In vitro bisphenol A impairs testicular energy metabolism and spermatogenesis through nuclear estrogen receptors activation in zebrafish.

This study investigated the effects of bisphenol A (BPA) and the involvement of nuclear estrogen receptors (ESR) on testicular energy metabolism and spermatogenesis in zebrafish. Testes were incubated with DMSO, 10 pM or 10μM BPA for 6 or 72h, with some samples pre-incubated with the ESRα/β antagonist ICI 182,780. Gene and protein expressions were analyzed using real-time PCR and Western blot, respectively.

Steroidogenesis and androgen/estrogen signaling pathways are altered in in vitro matured testicular tissues of prepubertal mice.

Children undergoing cancer treatments are at risk for impaired fertility. Cryopreserved prepubertal testicular biopsies could theoretically be later matured to produce spermatozoa for assisted reproductive technology. A complete spermatogenesis has been obtained from mouse prepubertal testicular tissue, although with low efficiency.

Early Castration in Horses Does Not Impact Osteoarticular Metabolism.

The castration of stallions is traditionally performed after puberty, at around the age of 2 years old. No studies have focused on the effects of early castration on osteoarticular metabolism. Thus, we aimed to compare early castration (3 days after birth) with traditional castration (18 months of age) in horses.

Ex vivo effects of 17β-estradiol on the prepubertal rat testis.

Although it is well established that testis produces estrogens, their precise effect is not fully documented, particularly during the prepubertal period. In a previous in vivo study, we demonstrated that an exposure of prepubertal rats (15-30 days post-partum (dpp)) to 17β-estradiol (E2) delays the establishment of spermatogenesis. In order to characterize the mechanisms of action and the direct targets of E2 on the immature testis, we developed an organotypic culture model of testicular explants obtained from prepubertal rats (15, 20 and 25 dpp).

Effects of bisphenol A and estradiol in adult rat testis after prepubertal and pubertal exposure.

Over the past few decades, male fertility has been decreasing worldwide. Many studies attribute this outcome to endocrine disruptors exposure such as bisphenol A (BPA), which is a chemical compound used in plastics synthesis and exhibiting estrogenic activity. In order to assess how the window of exposure modulates the effects of BPA on the testis, prepubertal (15 dpp to 30 dpp) and pubertal (60 dpp to 75 dpp) male Sprague-Dawley rats were exposed to BPA (50 µg/kg bw/day), 17-β-estradiol (E2) (20 µg/kg bw/day) as a positive control, or to a combination of these compounds.

Calcium influx and spermatogenesis in the testis and liver enzyme activities in the zebrafish are rapidly modulated by the calcium content of the water.

This study investigated the effects of varying environmental Ca concentrations on the influx of Ca to the testis, testicular morphology, and liver enzymes in the zebrafish. Adult zebrafish (Danio rerio) were held in water containing low (0.02 mM), control (0.

Investigation of equine testis contribution to vitamin D bioactivation.

Although vitamin D acts in various biological processes, it plays a critical role in the maintenance of bone health, and regulates calcium homeostasis. In humans and rodents, the main tissues involved in vitamin D metabolism are the liver and the kidneys, however it has been shown that the testis has strongly participated in its bioactivation. Indeed, in these different species, enzymes metabolizing vitamin D (CYP27A1, CYP27B1 and CYP2R1) have been demonstrated in this tissue.

In vivo and in vitro short-term bisphenol A exposures disrupt testicular energy metabolism and negatively impact spermatogenesis in zebrafish.

This study investigated the in vitro and short-term in vivo effects of Bisphenol A (BPA) on testicular energy metabolism and morphology in the zebrafish (Danio rerio). Testes were incubated in vitro for 1 h or fish were exposed in vivo to BPA in the tank water for 12 h. Testicular lactate, glycogen and cholesterol were measured and C-deoxy-d-glucose uptake and activity of lactate dehydrogenase (LDH), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were determined.

Estradiol and 1α,25(OH) vitamin D share plasma membrane downstream signal transduction through calcium influx and genomic activation in immature rat testis.

The aim of this study was to investigate the rapid response pathway and gene and protein expression profiles of the rat testis in response to estradiol (E) and 1α,25(OH) vitamin D (1,25-D), to understand how they mediate their effects on the first spermatogenic wave. To do this, we compared the effects of 1,25-D and E on calcium(Ca) uptake and the involvement of estrogen receptors (ESR) in their rapid responses. Additionally, we studied the downstream signal transduction effects of 1,25-D and E on cyclin A1/B1 and cellular cycle protein expression.

New ionic targets of 3,3',5'-triiodothyronine at the plasma membrane of rat Sertoli cells.

The functions of Sertoli cells, which structurally and functionally support ongoing spermatogenesis, are effectively modulated by thyroid hormones, amongst other molecules. We investigated the mechanism of action of rT on calcium (Ca) uptake in Sertoli cells by means of in vitro acute incubation. In addition, we performed electrophysiological recordings of potassium efflux in order to understand the cell repolarization, coupled to the calcium uptake triggered by rT.

Interactions between oestrogen and 1α,25(OH)-vitamin D signalling and their roles in spermatogenesis and spermatozoa functions.

Oestrogens and 1α,25(OH)-vitamin D (1,25-D) are steroids that can provide effects by binding to their receptors localised in the cytoplasm and in the nucleus or the plasma membrane respectively inducing genomic and non-genomic effects. As confirmed notably by invalidation of the genes, coding for their receptors as tested with mice with in vivo and in vitro treatments, oestrogens and 1,25-D are regulators of spermatogenesis Moreover, some functions of ejaculated spermatozoa as viability, DNA integrity, motility, capacitation, acrosome reaction and fertilizing ability are targets for these hormones. The studies conducted on their mechanisms of action, even though not completely elicited, have allowed the demonstration of putative interactions between their signalling pathways that are worth examining more closely.

Implication of the estrogen receptors GPER, ESR1, ESR2 in post-testicular maturations of equine spermatozoa.

Estrogen receptors ESR1, ESR2 and GPER are present on mature ejaculated horse spermatozoa, suggesting these cells as putative targets for estrogens. Indeed, spermatozoa are exposed to high level of estrogens during the transit in the male and female genital tracts but their roles are not investigated. So, we evaluated in vitro the role of 17β-estradiol during post-testicular maturations: regulation of motility, capacitation and acrosome reaction.

Differential effects of bisphenol A and estradiol on rat spermatogenesis' establishment.

Several studies have highlighted the negative effects of bisphenol A (BPA), a chemical compound with estrogenic activity, on reproductive health. To elucidate the impact of BPA on spermatogenesis' establishment and mechanisms of action of BPA and 17β-estradiol (E2), as both can be found in the environment, we exposed rats to BPA (50μg/kg bw/day of BPA), E2 (20μg/kg bw/day of E2) and BPA+E2 from 15 to 30days post-partum. Histological and gene expression studies revealed that BPA and BPA+E2 exposures promoted spermatogenesis establishment whereas E2 alone delayed it.

Differential expression patterns of three aromatase genes and of four estrogen receptors genes in the testes of trout (Oncorhynchus mykiss).

Estrogens are implicated in male gonad function, although their physiological roles remain uncertain. In the present study, we take advantage of the original model of spatio-temporal organization of trout spermatogenesis to revisit the synthesis and action sites of estrogens in fish testis. Within this system, somatic cell and germ cell development are synchronized due to a strict seasonal spermatogenetic cycle and the cystic organization of gonads.

Stallion spermatozoa: putative target of estrogens; presence of the estrogen receptors ESR1, ESR2 and identification of the estrogen-membrane receptor GPER.

Among mammals, the stallion produces the largest amount of testicular estrogens. These steroid hormones are produced mainly by Leydig and Sertoli cells in the testis and also in the epididymis. Their role in horse testicular physiology and their ability to act on spermatozoa are still unknown.

Estrogens in male germ cells.

The biosynthesis of steroids and the production of spermatozoa are two major functions of the mammalian testis which are tightly controlled by gonadotropins and numerous locally produced factors. Among these are the estrogens that are produced within the seminiferous epithelium via the irreversible transformation of androgens (C19) into estrogens (C18) by aromatase. We have recently reported that male germ cells are the new source of estrogens in the testis.

Role of estrogens in spermatogenesis.

Aromatase converts irreversibly androgens into estrogens and is present in the endoplasmic reticulum of various cells of mammalian testes ; at least in rodents, all testicular cells except peritubular cells express aromatase. In testis, high affinity estrogen receptors, ERalpha and/or ERbeta, together with a membrane rapid effect recently described, mediate the effects of estrogens. From the experimental models, in vitro studies and data collected in patients, it is now demonstrated that estrogens play an important role in the testis of vertebrates.

17β-Estradiol regulates cyclin A1 and cyclin B1 gene expression in adult rat seminiferous tubules.

Spermatogenesis, which is the fundamental mechanism allowing male gamete production, is controlled by several factors, and among them, estrogens are likely concerned. In order to enlighten the potential role of estrogen in rat spermatogenesis, seminiferous tubules (ST) from two groups of seminiferous epithelium stages (II-VIII and IX-I) were treated with either 17β-estradiol (E(2)) agonists or antagonists for estrogen receptors (ESRs). In this study, we show that cyclin A1 and cyclin B1 gene expression is controlled by E(2) at a concentration of 10(-9) M only in stages IX-I.

Estrogens: new players in spermatogenesis.

Aromatase that irreversibly transforms androgens into estrogens is present in the smooth endoplasmic reticulum of nearly all cell types in the mammalian testis. In rodents, all testicular cells except for myoid cells express aromatase activity. We have demonstrated the presence of the functional aromatase (transcript or protein, and biological activity) in adult rat germ cells including pachytene spermatocytes and round spermatids.

Regulation of aromatase expression by 1α,25(OH)2 vitamin D3 in rat testicular cells.

It is well known that the vitamin D endocrine system is involved in physiological and biochemical events in numerous tissues, especially gut, bone and kidney but also testis. Therefore, in this study the effect and mechanisms of action of 1α,25(OH)(2) vitamin D(3) (1,25D) on aromatase gene expression in immature rat Sertoli cells were evaluated. Vitamin D receptor transcripts were present in immature Sertoli cells as well as in adult testicular germ cells and somatic cells.

Nongenomic and genomic effects of 1α,25(OH)2 vitamin D3 in rat testis.

The steroid hormone 1α,25(OH)(2)-vitamin D(3) (1,25D(3)) regulates gene transcription through a nuclear receptor (VDRnuc) and initiation of rapid cellular responses through a putative plasma membrane-associated receptor (VDRmem). It has been described that successful mating and fertility rates are significantly decreased in vitamin D deficient male rats and a VDR null mutant rodent has decreased sperm count and motility and expresses rare spermatogenesis. Although the Sertoli cells are pointed as the major target of 1,25D(3) in the testis the mechanism of 1,25D(3) action, particularly in Sertoli cells, remains unclear.

Aromatase gene expression in immature rat Sertoli cells: age-related changes in the FSH signalling pathway.

Aromatase, the enzyme responsible for the transformation of androgens into oestrogens, is encoded by the cyp19 gene expressed in the testis. The aim of the present study was to analyse the evolution of aromatase gene expression under FSH control in rat Sertoli cells between 10 and 30 days post partum, corresponding to the end of the proliferative period of Sertoli cells, establishment of the blood-testis barrier and acquisition of the mature phenotype. The maximum stimulatory effect of FSH on aromatase gene expression was obtained in 20-day-old rat Sertoli cells, compared with cells from 10- and 30-day-old rats, in parallel with the differentiation of Sertoli cells.

17 beta-estradiol activates rapid signaling pathways involved in rat pachytene spermatocytes apoptosis through GPR30 and ER alpha.

Aim of the present study was to investigate whether estrogens were able to directly activate rapid signaling pathways controlling spermatogenesis in rat pachytene spermatocytes (PS). Classically, estrogens act by binding to estrogen receptors (ERs) alpha and beta. Recently, it has been demonstrated that rapid estrogen action can also be activated through the G-protein-coupled receptor (GPR)-30.

Mammalian sperm quality and aromatase expression.

In most mammalian species the aromatase is encoded by a single gene (cyp19), which contains 18 exons, 9 of them being translated. In adult rats, together with Leydig cells germ cells represent an additional source of estrogens. The amount of P450arom transcript is threefold higher in pachytene spermatocytes compared to younger cells (spermatogonia-preleptotene spermatocyte) or round spermatids; conversely, aromatase activity is more intense in haploid cells.

Protective effects of estrogens and caloric restriction during aging on various rat testis parameters.

Aim: To investigate the effects of 17beta-estradiol (E2), Peganum harmala extract (PHE) and caloric restriction (CR) on various testis parameters during aging.

Methods: Twelve month-old male rats were treated for 6 months with either E2 or PHE, or submitted to CR (40%).

Results: Our results show that estrogens and CR are able to protect the male gonad by preventing the decrease of testosterone and E2 levels as well as the decrease of aromatase and estrogen receptor gene expressions.