Biomedical subjects

Manuela Simoni

Publications and source records attributed to Manuela Simoni.

25 records · Page 2Linked to original sources

PubMed2003

Absence of exon 10 of the human luteinizing hormone (LH) receptor impairs LH, but not human chorionic gonadotropin action.

The LH receptor (LHR) mediates the actions of LH and human chorionic gonadotropin (hCG). In vivo data showed that deletion of exon 10 does not affect hCG action, whereas LH action is impaired. To investigate the role of exon 10 in LH/hCG action in vitro we created stable COS-7 cells expressing the LHR with (wt) or without (-ex10) exon 10. Binding experiments showed that the affinities of LH and hCG to the LHR wt and -ex10 were similar. Stimulation of wt with hCG or LH resulted in increased cAMP. cAMP production was significantly impaired in -ex10 stimulated with LH. This response was not altered by pertussis toxin, excluding that G(i) becomes activated in LHR -ex10. In desensitization experiments, intracellular cAMP of LHR wt and -ex10 declined to approximately 30%. No difference in intracellular cAMP was detected between LHR wt or -ex10 after recovery and restimulation with hCG or LH. These experiments show that impaired cAMP production of LHR -ex10 stimulated with LH is not due to anomalous receptor coupling or desensitization. We conclude that although exon 10 of the LHR plays no role in ligand binding, it is important for receptor activation by LH by a mechanism probably involving extracellular conformational changes.

Animals↗

PubMed2003

Targeted expression of human FSH receptor Asp567Gly mutant mRNA in testis of transgenic mice: role of human FSH receptor promoter.

AIM: To specifically express the Asp567Gly human follicle-stimulating hormone receptor (FSHR) under the control of its promoter to evaluate the phenotypic consequences in the presence of normal pituitary function. METHODS: We produced transgenic mice overexpressing the Asp567Gly human FSHR under the control of a 1.5kb 5'-flanking region fragment of its promoter. RESULTS: Mice were phenotypically normal and fertile. In males, mRNA could be detected in the testis and the brain, indicating that the 1.5kb promoter fragment drives expression not only in the gonads. The testis weight/body weight ratio and the testosterone levels in transgenic and non-transgenic littermates were similar. By in situ hybridisation we found that the transgenic FSHR was highly expressed in Sertoli cells, spermatocytes and round spermatids. However, a radioligand receptor assay failed to show a significant difference in total FSHR binding sites in testis homogenates of transgenic and wild type animals, suggesting that the transgenic FSHR is probably not translated into functional receptor protein. CONCLUSION: A 1.5kb 5'-region of the human FSHR drives mRNA expression of the transgene in the testis but leads to ectopic expression in germ cells and in the brain. No phenotypic consequences could be documented due to the lack of protein expression.

Animals↗

PubMed2002

CAG repeat length in the androgen receptor gene and gonadotrophin suppression influence the effectiveness of hormonal male contraception.

OBJECTIVE: Nonuniformity in suppression of spermatogenesis induced by various hormones or hormone combinations has impeded the development of an effective hormonal male contraceptive. The basis for this heterogeneity in response remained unresolved to date; however, the presence of ethnic differences points to an involvement of genetic factors. PATIENTS AND MEASUREMENTS: In a retrospective analysis we investigated the impact of a CAG repeat polymorphism in the androgen receptor and polymorphic sites in the oestrogen and FSH receptor genes on spermatogenic suppression in 85 Caucasian men treated with different regimens of hormonal contraception. RESULTS: Failure to reduce sperm concentrations below 3 million/ml was significantly associated with insufficient suppression of gonadotrophins. The extent of gonadotrophin suppression was not explained by any polymorphism but was primarily pharmacological, resulting from addition of gestagens to testosterone. When LH and FSH suppression was rapid and persistent none of the polymorphisms studied explained why some men failed to achieve azoospermia. In cases with incomplete gonadotrophin suppression the chances of becoming azoospermic were 2.5 times higher in men having more than 22 CAG repeats. CONCLUSIONS: In summary, our analysis shows that in a subset of men, effective hormonal male contraception can be achieved even in the absence of complete gonadotrophin suppression.

Adult↗

PubMed2002

An activated human follicle-stimulating hormone (FSH) receptor stimulates FSH-like activity in gonadotropin-deficient transgenic mice.

FSH mediates its testicular actions via a specific Sertoli cell G protein-coupled receptor. We created a novel transgenic model to investigate a mutant human FSH receptor (FSHR(+)) containing a single amino acid substitution (Asp567Gly) equivalent to activating mutations in related glycoprotein hormone receptors. To examine the ligand-independent gonadal actions of FSHR(+), the rat androgen-binding protein gene promoter was used to direct FSHR(+) transgene expression to Sertoli cells of gonadotropin-deficient hypogonadal (hpg) mice. Both normal and hpg mouse testes expressed FSHR(+) mRNA. Testis weights of transgenic FSHR(+) hpg mice were increased approximately 2-fold relative to hpg controls (P < 0.02) and contained mature Sertoli cells and postmeiotic germ cells absent in controls, revealing FSHR(+)-initiated autonomous FSH-like testicular activity. Isolated transgenic Sertoli cells had significantly higher basal ( approximately 2-fold) and FSH-stimulated ( approximately 50%) cAMP levels compared with controls, demonstrating constitutive signaling and cell-surface expression of FSHR(+), respectively. Transgenic FSHR(+) also elevated testosterone production in hpg testes, in the absence of circulating LH (or FSH), and it was not expressed functionally on steroidogenic cells, suggesting a paracrine effect mediated by Sertoli cells. The FSHR(+) response was additive with a maximal testosterone dose on hpg testicular development, demonstrating FSHR(+) activity independent of androgen-specific actions. The FSHR(+) response was male specific as ovarian expression of FSHR(+) had no effect on hpg ovary size. These findings reveal transgenic FSHR(+) stimulated a constitutive FSH-like Sertoli cell response in gonadotropin-deficient testes, and pathways that induced LH-independent testicular steroidogenesis. This novel transgenic paradigm provides a unique approach to investigate the in vivo actions of mutated activating gonadotropin receptors.

Amino Acid Substitution↗

PubMed2002

Self-adjusted postmenopausal hormone replacement therapy: effects on the biological and immunological profile of FSH and correlation to climacteric symptoms.

OBJECTIVE: The purpose of the present study was to evaluate the hormonal profile of patients of postmenopausal age during estrogen replacement therapy (ERT) with special reference to the serum levels of biologically active FSH (B-FSH) in a self-adjusted ERT model. DESIGN: The hormonal values found have been correlated to climateric symptoms reported by the patients (scored by the Kupperman menopausal index (KI)). METHODS: B-FSH was measured using an assay based on a cell system transfected permanently with FSH receptor cDNA. All women (n=32) applied estradiol percutaneously using 1 mg estradiol-17beta (E(2)) as an initial dose and were encouraged to increase the daily dose until they felt comfortable according to a specific scheme. Twelve of the 32 women were hysterectomized and treated, accordingly, with ERT only; 20 women received megestrol acetate monthly for 10 days. RESULTS: The initial average KI was 30 (range 10-54). A high degree of correlation (r=0.83; P<0.001) was observed between B-FSH and immunologically active FSH (I-FSH). Serum I-FSH and E(2) correlated negatively (r=-0.21; P<0.001); similarly, a negative correlation (r=-0.15; P<0.01) was observed between serum B-FSH and E(2) levels. Serum I-FSH and KI showed modest but significant positive correlation (r=0.13; P<0.01); a somewhat higher degree of correlation (r=0.19; P<0.005) was observed when B-FSH and KI were compared. E(2) showed positive correlation to serum sex-hormone binding globulin levels (r=0.22; P<0.001). CONCLUSIONS: This study shows that the transdermal self-adjusted hormone replacement therapy (HRT) model introduced is suitable for studies on endocrine changes during postmenopausal ERT. The finding of poor correlation between serum E(2) levels and KI emphasizes the importance of hormonal measurements during postmenopausal HRT.

Climacteric↗

PubMed2002

Maintenance of spermatogenesis in hypogonadotropic hypogonadal men with human chorionic gonadotropin alone.

OBJECTIVE: It is generally accepted that both gonadotropins LH and FSH are necessary for initiation and maintenance of spermatogenesis. We investigated the relative importance of FSH for the maintenance of spermatogenesis in hypogonadotropic men. SUBJECTS AND METHODS: 13 patients with gonadotropin deficiency due to idiopathic hypogonadotropic hypogonadism (IHH), Kallmann syndrome or pituitary insufficiency were analyzed retrospectively. They had been treated with gonadotropin-releasing hormone (GnRH) (n=1) or human chorionic gonadotropin/human menopausal gonadotropin (hCG/hMG) (n=12) for induction of spermatogenesis. After successful induction of spermatogenesis they were treated with hCG alone for maintenance of secondary sex characteristics and in order to check whether sperm production could be maintained by hCG alone. Serum LH, FSH and testosterone levels, semen parameters and testicular Volume were determined every three to six Months. RESULTS: After spermatogenesis had been successfully induced by treatment with GnRH or hCG/hMG, hCG treatment alone continued for 3-24 Months. After 12 Months under hCG alone, sperm counts decreased gradually but remained present in all patients except one who became azoospermic. Testicular Volume decreased only slightly and reached 87% of the Volume achieved with hCG/hMG. During treatment with hCG alone, FSH and LH levels were suppressed to below the detection limit of the assay. CONCLUSION: Once spermatogenesis is induced in patients with secondary hypogonadism by GnRH or hCG/hMG treatment, it can be maintained in most of the patients qualitatively by hCG alone, in the absence of FSH, for extended periods. However, the decreasing sperm counts indicate that FSH is essential for maintenance of quantitatively normal spermatogenesis.

Adult↗

PubMedDate not supplied

Follicle-stimulating hormone receptor gene haplotype distribution in normozoospermic and azoospermic men.

The human follicle-stimulating hormone (FSH) receptor (FSHR) gene possesses single nucleotide polymorphisms (SNP) in exon 10, which influence serum FSH levels in women, but not in men. In the present study we extend our previous investigation and for the first time analyze a novel, common SNP at position -29 of the FSHR core promoter in men. The SNP in codon 680 was analyzed in 438 men with nonobstructive azoospermia and in 304 controls. The SNP in codon 307 and at position -29 was analyzed in 345 men with nonobstructive azoospermia and 186 controls. SNPs were determined by allelic discrimination. No significant difference in the frequency of the polymorphism at position 680 and serum FSH levels was found. At position -29 (A/G) the A(-29) allele was less frequent than the G(-29) allele both in controls (25% vs 75%) and in patients (30% vs 70%) (P not significant). Together the three SNPs form four discrete haplotypes (A-Thr-Asn, G-Thr-Asn, A-Ala-Ser, and G-Ala-Ser) occurring in 10 combinations. A statistically significant difference in the allelic distribution between controls and azoospermic men was found (P < .05 by chi2 test). The A-Ala-Ser allele was more frequent in patients (9.1%) than in controls (5.4%), whereas the G-Thr-Asn allele was less frequent in patients (33.1%) than in controls (40.6%) (P < .01 by Fisher's exact test). No significant correlation between serum FSH levels and FSHR allele was found. We conclude that the FSHR haplotype does not associate with different serum FSH levels but it is differently distributed in normal and azoospermic men. The A-Ala-Ser and the G-Thr-Asn allele might represent genetic factors contributing to phenotypic expression of severe spermatogenetic impairment.

Follicle Stimulating Hormone↗