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PubMed1982

Testicular FSH receptor numbers and affinity in bulls of various ages.

Bulls (N = 42) ranging in age from 1 day to 5.5 years were used to determine whether a change in the concentration of FSH receptors in the bovine testis occurred as bulls matured. 125I-labelled human FSH was used as the ligand to evaluate binding to bovine testicular membranes. Membrane fractions were collected by centrifugation of testicular homogenates at 120 g and recentrifugation of the 120 g supernatant at 1250 g. Relative binding activity of membrane sedimented at 1250 g was determined after incubation of membranes with 125I-labelled FSH for 16--18h at 25 degrees C, followed by centrifugation (1250 g) to separate bound from free hormone. Specifically bound FSH when expressed as fmol/mg protein was negatively correlated with age (r = -0.73). The association constant (Ka) determined by Scatchard analysis was the same for bulls at all ages with a mean (+/- s.e.m.) Ka = 1.5 +/- 0.3 x 10(9) M-1. Concentration of FSH receptors on a per mg protein basis declined rapidly from birth to 2.5 years of age and remained low up to 5.5 years of age. On a whole testis basis the total number of receptors increased as the bulls matured. After 2.5 years of age total testicular binding did not change.

Aging↗

PubMed1987

Radioreceptor and autoradiographic analysis of FSH, hCG and prolactin binding sites in primary to antral hamster follicles during the periovulatory period.

As measured by radioreceptor assays, binding sites for FSH and prolactin were present at 09:00 h on the day of pro-oestrus in Stage 1-10 follicles (primary to antral) with prolactin receptors 3-6 times higher than FSH sites in Stages 1-3 (3 layers of granulosa cells). Specific binding sites for hCG were present in Stage 1 and 2 follicles (2 layers of granulosa cells) but thereafter their distribution was erratic and they were not consistently detectable until Stage 5, when thecal cells first appeared. Using topical autoradiography, specific binding for FSH was evident in Stage 1-4 follicles (4 layers granulosa cells) whereas specific hCG-binding was not. After the preovulatory gonadotrophin surges, by 21:00 h on pro-oestrus, FSH receptors declined in Stages 5-10, prolactin receptors fell in Stages 8 and 10 (small and large antral follicles) and hCG receptors were reduced in Stages 7 (start of antral cavity) to 10. On the morning of oestrus, for follicles from Stage 4 onwards, receptor numbers usually returned to levels found at 09:00 h on pro-oestrus. At oestrus, the few remaining Stage 10 follicles were all atretic and contained significantly reduced FSH and prolactin receptors but numbers of hCG binding sites comparable to those at 09:00 h of pro-oestrus. These results provide evidence of gonadotrophin receptors in small primary and secondary follicles which is consistent with increased DNA synthesis in small hamster follicles on the afternoon of pro-oestrus and on the morning and afternoon of oestrus. Periovulatory changes in gonadotrophin concentrations may therefore affect early stages of folliculogenesis.

Animals↗

PubMed1989

Quantitative autoradiographic study of FSH binding sites in prepubertal ovaries of three strains of rats.

Iodinated FSH was injected to 18- and 36-day-old rats of 3 strains (03, 04 and 12) with different sensitivity to FSH (12 less than 03 less than 04) and autoradiography was performed on histological sections of the labelled ovaries. Specific labelling was quantified by microphotometry on histological slides, on granulosa cells of individual follicles with different sizes (greater than 80 micron diameter) and qualities. In small preantral follicles (less than 160 micron diameter) the labelling was low and homogeneous within the granulosa; it increased between 18 and 36 days of age in the 3 strains. At 36 days, ovaries were characterized by the presence of large preantral and antral follicles with a higher labelling in the outer layers of granulosa (near the theca), compared to the inner layers. In definitely atretic follicles, a loss of binding sites was detected in the outer layers. In rats of Strains 03 and 04, the number of binding sites for FSH in the outer layers of granulosa of follicles with a diameter of greater than 160 micron increased with follicular size; no change was detected in follicles of Strain 12 rats. The low number of binding sites for FSH and the lack of terminal maturation which characterize the follicles of strain 12 rats can be related to the poor and delayed follicular development, the low sensitivity to exogenous FSH and the low fertility of the animals of this strain.

Animals↗

PubMed1986

Ovarian membrane receptors for LH, FSH and prolactin during the menstrual cycle and in polycystic ovary syndrome.

To investigate the role of ovarian membrane receptors for LH, FSH and prolactin of patients with developing polycystic ovary (PCO) syndrome, seven patients were selected and the receptor function was studied in relation to changes of several serum hormone levels. The results were compared with those from individuals with regular menstrual cycles in the late follicular (LF; n = 6) and midluteal (ML; n = 6) phases. LH receptor binding in the normal cycle remained low (1.73 +/- 0.14 fmole/mg homogenate protein) in the LF phase and elevated 3 fold in the ML phase. LH receptors in the PCO patients maintained a higher binding level than that in the LF phase, being close to the ML level. FSH receptors were at a high level in the LF phase (4.09 +/- 0.40 fmole/mg homogenate protein), but decreased by 23% in the ML phase. In the PCO group the ovarian FSH receptor showed a high level, near to that in the LF phase. Prolactin receptors showed no significant changes among the two controls and PCO group. PCO patients showed increased levels of serum LH and testosterone and a raised ratio of estrone to estradiol, although there was no change in the serum FSH level. These data suggested that the LH receptor binding in PCO was not so low as to the LF level. A lack of the down-regulation mechanism of LH receptors, in spite of the high level of serum LH in PCO, might be one of the clues to elucidate the pathophysiological mechanism in developing PCO syndrome. Elevated levels of the gonadotropin receptors, especially FSH receptors, seem to be involved in the high incidence of ovarian hyperstimulation during hormone treatment.

Adult↗

PubMed2003

Effects of follicular cells and FSH on the resumption of meiosis in equine oocytes matured in vitro.

It has been suggested that preculturing immature oocytes in a manner that maintains them in meiotic arrest may improve cytoplasmic maturation and, thereby, the eventual developmental competence of oocytes matured in vitro. This study examined the ability of follicular cells to maintain meiotic arrest in equine oocytes. Cumulus-oocyte complexes (COCs) recovered from dead mares were cultured for 38 h in M199 either attached to, or together with, different follicle wall components, as follows: (1) attached to the follicle wall, (2) cocultured with separated follicle wall, (3) attached to membrana granulosa (COCG), (4) COCGs cocultured with sheets of theca cells, (5) COCGs cultured in theca-cell conditioned medium, and (6) control COCs without any follicle wall components. When oocytes were cultured attached to their follicle wall, 79% remained in the GV stage throughout the 38 h incubation. However, when oocytes were cocultured with separate pieces of follicle wall, meiosis resumed and a similar proportion of oocytes progressed to metaphase II (79%) as under control conditions (84%). Only 16% of oocytes cultured while still attached to the membrana granulosa (COCGs) maintained the GV stage, whereas when COCGs were cocultured with theca cells or in theca-cell conditioned medium, significantly more oocytes remained in the GV stage (64 and 52%, respectively), indicating that theca cells secrete a meiosis-inhibiting factor. The effect of FSH on the meiosis-inhibiting activity of follicular cells was investigated by culturing COCs attached to the follicle wall and COCGs in the presence or absence of theca cells in medium containing FSH. Addition of 0.05 iu recombinant human FSH ml(-1) to the culture medium did not affect nuclear maturation and failed to overcome the suppressive effect exerted by the follicle wall or by theca cells, despite the fact that mRNA for the FSH receptor was found using RT-PCR in both cumulus and granulosa cells. These results demonstrate that the maintenance of meiotic arrest in equine oocytes during culture can be promoted by theca cells, which appear to act via a secreted inhibitory factor that cannot be suppressed or counteracted by FSH.

Animals↗

PubMed1992

[Inhibitory effect of transferrin on the binding and maintenance of FSH receptors in rat granulosa cells].

It has been recently demonstrated that transferrin (TRF) can inhibit the functional differentiation of rat granulosa cells, but the mechanism remains unknown. In present experiment, the effect of TRF on the binding of 125I-rFSH to receptors and on the maintenance of FSH receptors in granulosa cells from immature, diethylstilbestrol treated rats were studied. The results show that the physiological range of TRF partially blocked the binding of 125I-rFSH to granulosa cells in a dose-dependent manner. TRF also dose-dependently inhibited the maintenance of FSH receptors in accordance with the reduced production of progesterone and estradiol. In view of the present and our previous investigation, it could be concluded that mechanisms of the inhibitory effect of TRF on the functional differentiation of granulosa cells mainly involve blockade of FSH binding to its receptors and inhibition of FSH receptor maintenance by FSH.

Animals↗

PubMedDate not supplied

Contribution of specific amino acid residues within the hFSH alpha 26-46 sequence region to FSH receptor-binding activity.

The role of specific amino acid residues within the sequence region between Leu26 and Thr46 of the human follicle-stimulating hormone (hFSH) alpha-subunit in the FSH-receptor interaction has been investigated. Competitive binding activities of seven sets of synthetic peptides were evaluated with both FSH- and luteinizing hormone (LH)-radioreceptor assay procedures. Set 1 included two overlapping peptides (alpha 25-41 and alpha 31-45) spanning the alpha 26-46 region, while Sets 2-6 included peptides of different size or structure in which the alpha 26-46 sequence was (i) sequentially truncated either from the N-terminus or from the C-terminus or both; (ii) alternatively reduced to a series of overlapping 13-mer peptides; or (iii) modified at the C-terminal Arg and Lys residues with substitution by Ala residues. In Set 7, synthetic peptides related to the parent alpha 26-46 peptide were prepared in which all the cysteine residues were substituted either singly or multiply with serine residues (i.e., alpha 26-46 Cys28,31,32-->Ser28,31,32). The ED50 values of the parent alpha 26-46 peptide in the FSH-radioreceptor assay were 2 and 7 x 10(-5) M, depending on whether the C-terminus was present as the amide or the free acid form, respectively. The substituted peptide alpha 26-46 (Cys28,31,32-->Ser28,31,32) was totally inactive in the FSH-radioreceptor assay. The truncation studies indicated that Cys28, Cys31 and Cys32 all contribute to the hormone-receptor interaction, with Cys32 being the major contributory cysteine residue. Similar results were observed when these peptides were evaluated in the LH-radioreceptor assay where the ED50 value for the parent alpha 26-46 peptide was observed to be 2 or 3 x 10(-5) M, depending on whether the C-terminus was the amide or the free acid. The Cys31 residue did not appear to contribute to the LH-receptor interaction; however, removal of Cys28 and Cys32 resulted in significant decreases in binding activity. The C-terminal truncation studies of the alpha 26-46 peptide revealed that Lys44 contributes to FSH receptor binding activity but does not contribute to the LH-receptor interaction. Truncation of the Arg42 residue or substitution of Arg42 with alanine in the alpha 31-45 peptide sequence prepared as part of the Set 1 synthetic peptides (i.e., the alpha 31-45 Arg42-->Ala42 peptide) or as part of the Set 6 peptide series, alpha 26-46 Arg42-->Ala42, confirmed the involvement of this residue in the LH-receptor interaction.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗

PubMed1997

Stimulatory effect of a specific substance P antagonist (RPR 100893) of the human NK1 receptor on the estradiol-induced LH and FSH surges in the ovariectomized cynomolgus monkey.

Utilizing a human NK1 receptor antagonist (RPR 100893), the present in vivo study was designed to test the hypothesis that endogenous substance P (SP) modulates the action of 17beta-estradiol in inducing luteinizing hormone (LH) and follicle stimulating hormone (FSH) surges in ovariectomized cynomolgus monkey. Plasma concentrations of LH and FSH as well as NK1 receptor antagonist and SP were measured during the development of the negative and positive feedback phases which follow a single administration of estradiol benzoate (50 microg/kg) to long-term ovariectomized monkeys. Daily administration by gastric intubation of 1 mg/kg or 10 mg/kg of the NK1 receptor antagonist (RPR 100893) leads to detectable levels of the antagonist in the blood of treated animals for at least 6 hr after its administration. These levels are in agreement with the experimentally determined IC50 value of the antagonist. The most striking finding of this study is that LH and FSH releases are enhanced during the descending arm of the estradiol benzoate-induced LH and FSH surges, which suggests that endogenous SP normally has an inhibitory role during this time. The enhancement of LH release is approximately 50%, regardless of the amount of the NK1 antagonist used. However, the enhanced FSH release is more important. Furthermore, blockade of the NK1 receptor with the smaller dose of the antagonist leads to a small, but significant, increase in plasma levels of SP, indicating that blockade of SP receptors leads to an increased release of SP. Collectively, these results further substantiate the link which exists between the ovarian steroid 17beta-estradiol and SP systems. Also, for the first time, these results demonstrate an inhibitory involvement of the human NK1 receptor in the 17beta-estradiol-induced pseudo-ovulatory gonadotropin surges in the ovariectomized monkey.

Animals↗

PubMed2000

Age and methods of fatal self harm (FSH). Is there a link?

OBJECTIVES: To examine the methods of fatal self harm (FSH) used by the elderly compared to young adults. METHODS: We compared the methods of FSH used by all the elderly over 60 years of age to those used by all younger adults, over 16 and under 60, in the city of Birmingham and Solihull over a period of 4 years, 1995-1998. We applied the term FSH to all deceased who were subjects of Coroner's inquests and attracted verdicts of suicide and open verdicts. FINDINGS: A significantly higher proportion of the elderly who fatally harmed themselves did so by drowning and asphyxia compared to the younger age group (p < 0.05 and p < 0.01, respectively). Significantly more women over the age of 60 committed acts of FSH by tying a plastic bag around the neck than those under 60 (p < 0.05). Method of death was not ascertained in a much higher proportion of elderly FSH (p < 0.01). The most common method of suicide among elderly men and women were hanging and self-poisoning by overdose, respectively. CONCLUSION: The study shows that the most common method of suicide in the elderly is poisoning by drug overdose. It raises the question about the quantity of drugs prescribed for the elderly, e.g. antidepressants, sedatives and pain killers. The study did not confirm previous reports that violent methods are used more frequently with increasing age.

Adolescent↗

PubMed1991

FSH in testes of marmosets during development: immunocytochemical localization and de novo biosynthesis.

Immunocytochemical localization of FSH was carried out in various cell types of marmoset testes during development using antisera generated against intact as well as beta-subunit of human FSH. Significant differences in the intensity as well as distribution of FSH in various cell types were observed in neonatal, pubertal, and adult marmosets. Intensity of staining in Leydig cells was maximum at day 1 and in adults (1-3 years), whereas it was minimum at 3 months. In seminiferous tubules (Sertoli cells), FSH was present in trace amount until puberty and subsequently increased at maturity. Further studies demonstrate de novo biosynthesis of FSH-like moiety in vitro by testicular tissue, which was age dependent.

Animals↗

PubMedDate not supplied

Insulin-dependent diabetes affects testicular function by FSH- and LH-linked mechanisms.

A study was conducted to form a unified hypothesis regarding the gonadotropin-related mechanisms that underlie alterations in the male reproductive system in individuals with diabetes. Streptozotocin-induced diabetes resulted in reduced fertility, prolificacy, and libido. Testes showed a marked decrease in the number and function of Leydig cells, the latter manifested as changes in the expression of biochemical markers, including the GLUT-3 hexose transporter, c-kit, insulin-like growth factor I (IGF-I), androgen receptors, and overall tyrosine phosphorylation, as assessed by Western blot and immunocytochemical analyses. The expression of c-kit, IGF-I, insulin, and follicle-stimulating hormone (FSH) receptors in the seminiferous tubules was also affected. Serum levels of luteinizing hormone (LH), FSH, and testosterone significantly decreased. There was a significant (P <.05) correlation between the serum levels of insulin and FSH. No significant correlation was found between the serum levels of insulin or glucose and LH. On the basis of our results, we conclude that, in insulin-dependent diabetes, 1) Leydig cell function and testosterone production decrease because of the absence of the stimulatory effect of insulin on these cells and an insulin-dependent decrease in FSH, which, in turn, reduces LH levels; and 2) sperm output and fertility are reduced because of a decrease in FSH caused by a reduction in insulin.

Animals↗

PubMed2001

Gonadotropin-releasing hormone agonist affects rat ovarian follicle development by interfering with FSH and growth factors on the prevention of apoptosis.

Apoptosis is the biological process by which follicular cells are eliminated in atretic follicles. The aim of the present study was to examine the in vitro effect of a GnRH-a (leuprolide acetate, LA) and its interactions with FSH, dibutyryl cAMP, and growth factors (IGF-I, EGF, and FGF) on follicular apoptosis in early antral ovarian follicles obtained from prepubertal DES- treated rats. Follicles cultured 24 hr in the absence of hormones showed spontaneous onset of apoptotic DNA fragmentation. The presence of FSH suppressed the spontaneous onset of apoptotic DNA fragmentation (75-85%). Quantitative estimation of DNA cleavage from ovarian follicles revealed no significant changes in DNA fragmentation after in vitro LA treatment (1-100 ng/ml). However, coincubation with LA interfered partially with the effects of FSH on apoptosis suppression. This apoptosis suppression was also obtained by treatment with dibutyryl cAMP (80%), and was partially prevented by the presence of LA in the cultures. Follicles were cultured 24 hr with FGF, EGF, or IGF-I, and these factors suppressed DNA fragmentation (70, 60, and 70% respectively), while the presence of LA (100 ng/ml) in the culture medium prevented this effect. In conclusion, we show that the rescue from apoptotic DNA fragmentation produced in early antral follicles by FSH, cAMP, and growth factors, is prevented by coincubation with LA. This GnRH analog would thus interfere in the pathway of FSH, cAMP and/or growth factors by an as yet unknown mechanism.

Animals↗

PubMed1986

Involvement of prostate in the regulation of serum levels of FSH, LH, and prolactin in male rats.

Circulatory levels of LH and FSH were measured in serum of male rats (28, 35, 42, 63, 70, 77, and 207 days of age) 7 days following sham operation, castration (C), prostatectomy (P), and castration + prostatectomy (C + P). In C + P rats that were 49, 63, 70, 77, and 207 days of age, the plasma FSH was significantly elevated as compared to the C group. Administration of aqueous prostatic extract restored the circulatory FSH level in C + P animals to that observed in C animals, whereas in C animals FSH levels were suppressed, indicating inhibinlike activity. In rats 49 and 77 days of age, circulatory LH levels were significantly suppressed in C + P animals as compared to the C group. Both castration and prostatectomy alone suppressed circulatory prolactin levels. Administration of prostatic extract to castrated animals restored the prolactin levels to that of the sham-operated control animals. Results of the present study suggest a role of the prostate in feedback regulation of FSH and prolactin.

Animals↗

PubMed1991

Similarities in the modulation of pituitary and prostatic FSH by inhibin and related peptides.

Prostatic inhibin peptide (PIP) suppresses the synthesis as well as release of FSH from the rat pituitary whereas the carboxy terminal nonapeptide (86-94) of PIP elevated the release of pituitary FSH. Addition of a tyrosine residue at the NH2-terminal end of nonapeptide and blocking the sulfhydryl group of the cysteine residue at position 87 resulted in a decapeptide having the property of suppressing FSH release from rat pituitary. Human prostate has been shown to synthesize FSH in vitro. PIP, nonapeptide, and decapeptide modulate the prostatic FSH biosynthesis, the pattern of which was similar to that observed for pituitary.

Animals↗

PubMed2000

Retinoic acid (RA) represses follicle stimulating hormone (FSH)-induced luteinizing hormone (LH) receptor in rat granulosa cells.

The present study was undertaken to identify the mechanisms underlying the effect of retinoic acid (RA) on the luteinizing hormone receptor (LH-R) in rat granulosa cells. Treatment with FSH produced a substantial increase in LH-R mRNA level, as was expected, while concurrent treatment with increasing concentrations of RA brought about dose-dependent decreases in FSH-induced LH-R mRNA. RA, either alone or in combination with FSH, did not affect intracellular cAMP levels, while it inhibited the effect of 8-Br-cAMP on LH-R mRNA production. Whether the effect of RA and FSH on LH-R mRNA levels was the result of decreased transcription and/or altered mRNA stability was also investigated. The rate of LH receptor mRNA gene transcription, assessed by nuclear run-on transcription assay, was inhibited by the addition of RA. The effect of RA on LH-R mRNA stability was determined by measuring the decay of LH receptor mRNA under conditions known to inhibit transcription. The decay curves for the 5.4-kb LH-R mRNA transcript showed a significant decrease after the addition of RA. It may be possible that RA not only inhibits FSH-induced transcription but also stimulates the production of destabilizing factors for the LH-R mRNA. These findings assist in understanding the molecular mechanism underlying the effect of RA on reproductive function in rat granulosa cells.

Animals↗

PubMed2001

An immunoreactive peptide of the FSH involved in autoimmune infertility.

The purpose of this study was to identify autoantigens contained in human ovary extracts. Serum samples from 36 infertile women with anti-ovary antibodies as detected with an ELISA technique were tested in Western blot against human ovary extracts. A reactive protein with a molecular mass matching that of the FSH was detected in 34 cases. These serum samples also reacted strongly in Western blot and ELISA with purified FSH and, in immunofluorescence, with pituitary cells. Using the Pepscan approach, with overlapping peptides matching the amino acid sequence of the human FSH beta-chain, several immunoreactive regions were evidenced. The 78-93 amino acid sequence of the human FSH beta-chain appeared as one of the major epitopes. Synthetic peptides of this region were prepared and demonstrated to react with human serum samples from women with anti-ovary antibodies. These data demonstrate that FSH can be an autoantigen, recognized by autoantibodies associated with infertility.

Autoantibodies↗

PubMed1979

Evidence that the pituitary gland is the site of inhibitory action of porcine follicular fluid upon FSH secretion in the rat.

This study has examined the effects of porcine follicular fluid (PFF) on the adenohypophyseal secretion of LH and FSH following LHRH treatment. The animal model selected for study the the proestrous rat in which preovulatory LH and FSH surges were blocked with phenobarbital. To elicit the release of gonadotropins from this preparation, two different i.v. LHRH infusion protocols were used. The first elicited a proestrous-like LH and FSH surge while the second infusion schedule evoked the predominant release of FSH with only minor changes in LH. PFF suppressed LHRH-induced FSH secretion in both preparations but had only negligible effects on LH secretion. Interestingly, the suppressive effects of PFF were variable and depended upon the mode in which LHRH was presented.

Animals↗

PubMed1983

Control of FSH and LH secretion.

The control of FSH and LH secretion by the pituitary gland is clearly multifactorial. The evidence that LHRH influences the release and stores of both FSH and LH is considerable, and equally well documented is the fact that testosterone and oestradiol will suppress the secretion not only of LH but also of FSH. Recently evidence points to the existence of inhibin which will suppress FSH secretion but which in higher doses will also decrease LH levels. It is therefore likely that the ratio of FSH to LH secreted by the gonadotrope is determined by the summation of the action of these factors on cellular mechanisms that remain to be determined.

Animals↗