anti-Müllerian Hormone mRNA Research Articles

Anti-Müllerian hormone is highly expressed and secreted from cumulus granulosa cells of stimulated preovulatory immature and atretic oocytes

This study investigated anti-Müllerian hormone (AMH) expression and secretion from cumulus granulosa cells (GC) and steroidogenesis in follicular fluids (FF) with relation to oocyte maturational stages and fertilization capacity in large preovulatory follicles. This prospective study included 53 ovulatory women undergoing intracytoplasmic sperm injection. FF and cumulus GC from 140 large preovulatory follicles were individually obtained during oocyte retrieval. Main outcome measures were oocyte maturation, fertilization and embryo quality. FF were assayed for AMH, progesterone, 17β-oestradiol and testosterone. Cumulus GC were assayed for AMH mRNA expression. AMH mRNA expression and secretion in cumulus GC in preovulatory follicles containing germinal-vesicle (GV) and metaphase-I (MI) oocytes were significantly higher than follicles containing MII oocytes (P<0.01 and P<0.0001, respectively). In addition, FF AMH concentrations from atretic oocytes were significantly higher than from MII oocytes. No correlation was found between AMH expression and secretion to fertilization or embryo quality. FF of MI and GV oocytes had higher concentrations of testosterone and lower progesterone/oestradiol ratios than MII oocytes, and FF of atretic oocytes contained higher testosterone concentrations than FF of MII oocytes. AMH is highly expressed in and secreted from cumulus GC of preovulatory follicles containing premature and atretic oocytes.Anti-Müllerian hormone (AMH) is produced in the female exclusively by granulosa cells. AMH has recently been shown to be one of the most important markers of ovarian reserve and it is highly associated with ovarian follicular development. This study investigates AMH expression and secretion from cumulus granulosa cells (GC) and steroidogenesis in the follicular fluids (FF) with relation to oocyte maturational stages, and fertilization capacity in large preovulatory follicles. We conducted a prospective study with 53 ovulatory women undergoing intracytoplasmic sperm injection. FF and cumulus GC from 140 large preovulatory follicles were individually obtained during oocyte retrieval. The main outcome measures were oocyte maturation, fertilization and embryo quality. FF were assayed for AMH, progesterone, 17β-oestradiol and testosterone. Cumulus GC were assayed for AMH mRNA expression. AMH mRNA expression in cumulus GC and AMH concentrations in FF of preovulatory follicles containing premature oocytes (germinal vesicle (GV) and metaphase I (MI)) were significantly higher than preovulatory follicles containing mature oocytes (MII oocytes). In addition, FF AMH concentrations of atretic oocytes were significantly higher than FF AMH of MII oocytes. No correlation was found between AMH expression and secretion for fertilization or embryo quality. FF of preovulatory MI and GV oocytes had higher levels of testosterone and lower progesterone/oestradiol ratios than MII oocytes, and FF of atretic oocytes contained higher testosterone levels than FF of MII oocytes. This study shows that AMH is highly expressed in and secreted from cumulus GC of preovulatory follicles containing premature and atretic oocytes.

131 EFFECT OF PARABENS ON THE DISRUPTION OF OVARIAN FOLLICLE MATURATION IN A NEONATAL FEMALE RAT MODEL

Parabens are widely used as an antimicrobial agent in the preparation of cosmetic consumer products and pharmaceuticals. Parabens are esters of para-hydroxybenzoic acid typically including methyl-, ethyl-, butyl-, isobutyl- and isopropyl-paraben. Recently, parabens have been shown to act as xenoestrogens, a class of endocrine disruptors. In this study, we hypothesised that parabens might disrupt ovarian follicle maturation in female Sprague-Dawley rats during the neonatal period. A total of 55 female rats were divided into 11 groups, each composed of 5 rats. The pups were given daily subcutaneous injections of methyl-, propyl- or butyl-paraben at increasing concentrations of 62.5, 250, or 1000 mg kg–1 per day on neonatal Day 1 to 7. 17α-Ethinylestradiol (1 mg kg–1 per day) was used as a positive control. We examined the expression of anti-Müllerian hormone (AMH), which inhibits early folliculogenesis in the ovaries. Levels of AMH mRNA and protein were determined using real-time PCR and Western blot analysis, respectively. We found that the levels of AMH mRNA and protein were dose-dependently increased by methyl- and propyl-paraben compared with the vehicle. In particular, AMH mRNA and protein levels were markedly increased by parabens (methyl- and propyl-) at 1000 mg kg–1 per day. Data were analysed using a nonparametric one-way ANOVA followed by Dunnett's test for multiple comparisons. The ovaries were excised at postnatal Day 8 and fixed and stained with haematoxylin and eosin for histological analysis. The number of follicles were counted and classified into primordial, primary, or secondary stages via the largest serial sections at the centre of the ovary. Results showed that the total number of follicles and number of primordial follicles were increased by methyl- and propyl-parabens compared with the vehicle. Taken together, these results indicated that methyl- and propyl-parabens may have an estrogenic effect that disrupts the ovarian follicle development necessary for reproductive functions in a neonatal female rat model.

Anti-Müllerian hormone inhibits growth of AMH type II receptor-positive human ovarian granulosa cell tumor cells by activating apoptosis

Ovarian granulosa cell tumors (GCTs) are sex cord stromal tumors that constitute 3–5% of all ovarian cancers. GCTs usually present with an indolent course but there is a high risk of recurrence, which associates with increased mortality, and targeted treatments would be desirable. Anti-Müllerian hormone (AMH), a key factor regulating sexual differentiation of the reproductive organs, has been implicated as a growth inhibitor in ovarian cancer. GCTs and normal granulosa cells produce AMH, but its expression in large GCTs is usually downregulated. Further, as the lack of specific AMH-signaling pathway components leads to GCT development in mice, we hypothesized that AMH inhibits growth of GCTs. Utilizing a large panel of human GCT tissue samples, we found that AMH type I receptors (ALK2, ALK3 and ALK6) and type II receptor (AMHRII), as well as their downstream effectors Smad1/5, are expressed and active in GCTs. AMHRII expression was detected in the vast majority (96%) of GCTs and correlated with AMH mRNA and protein expression. AMH mRNA level was low in large GCTs, confirming previous findings on low-AMH protein expression in large human as well as mouse GCTs. To study the functional role of AMH in this peculiar ovarian cancer, we utilized a human GCT cell line (KGN) and 10 primary GCT cell cultures. We found that the AMH–Smad1/5-signaling pathway was active in these cells, and that exogenous AMH further activated Smad1/5 in KGN cells. Furthermore, AMH treatment reduced the number of KGN cells and primary GCT cells, with increasing amounts of AMH leading to augmented activation of caspase-3 and subsequent apoptosis. All in all, these data support the premise that AMH is a growth inhibitor of GCTs.

Molecular cloning of anti-Müllerian hormone from the American alligator, Alligator mississippiensis

Anti-Müllerian hormone (AMH) plays an important role in male sex differentiation in vertebrates. AMH produced by Sertoli cells of the fetal testis induces regression of the Müllerian duct in mammalian species. In alligators, sexual differentiation is controlled by the temperature during egg incubation, termed temperature-dependent sex determination (TSD). The TSD mechanism inducing sex differentiation is thought to be unique and different from that of genetic sex determination as no gene such as the SRY of mammals has been identified. However, many of the genes associated with gonadal differentiation in mammals also are expressed in the developing gonads of species exhibiting TSD. To clarify the molecular mechanisms associated with gonad formation during the temperature-sensitive period (TSP), we have cloned the full length AMH gene in the alligator, and quantitatively compared mRNA expression patterns in the gonad–adrenal–mesonephros (GAM) complex isolated from alligator embryos incubated at male and female producing temperatures. The deduced amino acid sequence of the alligator AMH cDNA showed high identity (59–53%) to avian AMH genes. AMH mRNA expression was high in the GAM of male alligator embryos at stage 24 (immediately after sex determination) and hatchlings, but suppressed in the GAM of estrogen-exposed hatchlings incubated at the male-producing temperature. In the alligator AMH proximal promoter, a number of transcriptional factors (for SF-1. GATA, WT-1 and SOX9) binding elements were also identified and they exhibit a conserved pattern seen in other species. SOX9 up-regulates transcriptional activity through the amAMH promoter region. These results suggested that AMH and SOX9 play important roles in TSD of the American alligator.

Distribution and responsiveness of rat anti-Müllerian hormone during ovarian development and VCD-induced ovotoxicity

Anti-Müllerian hormone (AMH) is produced by granulosa cells in primary to small antral follicles of the adult ovary and helps maintain primordial follicles in a dormant state. The industrial chemical, 4-vinylcyclohexene diepoxide (VCD) causes specific ovotoxicity in primordial and small primary follicles of mice and rats. Previous studies suggest that this ovotoxicity involves acceleration of primordial to primary follicle recruitment via interactions with the Kit/Kit ligand signaling pathway. Because of its accepted role in inhibiting primordial follicle recruitment, the present study was designed to investigate a possible interaction between AMH and VCD-induced ovotoxicity. Protein distribution of AMH was compared in neonatal and adult F344 rat ovaries. AMH protein was visualized by immunofluorescence microscopy in large primary and secondary follicles of the adult ovary, but in small primary follicles in neonatal rat ovaries. In cultured postnatal day (PND) 4 F344 rat ovaries, VCD exposure (30 μM, 2–8 days) decreased ( P < 0.05) AMH mRNA (d4–8) and protein (d6–8). Recombinant AMH (100–400 mg/ml) in PND4 ovaries cultured 8 days ± VCD (30 μM) caused an increase ( P < 0.05) in primordial, and a decrease ( P < 0.05) in small primary follicles, supporting that AMH retarded primordial follicle recruitment. However, no concentration of AMH had an effect on VCD-induced ovotoxicity. Whereas, VCD caused a reduction in expression of AMH (d4–d8), it followed previously reported initial disruptions in Kit signaling induced by VCD (d2). Thus, collectively, these results do not support a mechanism whereby VCD causes ovotoxicity via generalized activation of primordial follicle recruitment, but instead provide further support for the specificity of other intracellular mechanisms involved in VCD-induced ovotoxicity.

Gonadotropin releasing hormone antagonists suppress aromatase and anti-Müllerian hormone expression in human granulosa cells

To investigate the effects of a gonadotropin-releasing hormone antagonist (GnRH-ANT) on the expression of anti-Müllerian Hormone (AMH) and aromatase (via the exon CYP19IIa promoter), in cultured human granulosa cells (hGCs) and the human granulosa cell line (HGL5). Primary cell cultures of hGCs and culture of HGL5 cells. Academic center. Women undergoing IVF because of male factor, tubal infertility, or donor eggs. hGCs and HGL5 cells were treated with a GnRH-ANT (1 nM and 1 μM) alone or in combination with cAMP (1 mM). Media was collected and stored at -80°C until assayed. mRNA levels of CYP19 IIa, AMH, steroidogenic factor 1 (SF-1) and liver receptor homologue-1 (LRH-1) were determined by quantitative polymerase chain reaction. ELISA was used to determined estradiol (E(2)) levels in the culture media. Pooled results from triplicate experiments were analyzed using one-way analysis of variance with Student-Newman-Keuls multiple-comparison methods. The GnRH-ANT decreased the expressions of CYP19 IIa, AMH, SF-1, and LRH-1. cAMP induced aromatase and AMH expression. Cotreatment with cAMP and GnRH-ANT caused a dose-dependent suppression of AMH and CYP19 IIa mRNA. A GnRH agonist (GnRH-A) increased the mRNA expressions of CYP 19 IIa and AMH. The GnRH-ANT decreased E(2) production in cultured hGCs. GnRH-ANTs, in addition to their central suppressive effects on the pituitary, may have a direct effect on ovarian granulosa cells with inhibition of aromatase and AMH expression. Furthermore, the inhibitory effect could be mediated via suppression of SF-1 and LRH-1, and may play a role in estrogen-mediated ovarian folliculogenesis.

Testosterone-induced downregulation of anti-Müllerian hormone expression in granulosa cells from small bovine follicles

Polycystic ovary syndrome (PCOS) is characterized by the presence of hyperandrogenism and an increased follicular mass probably determined by deregulation of locally produced factors. Anti-Müllerian hormone (AMH) is a glycoprotein that inhibits follicular recruitment and determines the size of the follicular pool. To evaluate the role of androgens in the regulation of AMH expression in bovine granulosa cells from small follicles, granulosa cells from 3 to 4 mm follicles were isolated and incubated in basal culture media, or in media containing testosterone (T) at 10(-5)M, T 10(-8)M, or estradiol (E2) at 150 ng/ml for 48 h. AMH mRNA levels of these cells were determined using real-time PCR (RT PCR). AMH protein levels and E2 were determined in cell-conditioned media. A 3.4-fold decrease in AMH mRNA levels was observed in granulosa cells exposed to T 10(-5)M (P = 0.03, n = 5), but not in cells exposed to T 10(-8)M. AMH protein levels showed a 1.8-fold reduction in cell-conditioned media from cells exposed to T 10(-5)M (P = 0.01, n = 5), without significant changes in the group exposed to T 10(-8)M. Cells treated with E2 150 ng/ml showed no change in AMH protein levels. We propose that AMH expression is modulated by androgens in bovine granulosa cells from small follicles. Thus, it is possible to speculate that androgens, by inhibiting AMH expression, may promote follicle recruitment, increasing the early growing follicular pool. This new mechanism may have implications for the understanding of PCOS pathophysiology.

Lack of Androgen Receptor Expression in Sertoli Cells Accounts for the Absence of Anti-Mullerian Hormone Repression during Early Human Testis Development

Puberty is associated with increased testicular testosterone (TT) synthesis, which is required to trigger spermatogenesis and to repress anti-Mullerian hormone (AMH) production. However, testicular gonadotropin stimulation during fetal and newborn life neither initiates spermatogenesis nor represses AMH. We postulated that a lack of androgen receptor (AR) expression in Sertoli cells (SC) might explain why these processes do not occur during early human development. Using immunohistochemistry and quantitative PCR, we examined the relationship between AR, AMH, and FSH receptor expression in fetal, newborn, and adult human testis. The ability of testosterone to repress AMH secretion was evaluated in male newborns, neonates, and two adults with androgen insensitivity syndrome and also in vitro using SMAT1 SC. FSH receptor was present in SC at all developmental stages. In fetal and newborn testis, AR was expressed in peritubular and Leydig cells but not in SC. This coincided with the absence of spermatogenesis and with strong SC AMH expression. In adult testis, spermatogenesis was associated with AR expression and with a decrease in SC AMH content. Accordingly, AR mRNA expression was lower and AMH mRNA expression higher in fetal testes than in adult testes. In androgen insensitivity syndrome patients, combined gonadotropin stimulation induced an increase in circulating testosterone and AMH, a finding consistent with a failure of TT to repress AMH in the absence of AR signalling. Finally, direct androgen repression of AMH only occurred in AR-expressing SMAT1 cells. Functional ARs are essential for TT-mediated AMH repression in SC.

Anti-Mullerian Hormone Is an Endocrine Marker of Ovarian Gonadotropin-Responsive Follicles and Can Help to Predict Superovulatory Responses in the Cow

The major limitation to the development of embryo production in cattle is the strong between-animal variability in ovulatory response to FSH-induced superovulation, mainly due to differences in ovarian activity at the time of treatment. This study aimed to establish whether anti-Müllerian hormone (AMH) was an endocrine marker of follicular populations in the cow, as in human, and a possible predictor of the ovarian response to superovulation. Anti-Müllerian hormone concentrations in plasma varied 10-fold between cows before treatment and were found to be highly correlated with the numbers of 3- to 7-mm antral follicles detected by ovarian ultrasonography before treatment (r=0.79, P<0.001) and the numbers of ovulations after treatment (r=0.64, P<0.01). Between-animal differences in AMH concentrations were found to be unchanged after a 3-mo delay (r=0.87, P<0.01), indicating that AMH endocrine levels were characteristic of each animal on a long-term period. The population of healthy 3- to 7-mm follicles was the main target of superovulatory treatments, contained the highest AMH concentrations and AMH mRNA levels compared with larger follicles, and contributed importantly to AMH endocrine levels. In conclusion, AMH was found to be a reliable endocrine marker of the population of small antral gonadotropin-responsive follicles in the cow. Moreover, AMH concentrations in the plasma of individuals were indicative of their ability to respond to superovulatory treatments.

Anti-Mullerian Hormone, Its Receptor, FSH Receptor, and Androgen Receptor Genes Are Overexpressed by Granulosa Cells from Stimulated Follicles in Women with Polycystic Ovary Syndrome

In the polycystic ovary syndrome (PCOS), in addition to intrinsic thecal dysregulation leading to hyperandrogenism, a granulosa cell (GC) dysregulation may occur. Expression of anti-Müllerian hormone (AMH), FSH receptor (FSHR) and androgen receptor (AR) are suspected to be altered in PCOS GCs. The aim of this prospective study was to analyze the expression of these genes at the last stages of follicular maturation in GCs from 17 patients with PCOS and 15 controls undergoing controlled ovarian hyperstimulation during a cycle with in vitro fertilization. On the day of oocyte retrieval, follicular fluids were collected from small follicles (SF; 8-13 mm) and large follicles (17-22 mm) in separate tubes. Total RNAs and proteins were extracted from GCs. Reverse transcription was performed and quantification of gene expression levels was achieved by real-time quantitative PCR. AMH and FSHR mRNA levels were significantly higher in PCOS than in controls in GCs from both SF and large follicles. Likewise, AR and AMH receptor II mRNA levels in GCs from SF were significantly higher in PCOS compared with controls. In both PCOS patients and controls, AMH and AR mRNA levels correlated strongly, positively, and independently to FSHR mRNA levels. Using quantitative RT-PCR, AMH, AMH receptor II, FSHR, and AR genes were shown to be overexpressed by GCs from stimulated follicles of women with PCOS undergoing controlled ovarian hyperstimulation. This could be the sign of a maturation defect or may reflect hyperandrogenism.

Expression of P450arom, AMH and ER.ALPHA. mRNA in Gonads of Turkey, Duck and Goose within One Week of Age

Although many studies have shown that P450aromatase (P450arom), anti-Mullerian hormone (AMH) and estrogen receptor α (ERα) play pivotal roles in sexual differentiation of the gonads during early embryonic development in chickens and quail, few studies have been reported for other domestic birds. Furthermore, little information is available in relation to the mRNA expression in gonads after sexual differentiation in posthatching birds. The present study was conducted to assay mRNA expression of P450arom, AMH and ERα in gonads at day of hatch in turkey and duck and 2 days after hatching in goose using the real-time PCR. The mRNA expression was also determined at one week of age in gonads of these birds. At the time of collection of the left gonads for total RNA extraction, the external appearance of the left and right gonads of male and female was documented by digital camera. Clear asymmetry was observed in the female ovary in which the right ovary was regressed completely by 1-2 days in posthatching turkey, duck and goose. Although gonadal asymmetry was as remarkable as in females, the left testis was larger than the right one in males. Remarkable expression of P450arom mRNA was observed only in females in all the 3 species but substantially no expression was detected in males. Significantly higher expression of AMH mRNA was detected in males than females only in goose but there was no sex difference in turkey and duck at 1-2 days posthatching and one week of age. Weak ERα mRNA expression without a sex difference was detected in the 3 birds. These results suggest that estrogen plays a key role for ovarian development via P450arom mRNA expression after hatching, whereas absence of its expression in males leads to testis development in turkey, duck and goose.

Pituitary hormones inhibit the function and differentiation of fetal Sertoli cells.

Although the role of pituitary hormones in fetal Sertoli cell proliferation is well understood, their involvement in fetal Sertoli cell differentiation is poorly documented. In this study, we evaluated rat fetal Sertoli cell function by measuring basal transferrin secretion ex vivo and transferrin and anti-Müllerian hormone (AMH) mRNA levels in vivo. The differentiation state of the Sertoli cells was estimated from the amount of transferrin secreted ex vivo after acute stimulation with FSH. Surprisingly, we found that the amount of transferrin secreted by each Sertoli cell in basal condition and after acute FSH stimulation decreased between 18.5 and 21.5 day post coitum (dpc), which corresponds to the onset of pituitary hormone secretion. All of the Sertoli cell parameters measured (basal and FSH-stimulated transferrin secretion ex vivo, transferrin and AMH mRNA levels in vivo) were higher in 21.5-dpc fetuses that had been decapitated on 16.5 dpc than in control littermates. Furthermore, immunostaining for AMH was strongly increased after decapitation. Taken together, these results suggest that pituitary hormones in the fetus and in the immature or adult rat differently regulate Sertoli cells, which suggests that fetal Sertoli cells have their own particular physiology.

Expression of anti-Müllerian hormone mRNA during gonadal and follicular development in the brushtail possum (Trichosurus vulpecula).

The ontogeny of anti-Müllerian hormone (AMH) gene expression in the brushtail possum during formation of the ovary and growth of follicles was examined using in situ hybridization. For comparative purposes, the expression pattern of AMH was also examined in the developing testis. In the female, AMH mRNA was observed in the ovary of 50% (3/6) of pouch young collected around the time of sexual differentiation of the gonad (Days 1-5): the signal was predominately localized to the inner-cortical and outer-medullary region of the ovary. Thereafter, AMH mRNA was not observed in the developing ovary until Days 78-113 of postnatal life when follicles first formed at the cortical-medullary boundary. At this time, AMH mRNA was observed in the cuboidal granulosa cells of some early growing (i.e. transitional) follicles and in the granulosa cells of primary follicles. Thereafter, AMH mRNA was present in granulosa cells at all subsequent stages of follicular growth (i.e. primary through antral), but not in preovulatory follicles. In all cases, once follicles had formed, AMH mRNA was limited to the granulosa cells and was not observed in the surface epithelium, stromal cells, oocytes, theca, corpus luteum, medullary cords, rete or interstitial glands. In the possum testis, Sertoli cells strongly expressed AMH around the time of sexual differentiation of the gonad, but expression decreased to very low levels in adults, suggesting that AMH plays a similar role in brushtail possums to that observed in other mammalian species. In conclusion, localization of mRNA for AMH exclusively to granulosa cells of growing follicles in the brushtail possum is consistent with a central role for this hormone in control of granulosa cell function in marsupials. In addition, expression of AMH in the developing ovary around the time of morphological sexual differentiation raises intriguing questions regarding the possible role of AMH at this time.

GATA-1 is a potential repressor of anti-Müllerian hormone expression during the establishment of puberty in the mouse.

Anti-Müllerian hormone (AMH), also known as Müllerian inhibiting substance (MIS), is one of the earliest and best-known markers of Sertoli cell differentiation and is expressed until around puberty. The present study is aimed at the better understanding of the molecular pathways involved in testicular development and establishment of adult functions with regards to AMH regulation. We found, within the mouse AMH promoter, putative GATA motifs (A/T)GATA(A/G), known to be specifically bound by members of the GATA transcription factor family. We then carried out RNase protection assays and immunohistochemical techniques aimed at comparing precisely the chronological expression patterns of AMH and GATA-1, this latter being expressed in the testis after birth. Using both approaches we found an inverse and close relationship between AMH and GATA-1 mRNA and protein expression during the pre-pubertal period. These results allowed us to define a transitory 4-5-day period, starting from 3 dpp when both proteins are heterogeneously expressed in Sertoli cells and showed that the appearance of GATA-1 is associated with the decrease of AMH expression in these cells. Furthermore DNA-protein interaction in in vitro studies showed first that GATA-1 binds with various affinities on sites found in the AMH promoter and second that the proximity of the two strongest affinity sites leads to a synergistic binding effect. Altogether, the present study suggests that GATA-1 participates in AMH gene repression during the pre-pubertal period.

Sex differentiation and mRNA expression of p450c17, p450arom and AMH in gonads of the chicken

The present study was conducted to reveal effects of in ovo injection of nonsteroidal aromatase inhibitor (Fadrozole) or estradiol at day 3 of incubation on mRNA levels of P45017αhydroxylase (P450c17), P450 aromatase (P450arom) and anti-Müllerian hormone (AMH) in the chicken gonads. The mRNA levels in the gonads at days 4–8 of incubation were assessed by in situ hybridization analysis using digoxigenin labeling method. The in situ hybridization data were analyzed by relative expression of specific hybridizable signals of each mRNA corrected by the non-specific background by employing an image analyzer. P450c17 mRNA expression increased rapidly at day 6 of incubation in the male but decreased thereafter. In contrast to the transient expression in the male, the expression was gradually increased in the female. P450arom mRNA was not expressed in the male but was detectable in the female as early as day 6 and increased subsequently with days of incubation. AMH mRNA was expressed as early as day 5 of incubation followed by a sharp increase on day 6, which was maintained in the male thereafter. In contrast, the female showed very little expression. The injection of Fadrozole caused no effect on P450c17 mRNA expression, while it suppressed P450arom mRNA expression but increased AMH mRNA expression in the female. In contrast, the injection of estradiol induced P450arom mRNA expression significantly but suppressed AMH mRNA expression in the male. These results indicate that expression of P450arom and AMH is sexually dimorphic and is reciprocally regulated during early ontogenic life in chicken gonads. Mol. Reprod. Dev. 55:20–30, 2000. © 2000 Wiley-Liss, Inc.

Sex differentiation and mRNA expression of P450c17, P450arom and AMH in gonads of the chicken.

The present study was conducted to reveal effects of in ovo injection of nonsteroidal aromatase inhibitor (Fadrozole) or estradiol at day 3 of incubation on mRNA levels of P45017alphahydroxylase (P450c17), P450 aromatase (P450arom) and anti-Müllerian hormone (AMH) in the chicken gonads. The mRNA levels in the gonads at days 4-8 of incubation were assessed by in situ hybridization analysis using digoxigenin labeling method. The in situ hybridization data were analyzed by relative expression of specific hybridizable signals of each mRNA corrected by the non-specific background by employing an image analyzer. P450c17 mRNA expression increased rapidly at day 6 of incubation in the male but decreased thereafter. In contrast to the transient expression in the male, the expression was gradually increased in the female. P450arom mRNA was not expressed in the male but was detectable in the female as early as day 6 and increased subsequently with days of incubation. AMH mRNA was expressed as early as day 5 of incubation followed by a sharp increase on day 6, which was maintained in the male thereafter. In contrast, the female showed very little expression. The injection of Fadrozole caused no effect on P450c17 mRNA expression, while it suppressed P450arom mRNA expression but increased AMH mRNA expression in the female. In contrast, the injection of estradiol induced P450arom mRNA expression significantly but suppressed AMH mRNA expression in the male. These results indicate that expression of P450arom and AMH is sexually dimorphic and is reciprocally regulated during early ontogenic life in chicken gonads.

Effect of Prenatal Exposure to Diethylstilbestrol on Mullerian Duct Development in Fetal Male Mice

The clinical use of diethylstilbestrol (DES) by pregnant women has resulted in an increased incidence of genital carcinoma in the daughters born from these pregnancies. Also, in the so-called DES-sons abnormalities were found, mainly, the presence of Müllerian duct remnants, which indicates that fetal exposure to DES may have an effect on male sex differentiation. Fetal regression of the Müllerian ducts is under testicular control through anti-Müllerian hormone (AMH). In male mice, treated in utero with DES, the Müllerian ducts do not regress completely, although DES-exposed testes do produce AMH. We hypothesized that incomplete regression in DES-exposed males is caused by a diminished sensitivity of the Müllerian ducts to AMH. Therefore, the effect of DES on temporal aspects of Müllerian duct regression and AMH type II receptor (AMHRII) messenger RNA (mRNA) expression in male mouse fetuses was studied. It was observed that Müllerian duct regression was incomplete at E19 (19 days post coitum), upon DES administration during pregnancy from E9 through E16. Furthermore, analysis of earlier time points of fetal development revealed that the DES treatment had clearly delayed the onset of Müllerian duct formation by approximately 2 days; in untreated fetuses, Müllerian duct formation was complete by E13, whereas fully formed Müllerian ducts were not observed in DES-treated male fetuses until E15. Using in situ hybridization, no change in the localization of AMH and AMHRII mRNA expression was observed in DES-exposed male fetuses. The mRNA expression was quantified using ribonuclease protection assay, showing an increased expression level of AMH and AMHRII mRNAs at E13 in DES-exposed male fetuses. Furthermore, the mRNA expression levels of Hoxa 11 and steroidogenic factor-1 (SF-1) were determined as a marker for fetal development. Prenatal DES exposure had no effect on Hoxa 11 mRNA expression, indicating that DES did not exert an overall effect on the rate of fetal development. In DES-exposed male fetuses, SF-1 showed a similar increase in mRNA expression as AMH, in agreement with the observations that the AMH gene promoter requires an intact SF-1 DNA binding site for time- and cell-specific expression, although an effect of DES on SF-1 expression in other tissues, such as the adrenal and pituitary gland, cannot be excluded. However, the increased expression levels of AMH and AMHRII mRNAs do not directly explain the decreased sensitivity of the Müllerian ducts to AMH. Therefore, it is concluded that prenatal DES exposure of male mice delays the onset of Müllerian duct development, which may result in an asynchrony in the timing of Müllerian duct formation, with respect to the critical period of Müllerian duct regression, leading to persistence of Müllerian duct remnants in male mice.

Gene expression of steroidogenic enzymes in chicken embryonic gonads

This paper reviews the molecular aspects of sex differentiation in birds and describes the sex-reversal effects of aromatase inhibitor on mRNA expression of steroidogenic enzymes. Although it is unknown whether the sex-determining gene resides in the W chromosome or whether a gene-dosage mechanism is involved in sex determination, it is clear that anti-Müllerian hormone (AMH) and androgen play a key role for testicular development, whereas estrogen is important for ovarian formation. Our in situ hybridization results demonstrated that mRNA expression of P450aromatase first takes place on day 6.5 of incubation exclusively in the female gonad. Treatment with aromatase inhibitor in ovo suppressed mRNA expression in genetic females. This suggests that ovarian development is promoted by aromatase expression via estrogen production. On the other hand, previous reports demonstrated that formation of the testis is accompanied by Sox9 and AMH mRNA expression, which start on days 6 and 8, respectively. This suggests that Sox9 plays an important role for the male determining pathway which leads to AMH expression and formation of the testis. J. Exp. Zool. 281:450–456, 1998. © 1998 Wiley-Liss, Inc.

Gene expression of steroidogenic enzymes in chicken embryonic gonads

This paper reviews the molecular aspects of sex differentiation in birds and describes the sex-reversal effects of aromatase inhibitor on mRNA expression of steroidogenic enzymes. Although it is unknown whether the sex-determining gene resides in the W chromosome or whether a gene-dosage mechanism is involved in sex determination, it is clear that anti-Müllerian hormone (AMH) and androgen play a key role for testicular development, whereas estrogen is important for ovarian formation. Our in situ hybridization results demonstrated that mRNA expression of P450aromatase first takes place on day 6.5 of incubation exclusively in the female gonad. Treatment with aromatase inhibitor in ovo suppressed mRNA expression in genetic females. This suggests that ovarian development is promoted by aromatase expression via estrogen production. On the other hand, previous reports demonstrated that formation of the testis is accompanied by Sox9 and AMH mRNA expression, which start on days 6 and 8, respectively. This suggests that Sox9 plays an important role for the male determining pathway which leads to AMH expression and formation of the testis.

Effect of prenatal exposure to diethylstilbestrol on Müllerian duct development in fetal male mice.

The clinical use of diethylstilbestrol (DES) by pregnant women has resulted in an increased incidence of genital carcinoma in the daughters born from these pregnancies. Also, in the so-called DES-sons abnormalities were found, mainly, the presence of Müllerian duct remnants, which indicates that fetal exposure to DES may have an effect on male sex differentiation. Fetal regression of the Müllerian ducts is under testicular control through anti-Müllerian hormone (AMH). In male mice, treated in utero with DES, the Müllerian ducts do not regress completely, although DES-exposed testes do produce AMH. We hypothesized that incomplete regression in DES-exposed males is caused by a diminished sensitivity of the Müllerian ducts to AMH. Therefore, the effect of DES on temporal aspects of Müllerian duct regression and AMH type II receptor (AMHRII) messenger RNA (mRNA) expression in male mouse fetuses was studied. It was observed that Müllerian duct regression was incomplete at E19 (19 days post coitum), upon DES administration during pregnancy from E9 through E16. Furthermore, analysis of earlier time points of fetal development revealed that the DES treatment had clearly delayed the onset of Müllerian duct formation by approximately 2 days; in untreated fetuses, Müllerian duct formation was complete by E13, whereas fully formed Müllerian ducts were not observed in DES-treated male fetuses until E15. Using in situ hybridization, no change in the localization of AMH and AMHRII mRNA expression was observed in DES-exposed male fetuses. The mRNA expression was quantified using ribonuclease protection assay, showing an increased expression level of AMH and AMHRII mRNAs at E 13 in DES-exposed male fetuses. Furthermore, the mRNA expression levels of Hoxa 11 and steroidogenic factor-1 (SF-1) were determined as a marker for fetal development. Prenatal DES exposure had no effect on Hoxa 11 mRNA expression, indicating that DES did not exert an overall effect on the rate of fetal development. In DES-exposed male fetuses, SF-1 showed a similar increase in mRNA expression as AMH, in agreement with the observations that the AMH gene promoter requires an intact SF-1 DNA binding site for time- and cell-specific expression, although an effect of DES on SF-1 expression in other tissues, such as the adrenal and pituitary gland, cannot be excluded. However, the increased expression levels of AMH and AMHRII mRNAs do not directly explain the decreased sensitivity of the Müllerian ducts to AMH. Therefore, it is concluded that prenatal DES exposure of male mice delays the onset of Müllerian duct development, which may result in an asynchrony in the timing of Müllerian duct formation, with respect to the critical period of Müllerian duct regression, leading to persistence of Müllerian duct remnants in male mice.