive organs were determined. Significant increase in the indices of testis, epididymis, seminal vesicles, vas deferens and prostate glands was observed in testosterone (T)-treated rats when compared to those of lead-exposed rats. Testosterone treatment significantly increased epididymal sperm count, motile spermatozoa, viable spermatozoa and HOS tail-coiled spermatozoa and also the activity levels of testicular 3β- and 17β-hydroxysteroid dehydrogenases when compared to those of lead-exposed males. From the results, it can be hypothesised that supplementation of testosterone mitigated lead-induced suppressed reproduction in male rats.

Immunolocalization of estrogen and androgen receptors in the caput epididymidis of the fat sand rat (Psammomys obesus): Effects of seasonal variations, castration and efferent duct ligation

The fat sand rat (Psammomys obesus) is a model to study seasonal reproductive cycle changes and several metabolic disorders. In order to show a possible involvement of estrogens in the male reproductive functions, the expression of estrogen receptors (ESR1 and ESR2) and androgen receptor (AR) were investigated in the caput epididymidis of fat sand rats during the breeding season, resting season, after castration, after castration followed by testosterone treatment, and after ligation of efferent ducts. In the breeding season, principal cells presented a strong immunostaining of AR in both nuclei and cytoplasm, a strong staining of ESR1, mainly in the apical zone, and a strong immunoexpression of ESR2, mainly in nuclei. In the resting season, a moderate immunostaining of AR in both cytoplasm and nuclei was observed. ESR1 staining showed a strong immunoreactivity in the nuclei. In contrast, the nuclei were negative for ESR2. After castration, a low and selective signal distribution was observed: the nuclei were moderately positive for AR and ESR2, and negative for ESR1. After castration and testosterone treatment, an androgen-dependence for AR and the restoration of ESR1 but not ESR2 immunoexpression were observed. After ligation of the efferent ducts, a considerable reduction of AR immunoreactivity was observed in contrast to ESR1 and ESR2, which gave a strong immunostaining signal. These results illustrate the complexity of the regulation of the androgen and estrogen receptor expression in the epididymis and argue for the coexistence of both androgenic and estrogenic pathways.

A 13-week repeated dose study of three 3-monochloropropane-1,2-diol fatty acid esters in F344 rats

3-monochloropropane-1,2-diol (3-MCPD), a rat renal and testicular carcinogen, has been reported to occur in various foods and food ingredients as free or esterified forms. Since reports about toxicity of 3-MCPD esters are limited, we conducted a 13-week rat subchronic toxicity study of 3-MCPD esters (palmitate diester: CDP, palmitate monoester: CMP, oleate diester: CDO). We administered a carcinogenic dose (3.6 × 10(-4) mol/kg B.W./day) of 3-MCPD or these esters at equimolar concentrations and two 1/4 lower doses by gavage with olive oil as a vehicle five times a week for 13 weeks to F344 male and female rats. As a result, five out of ten 3-MCPD-treated females died from acute renal tubular necrosis, but none of the ester-treated rats. Decreased HGB was observed in all high-dose 3-MCPD fatty acid ester-treated rats, except CDO-treated males. The absolute and relative kidney weights were significantly increased in the ester-treated rats at medium and high doses. Relative liver weights were significantly increased in the esters-treated rat at high dose, except for CMP females. Significant increase in apoptotic epithelial cells in the initial segment of the epididymis of high-dose ester-treated males was also observed. The results suggested that although acute renal toxicity was lower than 3-MCPD, these three 3-MCPD fatty acid esters have the potential to exert subchronic toxicity to the rat kidneys and epididymis, to a similar degree as 3-MCPD under the present conditions. NOAELs (no-observed-adverse-effect levels) of CDP, CMP and CDO were suggested to be 14, 8 and 15 mg/kg B.W./day, respectively.

An androgen receptor-microrna-29a regulatory circuitry in mouse epididymis

MicroRNAs are involved in a number of cellular processes; thus, their deregulation is usually apt to the occurrence of diverse diseases. Previous studies indicate that abnormally up-regulated miR-29a is associated with several diseases, such as human acute myeloid leukemia and diabetes; therefore, the proper level of miR-29a is critical for homeostasis. Herein, we observed that miR-29a was repressed by androgen/androgen receptor signaling in mouse epididymis by targeting a conserved androgen response element located 8 kb upstream of miR-29b1a loci. It is well known that multiple regulatory programs often form a complicated network. Here, we found that miR-29a reversibly suppressed androgen receptor and its target genes by targeting IGF1 and p53 pathways. miR-29b1a-overexpressing transgenic mice displayed epididymis hypoplasia partially similar to the phenotype of those mice with an impaired androgen-androgen receptor signal system. Taken together, the results demonstrated that there is a regulatory circuitry between the androgen signaling pathway and miR-29a in mouse epididymis that may be vital for epididymal development and functions.

Sperm-associated antigen 11A is expressed exclusively in the principal cells of the mouse caput epididymis in an androgen-dependent manner

BACKGROUND

Epididymal sperm maturation occurs via interactions between sperm and proteins secreted by the epididymal epithelium. Although this is an important process, the genes that encode the involved proteins remain largely uncharacterized. Previous studies have demonstrated that the genes involved in sperm maturation are regulated by androgen. Spag11a is an epididymal gene that is influenced by androgen. However, little is known about the putative role of this gene in the sperm maturation process. The objective of this study was to characterize Spag11a in the mouse epididymis.

METHODS

In silico analyses were performed to predict signal peptides and functional domains. Spag11a expression was measured by quantitative real-time RT-PCR. Western blots and immunocytochemistry were performed to determine protein expression.

RESULTS

SPAG11A is a member of the beta defensin protein family and constitutes a secretory protein. Spag11a was expressed exclusively in the epididymis. Moreover, it exhibited region-specific expression in the caput, which is typical for genes that are involved in creating a suitable microenvironment for sperm maturation. Mouse Spag11a was regulated by androgen. A significant decrease of Spag11a expression was observed at third day following a gonadectomy (P < 0.001). Interestingly, testosterone replacement therapy was able to maintain the expression almost at the normal level, indicating a dependency on androgen. Besides androgen, testicular factors influenced Spag11a expression in a different way. This was revealed by efferent duct ligation in which Spag11a was transiently up-regulated at the third day following the ligation before returning to the normal level at day 5. Spag11a regional expression was also observed at protein level detected by western immunoblotting which revealed a clear band in the caput but not in other regions. The prediction that SPAG11A is a secretory protein was confirmed by immunocytochemical analyses indicating cell-specific expression mainly in the caput principal cells and detection of the protein in epididymal luminal fluid and spermatozoa.

CONCLUSIONS

Based on the characteristics of Spag11a, it is likely that this gene has a specific role in epididymal sperm maturation. Further studies using functional assays are necessary to confirm this finding.

Testosterone influences the expression and distribution of the cation-dependent mannose-6-phosphate receptor in rat epididymis. Implications in the distribution of enzymes

The mammalian epididymis plays a role in sperm maturation through its secretory activity. Among the proteins secreted by the epithelium, there are significant amounts of acid hydrolases. In most cell types, the normal distribution of lysosomal enzymes is mediated by mannose-6-phosphate receptors (MPRs). In this study, we analysed the expression and distribution of the cation-dependent MPR (CD-MPR) in epididymis from control, castrated or castrated rats with testosterone replacement. It was observed that expression of CD-MPR increased due to castration in all regions of the epididymis, which was reversed by injection of testosterone. We also measured the activity of α-mannosidase and observed that the castration tends to increase the retention of this enzyme in the tissue, which is reversed by the hormone replacement. In corpus, this resulted in a reduced secretion of the enzyme. Immunohistochemistry showed that CD-MPR has a supranuclear location (different from the cation-independent MPR), most likely in principal cells, and low reactivity in other cell types. The signal in castrated animals was more intense and tended to redistribute towards the apical cytoplasm. Thus, we concluded that expression and distribution of CD-MPR is affected by decrease of testosterone in rat epididymis, and this could change the distribution of lysosomal enzymes.

Why are epididymal tumours so rare?

Epididymal tumour incidence is at most 0.03% of all male cancers. It is an enigma why the human epididymis does not often succumb to cancer, when it expresses markers of stem and cancer cells, and constitutively expresses oncogenes, pro-proliferative and pro-angiogenic factors that allow tumour cells to escape immunosurveillance in cancer-prone tissues. The privileged position of the human epididymis in evading tumourigenicity is reflected in transgenic mouse models in which induction of tumours in other organs is not accompanied by epididymal neoplasia. The epididymis appears to: (i) prevent tumour initiation (it probably lacks stem cells and has strong anti-oxidative mechanisms, active tumour suppressors and inactive oncogene products); (ii) foster tumour monitoring and destruction (by strong immuno-surveillance and -eradication, and cellular senescence); (iii) avert proliferation and angiogenesis (with persistent tight junctions, the presence of anti-angiogenic factors and misplaced pro-angiogenic factors), which together (iv) promote dormancy and restrict dividing cells to hyperplasia. Epididymal cells may be rendered non-responsive to oncogenic stimuli by the constitutive expression of factors generally inducible in tumours, and resistant to the normal epididymal environment, which mimics that of a tumour niche promoting tumour growth. The threshold for tumour initiation may thus be higher in the epididymis than in other organs. Several anti-tumour mechanisms are those that maintain spermatozoa quiescent and immunologically silent, so the low incidence of cancer in the epididymis may be a consequence of its role in sperm maturation and storage. Understanding these mechanisms may throw light on cancer prevention and therapy in general.

Morphological and functional alterations in adult boar epididymis: Effects of prenatal and postnatal administration of flutamide

Background

The dynamic cross-talk between epididymal cells is hormonally regulated and, in part, through direct cell-to-cell interactions. To date, no information is available regarding possible impact of anti-androgens on the proteins involved in the gap junctional communication within the boar epididymis. Thus, a question arised whether prenatal or postnatal exposure to an anti-androgen flutamide alters the expression of gap junction protein - connexin43 (Cx43) and androgen receptor (AR) expression in the caput, corpus and cauda epididymis and leads to delayed effects on morphology and function of adult pig epididymis.

Methods

First two experimental groups received flutamide prenatally on gestational days 20-28 and 80-88 (GD20 and GD80) and further two groups were exposed to flutamide postanatally on days 2-10 and 90-98 after birth (PD2 and PD90). Epididymides were collected from adult boars. Routine histology was performed using hematoxylin-eosin staining. The expression of Cx43 and AR were analyzed using immunohistochemistry and Western blotting. Both analyses were supported by quantitative approaches to demonstrate the variations of the expression levels following the treatment. Apoptotic cells were identified using TUNEL assay.

Results

Histological examination revealed differences in epididymal morphology of flutamide-exposed boars when compared to controls. Scarce spermatic content were seen within the corpus and cauda lumina of GD20, PD2 and PD90 groups. Concomitantly, frequency of epididymal cell apoptosis was significantly higher (p < 0.05) after exposure to flutamide at GD20. Moreover, in GD20, PD2, and PD90 groups, significantly lower AR expression (p < 0.05) was found in the principal and basal cells of the corpus and cauda regions, while in the stromal cells AR expression was significantly reduced (p < 0.05) along the epididymal duct. Concomitantly, a decrease in Cx43 expression (p < 0.05) was noticed in the stromal cells of the cauda region of GD20 and PD2 groups. This indicates high sensitivity of the stromal cells to androgen withdrawal.

Conclusions

The region-specific alterations in the epididymis morphology and scarce spermatic content within the lumina of the corpus and cauda indicate that flutamide can induce delayed effects on the epididymal function of the adult boar by decrease in AR protein levels that results in altered androgen signaling. This may cause disturbances in androgen-dependent processes including Cx43 (de)regulation, however, we can not exclude the possibility that in response to flutamide decreased Cx43 expression may represent one mechanism responsible for functional disturbance of the boar epididymis.

Androgen receptor expression in the caput epididymal epithelium is essential for development of the initial segment and epididymal spermatozoa transit

The epididymis plays an essential role in male fertility, and disruption of epididymal function can lead to obstructive azoospermia. Formation and function of the epididymis is androgen-dependent. The androgen receptor (AR) is expressed in both the stromal and epithelial compartments of the epididymis, and androgen action mediated via stromal cells is vital for its normal development and function. However the impact of epithelial specific AR-dependent signaling in the epididymis remains underexplored. To address this, we used conditional gene-targeting in mice to selectively ablate AR from the caput epididymal epithelium, and characterized the resulting phenotype at multiple postnatal ages. Caput epithelium androgen receptor knock-out mice have normal serum testosterone concentrations at day (d) 21 and d100, but do not develop an epididymal initial segment. The remaining caput epithelium displays a significant decrease in epithelial cell height from d11 and lumen diameter from d21 and disruption of the smooth muscle layer of the caput epididymis at d100. From d21, caput epithelium androgen receptor knock-out mice accumulate cell debris, proteinaceous material, and, at later ages, spermatozoa in their efferent ducts, which prevents normal passage of spermatozoa from the testis into the cauda epididymis resulting in infertility when tested at d100. This efferent duct obstruction leads to fluid back-pressure and disruption of the seminiferous epithelium of the adult testis. We conclude that epithelial AR signaling is essential for postnatal development and function of the epididymal epithelium and that disruption of this signaling can contribute to obstructive azoospermia.

Di-n-butyl phthalate (DBP) exposure induces oxidative stress in epididymis of adult rats

Di-n-butyl phthalate (DBP) is a ubiquitous environmental pollutant, extensively used as a plasticizer in many products including plastics, cosmetics and medical devices. Previous studies have shown that DBP has potential testicular toxicity. Epididymis is known to play an important role in the maturation and storage of sperm. However, the effect and mechanism of action of DBP on epididymis is unclear. The present study was designed to investigate the effect of DBP on structure and function of epididymis in adult male rats by histological and biochemical study. Oxidative stress was also assessed in rat epididymis as an underlying mechanism. Forty SD adult rats were randomly allotted to four groups, and DBP was administered to each group by oral gavage at doses of 0 (control), 100, 250 and 500 mg/kg/day for 2 consecutive weeks. The results indicated that the epididymal toxicity of DBP is dose-dependent. Epididymal weight, activities of epididymal alpha-glucosidase and glutathione peroxidase (GSH-Px) was significantly decreased in rats of 500 mg/kg DBP exposure group compared to the control. The activity of superoxide dismutase (SOD) was significantly decreased while the level of malondialdehyde (MDA) was significantly increased in the epididymal tissue of the 250 and 500 mg/kg DBP exposure groups compared with the control group. Moreover, microscopy with hematoxylin and eosin (HE) staining showed that atrophy of epididymal tubules, the interstitial vascular was hyperemia and the lumina were oligozoospermic in rats of 500 mg/kg DBP exposure group. In conclusion, DBP exposure alters the epididymal structure and function by inducing oxidative stress in epididymis of adult rats.

Identification of early response genes and pathway activated by androgens in the initial segment and caput regions of the regressed rat epididymis

To identify the initial response to androgens and estrogens in the orchidectomized, regressed epididymis, we determined the gene expression changes triggered by the administration of either of two metabolites of testosterone, 5alpha-dihydrotestosterone (DHT) or 17beta-estradiol (E2), in the regressed rat epididymis. Adult rats were orchidectomized and 8 d later implanted with either empty implants (control), DHT-filled-, or E2-filled-polydioxanone implants. Rats were euthanized 12 h, 1 d, and 7 d later, and RNA was extracted and probed on Rat230-2.0 Affymetrix arrays. Probe sets that respond to DHT or E2 were identified at early time points; although the expression of some was repressed, the expression of many others was either transiently or chronically elevated. Nerve growth factor receptor (Ngfr) and S100 calcium binding protein G (S100g) were two E2 up-regulated genes detected at 12 h. Among the genes that showed a dramatic early response to DHT were endothelin 1 (Edn1), bone morphogenetic protein 4 (Bmp4), and IGF binding protein 3 (Igfbp3), which were suppressed, and IGF-I (Igf1), which was induced. Genes that were up- or down-regulated by DHT were classified based on biological function. Using PathwayStudio 4.0, we identified genes that were linked and directly influenced either the expression or regulation of one another. Epidermal growth factor and IGF-I play an important role in the pathway due to their function in regulation and expression of many other genes. These results provide novel insights into the impact of androgen action on the expression of genes that are important for epididymal function.

Androgens and the male reproductive tract: an overview of classical roles and current perspectives

Androgens are steroid hormones that play key roles in the development and maintenance of male phenotype and reproductive function. These hormones also affect the function of several non-reproductive organs, such as bone and skeletal muscle. Endogenous androgens exert most of their effects by genomic mechanisms, which involve hormone binding to the androgen receptor (AR), a ligand-activated transcription factor, resulting in the modulation of gene expression. AR-induced non-genomic mechanisms have also been reported. A large number of steroidal and non-steroidal AR-ligands have been developed for therapeutic use, including the treatment of male hypogonadism (AR agonists) and prostate diseases (AR antagonists), among other pathological conditions. Here, the AR gene and protein structure, mechanism of action and AR gene homologous regulation were reviewed. The AR expression pattern, its in vivo regulation and physiological relevance in the developing and adult testis and epididymis, which are sites of sperm production and maturation, respectively, were also presented.

Cellular signaling by fibroblast growth factors (FGFs) and their receptors (FGFRs) in male reproduction

The major function of the reproductive system is to ensure the survival of the species by passing on hereditary traits from one generation to the next. This is accomplished through the production of gametes and the generation of hormones that function in the maturation and regulation of the reproductive system. It is well established that normal development and function of the male reproductive system is mediated by endocrine and paracrine signaling pathways. Fibroblast growth factors (FGFs), their receptors (FGFRs), and signaling cascades have been implicated in a diverse range of cellular processes including: proliferation, apoptosis, cell survival, chemotaxis, cell adhesion, motility, and differentiation. The maintenance and regulation of correct FGF signaling is evident from human and mouse genetic studies which demonstrate that mutations leading to disruption of FGF signaling cause a variety of developmental disorders including dominant skeletal diseases, infertility, and cancer. Over the course of this review, we will provide evidence for differential expression of FGFs/FGFRs in the testis, male germ cells, the epididymis, the seminal vesicle, and the prostate. We will show that this signaling cascade has an important role in sperm development and maturation. Furthermore, we will demonstrate that FGF/FGFR signaling is essential for normal epididymal function and prostate development. To this end, we will provide evidence for the involvement of the FGF signaling system in the regulation and maintenance of the male reproductive system.

Differential Gene Expression among the Proximal Segments of the Rat Epididymis Is Lost after Efferent Duct Ligation1

The epididymis has traditionally been divided into the caput, corpus, and cauda regions, which are further organized into intraregional segments. In the rat and mouse, these segments have high degrees of transcriptional differentiation, and what has traditionally been called the initial segment of the rat epididymis actually consists of three transcriptionally different intraregional segments. These segments are regulated by endocrine, lumicrine, and paracrine factors, whose relative importance remains a topic of investigation. In the present study, 15-day unilateral efferent duct ligation (EDL) was used to deprive ipsilateral rat epididymides of lumicrine regulation. Segments 1-4 of EDL epididymides and contralateral, sham-operated tissues were collected individually. Microarray analysis of gene expression was used to determine the effect of lumicrine factor deprivation on the transcriptome-wide gene expression of each segment studied. More than 11 000 genes were detected as being expressed in each of the four segments examined. More than 2000 genes responded significantly to EDL in segment 1, although this number of genes declined in each succeeding segment. Segments 1 and 2 of control tissues were the most different transcriptionally and the most affected by EDL. In the absence of lumicrine factors, the four segments regressed to a transcriptionally undifferentiated state, which was consistent with the less-differentiated histology seen after EDL. Interestingly, for an individual gene, lumicrine factor deprivation could stimulate expression in some segments and suppress expression in other segments. These results reveal a higher complexity to the regulation of rat epididymal segments than heretofore appreciated.

Spermatozoa modulate epididymal cell proliferation and protein secretion in vitro

Normal epididymal function, such as protein expression and secretion, is primarily regulated by testicular androgens and temperature. However, the role of spermatozoa in this critical process has never been studied. In order to determine whether sperm itself could regulate epididymal function, we have developed a cell culture system of bovine epididymal cells to study the interactions between spermatozoa and the epididymal epithelium. Primary cells from caput, corpus, and cauda epididymal tissues were cultured in the presence of androgens at 32 degrees C (scrotal) and 37 degrees C (abdominal). Newly synthesized proteins were metabolically labeled with (35)S-methionine after sperm co-incubation and the pattern of secreted proteins was analyzed by two-dimensional polyacrylamide gel electrophoresis. Proliferation rate, protein secretion rate and electrophoretic patterns of secreted proteins were evaluated 48 hr post-co-incubation. Incubation at 32 degrees C indicated that spermatozoa stimulation increases the level of protein secretion of cultured cells from all epididymal sections while it slightly decreases proliferation of corpus cells. At 37 degrees C, spermatozoa co-incubation significantly decreases the protein secretion rate of cultured cells from all epididymal sections. Independently of cell incubation temperature, spermatozoa stimulation induces both an increase in the intensity of radiolabeled proteins and the appearance of new secreted proteins of caput cells without affecting the protein pattern of corpus or cauda cells. Incubation at 37 degrees C, however, greatly modifies the pattern of proteins expressed at 32 degrees C by cauda cells. Taken together, these results support the hypothesis that spermatozoa themselves affect epididymal cell function, most importantly for caput epididymides.

Effects of 3-beta-diol, an androgen metabolite with intrinsic estrogen-like effects, in modulating the aquaporin-9 expression in the rat efferent ductules

BACKGROUND

Fluid homeostasis is critical for normal function of the male reproductive tract and aquaporins (AQP) play an important role in maintenance of this water and ion balance. Several AQPs have been identified in the male, but their regulation is not fully comprehended. Hormonal regulation of AQPs appears to be dependent on the steroid in the reproductive tract region. AQP9 displays unique hormonal regulation in the efferent ductules and epididymis, as it is regulated by both estrogen and dihydrotestosterone (DHT) in the efferent ductules, but only by DHT in the initial segment epididymis. Recent data have shown that a metabolite of DHT, 5-alpha-androstane-3-beta-17-beta-diol (3-beta-diol), once considered inactive, is also present in high concentrations in the male and indeed has biological activity. 3-beta-diol does not bind to the androgen receptor, but rather to estrogen receptors ER-alpha and ER-beta, with higher affinity for ER-beta. The existence of this estrogenic DHT metabolite has raised the possibility that estradiol may not be the only estrogen to play a major role in the male reproductive system. Considering that both ER-alpha and ER-beta are highly expressed in efferent ductules, we hypothesized that the DHT regulation of AQP9 could be due to the 3-beta-diol metabolite.

METHODS

To test this hypothesis, adult male rats were submitted to surgical castration followed by estradiol, DHT or 3-beta-diol replacement. Changes in AQP9 expression in the efferent ductules were investigated by using immunohistochemistry and Western blotting assay.

RESULTS

Data show that, after castration, AQP9 expression was significantly reduced in the efferent ductules. 3-beta-diol injections restored AQP9 expression, similar to DHT and estradiol. The results were confirmed by Western blotting assay.

CONCLUSION

This is the first evidence that 3-beta-diol has biological activity in the male reproductive tract and that this androgen metabolite has estrogen-like activity in the efferent ductules, whose major function is the reabsorption of luminal fluid.

Differential Endocrine Regulation of Genes Enriched in Initial Segment and Distal Caput of the Mouse Epididymis as Revealed by Genome-Wide Expression Profiling1

We have performed genome-wide expression profiling of endocrine regulation of genes expressed in the mouse initial segment (IS) and distal caput of the epididymis by using Affymetrix microarrays. The data revealed that of the 15 020 genes expressed in the epididymis, 35% were enriched in one of the two regions studied, indicating that differential functions can be attributed to the IS and the more distal caput regions. The data, furthermore, showed that 27% of the genes expressed in the IS and/or distal caput epididymidis are under the regulation of testicular factors present in the duct fluid, while bloodborne androgens can regulate for 14% of them. This is in line with the high testis dependency of epididymal physiology. We then focused on genes with moderate or strong expression, showing strict segment enrichment and strong dependency on testicular factors. Analyses of the 59 genes, including upregulated and downregulated genes, fulfilling the criteria indicated that the expression of 18 (17 downregulated genes; 1 upregulated gene) of 19 gonadectomy-responsive genes enriched in the IS was not maintained by the androgen treatment, whereas the expression of all six downregulated genes enriched in the distal caput and the majority of those with no strict segment enrichment of expression (28 of 34; consisting of 23 downregulated and 5 upregulated genes) were maintained by androgens. Hence, it is evident that testicular factors other than androgens are important for the expression of IS-enriched genes, whereas the expression of distal caput-enriched genes is typically regulated by androgens. Identical data were obtained by independent clustering analyses performed for the expression data of 3626 epididymal genes. Several novel genes with putative involvement in epididymal sperm maturation, such as a disintegrin and metallopeptidase domain 28 (Adam28) and a solute carrier organic anion transporter family, member 4C1 (Slco4c1), were identified, indicating that this approach is successful for identifying novel epididymal genes.

Sonic hedgehog pathway genes are expressed and transcribed in the adult mouse epididymis

One role of the hedgehog (hh) signaling pathway during development is to assist in establishing pattern orientation in the embryo. The structure and function in the adult epididymis is highly patterned, and since the sonic hedgehog (Shh) pathway is known to be functional in the developing male tract and the expression of other pattern-influencing genes has recently been found in the adult epididymis, we have examined the adult mouse epididymis for Shh pathway molecules. Examination was at both the gene and protein level. Shh, the secreted signal molecule, patched (Ptc), its membrane receptor, and Gli-1, a downstream transcription factor, were detected at the gene level with semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) and at the protein level with Western blot analysis. Immunohistochemical localization further detected Shh specifically in the epididymal epithelium. It was hypothesized that efferent duct ligation (EDL) would alter epididymal segmentation within 30 days of the ligation, especially in the proximal segments of the caput epididymis. It was further hypothesized that these alterations would be correlated with changes in the expression of genes in the Shh pathway. EDL did not alter epididymal segmentation, but Shh, Ptc, and Gli1 expression was significantly altered at specific times after the ligation. The presence of the signaling pathway in the adult epididymis is a novel finding, as is the fact that in the distal epididymis, the specific gene expressions are altered by EDL. This suggests that the genes are capable of being regulated in a manner that is influenced by testicular contribution, and it implies that those genes have a function in the epididymis subject to that regulation.

Fos plays no role in apoptosis of epithelia in the mouse male accessory sex organs and uterus

Roles of Fos in apoptosis of epithelia in the mouse male accessory sex organs and uterus were investigated using Fos-deficient mice. Normal 30- and 50-day-old and Fos-deficient 50-day-old male and female mice were castrated, and testosterone propionate and estradiol-17 beta were daily injected into male and female mice, respectively, for 5 days. An apoptotic index (a percentage of apoptotic cells) in the epithelium was examined from the day following the last injection (day 1) to day 8. The body weights and the weights of the ventral prostate (VP), coagulating gland (C), seminal vesicle (SV) and epididymis (Ep) and uterus of 50-day-castrated Fos-deficient mice on day 1 suggested that the development of these mice corresponded to that of 30-day-castrated normal mice at the most. The extents of apoptosis estimated by an apoptotic index in the VP, C, SV, Ep and uterus in 50-day-castrated Fos-deficient mice were comparable to those in 30-day-castrated normal mice. The extents of apoptosis in the SV, Ep and uterus in 30-day-castrated normal and 50-day-castrated Fos-deficient mice were similar to those in 50-day-castrated normal mice, while the extents of apoptosis in the VP and C in the former two groups of mice were less than those in the latter mice. The present results show that Fos-deficiency does not affect apoptosis in the SV, EP and uterus. However, the extents of apoptosis in the VP and C were less in 50-day-castrated Fos-deficient mice than in 50-day-castrated normal mice. This seems to be due to the retarded development of 50-day-castrated Fos-deficient mice, but not to a role of Fos in apoptosis.

Differential hormonal regulation of estrogen receptors ERalpha and ERbeta and androgen receptor expression in rat efferent ductules

Estrogen receptors, in addition to the androgen receptor (AR), are expressed at high levels in efferent ductules of the male reproductive tract and it is now well recognized that estrogen receptor (ER) alpha is required for the maintenance of normal structure and function of the ductules. However, little is known regarding the hormonal regulation of the receptors themselves in the male. In the present study, efferent ductule ligation and castration, followed by replacement with testosterone, dihydro-testosterone (DHT) or estradiol was used to investigate the relative importance of circulating and luminal sources of steroid for the modulation of ERalpha, ERbeta and AR in rat efferent ductules. Uni- or bilateral castration and ligation did not affect the expression of ERalpha and ERbeta, but bilateral castration caused down-regulation of AR. Replacement with DHT and testosterone alone or in combination with estradiol caused the recovery of AR expression to control levels. A slight recovery of AR was also observed after estrogen replacement. ERalpha expression was decreased to nearly undetectable levels after estrogen replacement. On the other hand, ERbeta did not show evident effects following any of the treatments, suggesting a constitutive expression of this receptor. This differential modulation of the steroid hormone receptors highlights the importance of maintaining a physiological androgen-estrogen balance to regulate the structure and function of efferent ductules in the male.