Inhibin, activin, and follistatin in reproductive medicine

Elevated IGFBP7 expression in follicular granulosa cells promotes PCOS pathogenesis

Polycystic ovary syndrome (PCOS) can result in female infertility, menstrual irregularities, metabolic disturbances, hormonal imbalances, and significantly impact the reproductive health of women of childbearing age. Hyperandrogenism and insulin resistance are typical primary endocrine features of PCOS, which are also regarded as its core pathogenesis. In this study, IGFBP7 expression in granulosa cells (GCs) from women with and without PCOS was analyzed using bulk RNA-seq. A PCOS-like mouse model was constructed using dehydroepiandrosterone in IGFBP7 knockout and wild-type mice to explore the role of IGFBP7 in PCOS. Primary GCs from mice were cultured and transfected with IGFBP7 overexpression plasmid and siRNA fragments. Proliferation, apoptosis, and steroid hormone levels were measured to investigate the effects of IGFBP7 on granulosa cells. IGFBP7 expression was found to be elevated in patients with PCOS. Following IGFBP7 knockdown in mouse GC, there was a significant increase in GC proliferation, a decrease in GC apoptosis, and a notable decrease in testosterone secretion by GC. Conversely, overexpression of IGFBP7 in mouse granulosa cells significantly inhibited GC proliferation, significantly increased GC apoptosis, and led to a marked increase in testosterone secretion by GCs. With mouse model, a reduction in PCOS symptoms in mice after IGFBP7 deletion was observed. Elevated IGFBP7 expression in PCOS granulosa cells may induce apoptosis, hinder insulin signaling, and enhance androgen synthesis. These insights offer novel avenues for understanding and treating PCOS.

Circular RNA circRPS19 promotes chicken granulosa cell proliferation and steroid hormone synthesis by interrupting the miR-218-5p/INHBB axis

Ovarian follicle development is an important physiological activity for females and makes great significance in maintaining female health and reproduction performance. The development of ovarian follicle is mainly affected by the granulosa cells (GCs), whose growth is regulated by a variety of factors. Here, we identified a novel circular RNA (circRNA) derived from the Ribosomal protein S19 (RPS19) gene, named circRPS19, which is differentially expressed during chicken ovarian follicle development. Further explorations identified that circRPS19 promotes GCs proliferation and steroid hormone synthesis. Furthermore, circRPS19 was found to target and regulate miR-218-5p through a competitive manner with endogenous RNA (ceRNA). Functionals investigation revealed that miR-218-5p attenuates GCs proliferation and steroidogenesis, which is opposite to that of circRPS19. In addition, we also confirmed that circRPS19 upregulates the expression of Inhibin beta B subunit (INHBB) by binding with miR-218-5p to facilitate GCs proliferation and steroidogenesis. Overall, this study revealed that circRPS19 regulates GCs development by releasing the repression of miR-218-5p on INHBB, which suggests a novel mechanism in respect to circRNA and miRNA regulation in ovarian follicle development.

Serum INHB Levels and ACE Gene I/D Polymorphism with Increased Risk for Unexplained Infertility

ACE has a significant role in the angiogenesis of ovarian endothelium and the resumption of meiosis and folicular growth. However, there is no any study concerning ACE polymorphism and UI. The main aim of this study is that both identify ACE polymorphism and measure the serum ACE, AMH and INHB levels in UI patients and controls in Turkish population. 47 UI patients and 41 controls were involved in this study. To determine the ACE polymorphisms, DNA isolation and PCR were performed. Then, serum ACE, AMH and INHB levels were measured spectrophotometrically. Patients with UI had significantly higher serum INHB levels compared with controls (p < 0.05). Serum ACE levels were decreased, compared to controls, however the decrease were not significant. Serum AMH levels did not significantly differ from controls. When the relationship were analyzed between ACE I/D polymorphism and infertility risk, and ID genotype were chosen as reference, it was found to be 2.33 times more risk of UI that the women have DD genotype (DD vs. ID: odds ratio = 2.33, 95% confidence interval (0,88-6,19); p = 0,086). This finding indicates that DD genotype may be high risk for UI. Further studies are warranted to confirm this finding, especially with a larger population.

Anatomy and physiology of genital organs - men

Male sexual functions involve a number of organs and structures in genitalia whose role is to produce fertilizing gametes and to allow female-partner insemination. The testes belong to the reproductive and endocrine systems as they synthesize spermatozoa and androgens, and are under finely regulated hormonal control by the hypothalamopituitary axis. Sexual responses are controlled by a complex and coordinated interplay of both the somatic and the autonomic nervous system in multiple components of the brain, spinal cord, and relevant peripheral organs. Erectile bodies are an essential element of the penis and engorgement of the penis with blood leads to penile tumescence. Blood engorgement is due to relaxation of smooth-muscle cells of erectile tissue and endothelium of the penile arteries. The penis gains additional rigidity when the ischiocavernosus muscles contract. Stimuli from peripheral and/or central origins activate particular spinal nuclei, causing penile erection. Ejaculation consists of two phases, emission and expulsion, which correspond, respectively, to secretion of the different components of the semen by sex glands and forceful expulsion of semen due to rhythmic contractions of the bulbospongiosus muscle. A spinal generator of ejaculation integrates genital stimuli and sexual cues and, when the excitatory threshold is reached, triggers ejaculation by orchestrating the activation of autonomic and somatic pathways commanding the peripheral events of ejaculation.

Association of inhibin α gene promoter polymorphisms with risk of idiopathic primary ovarian insufficiency in Korean women

OBJECTIVE

The aim of this study was to investigate whether two polymorphisms in the promoter region of inhibin alpha (INHA) are associated with risk of idiopathic primary ovarian insufficiency (POI) in Korean women, which is a controversial topic.

STUDY DESIGN

We genotyped the INHA polymorphisms c.-16C>T (rs35118453) and c.-124A>G (rs11893842) of 136 POI patients and 225 controls in Korean women by polymerase chain reaction and restriction fragment length polymorphism analysis. We then compared differences in genotype and allele frequencies (AF) of the polymorphisms between the two groups to determine odds ratios (OR) and 95% confidence intervals (CI) as measures of the strength of association between genotype and POI.

RESULTS

There were no significant differences in genotype or AF of the polymorphisms between the POI patients and controls. Haplotype analysis revealed that the T-G haplotype of the two variant alleles was more frequent in POI patients than in the controls (OR=1.630, 95% CI=1.081-2.457). Combination genotype analysis showed that the CT+TT/GG genotype frequency was higher in POI patients than in the controls (OR=2.414, 95% CI=1.190-4.895).

CONCLUSIONS

We provide evidence to suggest that when the two variant alleles are combined, the c.-16C>T and c.-124A>G polymorphisms are associated with increased POI risk in Korean women. We postulate that interactions between the INHA polymorphisms may affect POI risk.

Autoimmune mediated regulation of ovarian tumor growth

OBJECTIVES

An immune response sufficient to induce organ failure may provide protection and therapy against tumors derived from the targeted organ particularly when removal or ablation of the organ is part of the standard therapy and does not threaten survival. We have previously shown that a targeted immune response directed against the ovarian-specific protein, inhibin-α, causes ovarian failure. Here we determined whether inhibin-α autoimmunity is effective in both prevention and treatment of ovarian tumors.

METHODS

A transgene consisting of the SV40 large tumor transformation antigen under the regulation of an anti-Mullerian hormone promoter (AMH-SV40Tag) was transferred by backcrossing for 12 generations to SJL/J mice producing SJL.AMH-SV40Tag (H-2(s)) females that develop a high incidence of autochthonous granulosa cell tumors. We determined whether immunization of SJL.AMH-SV40Tag female mice with the IA(s)-restricted p215-234 peptide of mouse inhibin-α was capable of preventing and treating these ovarian tumors.

RESULTS

The growth of autochthonous ovarian granulosa cell tumors in SJL.AMH-SV40Tag transgenic mice was significantly inhibited in mice immunized with Inα 215-234. In addition, significant inhibition of tumor growth occurred when mice with established ovarian granulosa cell tumors were therapeutically vaccinated with Inα 215-234.

CONCLUSIONS

Our results indicate that induction of ovarian-specific autoimmunity may serve as an effective way to prevent the emergence of autochthonous ovarian tumors and control the growth of established ovarian malignancies.

Follicular Development and Expression of the Messenger Ribonucleic Acid for the Inhibin/Activin Subunits in Two Genetic Lines of Turkey Hens that Differ in Total Egg Production

The characterization of the follicular hierarchy and the expression of the mRNA for the inhibin/activin subunits was investigated in the follicles of 2 lines of turkey hens selected for over 40 generations for increased egg production (Egg line) or increased body weight (Growth line). The follicular hierarchies of 6 hens from the Egg and Growth lines were characterized in middle (45 wk of age) and late production (58 wk of age). Relative follicular weights for individual hierarchical follicles (>12 mm), pooled small yellow follicles (5 to 12 mm), and large white follicles (2 to 5 mm) were calculated. Total RNA was extracted for Northern blot analysis from individual granulosa cell layers of the F1 through F4 follicles, and from the combined granulosa and theca layers of small yellow follicles and large white follicles from an additional 6 hens from each genetic line. Egg line hens displayed a more distinct follicular size hierarchy than Growth line hens at 45 and 58 wk. Although total follicular weight relative to body size was greater at 45 and 58 wk of age for the Egg line hens than the Growth line hens, the total number of hierarchical follicles was greater in the Growth line hens at 45 and 58 wk of age. Expression of follistatin and the inhibin beta(B)-subunit was highest in nonhierarchical follicles, whereas the expression of the inhibin alpha- and beta(A)-subunits was highest in the hierarchical follicles. The inhibin alpha- and beta(A)-subunit mRNA expression pattern in the 4 largest follicles of the Growth line hens was not similar to the Egg line hens or characteristic of laying hens that have a high rate of egg production. The unusual inhibin subunit mRNA expression in the largest hierarchical follicles of the Growth line hens may account for their development of an abnormal follicular size hierarchy and for their poor egg production.

Anterior pituitary gene expression with reproductive aging in the female rat

Although reproductive aging in women is classically attributed to loss of ovarian follicles, recent data have suggested that the entire hypothalamic-pituitary-ovarian axis undergoes functional changes with time. The aim of this study was to characterize age-related changes in pituitary gene expression for factors with known importance for gonadotroph function, including 1) steroid hormone receptors (Esr and Pgr), 2) orphan nuclear receptors [Nr5a1 (steroidogenic factor-1) and Nr5a2 (liver receptor homologue-1)], and 3) pituitary-derived polypeptides (activin, inhibin, and follistatin), as well as 4) gonadotropin subunits and 5) GnRH receptors. We chose to utilize a middle-aged rat model for these studies. Young (Y; 3-mo-old) and middle-aged (MA; 9- to 12-mo-old) rats were ovariectomized, primed with estradiol, and injected with progesterone to induce an LH surge. The mRNA levels for the gonadotropin subunits and GnRH receptors were decreased in middle-aged females relative to young animals. Nr5a1 and follistatin mRNA levels were significantly greater in Y versus MA animals following ovariectomy. Furthermore, steroid-induced regulation of these genes was lost in the MA animals. Regulation of the Nr5a2, Inhba, and Inhbb transcripts was also limited to the young animals. In contrast, there were no significant differences in the mRNA levels of Esr or Pgr family members between age groups at any time point. Although this in vivo model normalizes ovarian steroid levels, it does not control for potential differences in GnRH stimulation with aging. Therefore, in a second set of experiments, we used an in vitro perifusion system to compare the effects of pulsatile GnRH in the two age groups. Nr5a1 mRNA expression was greater in Y than MA animals and was significantly decreased by GnRH pulses in both age groups. Follistatin mRNA levels increased significantly with GnRH treatment in Y animals but were not significantly changed in the MA females. Taken together, these data demonstrate gene-specific blunting of pituitary gene expression postovariectomy and during the steroid-induced surge in middle-aged rats. We propose that age-related changes in pituitary physiology may contribute to reproductive senescence.

Use of oral contraceptives in infertile patients: A descriptive review

In the past and currently, there are several applications of oral contraceptives (OCs) in the field of infertility. The aim of the present descriptive review is to analyze the old and new uses of OCs in infertile patients undergoing simple or multiple ovulation-induction programs. Available data seem to indicate that OCs given before treatment could be effective in patients who are resistant to clomiphene citrate and in poor responders. In addition, the use of OCs is useful for scheduling in vitro fertilization programs downregulated with gonadotropin-releasing hormone-antagonists.

Autoimmune targeted disruption of the pituitary-ovarian axis causes premature ovarian failure

Premature ovarian failure (POF) is characterized by amenorrhea and high serum levels of follicle-stimulating hormone (FSH). POF causes female infertility and represents a substantial women's health risk affecting 1% of women by age 40. Although ovarian autoimmunity has been associated with POF, the identity of ovarian Ags recognized is unknown. In this study, we show that autoimmune-targeted disruption of the pituitary-ovarian axis leads to POF. Immunization of SWXJ female mice with the p215-234 peptide derived from mouse inhibin-alpha activates CD4(+) T cells and induces experimental autoimmune oophoritis with a unique biphasic phenotype characterized by an early stage of enhanced fertility followed by a delayed stage of POF. Affected mice show high serum levels of inhibin-alpha-neutralizing Abs that prevent inhibin-mediated down-regulation of activin-induced pituitary FSH release. The loss of activin/FSH down-regulation leads to prolonged metestrus-diestrus, superovulation, increased numbers of mature follicles, increased offspring, accelerated depletion of primordial follicles, and ultimately premature infertility. Thus, inhibin-alpha-targeted experimental autoimmune oophoritis is initiated by CD4(+) Th1 T cells that stimulate B cells to produce inhibin-alpha-neutralizing Abs directly capable of mediating POF and transferring disease into naive recipients. Our inhibin-alpha autoimmune model of POF shows how premature infertility may develop in the context of elevated FSH levels thereby closely mimicking the hallmark features of human POF.

Uterine vascularization and pregnancy outcome in patients undergoing intracytoplasmatic sperm injection: the role of nitric oxide

PURPOSE

To evaluate whether, after pituitary desensitisation, the impedance to flow in the uterine vessels may be an indicator of an ICSI programme outcome, and to test the relationship between intrafollicular nitric oxide and oocyte/embryo quality.

METHODS

Thirty-eight women, on the basis of impedance to flow at the level of uterine artery, evaluated on the first day of COH, were divided in patients with normal (Pulsatility Index--PI, 2.5; Group II, n=27) PI values. The patients were submitted to hormonal, ultrasonographic and Doppler evaluations. Plasma and follicular fluid concentrations of nitrites/nitrate (NO(2) (-)/NO(3) (-)) were assayed.

RESULTS

In the Group I, the impedance to flow remained lower than in Group II and was associated to good quality embryos and to a higher pregnancy rate. Follicular fluid NO(2) (-)/NO(3) (-) levels were inversely correlated with the embryo quality. The uterine artery PI and the pregnancy rate were inversely correlated. The PIs analysed on the day 1 of stimulation, were positively correlated with those registered on day 8 and on the day of ovum pick-up.

CONCLUSIONS

A Doppler analysis done on day 1 of controlled ovarian hyperstimulation may be an useful indicator of ART outcome.

Evidence for increased ovarian follicular activity in girls with premature thelarche

OBJECTIVE

Inhibin B is produced by granulosa cells in small antral follicles, under the influence of FSH, and has a paracrine role in oestradiol synthesis. To test the hypothesis that premature thelarche is associated with increased FSH-driven follicular development, we measured inhibin B and FSH in girls with premature thelarche, girls with central precocious puberty (CPP) and controls matched either for age or breast stage.

PATIENTS

Blood samples were collected from 11 girls with premature thelarche (breast stage 2, aged 0.4-5.6 years), 11 prepubertal controls age-matched to the thelarche girls (0.5-5.4 years), 13 girls with CPP (breast stage 2, 3.9-8.2 years) and nine normal pubertal controls (breast stage 2, 9.0-13.2 years).

MEASUREMENTS

Dimeric inhibin B was measured in plasma by double-antibody enzyme-linked immunoassay and FSH by immunoradiometric assay. Pelvic ultrasonography was performed on all girls with CPP and 10/11 girls with premature thelarche.

RESULTS

Seven of the 13 girls with CPP and three of the eight girls with premature thelarche whose ovaries could be visualized had visibly nonhomogeneous ovarian structure on ultrasonography. Girls with premature thelarche had inhibin B and FSH concentrations higher than those in their age-matched controls (P < 0.01 and P < 0.05, respectively), and similar to those observed in girls with CPP and normal pubertal controls matched for breast stage. In thelarche girls, as in precocious puberty girls and normal pubertal controls, inhibin B and FSH were positively related (rs = 0.54-0.61).

CONCLUSIONS

This study provides further evidence that premature thelarche is associated with enhanced follicular development, similar to that which occurs in early puberty, probably under the influence of FSH.

Messenger RNA and Protein Expression Analysis of Betaglycan in the Pituitary and Ovary of the Domestic Hen1

Betaglycan was originally characterized as the type III receptor for TGFbeta, yet recent research has indicated that betaglycan can serve as an accessory receptor for inhibin. To understand better the action of inhibin in avian follicular development, we have investigated the expression of betaglycan in the pituitary gland and ovary of the hen. In experiments 1 and 2, betaglycan mRNA was detected at 6 kilobases (kb) by Northern blot analysis (n = 5) in chicken pituitary, granulosa, and theca layers and whole ovary. Expression of betaglycan was greatest in the pituitary gland in experiment 1 and greater in the granulosa layer of small yellow follicles (SYF) compared with the granulosa layer of larger follicles. In experiment 2, betaglycan mRNA was more abundantly expressed in the theca layer compared with the granulosa layer for all follicle sizes, although there was no significant difference in betaglycan expression in the theca layer among follicle sizes. In experiment 3, immunohistochemical analysis revealed betaglycan protein in the anterior pituitary as well as in the ovary (n = 4) and SYF (n = 4). Colocalization studies revealed a high abundance of cells within the anterior pituitary expressing both betaglycan and FSH (n = 4). Betaglycan protein was found in the granulosa layer; however, markedly enhanced staining was observed in the theca layer of ovarian follicles. Our results provide evidence for expression of betaglycan mRNA and protein colocalization with FSH in the anterior pituitary, consistent with known inhibin effects. Ovarian localization of betaglycan, particularly in the theca layer, suggests a paracrine role for inhibin in the hen.

Localization of inhibins and activins in normal endocrine cells and endocrine tumors of the gut and pancreas: an immunohistochemical and in situ hybridization study

Activins and inhibins, which belong to the TGF beta family, are composed of different combinations of alpha-, betaA-, and betaB-subunits, resulting in inhibin A (alphabetaA), inhibin B (alphabetaB), activin A (betaAbetaA), activin B (betaBbetaB), and activin AB (betaAbetaB). They regulate several cell functions, acting as paracrine/autocrine factors. Their actions, which depend on binding to specific receptors, are also modulated by follistatin. Gastroenteropancreatic (GEP) endocrine cells and endocrine tumors (ETs) produce several growth factors, but it is not well known whether they express follistatin and the various inhibin/activin subunits. We studied their expression in 65 GEP ETs using immunohistochemistry (IHC) and in situ hybridization (ISH). The alpha-subunit and follistatin were not identified in normal GEP endocrine cells and were poorly expressed in ETs. A betaA-subunit immunoreactivity (IR) was detected in A-, G-, EC-, and GIP-cells, while betaB-chain IR was present only in D-cells. The mRNAs encoding for these molecules were poorly expressed in normal tissues. BetaA- and betaB-subunits were identified in several ETs by both IHC and ISH: betaA-subunit mainly in G-cell and A-cell ETs, and betaB-subunit in D-cell, A-cell, and EC-cell ETs. Our results demonstrate a differential expression of activin/inhibin subunits among different types of GEP endocrine cells and related tumors, suggesting a role in modulation of biological functions of these normal and neoplastic endocrine cells.

Localization and secretion of inhibins in the equine fetal ovaries

To clarify the source of inhibins in equine female fetuses, concentrations of immunoreactive (ir-) inhibin, inhibin pro-alphaC, and inhibin A in both fetal and maternal circulation and in fetal ovaries were measured. In addition, the localization of inhibin alpha and inhibin/activin beta(A), and beta(B) subunits and the expression of inhibin alpha(A) and inhibin/activin beta(A) subunit mRNA in fetal ovaries were investigated using immunohistochemistry and in situ hybridization. Concentrations of circulating ir-inhibin, inhibin pro-alphaC, and inhibin A were remarkably more elevated in the fetal than in the maternal circulation between Days 100 and 250 of gestation. Fetal ovaries contained large amounts of ir-inhibin, inhibin pro-alphaC, and inhibin A. In contrast, these inhibin forms were undetectable in both the maternal ovaries and placenta. The inhibin alpha and inhibin/activin beta(A) and beta(B) subunit proteins were localized to enlarged interstitial cells of the equine fetal ovary. Expression of inhibin alpha and inhibin/activin beta(A) subunit mRNAs were also observed in the interstitial cells. We conclude that the main source of large amounts of inhibins in fetal circulation is interstitial cells of fetal ovary and is not of maternal origin. Furthermore, these inhibins may play some important physiological roles in the development of gonads in the equine fetus.

Direct binding of AP-1 (Fos/Jun) proteins to a SMAD binding element facilitates both gonadotropin-releasing hormone (GnRH)- and activin-mediated transcriptional activation of the mouse GnRH receptor gene

The response of pituitary gonadotropes to gonadotropin-releasing hormone (GnRH) correlates directly with the concentration of GnRH receptors (GnRHR) on the cell surface, which is mediated in part at the level of gene expression. Several factors are known to affect expression of the mouse GnRHR (mGnRHR) gene, including GnRH and activin. We have previously shown that activin augments GnRH-mediated transcriptional activation of mGnRHR gene, and that region -387/-308 appears to be necessary to mediate this effect. This region contains two overlapping cis-regulatory elements of interest: GnRHR activating sequence (GRAS) and a putative SMAD-binding element (SBE). This study investigates the role of these elements and their cognate transcription factors in transactivation of the mGnRHR gene. Transfection studies confirm the presence of GnRH- and activin-response elements within -387/-308 of mGnRHR gene promoter. Competition electrophoretic mobility shift assay experiments using -335/-312 as probe and alphaT3-1 nuclear extract or SMAD, Jun, and Fos proteins demonstrate direct binding of AP-1 (Fos/Jun) protein complexes to -327/-322 and SMAD proteins to -329/-328. Further transfection studies using mutant constructs of these cis-regulatory elements confirm that both are functionally important. These data define a novel cis-regulatory element comprised of an overlapping SBE and newly characterized non-consensus AP-1 binding sequence that integrates the stimulatory transcriptional effects of both GnRH and activin on the mGnRHR gene.

Hormone-independent ovarian influence on adhesion development

OBJECTIVE

To determine which ovarian sex steroid(s), when removed from an intact organism, reduce(s) postoperative adhesion development.

DESIGN

Randomized, prospective, blinded study.

SETTING

University vivarium.

PATIENT(S)

One hundred twenty sexually mature female Sprague-Dawley rats, 226-250 g.

INTERVENTION(S)

Day 0, sham ovariectomy or bilateral ovariectomy, accompanied by continuous-release sex steroid replacement of either no steroids (control), 17beta-E(2), natural P (P4), or combined E(2)/P4. Day 7, standardized cecal abrasion; day 14, necropsy with assessment of adhesion presence or absence.

MAIN OUTCOME MEASURE(S)

Adhesion formation.

RESULT(S)

Three rats died because of anesthesia or surgical complications, and 117 rats reached necropsy. The ovary-intact (sham) rats adhesion incidence was 60.9%; ovariectomized control rats, 20.8%; E(2), 28.6%; P4, 33.3%; and combined E(2)/P4, 24.0%. Despite differing sex steroid replacement, two-tailed chi(2) testing with correction for multiple comparisons showed no statistical difference in adhesion incidence among the four ovariectomy groups. A statistically significant lower adhesion incidence was noted between the ovary-intact sham cohort and the collective ovariectomy groups and between the sham and ovariectomized control cohorts.

CONCLUSION(S)

Ovarian presence or absence at the time of surgical wounding, and not the 17beta-E(2) or P milieu, modulates adhesion development. This implicates other ovarian factor(s) in postoperative adhesion development.

Active immunization of broiler breeder hens with a recombinant chicken inhibin fusion protein enhances egg lay

We have demonstrated that inoculation of female Coturnix with an inhibin-based immunogen (MBP-cINA521) accelerated puberty and enhanced hen-day egg production (HDEP). Herein, MBP-cINA521, a fusion protein, which consists of the bacterial maltose binding protein (MBP) and a fragment of the infinity-subunit of chicken inhibin (cINA521), was tested for its ability to enhance production performance in broiler breeders. Pullets (Arbor Acres Classic Females; n = 60 birds/treatment group) were given (subcutaneously) 0, 1, 3, or 5 mg of MBP-cINA521 in Freund's complete adjuvant at 20 wk and 4 d of age. Booster immunizations (one-half of the primary dosages) were given at 23 wk of age. The vehicle for controls (CON; no booster) and MBP-cINA521-boosted birds was Freund's incomplete adjuvant. Blood samples were obtained at the end of the trial to assess immunological response to the antigen with a titer ELISA. The onset of puberty was assessed by calculation of the average ages at first lay (FIRST) and at 50% egg production (FIFTY). Cumulative percentage HDEP was determined weekly throughout the laying period (40 wk). Egg weight (EWT) and specific gravity (SG) assessments were made periodically during the trial. Body weight gain (BWG) and mortality (MORT) data were also collected. Significant injection treatment differences (P < 0.01) in inhibin antibody titers were detected according to the following order: low dose = intermediate dose > high dose > CON. A dose of MBP-cINA521 capable of accelerating puberty and increasing overall egg lay was identified. FIRST and FIFTY responses were decreased (P < 0.05) in birds given the intermediate dose (3.0 mg) of MBP-cINA521 when compared to the CON. FIFTY responses were also lower (P < 0.05) than CON responses in those birds given the highest dose (5.0 mg) of the inhibin antigen. Cumulative HDEP was also higher (P < 0.05), beginning at 3 wk of lay and weekly thereafter (P < 0.05, for the remaining 40 wk), in birds given the intermediate immunogen dosage when compared to the CON. By Week 40, an average increase of 9.5% HDEP was realized in birds given 3.0 mg of MBP-cINA521. MORT rates were similar in the CON and in the two lowest MBP-cINA521 treatment groups but were higher (P < 0.05) in those birds given 5.0 mg of the antigen. EWT, SG, and BWG measurements were unaffected by treatment with the inhibin vaccine. In agreement with our findings in quail, immunoneutralization of inhibin enhanced production performance in breeder hens.

Activin A augments GnRH-mediated transcriptional activation of the mouse GnRH receptor gene

The response of pituitary gonadotropes to GnRH correlates directly with the concentration of GnRH receptors (GnRHRs) on the cell surface, which is mediated in part at the level of GnRHR gene expression. We have previously localized GnRH responsiveness in the mouse GnRHR (mGnRHR) gene promoter to two elements: activating protein-1 and sequence underlying responsiveness to GnRH-1. This study was designed to investigate potential synergy between GnRH and activin A in transcriptional activation of the mGnRHR gene. In functional transfection studies using alphaT3-1 cells, GnRH agonist stimulation of the mGnRHR gene promoter (-765/+62) resulted in a 10.9-fold increase in activity, which was further increased 2-fold (to 21.3-fold) following activin pretreatment. Activin pretreatment alone had no effect. Deletion of region -387/-308 or mutation of a putative SMAD-binding element at -331/-324 (5'-GTCTAG[T]C-3') abrogated the augmented response to GnRH in the presence of activin but not the response to GnRH alone. Overexpression of SMAD2 and SMAD3 along with SMAD4 increased transcriptional activity of the mGnRHR gene, which was further increased by GnRH agonist stimulation. These data demonstrate that activin augments GnRH-mediated transcriptional activation of the mGnRHR gene and suggest that this effect may be mediated through SMAD transcription factors.

Dimeric inhibins in girls from birth to adulthood: relationship with age, pubertal stage, FSH and oestradiol

OBJECTIVE

Inhibin B is produced by granulosa cells in small antral follicles under the influence of FSH, whilst inhibin A is produced by larger follicles and the corpus luteum. The aims of our study were to investigate how these inhibins change from birth to late adolescence in girls, to derive reference data and to explore their relation with pubertal stage, FSH, oestradiol and each other.

STUDY DESIGN AND SUBJECTS

Blood samples were collected from: (a) 345 girls aged 0--18 years to obtain age-related reference data, and (b) 80 pre-menarcheal girls with full pubertal staging, of whom 40 were on GH treatment at the time of sampling.

MEASUREMENTS

Dimeric inhibins A and B were measured by double antibody enzyme-linked immunosorbent assay (ELISA), FSH by immunoradiometric assay (IRMA) and oestradiol by radioimmunoassay.

RESULTS

Median inhibin B was low until age 6 years, slightly higher from 6 to 10 years, then increased from 10 to 12 years to reach a plateau from 12 to 18 years. Inhibin A was usually detectable in girls younger than 3 months but thereafter became undetectable in most samples until after age 10 years, when median levels rose progressively to 14 years, then stabilized from 14 to 18 years. Both inhibins displayed considerable scatter about the median throughout infancy, childhood and adolescence. Girls aged 0--10 years showed a positive correlation between inhibins A and B (P < 0.0001), whereas those aged 14--18 years showed an inverse relationship (P < 0.001), indicating the onset of ovulatory cycles. Age-related reference ranges and data for calculation of SD scores are presented. GH-treated girls at pubertal stage B2 (but not at B1 or B3--5) had higher inhibin B and FSH levels than untreated girls and were excluded from further analysis. Both inhibins A and B increased during puberty (P < 0.0001) and were positively correlated with each other (P < 0.01). Both inhibins were also positively correlated with FSH in pre-pubertal girls (P < 0.05) but not at pubertal stages B3--5.

CONCLUSIONS

Although median levels of inhibins A and B remained low until after age 10 years in girls, the increased levels of both inhibins in individual samples, together with their positive relationship with FSH, provide further evidence of sporadic follicular development throughout infancy and childhood under the influence of FSH. The increase in both inhibins during puberty and their changing relationship with FSH are in keeping with the concept of follicular growth being dependent on the duration of FSH elevation above a critical threshold rather than the degree of elevation per se.

Activin A and gonadotropin regulation of follicle-stimulating hormone and luteinizing hormone receptor messenger RNA in avian granulosa cells

Activin A regulation of the expression of mRNA for the LH receptor, FSH receptor, and the inhibin alpha subunit as well as the effect of activin A on the secretion of progesterone were investigated in chicken granulosa cell cultures. Granulosa layers were isolated from the F(1) and F(3) + F(4) follicles from five hens, pooled according to size, dispersed, and cultured for 48 h. In experiment 1 (n = 3 replications), granulosa cells were cultured with or without highly purified ovine (o) FSH at 50 ng/ml and in the presence of 0, 10, or 50 ng/ml of recombinant chicken activin A. Experiment 2 (n = 4 replications) followed the same protocol as experiment 1, except that oFSH was replaced with oLH. Results from these experiments showed that addition of activin A to the granulosa cell cultures had no effect on the expression of mRNA for the inhibin alpha subunit or the FSH receptor, but it did affect the expression of mRNA for the LH receptor. Treatment of F(3) + F(4) granulosa cells with LH stimulated the expression of mRNA for the LH receptor; however, when LH was combined with either dose of activin A, this induction was prevented. The highest dose of activin A with or without LH resulted in decreased expression of the LH receptor compared to the untreated controls in the F(3) + F(4) cell cultures. Progesterone secretion by the granulosa cells from both follicle sizes was not altered by activin A. In experiment 3 (n = 3 replications), the effect of activin A on the growth of granulosa cells was examined with the following treatments: 0, 10, or 50 ng/ml of activin A; 50 ng/ml of either oLH or oFSH; and oLH or oFSH combined with 10 ng/ml of activin A. The highest dose of activin reduced the rate of granulosa cell proliferation in both follicle types. Growth of F(1) and F(3) + F(4) granulosa cells was stimulated by the addition of either gonadotropin, and the presence of 10 ng/ml of activin A with either gonadotropin did not alter this proliferation, except for the LH-treated F(3) + F(4) granulosa cells, in which the increase in proliferation was prevented. The results suggest that activin A could act as a local factor that regulates follicular maturation by preventing excessive or untimely LH receptor expression.

Immunohistochemical detection of inhibin-alpha, -betaB, and -betaA chains and 3beta-hydroxysteroid dehydrogenase in canine testicular tumors and normal testes

Immunohistochemical detection of inhibin-alpha, -betaA and -betaB chains and 3beta-hydroxysteroid dehydrogenase (HSD) was carried out on primary testicular tumors from 15 dogs and normal testes from three adult dogs. Histopathologically, the tumors were composed of three types: Leydig cell tumors in five dogs, Sertoli cell tumors in five dogs, and seminoma in five dogs. In normal testes, immunostaining against inhibin-alpha, -betaA, and -betaB chains and 3beta-HSD revealed positive reactivity in the cytoplasm of Leydig cells. In testicular tumors, immunoreactive cells against inhibin-alpha, -betaA, and -betaB chains and 3beta-HSD were localized in all Leydig cell tumors but not in any Sertoli cell tumors or seminomas. The results of radioimmunoassay for plasma inhibin in dogs with Leydig cell tumors showed higher concentrations than those in dogs with Sertoli cell tumors and seminomas and those in normal dogs. The concentration of inhibin in the plasma was markedly decreased by the surgical removal of the Leydig cell tumor in one dog. Our findings suggest that inhibin is synthesized by normal and neoplastic Leydig cells in the canine testis, and the secreted inhibin may be inhibin A and inhibin B.

Activin stimulates proliferation of rat ovarian thecal-interstitial cells

There is growing evidence that the function of ovarian theca-interstitial (T-I) cells may be modulated by paracrine actions of activin, inhibin, and follistatin. Furthermore, either dysregulation, dysfunction, or both, of these peptides may play a role in conditions associated with T-I hyperplasia, such as polycystic ovary syndrome (PCOS) and hyperthecosis. This study was designed to evaluate the role of activin, inhibin, and follistatin in the modulation of T-I cell proliferation. Interaction of these peptides with insulin-like growth factor-I (IGF-I), a known stimulator of T-I cell proliferation, was also assessed. Purified rat T-I cells were cultured for 48 h in chemically defined media and with or without activin (3-30 ng/ml), inhibin (3-30 ng/ml), follistatin (100 ng/ml), and/or IGF-I (10 nM). T-I cell proliferation was assessed using radiolabeled thymidine incorporation assay. Activin alone stimulated proliferation of T-I cells in a dose-dependent fashion (by up to 320% above control; P < 0.001), whereas inhibin alone or follistatin alone had no significant effect. Inhibin had also no effect on activin-induced proliferation. Follistatin significantly reduced the stimulatory effects of activin and decreased proliferation by up to 46% (P < 0.01) below the level attained in the presence of activin alone. IGF-I (10 nM), at a dose producing a near-maximal effect, increased proliferation by 175% above control (P < 0.001); insulin (10 nM) increased proliferation by 52% above control (P < 0.03). A combination of IGF-I (10 nM) and activin (30 ng/ml) resulted in a 1090% increase of proliferation above control (P < 0.001); this stimulatory effect was significantly greater than that achieved in the presence of either activin alone or IGF-I alone (P < 0.001). Similarly, a combination of insulin (10 nM) and activin (30 ng/ml) increased proliferation by 506% above control levels. Flow cytometry evaluation revealed that activin increased the proportion of actively dividing cells (in S or G2/M phase of the cell cycle) by 42% (P < 0.02), whereas IGF-I had no effect on the proportion of actively dividing cells. The present findings indicate that an activin-follistatin system may be involved in the regulation of the size of ovarian thecal-stromal compartment. In view of the synergy between activin and IGF-I, and the difference in the effects on the cell cycle distribution, stimulation of T-I proliferation by these agents is likely to be mediated via separate transduction pathways. Excess activin or insufficient follistatin may contribute to T-I hyperplasia.

Follicle-stimulating hormone regulation of inhibin alpha- and beta(B)-subunit and follistatin messenger ribonucleic acid in cultured avian granulosa cells

FSH regulation of inhibin alpha-, beta(B)-subunit and follistatin mRNA was investigated in cultured chicken granulosa cells, which were isolated and pooled according to size from the F(4) + F(5) follicles, small yellow follicles (SYF), and large white follicles (LWF). In experiment 1 (four replicate experiments), granulosa cells were cultured, and the effect of FSH (50 ng/ml) on the growth of cells from the different follicles was examined at 24 and 48 h of culture. Cell viability was >95% for all of the granulosa cell cultures at 24 and 48 h. At 24 h, the number of granulosa cells in both the FSH-treated and the untreated cultures for all follicle types was numerically greater than the number of cells originally plated. At 48 h, FSH-treated cultures for all follicle types had twice (P: < 0. 05) the number of cells as the untreated cultures. In experiment 2 (three replicate experiments), FSH increased expression of the mRNA for inhibin alpha-subunit in LWF granulosa cells at 4 and 24 h to detectable levels and increased inhibin alpha-subunit protein accumulation to detectable levels by 24 h in granulosa cells from the LWF. FSH also increased (P: < 0.05) mRNA levels for the inhibin alpha-subunit at 4 and 24 h in SYF granulosa cells and at 24 h in F(4) + F(5) granulosa cells. The effects of FSH on follistatin and ss(B)-subunit were variable with respect to follicle development and culture duration. These results suggest that FSH plays an important role in stimulating the production of mRNA and protein for the inhibin alpha-subunit in small prehierarchical follicles.

Correlation between serum inhibin B and other indicators of the ovarian function

OBJECTIVE

To investigate the correlation between the early follicular phase serum inhibin B levels and other indicators of ovarian reserve.

STUDY DESIGN

Seventy-four women aged 24-40 years (mean 32) with different infertility etiologies were investigated in the early follicular phase of a spontaneous mentrual cycle. The volume of the ovaries was measured and the total number of follicles <5 mm in size counted by ultrasound. Serum levels of FSH, estradiol (E2) and inhibin B were measured on the same day. In stepwise regression analysis inhibin B levels were correlated with age, body-mass-index, the ultrasound measurements, cause of infertility, parity, FSH and E2.

RESULTS

FSH, BMI and the number of follicles proved to be statistically significant independent predictive factors for the inhibin B levels, FSH and BMI correlating negatively and the number of follicles positively with inhibin B serum concentrations.

CONCLUSION

The number of small follicles reflect the inhibin B production of the ovaries. BMI being as strong predictive factor of inhibin B levels as FSH could in part explain the impaired likelihood of conceiving in obese patients.

Inhibin: a candidate gene for premature ovarian failure

Premature ovarian failure (POF) occurs in 1% of all women, and in 0.1% of women under the age of 30 years. The mechanisms that give rise to POF are largely unknown. Inhibin has a role in regulating the pituitary secretion of FSH, and is therefore a potential candidate gene for ovarian failure. Using single-stranded conformation polymorphism (SSCP) and DNA sequencing, DNA samples were screened from 43 women with POF for mutations in the three inhibin genes. Two variants were found: a 1032C-->T transition in the INHssA gene in one patient, and a 769G-->A transition in the INHalpha gene in three patients. The INHssA variant appears to be a polymorphism, as there was no change in the amino acid sequence of the gene product. The INHalpha variant resulted in a non-conservative amino acid change, with a substitution from alanine to threonine. This alanine is highly conserved across species, and has the potential to affect receptor binding. The INHalpha variant is significantly associated with POF (3/43 patients; 7%) compared with control samples (1/150 normal controls; 0.7%) (Fisher's exact test, P < 0.035). Further analysis of the inhibin gene in POF patients and matched controls will determine its role in the aetiology of POF.

Stem cell factor functions as a survival factor for mature Leydig cells and a growth factor for precursor Leydig cells after ethylene dimethane sulfonate treatment: implication of a role of the stem cell factor/c-Kit system in Leydig cell development

The significance of the interaction between Sertoli cell-produced stem cell factor (SCF) and its receptor, c-kit, on Leydig cells (LCs) during LC development and differentiation is unknown. In the present study, we investigated the potential role of the SCF/c-kit system in LC apoptosis and precursor LC proliferation after ethylene dimethane sulfonate (EDS) treatment in rats. A function-blocking anti-c-kit antibody, ACK-2, was used to block SCF/c-kit interaction at four time points, corresponding to the peak of LC apoptosis and three waves of proliferation of precursor LCs. Blockade of SCF/c-kit interaction by ACK-2 accelerated LC apoptosis and inhibited proliferation of precursor LCs during the first two waves of precursor LC proliferation around days 3-4 and day 10, but not the third wave of precursor LC proliferation around day 20 after EDS treatment. The data suggest that the soluble SCF might act as a survival factor for mature LCs and a growth factor for precursor LCs after EDS-induced LC depletion. This is also supported by a close correlation between the oscillating levels of soluble SCF mRNA and the profiles of LC apoptosis and regeneration. Since regeneration of the LC population after EDS treatment resembles the development of adult-type LCs during prepubertal life, the present findings imply that soluble SCF might participate in regulation of the formation of the LC population during testicular development. Our data also support a model in which delicate and reciprocal regulation exists between soluble SCF production by Sertoli cells, testosterone production by LCs, and pituitary gonadotropins.

Localization of inhibin/activin subunits in normal pituitary and in pituitary adenomas

The localization of inhibin/activin (I/A) subunits was investigated in human normal adenohypophysial cells and in 87 pituitary adenomas of different types, using immunohistochemistry. Monoclonal antibodies directed against alpha, beta A and beta B subunits of I/A were employed. In normal pituitary, alpha subunit of inhibin was detected only in FSH-positive gonadotrophs, while beta A subunit of I/A was expressed in FSH-positive gonadotrophs, GH-cells and in a few PRL-cells. beta B subunit was found in FSH-positive gonadotrophs, TSH-cells and a few LH-positive gonadotrophs. The three subunits of I/A were detected in the majority of nonfunctioning tumors, while functioning adenomas showed a significantly lower expression. This study shows that alpha, beta A and beta B subunits of I/A are expressed by specific adenohypophysial cell types and that they are characteristically present in nonfunctioning adenomas. These results suggest that inhibins and activins may play a role in the local regulation of pituitary hormonal secretion both in normal adenohypophysial cells and in pituitary adenomas.

Estradiol regulation of follistatin and inhibin alpha- and beta(B)-subunit mRNA in avian granulosa cells

Estradiol modulation of granulosa cell growth and regulation of follistatin and inhibin alpha- and beta(B)-subunit mRNA were investigated in cultured chicken granulosa cells. Granulosa cells were isolated and pooled according to size from the F(4) + F(5), small yellow (SYF), and large white (LWF) follicles. Isolated and dispersed granulosa cells were then cultured in the absence or presence of 1 x 10(-5) M 17 beta-estradiol. In Experiment 1 (n = 4 replications) the effect of estradiol on the growth of granulosa cells from the different-sized follicles was examined at 24 and 48 h of culture. Untreated and treated granulosa cells from all three follicle sizes proliferated during culture, and cell viability for all cultures was over 95% throughout the experiment. After 48 h the untreated cultures for all follicle types had 1.6 to 2.2 times (P < 0.05) more cells than the estradiol-treated cultures. In Experiment 2 (n = 3 replications), the cultures were terminated at 4 and 24 h after plating. Follistatin mRNA levels were higher in estradiol-treated cells at 24 h in F(4) + F(5) follicles, at 4 and 24 h in the SYF, and at 4 h in the LWF. beta(B)-subunit mRNA levels were also increased by estradiol at 4 h in F(4) + F(5) cells and at 4 and 24 h in the LWF. Steady state mRNA levels for the alpha-subunit were higher (P < 0.05) in estradiol-treated cultures at 4 and 24 h in F(4) + F(5) follicles and at 24 h in the SYF. Immunoreactive alpha-subunit protein, however, was not increased by estradiol treatment. Thus, whereas estradiol inhibited granulosa cell growth, it exerted a generally stimulatory effect on the expression of FS and the inhibin alpha- and beta(B)-subunit mRNA.

Molecular cloning and expression analysis of the complementary deoxyribonucleic acid for chicken inhibin/activin beta(B) subunit

Inhibins and activins are dimeric peptide hormones that play an integral role in the intraovarian regulation of folliculogenesis. The domestic hen, with its well-defined follicular hierarchy, provides a unique model in which to study the role of these hormones in follicular development. In the present study, the complete coding sequence and deduced amino acid sequence for the chicken inhibin/activin beta(B) subunit has been determined from cDNA clones isolated from a chicken ovarian granulosa cell library. This beta(B)-subunit cDNA predicts a precursor protein of 392 amino acids containing the mature C-terminal 115 amino acid beta(B) subunit. When compared to the beta(B) subunit isolated from a variety of species, the chicken cDNA clone showed high nucleotide identity in the full-length coding region (>70%) and in the mature coding region (>80%). In addition, the deduced amino acid sequence of chicken beta(B) subunit showed greater than 95% identity compared to other species in the mature peptide region. Expression of the beta(B)-subunit mRNA was detected by reverse transcription-polymerase chain reaction in both gonadal and extragonadal tissues. Northern blot analysis detected expression in the gonadal tissues only, specifically in the granulosa tissue from the F3-F5 follicles, small yellow follicles (SYF), large white follicles, and immature and mature rooster testes. A major transcript of approximately 4.1 kilobases (kb) and three minor transcripts of approximately 8.4 kb, 6.5 kb, and 1.7 kb were detected in the SYF granulosa samples. To examine the expression pattern of the beta(B) subunit around the stage of follicle selection, the SYF granulosa was subdivided into two groups: 6-8 mm and 9-12 mm. Quantification of RNA expression (n = 3) showed that expression of the beta(B) subunit was maximal in the 6-8 mm SYF. Activin B, as well as other intraovarian signals, may regulate early follicle selection and/or development in the chicken.

Does pretreatment with progestogen or oral contraceptive pills in low responders followed by the GnRHa flare protocol improve the outcome of IVF-ET?

PURPOSE

Women undergoing in vitro fertilization with low ovarian reserve and poor response to controlled ovarian hyperstimulation (COH) present a management dilemma. In a retrospective observational study, we compared the pretreatment use of the gestogen medroxyprogesterone acetate (10 mg twice daily from day 15 of the cycle for a minimum of 2 weeks) with an oral contraceptive pill (one tablet daily from day 4 of the cycle for a minimum of 3 weeks).

METHODS

The criteria for inclusion in the study included one or more of the following: abandoned cycles due to poor response, fewer than four oocytes retrieved following a standard COH protocol, age > 39 years, and elevated basal serum follicle-stimulating hormone (FSH). Thirty-eight women received pretreatment with gestogen, and a similar number of women received pretreatment with the pill. The flare protocol was used in all treatment cycles combined with an individualized dose of human menopausal gonadotropin (hMG) (4-8 ampoules/day of 75 units FSH/ampoule) depending on previous response, age, and early follicular serum FSH level. Both groups were similar in mean age, duration of infertility, early follicular FSH levels, and the distribution of various aetiologies.

RESULTS

Twenty-nine cycles were abandoned before oocyte retrieval, 15 (39.5%) in the pill group and 14 (36.8%) in the gestogen group, because of an inadequate ovarian response. The mean (+/- SD) number of ampoules (75 IU FSH/ampoule) of hMG used per cycle was similar in the pill and gestogen groups (59.7 +/- 19.3 vs. 70.2 +/- 29.4, respectively). There also was no difference seen in the numbers of oocytes retrieved (4.4 +/- 2.3 vs. 4.2 +/- 2.5), total number of embryos (2.5 +/- 2.4 vs. 2.2 +/- 1.1), or the number of embryos transferred (1.8 +/- 1.2 vs. 2.1 +/- 1.0) in the pill and gestogen groups, respectively. One pregnancy in each group resulted following embryo transfer in 22 women in the pill group and in 24 women in the gestogen group.

CONCLUSIONS

We conclude that pre-IVF treatment with oral contraceptive pill or gestogen combined with the flare protocol in women at high risk of or with a history of poor ovarian response, as defined in this study, did not appear to result in an improvement in outcome of IVF-embryo transfer.

Gonadotropin regulation of inhibin alpha-subunit mRNA and immunoreactive protein in cultured chicken granulosa cells

Gonadotropin regulation of the inhibin alpha-subunit was investigated in chicken granulosa cell cultures. Granulosa layers were isolated from the F(1) and F(3) + F(4) follicles from three to four hens, pooled according to size, dispersed, and cultured (n = 3 replications for each experiment). In Experiments 1 and 2 either ovine LH or FSH was added to the cultures at doses of 0, 5, and 25 ng/ml. The cultures were terminated at 4, 24, and 48 h after plating. For both follicle sizes the expression of mRNA for the inhibin alpha-subunit was less (P < 0.05) at 24 and 48 h in untreated cells than in those treated with both doses of LH. Expression of the mRNA for the inhibin alpha-subunit was significantly increased only by the 25 ng/ml dose of FSH and only in the F(1) follicle at 24 and 48 h compared to the untreated cells. After 48 h of culture, immunoreactive alpha-subunit protein accumulation was greater for both follicle types in the media of cells treated with the highest dose of LH and FSH than in the media from untreated cells. In Experiment 3, doses of 0, 5, 25, or 50 ng/ml of either LH or FSH were added to F(1) and F(3) + F(4) granulosa cells. All cultures were terminated at 48 h. LH and FSH increased the expression of the mRNA and immunoreactive protein for the inhibin alpha-subunit equally in a time-dependent manner. These experiments indicate that gonadotropins enhance the expression of both the mRNA and the protein for the inhibin alpha-subunit in chicken granulosa cells.

Secretion of activin A in recurrent epithelial ovarian carcinoma

OBJECTIVES

Activin A is a dimeric protein, composed of two beta-A subunits, that belongs to the TGF-beta family of growth factors. Most primary epithelial ovarian tumors (96%) synthesize and secrete activin protein in vitro and preliminary studies show that serum levels of activin are frequently elevated in women with epithelial ovarian cancer. Our objectives were to expand on studies of serum activin A levels in women with epithelial ovarian cancer and to determine whether levels of activin A correlate with the clinical course of disease.

METHOD

Preoperative serum activin A levels were measured in 41 patients with epithelial ovarian cancer. In addition, serum activin A levels were measured in all available postoperative samples from the subset of these patients (n = 26) who had an elevated preoperative serum activin A level. Medical record information was used to compare each patient's serum levels of activin A to the clinical course of disease.

RESULTS

Seventy-two percent of the stage III and IV patients (26/36), and none (0/5) of the stage I patients, had an elevated preoperative serum activin level. In postoperative samples, activin A levels were increased with persistent or recurrent (n = 9) stage III or IV ovarian cancer. Activin A levels dropped postoperatively and remained at or below the control level in patients in remission.

CONCLUSION

Serum activin A levels correlate with recurrent or persistent disease in patients with epithelial ovarian cancer.

Inhibin A and B in peri- and postmenopause

OBJECTIVE

The aim of the study was to investigate the origin of inhibin A and B during the last years of the reproductive age and after menopause by measuring their levels in the ovarian and peripheral venous blood.

METHODS

The study population consisted of 43 women, aged 42-69 years (mean 50), who underwent hysterectomy with ovarian removal for a benign disease. A total of 24 of them were in follicular phase, 11 in luteal phase, and eight were postmenopausal. Peripheral and ovarian venous blood was collected for measurement of inhibin A and B. In addition, sex steroid hormone and gonadotropin levels were measured.

RESULTS

Ovarian venous inhibin B correlated significantly with ovarian estradiol secretion (r = 0.5, P = 0.001). The levels of inhibin B were significantly higher in the ovarian vein than in the peripheral vein (P = 0.006). The highest inhibin B concentrations were detected in the mid-proliferative (mid-follicular) phase (median 31.6 pg/ml range 25.9-47.9). In postmenopausal women, inhibin B was not detectable. No correlation between FSH and ovarian inhibin B was found. Inhibin A rose rapidly in late proliferative (late follicular) phase (median 28.5, range < 2-51.8) and dominated in the circulation throughout the luteal phase (median 20.9, range 8.8-60). For inhibin A, no concentration gradient existed between the ovarian and peripheral vein. Unlike inhibin B, inhibin A was detectable in ovarian and peripheral blood in postmenopausal women. A significant negative correlation between ovarian and peripheral inhibin A and FSH was found (r = -0.386, P = 0.015; r = -0.345, P = 0.034, respectively).

CONCLUSION

Inhibin B correlates with ovarian estradiol secretion and seems to reflect follicular function. Inhibin A dominates in circulation during the luteal phase but is detectable at low concentrations both in follicular phase and even in postmenopause. Our findings suggest that inhibin A may play a role in FSH suppression in the female reproduction. In addition to the ovary, there may be extragondal source(s) of inhibin A.

Expression pattern of messenger ribonucleic acid for follistatin and the inhibin/activin subunits during follicular and testicular development in gallus domesticus

The expression of mRNA for follistatin and the inhibin/activin subunits was investigated in the follicles of laying hens and the testes of immature and mature roosters. Total RNA was isolated from immature and mature testes and from individual granulosa layers of the F1 through F5 follicles, from a pool of the F6-F8 follicles, from the small yellow follicles, and from the combined granulosa and theca layers of the large white follicles. Northern blot analysis was performed, and a follistatin mRNA transcript of approximately 2. 4 kilobases (kb) was detected in immature testes and in the following follicles: F5, the pool of F6-F8, and small yellow and large white follicles. The greatest expression of follistatin occurred in the small yellow follicles, and in this tissue two minor transcripts of approximately 1.7 and 3.7 kb were also detected. The inhibin alpha subunit was expressed in both testes samples and in all of the follicles except the large white follicles. Expression of the alpha subunit was greatest in the F5 follicle, and expression decreased with follicle maturity. As previously reported, the inhibin/activin ssA subunit was found in the greatest abundance in the F1 follicle, with lesser amounts detected in the other hierarchical follicles and immature testes. In contrast to the ssA subunit, the inhibin/activin ssB subunit was not detected in the four largest hierarchical follicles but was expressed in greatest abundance in the pool of F6-F8 and small yellow follicles. This represents the first report, to our knowledge, of the detection of follistatin mRNA in the hen ovary and rooster testes. The restriction of follistatin mRNA expression to the small follicles suggests that follistatin, by regulating activin and/or inhibin availability, may play a critical role in early follicular development.

Expression of inhibin alpha-subunit in horse testis

Inhibin is believed to play roles in the pituitary secretion of FSH and in the paracrine regulation of testicular function. Although it has been generally accepted that inhibin is produced in Sertoli cells, there was a recent evidence for the localization of inhibin in Leydig cells of primates, rat and sheep. However, there is no report on the expression of inhibin in the adult horse testis. Therefore, using immunohistochemistry, western blotting and in situ hybridization techniques, the present study examined inhibin alpha-subunit (Ih-alpha) expression in the adult horse testis. For the detection of Ih-alpha protein, we used anti-porcine Ih-alpha antibody in immunohistochemistry and western blotting. Furthermore, digoxigenin-labeled complementary RNA probes were prepared to detect intracellular messenger RNA (mRNA) of Ih-alpha. Immunostainings for Ih-alpha were found not only in Leydig cells but also in Sertoli cells. The intensity in Leydig cells was stronger than in Sertoli cells. Immunoreactivities for Ih-alpha were found at approximately 46 kDa, 56 kDa and 90 kDa in the homogenates from testicular interstitial tissues. The bands at 56 kDa and 90 kDa agree with previous report, but not at 46 kDa. Signals for mRNA of Ih-alpha by in situ hybridization were detected in Leydig cells and in the basal region of seminiferous epithelium including Sertoli cells. These results suggest that Ih-alpha is expressed in Leydig cells and Sertoli cells of horse testis, and the expression level should be higher in Leydig cells than Sertoli cells.

Ovarian follicular dynamics: from basic science to clinical practice

The management of low responders (LR) to ovarian stimulation in cycles of assisted reproduction (AR) is a difficult challenge. Aging of the ovary and LR are coincidental in many situations, but LR is also present in young patients undergoing AR. In fact, today it is a recognized cause of infertility. When the aged ovary is considered, there is evidence that the functioning of the granulosa cells as well as the quality of the oocytes and resulting embryos are affected. Similarly, in young LR, the production of inhibin is affected. However, there is no evidence that the quality of the oocyte and/or the resulting embryo is affected. In this study, we have retrospectively analyzed our files and observed that the quality of the oocytes and embryos was similar between younger and older LR and normal responders (NR). Studies using color Doppler vaginal ultrasound have shown that the pulsatility index (PI) and the resistance index (RI) were increased in LR as compared with NR, suggesting that there was some degree of vascular resistance to flow. Treatment of LR is also a difficult challenge. Ovum donation is a successful treatment for LR, since cumulative birth rates are > 85% with four attempts of embryo transfer. The future may be promising for LR once new technologies are introduced into clinical practice. The use of recombinant gonadotropins and genetically engineered human gonadotropin derivatives may be of considerable help for LR. Similarly, non-gonadotropin hormones, such as cytokines or growth factors, may be shown to play a role in the stimulation of the ovary in the near future, and may therefore open new frontiers for treatment of LR.

Hypoplasia of pancreatic islets in transgenic mice expressing activin receptor mutants

Activin, a member of the TGF-beta superfamily, regulates the growth and differentiation of a variety of cell types. Based on the expression of activin in pancreatic rudiments of rat embryos and stimulation of insulin secretion from adult rat pancreatic islets by activin, activin is implicated in the development and function of islets. To examine the significance of activin signaling in the fetal and postnatal development of islets, transgenic mice expressing a dominant negative form of activin receptor (dn-ActR) or a constitutively active form of activin receptor (ActR-T206D) in islets were generated together with the transgenic mice expressing intact activin receptor (intact ActR) as a negative control. Transgenic mice with both dn-ActR and ActR-T206D showed lower survival rates, smaller islet area, and lower insulin content in the whole pancreas with impaired glucose tolerance when compared with transgenic mice with intact ActR or littermates, but they showed the same alpha cell/beta cell ratios as their littermates. In addition to islet hypoplasia, the insulin response to glucose was severely impaired in dn-ActR transgenic mice. It is suggested that a precisely regulated intensity of activin signaling is necessary for the normal development of islets at the stage before differentiation into alpha and beta cells, and that activin plays a role in the postnatal functional maturation of islet beta cells.

Transforming growth factor-beta1, insulin-like growth factors, and insulin-like growth factor binding proteins in ovarian follicular fluid are differentially regulated by the type of ovarian hyperstimulation used for in vitro fertilization

OBJECTIVE

To determine the effects of hMG and highly purified FSH on follicular production of the ovarian growth factors transforming growth factor-beta1 (TGF-beta1), insulin-like growth factors I and II (IGF-I and IGF-II), and insulin-like growth factor binding proteins-1 and -3 (IGFBP-1 and IGFBP-3).

DESIGN

Controlled clinical study.

SETTING

University IVF program.

PATIENT(S)

One hundred twenty women who were <38 years old and had a >3-year duration of infertility in their present relationship participated in the study.

INTERVENTION(S)

Follicular fluid and matched serum were collected at oocyte pick-up and analyzed for growth factors and E2 with the use of ELISA and RIA.

MAIN OUTCOME MEASURE(S)

Levels of TGF-beta1, IGF-I. IGF-II, IGFBP-1 and IGFBP-3 in follicular fluid and levels of E2 in serum were measured.

RESULT(S)

Compared with highly purified FSH, ovarian hyperstimulation with hMG produced lower levels of TGF-beta1 and IGF-I and higher levels of IGFBP-1. Levels of IGF-II and IGFBP-3 were similar with the 2 treatments.

CONCLUSION(S)

In patients undergoing IVF, the follicular expression of TGF-beta1, IGF-I, and IGFBP-1 was regulated differently by highly purified FSH compared with a preparation containing FSH and LH in a 1:1 ratio (hMG). The results indicate that FSH and LH control ovarian production of these growth factors differentially.

Loss of heterozygosity at the alpha-inhibin locus on chromosome 2q is not a feature of human granulosa cell tumors

The alpha-inhibin gene has been shown in knockout mouse models to be a suppressor of granulosa tumorigenesis in the mouse. To determine if alpha-inhibin has the same function in humans, we have assessed the frequency of loss of heterozygosity (LOH) of the alpha-inhibin gene locus on chromosome 2q in 17 human granulosa cell tumors and 36 epithelial ovarian cancers. LOH was detected in 12 of 36 (33.3%) epithelial tumors but in only 1 of 17 (6%) granulosa cell tumors. These data suggest that in contrast to the suggestions from the mouse model alpha-inhibin does not function as a granulosa cell tumor suppressor gene in the human. Furthermore, analysis of the TP53 gene in the granulosa cell tumors failed to detect either LOH or point mutations, indicating that they have a developmental pathway distinct from that of epithelial ovarian tumors.

Bioassays of gonadotropins based on cloned receptors

Because of the microheterogeneities of gonadotropins, immunoreactive measurements of gonadotropins do not necessarily reflect their bioactivity. Follicle-stimulating hormone (FSH) bioassays have relied on measurement of aromatase activity in primary cultures of immature rat Sertoli cells or rat granulosa cells (GAB assay). Luteinizing hormone (LH) bioassays have relied on measurement of androgen production in primary cultures of rat interstitial testicular cells (RICT) or mouse Leydig cells. Those bioassays are cumbersome because they rely on primary culture and on indirect measurement of estradiol or testosterone by RIAs. The cloning of the cDNAs of FSH and LH receptors has allowed the establishment of cell lines expressing human receptors. The cotransfection of the recombinant gonadotropin receptor with a cAMP reporter gene allows a nonisotopic measurement of gonadotropin bioactivity. Furthermore, patient serum can be tested directly without prior extraction. We and other groups have developed a CHO cell line expressing the human FSH receptor and a luciferase reporter gene (CHO-FSHR). The CHO-FSHR assays is specific for FSH and free of serum interference up to a final concentration of 20%. The clinical sensitivity is 3 IU/l, the interCV 16%, the intraCV 8%. Studies were performed in normal women (n = 11) during the menstrual cycle using the CHO-FSHR cells. The ratio of bioactive to immunoactive FSH (B/I) equals 1.1 +/- 0.04 across the follicular and early luteal phase. During the mid to late luteal phase the mean B/I rises significantly to 1.65 +/- 0.07 (P < 0.001). Gonadotropin bioassays based on cloned receptors have been used to search for immunoglobulins, directed against the FSH or the LH receptors in premature ovarian failure patients. No blocking antibodies were found among the 38 women studied. A recent study of FSH bioactivity in patients with FSH secreting pituitary adenomas shows increased values of the B/I ratio. In summary, cell lines expressing the LH and the FSH human receptors are now available. Those homologous systems enable clinicians to study potential forms of mutated FSH or antibodies directed against gonadotropin receptors. Furthermore, bioassays based on cloned receptors are interesting tools to test anti-LH or anti-FSH molecules mainly in contraceptive research.