Role Of Follicle-stimulating Hormone Research Articles

Role of follicle stimulating hormone and epidermal growth factor in the development of porcine preantral follicle in vitro

The aim of the present study was to assess the role of follicle stimulating hormone (FSH), epidermal growth factor (EGF) or a combination of EGF and FSH on the in vitro growth of porcine preantral follicles, estradiol secretion, antrum formation, oocyte maturation and subsequent embryonic development. Porcine preantral follicles were cultured for 3 days in the absence or in the presence of FSH or EGF. Oocytes from these follicles were then matured, fertilized in vitro and embryos were cultured. Estradiol secretion and histological analysis of cultured follicles were also carried out. The results showed that when FSH, or a combination of EGF and FSH, was added to the culture medium, most of preantral follicles grew to antral follicles with high estradiol secretion and the oocytes from these antral follicles could mature, fertilize and develop to the blastocyst stage. Without FSH, or a combination of EGF and FSH, preantral follicles were unable to develop to the antral stage. Histology demonstrated that the resulting follicles were nonantral, estradiol production was reduced and none of their oocytes matured after in vitro maturation. The results indicate the essential role of FSH in promoting in vitro growth of porcine preantral follicle, estradiol secretion, antrum formation, oocyte maturation and subsequent embryonic development. EGF with FSH treatment of porcine preantral follicles improves the quality of oocytes, shown by a higher frequency of embryonic development.

Essential role of follicle stimulating hormone in the maintenance of caprine preantral follicle viability in vitro

The aims of the present study were to investigate the effects of follicle-stimulating hormone (FSH) on survival, activation and growth of caprine primordial follicles using histological and ultrastructural studies. Pieces of caprine ovarian cortex were cultured for 1 or 7 days in minimum essential medium (MEM - control medium) supplemented with different concentrations of FSH (0, 10, 50 or 100 ng/ml). Small fragments from non-cultured ovarian tissue and from those cultured for 1 or 7 days in a specific medium were processed for classical histology and transmission electron microscopy (TEM). Additionally, effects of FSH on oocyte and follicle diameter of cultured follicles were evaluated. The results showed that the lowest percentage of normal follicles was observed after 7 days of culture in control medium. After 1 day of culture, a higher percentage of growing follicles was observed in the medium supplemented with 50 ng/ml of FSH. In the presence of 10 and 50 ng/ml of FSH, an increase in diameter of both oocyte and follicle on day 7 of culture was observed. TEM showed ultrastructural integrity of follicles after 1 day of culture in MEM and after 7 days in MEM plus 50 ng/ml FSH, but did not confirm the integrity of those follicles cultured for 7 days in MEM. In conclusion, this study demonstrated that FSH at concentration of 50 ng/ml not only maintains the morphological integrity of 7 days cultured caprine preantral follicles, but also stimulate the activation of primordial follicles and the growth of activated follicles.

Recombinant luteinizing hormone in assisted reproductive technology

The separate but complementary roles of follicle stimulating hormone (FSH) and luteinizing hormone (LH) in stimulating folliculogenesis and ovulation are well established. However, it is not known if there are levels under which low LH concentrations may be equally or suboptimal for oocyte quality and subsequent embryonic development competence. On the other hand, there are some conflicting data related to the high levels of LH promoting follicular atresia and early miscarriage. This has lead to the concept of a ‘therapeutic window’ of LH for successful conception in assisted reproductive technology (ART) and ovulation induction. In hypogonadotrophic hypogonadism (HH), rLH is effective for supporting FSH-induced follicular development, in a dose related manner and rLH promotes estradiol secretion, enhances the effect of FSH on follicular growth, and permits successful luteinization. Some patients with prolonged and profound down-regulation response like hypogonadotrophic hypogonadal patients and may benefit from concomitant exogenous administration of LH. Retrospective meta-analyses comparing LH-containing regimens with LH-free stimulations have provided conflicting results in normal ovulatory patients. Until recently, human menopausal gonadotrophin (HMG) preparations were the only source of exogenous LH, however, recombinant human luteinizing hormone (rLH) is now available for clinical use, providing a new treatment option. rLH is well characterized and production is tightly controlled resulting in a highly consistent product. In addition, it has been shown that rLH is as effective but safer than human chorionic gonadotrophin (hCG) in inducing final follicular maturation and ovulation.

Evaluation of the role of FSH in regulation of Leydig cell function during different stages of its differentiation

The role of follicle stimulating hormone (FSH) in Leydig cell function was evaluated by a passive neutralization approach at different stages of Leydig cell development. Neutralization of endogenous FSH in neonatal rats (10-day-old) resulted in reduction of testes weight, however the testicular testosterone levels and in vitro testosterone production by purified Leydig cells were elevated. Administration of FSH antiserum to immature (25–28-day-old) and adult (90-day-old) rats did not have any effect on testes weight, serum testosterone and testicular testosterone. Interestingly, there was a significant reduction in testosterone production by isolated Leydig cells under hCG stimulated and 22-R-hydroxycholesterol (22-R-OH CHOL) saturated conditions. In support of this observation administration of recombinant FSH to immature and adult rats resulted in significant increase in testosterone production by Leydig cells following incubations in presence of hCG and saturating concentrations of 22-R-OH CHOL, although there was no change in serum and testicular testosterone levels. The role of FSH in immature rats was also confirmed employing FSH receptor antiserum which was raised against the unique domains of FSH receptor. RT-PCR analysis revealed a significant reduction in the mRNA levels of StAR and IGF-1 following blockade of FSH action by FSH receptor antiserum. The results of our studies suggest a stage specific function for FSH in regulation of Leydig cell development by modulating the LH responsiveness and steroidogenesis.

Evidence of a Role for Follicle-Stimulating Hormone in Controlling the Rate of Preantral Follicle Development in Sheep

Autografting ovarian cortex results in the loss of growing follicles and elevated gonadotropins. This paradigm was employed to examine the effect of gonadotropins on preantral follicle development in sheep. Ovarian tissue was recovered at 1, 2, 3, and 4 months after grafting from ewes that were either hyper- (n = 12; untreated) or hypogonadotropic (n = 12; GnRH-agonist and estradiol implants). Compared with the Hypo group, Hyper ewes had higher (P < 0.001) gonadotropins, had greatly enlarged grafts, had reestablished a normal follicular hierarchy 2 months earlier (P < 0.05), had higher (P < 0.05) levels of proliferating cell nuclear antigen expression in tertiary, preantral, and antral follicles, and had higher (P < 0.01) concentrations of inhibin A and estradiol. Compared with time zero controls, increases in the number of primary follicles and the rate of proliferation in primary and secondary follicles in both groups of autografts (P < 0.05) were also observed. In conclusion, the results of this experiment provide the first evidence that gonadotropins can affect the rate of development of preantral follicles in vivo in a large monovulatory species. Furthermore data are presented to support the existence of a gonadotropin-independent intraovarian feedback loop regulating both the rate of primordial follicle initiation and primary and secondary follicle development.

Role of follicle-stimulating hormone in the control of foetal Sertoli cell transferrin expression

Role of follicle-stimulating hormone in the control of foetal Sertoli cell transferrin expression

Sertoli cell proliferation and FSH signalling in African catfish, Clarias gariepinus

Sertoli cell proliferation occurs mainly during the phase of rapid spermatogonial proliferation, allowing the cyst-forming Sertoli cells to form an increasingly large space for housing the growing germ cell clone. There is no information in fish on the regulation of Sertoli cell proliferation; follicle-stimulating hormone (FSH) stimulates Sertoli cell proliferation in mammals. Increasing or decreasing FSH and FSH receptor expression experimentally in male African catfish was associated with respective changes in Sertoli cell proliferation or testis growth, suggesting that also in fish, one role of FSH may be to regulate Sertoli cell numbers.

The expression of the follicle-stimulating hormone receptor in spermatogenesis.

Results from experiments using mouse models suggest that the role of follicle-stimulating hormone (FSH) in spermatogenesis is the regulation of Sertoli cell proliferation and, ultimately, the size and spermatogenic capacity of the testis. The regulation of the expression of the FSH receptor (FSHR) gene is very cell specific and plays an initial role in the ultimate response of the Sertoli cells to FSH. The extreme cell specificity and the importance of the FSH response to spermatogenesis have led to an extensive characterization of the promoter of the FSHR gene. Several widely expressed transcription factors - including USF 1 and 2, GATA-1, and SF-1 and potential elements such as an E2F site and an Inr region - have been shown to contribute to the maximal transcription of the transfected FSHR gene. However, these experiments have failed to provide clues as to the cell-specific expression of the FSHR gene. In both cell transfections and in transgenic mice, the promoter can direct expression of transgenes promiscuously. The rodent FSHR promoter contains conserved CpG dinucleotides that were shown to be methylated in nonexpressing cells and tissue but unmethylated in Sertoli cells. The methylated CpG sites could interfere with the binding of general transcription factors and/or lead to a repressive chromatin structure in the nonexpressing cells. While yet-undiscovered cell-specific factors may play a role in the expression of the FSHR gene, repression and activation of local chromatin structure are likely to be involved.

Advancing perspectives on prostate cancer: multihormonal influences in pathogenesis.

Nonandrogenic hormones are implicated in the growth and function of the prostate, which is itself an endocrine gland that synthesizes and secretes hormones and growth factors, including follicle-stimulating hormone (FSH) and prostatic inhibin peptide (PIP). Findings of increased FSH concentrations and receptor expression in diseased prostate tissue suggest a role for FSH in prostate cancer growth. Not only does PIP suppress circulating levels of FSH, but it responds to and modulates prostatic FSH, suggesting a close interlinkage of these compounds in controlling both healthy and diseased prostate cells. Other focuses of endocrinologic research include androgen receptors, vitamin D, growth factors (including insulin-like growth factors I and II), and retinoids. Issues such as optimal therapy timing, intermittent administration, and the adoption of a multihormonal approach to the management of prostate cancer remain to be resolved.

Endocrine Influences on Normal and Neoplastic Ovarian Surface Epithelium (OSE) Cell Growth

Objectives: Over 85% of human ovarian carcinomas are thought to arise in the OSE, i.e. the mesothelium that covers the ovary. Increasing evidence suggests that endocrine factors play an important role in ovarian tumorigenesis. In the present study, the roles of follicle-stimulating hormone (FSH), estradiol (E2) and gonadotropin-releasing hormone (GnRH) were investigated using normal and neoplastic OSE cell lines directly generated from human OSE.

FSH immunoneutralization acutely impairs spermatogonial development in normal adult rats.

Follicle-stimulating hormone (FSH) plays an important part in testicular development. Its role in the regulation of spermatogenesis in the adult, however, remains controversial. This study aimed to explore the role of FSH in the maintenance of adult rat spermatogenesis by using immunoneutralization to selectively withdraw FSH action for periods of up to 8.5 days and then assessing the outcome by quantification of germ cell number. Adult rats received either an ovine polyclonal rat FSH antibody (FSHAb, 2 mg/kg subcutaneous daily-a dosage known to neutralize >90% of FSH in serum) for 2, 4, 7, or 8.5 days or a control sheep immunoglobulin (ConAb, 2 mg/kg) for 8.5 days. Testes were perfusion fixed, and germ cell numbers per testis were quantified using the optical disector (sic) stereological method. The percentage of seminiferous tubules displaying apoptotic cells was determined by the in situ end labeling method (TUNEL). FSHAb treatment for 4, 7, or 8.5 days significantly reduced the number of type A/intermediate spermatogonia (approximately 74% of control values) associated with stages I-IV. Similar reductions were seen in type B spermatogonial and preleptotene spermatocyte numbers after 8.5 days of FSHAb treatment (approximately 69% of control values; P < 0.05). Decreases (P < 0.05) in the numbers of pachytene spermatocytes in stages I-III and VIII, round spermatids in stages I-III, VII, and VIII (approximately 70% of control values), and step 19 elongated spermatids in stage VII (51% of control values) were achieved after 8.5 days of FSHAb treatment. Compared with control, FSHAb treatment increased the percentage of stage XIV-III tubules containing TUNEL-positive cells by about twofold after 7 days of FSHAb treatment (P < 0.05). This study supports a role for FSH in the maintenance of quantitatively normal adult rat spermatogenesis, specifically by regulating A3 and A4 spermatogonial subtypes. FSH may act on these spermatogonia by enhancing the stage-dependent survival of type A spermatogonia. Effects at other sites in spermatogenesis are suggested by the changes in spermatocyte and spermatid populations. However, to clarify these effects, selective FSH withdrawal would need to be prolonged until steady state had been achieved.

Evidence for a Stimulatory Role of Follicle-Stimulating Hormone on the Spermatogonial Population in Adult Males

Abstract Objective: To evaluate the effects of treatment with FSH on seminal indices and on the seminiferous epithelium of oligozoospermic subjects with normal FSH plasma levels. Design: Placebo-controlled, double-blind randomized study. Setting: Academic setting. Patient(s): Ninety subjects with idiopathic oligozoospermia (sperm count of 6 /mL) and normal plasma levels of FSH. Intervention(s): Three months of treatment with FSH (60 patients) or placebo (30 patients); bilateral testicular fine-needle aspiration. Main Outcome Measure(s): Seminal indices; testicular cytologic features; plasma levels of FSH, LH, and testosterone; and ultrasonographic testicular examination. Result(s): According to seminal indices, patients treated with FSH and placebo were classified as nonresponders or as responders (as determined by at least a doubling of sperm count). No placebo-treated patients responded to treatment. Among FSH-treated patients, 20 responded to hormonal treatment and 40 did not. The results of pretreatment cytologic examination of testicular specimens from patients who did not respond to FSH treatment were consistent with hypospermatogenesis associated with maturational disturbances at the spermatid level. In contrast, patients who responded to treatment with FSH had isolated hypospermatogenesis without maturational disturbances. After FSH therapy, we detected an increase of spermatogonia and spermatocyte population in both the responder and nonresponder subjects. This increase was associated with an activation of spermatogenic and spermiogenic processes and with a rise in ejaculated sperm concentration only when isolated hypospermatogenesis was present (responder patients). Conclusion(s): The findings of this study demonstrate that FSH treatment increases the spermatogonial population in men. This treatment may be appropriate for oligozoospermic subjects who have normal FSH plasma levels and a testicular evaluation characterized by hypospermatogenesis without maturational disturbances.

Evidence for a Stimulatory Role of Follicle-Stimulating Hormone on the Spermatogonial Population in Adult Males

Evidence for a Stimulatory Role of Follicle-Stimulating Hormone on the Spermatogonial Population in Adult Males

Follicle-stimulating hormone is required for the initial phase of spermatogenic restoration in adult rats following gonadotropin suppression.

The role of follicle-stimulating hormone (FSH) in adult rat spermatogenesis is unclear. Although exogenous testosterone (T) restores spermatogenesis following gonadotropin-releasing hormone (GnRH) immunization or T plus estradiol (TE) treatments, an assessment of the independent action of T and FSH was not possible, as exogenous T treatment maintains serum FSH levels. We have used passive immunization against FSH to determine whether T alone is capable of reinitiating spermatogenesis after chronic and acute FSH withdrawal. Adult rats received T-filled Silastic implants 6 cm (T6) or 8 cm (T24) in length for 7 days in combination with either a polyclonal sheep antisera raised against rat FSH (FSHAb, 2 mg/kg SC daily) or control sheep immunoglobulin (ConAb) after either GnRH immunization (12 weeks) or TE treatment (9 weeks). The neutralizing capacity of the FSHAb was determined using a FSH in vitro bioassay; this analysis demonstrated that administration of FSHAb in vivo reduced FSH levels by >90%. Testes were fixed and germ cell number per testis quantified using the optical dissector. GnRH immunization reduced spermatogonia, pachytene spermatocytes, and round spermatids to 50, 13, and <1% of normal, respectively. T6 and T24 Silastic implants with the inclusion of the FSHAb did not increase the number of spermatogonia, pachytene spermatocytes, and round spermatids (50, 15, and 1% of normal, respectively). T6+ConAb treatment increased spermatogonial, pachytene spermatocyte, and round spermatid numbers to 74, 30, and 3% of normal, respectively (P < 0.05). No further increases were seen with T24 implants. TE treatment suppressed pachytene spermatocytes and round spermatids to 33 and 1% of normal, respectively (P < 0.05). T6+FSHAb treatment did not increase the number of pachytene spermatocytes and round spermatids (36 and 8%, respectively), whereas T6+ConAb treatment increased pachytene spermatocyte and round spermatid number to 50 and 28% of normal, respectively (P < 0.05). T24+FSHAb treatment increased the number of pachytene spermatocyte and round spermatids (56 and 22% of normal, respectively; P < 0.05), whereas T24+ConAb treatment increased these cells forms to 79 and 31% of normal, respectively. In conclusion, T alone is unable to restore spermatogenic cell populations in the setting of chronic FSH withdrawal. Although acute FSH withdrawal markedly impairs the restoration process, higher doses of T can partially compensate for the lack of FSH. These data suggest that FSH is important for the initial phase of spermatogenic restoration.

Immunoneutralization of follicle stimulating hormone does not affect gonadotrophin surge-inhibiting factor/attenuating factor bioactivity during the rat ovarian cycle.

The physiological role of follicle stimulating hormone (FSH) in the regulation of the release of the putative ovarian factor gonadotrophin surge-inhibiting or -attenuating factor (GnSIF/AF) was investigated. Blood FSH concentrations were immunoneutralized in female rats during different days of the ovarian cycle. FSH antiserum was injected in different protocols to neutralize the FSH surge(s) and/or basal FSH concentrations. All animals were killed on the morning of the day of pro-oestrus of the control rats. Hemi-pituitaries were incubated and gonadotrophin-releasing hormone (GnRH) stimulated and basal luteinizing hormone (LH) and FSH releases and pituitary contents were measured. The biological effectiveness of the FSH antiserum was established by monitoring the histology of vaginal smears and inhibin concentrations in trunk-blood. The predominance of small leukocytes in the smears (low oestradiol bioactivity) and the decreased (bioactive) inhibin secretion imply that anti-FSH neutralizes FSH bioactivity. Simultaneously, the results showed that all anti-FSH injections did not affect the biphasic LH response to GnRH in vitro, which shows an unaltered presence of GnSIF/AF bioactivity in the blood circulation. The results suggest that under physiological conditions GnSIF/AF bioactivity, which keeps the LH responsiveness of the pituitary gland suppressed to the action of GnRH, is not supported by inhibin and not controlled by FSH.

Localization of human follicle-stimulating hormone in the testis.

Localization of the follicle-stimulating hormone (FSH) molecule and its receptor (FSHR), as well as the role of FSH in Sertoli cell mitosis and maturation, has been demonstrated by several investigators in human and murine testis by detecting the localization of anti-FSH antibodies or [(131)I]-labeled FSH and by detecting FSH receptor (FSHR) mRNA by in situ hybridization, or FSHR by anti-FSHR antibodies. The presence of FSH in germinal cells is controversial or, in humans, excluded. We have investigated the distribution of the human FSH molecule and its receptor in human and mouse testicular cells under different experimental conditions, at the submicroscopical level, by using a better antigenicity conservative procedure. Thus, the distribution of FSH and of the messenger RNA for its receptor in Sertoli cells has now been clarified. In germinal cells, our observations demonstrate the presence of FSH and the FSHR mRNA: the first on the plasma membrane and in endocytotic vesicles, and the second scattered in the cytoplasm. The cells presenting the higher amount of positivity ranged from spermatogonia to spermatocytes, including round spermatids. Penetration was by the endocytosis via membrane vesicles in which the FSHR is present, whereas its messenger is largely present in the cytoplasm and is responsible for the binding and subsequent internalization of the FSH molecule. As a control, human FSH was administered in vitro to the Y1 mouse cell line, which was stably transfected with cDNA for FSHR and devoid of endogenous FSH. The FSH molecule has been localized by monoclonal antibodies on plasma membranes and vesicles, and the FSHR mRNA was found scattered in the cytoplasm after in situ hybridization. We can now conclude that FSH is present in Sertoli cells and in round germinal cells, both expressing the FSHR. FSH penetrates in a similar way in both kinds of cells via endocytosis, and is therefore subsequently localized in the same membranous organelles.

Is there a true requirement for follicle stimulating hormone in promoting spermatogenesis and fertility in primates?

Although the role of follicle stimulating hormone (FSH) in regulating ovarian function is well accepted, its need in regulating testicular function of the adult continues to be debated. Sertoli cells of all mammals have FSH receptors and are known to regulate differentiation and transformation of germ cells to spermatozoa. However, there appear to be species and age differences in the way in which FSH regulates spermatogenesis. An attempt has been made in the current paper to examine critically the newer data available in support of and against the concept that FSH is required to regulate spermatogenesis and fertility of the primate. As there is no evidence to indicate that testicular function in monkeys and humans is regulated differently, the information available using the monkey as the experimental surrogate model is discussed in some depth. These are correlated, wherever feasible, to the newer information emerging from clinical studies. It appears from these studies that in the primate (including humans) FSH, besides promoting quantitative spermatogenesis leading to production of a normal number of spermatozoa, has a critical role in regulating spermiogenesis, the process that controls the formation of normal fertilizable mature spermatozoa. While the requirement for FSH in promoting fertility in the male monkey is reasonably well established, in humans the evidence currently available in favour of the concept is still circumstantial and more work needs to be done to establish the hypothesis beyond any doubt.

Evidence for the role of follicle stimulating hormone in maintaining the oocyte meiotic arrest in pre-antral follicles

The study was designed to clarify the physiological role of FSH in maintaining the meiotic arrest in vitro of oocytes derived from intact and from hypophysectomized hamsters. The sensitivity to FSH in maintaining the meiotic arrest of oocytes during incubation of preantral follicles of adult golden hamsters was estimated: log doseresponse curves were characterized by an ED50 of about 0.2 pg FSH ml (= 1 μ U) . After hypophysectomy oocytes of the pre-antral follicles were screened for the presence of a germinal vesicle (GV). The breakdown of the GV (GVBD) rose from 0 on day 0 to 48.8 ± 13.8% on day 1, to 55.9 ± 6.8% on day 2 and to 64.3 ± 7.4 on day 6 (p < 0.001 vs day 0). Incubation without FSH of the pre-antral follicles obtained from the same hypophysectomized animals showed an almost complete disappearance of the GV at the same time intervals. Incubation with 2 pg FSH ml (= 10 μ U) still demonstrated the inhibiting effect of FSH on the meiotic resumption: 13.4 ± 4.3% (day 0), 36.9 ± 16.3% (day 1), 38.7 ± 21.0% (day 2) and of 38.1 ± 12.6% (p > 0.1) on day 6. These results demonstrate that very low doses of FSH are able to maintain the meiotic arrest in oocytes of pre-antral follicles of the golden hamster and that deprivation of FSH by hypophysectomy involves a disappearance of GV oocytes to a certain extent.

Immunocytochemical Investigations on the Vascularization of Pituitary Adenomas.

Blood vessels within pituitary adenomas were visualized using the immunocytochemical reaction for Factor VIII (von Willebrand Factor), a specific marker of the vascular endothelium. The number of immunopositive vascular profiles were counted and expressed as a mean number per one microscopic field. The results were related to the type of adenoma, established on the basis of immunocytochemical investigation using the antibodies against pituitary hormones or a-subunit (a-SU). It was found that the richest vascularization occurred in adenomas expressing follicle-stimulating hormone (FSH). The possible role of FSH in pituitary angiogenesis is discussed.

Decreased spermatogenesis as the result of an induced autoimmune reaction directed against the gonadotropin receptors in male rats.

The presence of luteinizing hormone (LH) and testosterone is considered critical for the maintenance of spermatogenesis in the rat. However, the role and importance of follicle-stimulating hormone (FSH) in the initiation and maintenance of spermatogenesis has been a subject of debate for some time. The objective of this study was to examine the role of FSH and LH in vivo in the developing and adult rat by inducing an autoimmune reaction against the receptors to these gonadotropins. Sperm numbers were reduced in animals immunized against either the FSH or LH receptor (FSHR/LHR). In animals immunized against both FSHR and LHR there was also a significant reduction in sperm number although spermatogenesis was never completely ablated. These results were seen in male rats immunized either prepubertally (18 days of age) or as adults (80 days of age). To examine the requirements for FSH in early postnatal-testicular development, pregnant females were also immunized against either FSHR, LHR, or both of the receptors, and the male offspring were examined at 30 days of age. Again, germ-cell number was decreased with the greatest effect in those pups whose mothers were immunized against both FSHR and LHR. Radioligand-receptor-binding assays revealed that the antibody produced in the rats against FSHR was able to compete with FSH for binding sites in receptor-membrane preparations. Therefore, the mechanism of disruption of spermatogenesis is probably due to suppression of hormone to receptor binding. The results of this study support a role for FSH in spermatogenesis not only during neonatal and early postnatal development but also in the adult animal.