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2.
Eur J Cancer ; 173: 146-166, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35932626

RESUMO

AIM: To provide practice guidelines about fertility preservation (FP) in oncology. METHODS: We selected 400 articles after a PubMed review of the literature (1987-2019). RECOMMENDATIONS: Any child, adolescent and adult of reproductive age should be informed about the risk of treatment gonadotoxicity. In women, systematically proposed FP counselling between 15 and 38 years of age in case of treatment including bifunctional alkylating agents, above 6 g/m2 cyclophosphamide equivalent dose (CED), and for radiation doses on the ovaries ≥3 Gy. For postmenarchal patients, oocyte cryopreservation after ovarian stimulation is the first-line FP technique. Ovarian tissue cryopreservation should be discussed as a first-line approach in case of treatment with a high gonadotoxic risk, when chemotherapy has already started and in urgent cases. Ovarian transposition is to be discussed prior to pelvic radiotherapy involving a high risk of premature ovarian failure. For prepubertal girls, ovarian tissue cryopreservation should be proposed in the case of treatment with a high gonadotoxic risk. In pubertal males, sperm cryopreservation must be systematically offered to any male who is to undergo cancer treatment, regardless of toxicity. Testicular tissue cryopreservation must be proposed in males unable to cryopreserve sperm who are to undergo a treatment with intermediate or severe risk of gonadotoxicity. In prepubertal boys, testicular tissue preservation is: - recommended for chemotherapy with a CED ≥7500 mg/m2 or radiotherapy ≥3 Gy on both testicles. - proposed for chemotherapy with a CED ≥5.000 mg/m2 or radiotherapy ≥2 Gy. If several possible strategies, the ultimate choice is made by the patient.


Assuntos
Preservação da Fertilidade , Neoplasias , Criopreservação/métodos , Feminino , Preservação da Fertilidade/métodos , Humanos , Masculino , Neoplasias/tratamento farmacológico , Neoplasias/radioterapia , Ovário , Sêmen
3.
Front Endocrinol (Lausanne) ; 13: 855082, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35432221

RESUMO

Background: NR0B1 pathogenic variants can cause congenital adrenal hypoplasia or primary adrenal insufficiency in early childhood usually associated with hypogonadotropic hypogonadism. NR0B1 is necessary for organogenesis of the adrenal cortex and to maintain normal spermatogenesis. In humans, restoration of fertility in patients carrying NR0B1 pathogenic variants is challenging. Objective: The aim of the study was to investigate the clinical, hormonal, histological, spermiological, and molecular genetic characteristics of a cohort of patients with NR0B1 pathogenic variants, monitored for fertility preservation. Patients: We included five patients, including four teenagers, with NR0B1 pathogenic or likely pathogenic variants. They all had primary adrenal insufficiency and were receiving replacement therapy with glucocorticoids and mineralocorticoids. Patients received recombinant follicle-stimulating hormone and recombinant human chorionic gonadotropin in order to induce spermatogenesis. Combined gonadotropin treatment was initiated between 13 years and 15 years and 6 months for the four teenagers and at 31 years and 2 months for the only adult. Physical and hormonal assessments were performed just before starting gonadotropin treatment. After 12 months of gonadotropin treatment, physical examination and hormonal assessments were repeated, and semen analyses were performed. If no sperm cells were observed in at least 2 semen collections at 3-month interval, testicular biopsy for testicular sperm extraction was proposed. Results: Bilateral testicular volume increased from 8 ml (interquartile range, 6-9) to 12 ml (10-16) after gonadotropin treatment. Inhibin B levels were relatively stable: 110 ng/L (46-139) before and 91 ng/L (20-120) at the end of gonadotropin treatment. Azoospermia was observed in all semen analyses for all cases during gonadotropin treatment. Three patients agreed to testicular biopsy; no mature sperm cells could be retrieved in any. Conclusion: We characterized a cohort of patients with NR0B1 pathogenic or likely pathogenic variants for fertility preservation by recombinant gonadotropin treatment, which began either at puberty or in adulthood. No sperm cells could be retrieved in semen samples or testicular biopsy even after gonadotropin treatment, indicating that gonadotropin treatment, even when started at puberty, is ineffective for restoring fertility.


Assuntos
Doença de Addison , Hipogonadismo , Doença de Addison/tratamento farmacológico , Adolescente , Adulto , Pré-Escolar , Gonadotropina Coriônica/uso terapêutico , Receptor Nuclear Órfão DAX-1/genética , Humanos , Hipogonadismo/tratamento farmacológico , Masculino , Substâncias para o Controle da Reprodução , Espermatozoides , Testículo
4.
Basic Clin Androl ; 31(1): 31, 2021 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-34906089

RESUMO

BACKGROUND: Androgens are well known to be necessary for spermatogenesis. The purpose of this study was to determine Sertoli cell responsiveness to androgens according to age from birth to puberty. RESULTS: Testicular tissue samples were studied in a population of 84 control boys classified into seven groups according to age: group 1 (1-30 days), group 2 (1-3 months), group 3 (3-6 months), group 4 (0.5-3 years), group 5 (3-6 years), group 6 (6-12 years), and group 7 (12-16 years). We compared these data with those of 2 situations of pathology linked to androgens: 1/premature secretion of testosterone: 4 cases of Leydig cell tumor (LCT) in childhood; and 2 /defect of androgen receptors (AR): 4 cases of complete form of insensitivity to androgen syndrome (CAIS). In control boys, AR immunoreactivity (ir) in Sertoli cells appeared between 4.6 and 10.8 years of age, Anti-Mullerian Hormone (AMH) ir in Sertoli cells disappeared between 9.2 and 10.2 years of age. Connexin 43 (Cx43) ir in Sertoli cells and histological features of the onset of spermatogenesis appeared between 10.8 and 13,8 years of age. Cx43 ir was significantly higher in 12-16 year-olds than in younger boys. In case of CAIS, no spermatogenesis was observed, both AR and Cx43 ir were undetectable and AMH ir was elevated in Sertoli cells even at pubertal age. In the vicinity of LCTs, spermatogenesis occurred and both AR and Cx43 ir were strongly positive and AMH ir in Sertoli cells was low for age. CONCLUSIONS: Androgen action on Sertoli cells is required for onset of spermatogenesis and premature androgen secretion by LCT can induce spermatogenesis in the vicinity of the tumor. AR ir appeared earlier than onset of spermatogenesis, with large interindividual variability. The timing and mechanisms of Sertoli cell responsiveness to androgens are important issues for understanding the induction of spermatogenesis at puberty.


RéSUMé: CONTEXTE: Les androgènes sont bien connus pour être nécessaires à la spermatogenèse. Le but de l'étude était de déterminer l'évolution de la réactivité des cellules de Sertoli aux androgènes en fonction de l'âge depuis la période néonatale jusqu'à la puberté. RéSULTATS: Des échantillons de tissu testiculaire ont été étudiés dans une population de 84 garçons témoins classés en 7 groupes selon l'âge: groupe 1 (1­30 jours), groupe 2 (1­3 mois), groupe 3 (3­6 mois), groupe 4 (0,5­3 ans), groupe 5 (3­6 ans), groupe 6 (6­12 ans), groupe 7 (12­16 ans). Nous avons comparé ces données avec celles de deux situations de pathologies liées aux androgènes: 1/ une sécrétion prématurée de testostérone: 4 cas de tumeur à cellules de Leydig (LCT) dans l'enfance; 2/ une résistance aux androgènes par mutation du récepteur aux androgènes (AR): 4 cas de forme complète de syndrome insensibilité aux androgènes (CAIS). Chez les garçons témoins, l'immunoreactivité (ir) au AR dans les cellules de Sertoli est. apparue entre 4,6 et 10,8 ans, l'ir de l'hormone anti-mullerienne (AMH) dans les cellules de Sertoli a disparu entre 9,2 et 10,2 ans. L'ir de la connexine 43 (Cx 43) dans les cellules de Sertoli et les caractéristiques histologiques du début de la spermatogenèse sont apparues plus tard entre 10,8 et 13,8 ans. L'intensité de Cx 43 ir était significativement plus élevée chez les 12­16 ans que chez les garçons plus jeunes. Dans les cas de CAIS, aucune spermatogenèse n'a été observée, AR ir et Cx 43 ir étaient indétectables et AMH ir restait élevée dans les cellules de Sertoli à l'âge de la puberté. En outre à proximité des LCT, il est. observé une initiation de la spermatogenèse; AR ir et Cx43 ir étaient franchement augmentées et AMH ir dans les cellules de Sertoli était faible pour l'âge. CONCLUSIONS: L'action des androgènes au niveau des cellules de Sertoli est. nécessaire pour initier la spermatogenèse. De plus, une sécrétion prématurée d'androgènes, comme dans la situation de cas de LCT, est. capable induire une spermatogenèse à proximité de la tumeur. AR ir apparait un peu avant le démarrage de la spermatogenèse, il existe cependant avec une grande variabilité interindividuelle. L'apparition d'une réponse aux androgènes apparait comme un paramètre important à évaluer pour améliorer la compréhension de l'induction de la spermatogenèse.

5.
Prog Urol ; 31(3): 131-144, 2021 Mar.
Artigo em Francês | MEDLINE | ID: mdl-33309127

RESUMO

BACKGROUND: The aim of these Association Française d'Urologie (AFU) and Société d'Andrologie de Langue Française (SALF) common recommendations are to provide practice guidelines for the French Urological and Andrological community regarding the evaluation of infertile men. MATERIAL AND METHODS: Literature search in PubMed using the keywords "male infertility", "diagnosis", "management" and "evaluation" limited to clinical articles in English and French prior to 1/01/2020. To inform the level of evidence, the HAS grading system (2013) was applied. RESULTS: Concerning the evaluation of infertile men, the AFU and the SALF recommend : (1) a systematic interview exploring the family history, the fertility history of the man outside the couple, the patient's personal history that may have an impact on his fertility, lifestyle habits, treatments, symptoms and possible sexual difficulties of the couple; (2) a general physical examination to assess signs of hypogonadism and secondary sexual characters; (3) a scrotal physical examination performed by an urologist or andrologist to assess (i) the testes for volume and consistency, (ii) vas deferens and epididymes for total or partial absence or nodules, and (iii) presence of varicoceles; (4) Performing two semen analyses, according to World Health Organization guidelines, if the first one has at least one abnormaly; (5) a scrotal ultrasound as part of routine investigation, that can be completed with an endorectal pelvic ultrasound according to the clinic; (6) an endocrine evaluation with at least a Testosterone and FSH serum determination; (7) Karyotype analysis in infertile men with a sperm concentration ≤10 106/mL; (8) assessment of Yq microdeletions in infertile men with a sperm concentration ≤1 106/mL; (9) Cystic fibrosis transmembrane conductance regulator gene evaluation in case of suspicion for bilateral or unilateral congenital agenesis of vas deferens and seminal vesicles. The interest of tests analyzing DNA fragmentation (TUNEL, SCSA) is still under investigation. CONCLUSION: These guidelines can be applied in routine clinical practice in all infertile men.


Assuntos
Infertilidade Masculina/diagnóstico , Humanos , Masculino
6.
Pediatr Blood Cancer ; 67(9): e28526, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32618059

RESUMO

Testicular transposition (TT) before scrotal external radiotherapy (RT) is poorly reported in children with cancer, with only rare case reports published. TT surgical techniques, dosimetric parameters, and testicular functions are retrospectively reported in 12 children, median age 12.8 years, after scrotal RT for sarcomas. TT has low morbidity and allows a dramatic RT dose decrease in the healthy testicle. Endocrine functions seem preserved while more follow-up is needed to assess fertility. Though a rare situation, TT should be discussed in children and young adult cases when a scrotal high-dose RT is needed.


Assuntos
Preservação da Fertilidade/métodos , Tratamentos com Preservação do Órgão/métodos , Escroto/efeitos da radiação , Neoplasias Testiculares/radioterapia , Neoplasias Testiculares/cirurgia , Testículo/cirurgia , Adolescente , Criança , Pré-Escolar , Seguimentos , Humanos , Masculino , Prognóstico , Estudos Retrospectivos
7.
Cancers (Basel) ; 11(11)2019 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-31744224

RESUMO

Ewing sarcoma (EWS) is a common pediatric solid tumor with high metastatic potential. Due to toxic effects of treatments on reproductive functions, the cryopreservation of ovarian tissue (OT) or testicular tissue (TT) is recommended to preserve fertility. However, the risk of reintroducing residual metastatic tumor cells should be evaluated before fertility restoration. Our goal was to validate a sensitive and specific approach for EWS minimal residual disease (MRD) detection in frozen germinal tissues. Thawed OT (n = 12) and TT (n = 14) were contaminated with tumor RD-ES cells (10, 100, and 1000 cells) and EWS-FLI1 tumor-specific transcript was quantified with RT-qPCR. All contaminated samples were found to be positive, with a strong correlation between RD-ES cell numbers and EWS-FLI1 levels in OT (r = 0.93) and TT (r = 0.96) (p < 0.001). No transcript was detected in uncontaminated control samples. The invasive potential of Ewing cells was evaluated using co-culture techniques. After co-culturing, tumor cells were detected in OT/TT with histology, FISH, and RT-qPCR. In addition, four OT and four TT samples from children with metastatic EWS were tested, and no MRD was found using RT-qPCR and histology. We demonstrated the high sensitivity and specificity of RT-qPCR to detect EWS MRD in OT/TT samples. Clinical trial: NCT02400970.

8.
J Clin Endocrinol Metab ; 100(3): 961-7, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25423570

RESUMO

CONTEXT: Testicular sperm extraction (TESE) in adult patients with nonmosaic 47,XXY provides a sperm retrieval rate (SRR) of approximately 50%. Age is the only significant prognostic factor. Whether TESE should be performed in adolescent patients for sperm cryopreservation remains to be determined. OBJECTIVE: The objective of the study was to compare SRR between young (15-23 y) and adult (> 23 y) patients with 47,XXY, and to determine whether previous androgenic treatment had a deleterious effect. DESIGN: We designed a prospective comparative study between two groups enrolled in parallel from September 2010 onward. SETTING: University hospital. PATIENTS: Forty one patients with nonmosaic 47,XXY karyotype and azoospermia were included. Twenty five patients from 15-22 years of age were assigned to the "Young" group, and 16 patients age 23 years or more, to the "Adult" group. INTERVENTION: A bilateral testicular open biopsy was performed by a single surgeon. The reproductive biologist who performed TESE was blind to the patient's age. Principal Outcome Measure: The main outcome measure was the SRR. The TESE procedure was considered positive if at least 20 sperm cells could be cryopreserved for intracytoplasmic sperm injection. RESULTS: SRR was 13/25 = 52% in the Young group and 10/16 = 62.5% in the Adult group, the difference being nonsignificant (P = .73). Ages were 24.3 ± 7.4 years in the 23 cases of positive TESE, and 23.7 ± 7.4 in the 18 cases of negative TESE, the difference being nonsignificant (P = .42). SRR was 9/17 = 52.9% for patients with and 14/24 = 59.1% for patients without previous testosterone (T) treatment, the difference being nonsignificant (P = .98). CONCLUSIONS: According to the present results, performing TESE at a younger age (15-23 y) in patients with azoospermic nonmosaic 47,XXY Klinefelter did not increase SRR relative to adult patients (25-39 y). Previous replacement treatment with moderate doses of T did not seem to be deleterious for the recovery of sperm cells by TESE.


Assuntos
Síndrome de Klinefelter/terapia , Recuperação Espermática , Adolescente , Adulto , Fatores Etários , Criopreservação , Transferência Embrionária , Feminino , Preservação da Fertilidade/métodos , Humanos , Infertilidade Masculina/terapia , Síndrome de Klinefelter/patologia , Masculino , Projetos Piloto , Gravidez , Análise do Sêmen , Preservação do Sêmen , Injeções de Esperma Intracitoplásmicas , Adulto Jovem
9.
Hum Reprod ; 21(9): 2340-5, 2006 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-16709604

RESUMO

BACKGROUND: Sertoli cells nurse germ cells during spermatogenesis, and alterations of Sertoli cell functions have been suggested in cases of spermatogenic failures. METHODS: In this work, we measured stem cell factor (SCF) and clusterin mRNA levels, by quantitative RT-PCR, in RNA extracted from testicular biopsies of 49 azoospermic patients classified according to testicular histology as having normal spermatogenesis or spermatogenic failure. RESULTS: When related to the percentage of Sertoli cells counted on a histological section of a neighbouring tissue sample, SCF and clusterin mRNA levels were significantly lower in the 'spermatogenic failure' group compared with the control group (P = 0.0297 and P = 0.0043, respectively). These levels were also significantly lower in the cases of 'constitutive' (cryptorchidism and Yq microdeletion) and 'idiopathic' spermatogenic failures when compared with the control group; conversely, they were not significantly decreased in the group with 'acquired spermatogenic failure' (orchitis, testicular traumatism, chemoradiotherapy and varicocele). CONCLUSIONS: These data further demonstrate an alteration of Sertoli cell functions in some human spermatogenic failures and suggest that a lack of Sertoli cell maturation may be involved in cases of constitutive or idiopathic spermatogenic failures.


Assuntos
Azoospermia/metabolismo , Clusterina/biossíntese , RNA Mensageiro/metabolismo , Fator de Células-Tronco/biossíntese , Testículo/metabolismo , Adulto , Ligação Competitiva , Biópsia , Clusterina/metabolismo , Deleção de Genes , Humanos , Masculino , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Células de Sertoli/metabolismo , Espermatogênese
10.
J Clin Endocrinol Metab ; 89(2): 917-24, 2004 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-14764814

RESUMO

SHBG is the specific plasma transport protein for sex steroid hormones in humans. Plasma SHBG concentration follows a gender dimorphism but varies with nutritional and hormonal status in both sexes. In addition, a genetic influence on SHBG in humans has recently been suggested by family studies. We investigated the relationship between a point mutation (D327N) in SHBG gene exon 8 that delays human SHBG half-life and a pentanucleotide repeat polymorphism [PNRP (TAAAA)(n)] in the SHBG gene 5' untranslated region that influences transcription in vitro, on the one hand, and SHBG levels on the other, in a population of 303 women referred for hirsutism. Of these patients, 154 (51%) met the criteria for polycystic ovary syndrome (PCOS) and 124 (41%) were overweight [body mass index (BMI) > or = 25 kg/m(2)]. The two SHBG gene alleles for D327N substitution, wild-type (W) and variant (v), were identified by restriction fragment length polymorphism in the whole population, and the GeneScan method was used to identify PNRP alleles in 245 subjects. Six alleles of the pentanucleotide motif with six to 11 repeats were present in our population. Plasma SHBG concentration was related to PCOS status, non-SHBG-bound testosterone, BMI, fasting blood glucose level, fasting insulinemia, and D327N allele v. The v allele was associated with higher SHBG levels [36.9 +/- 15.9 nmol/liter for W/v (n = 52) and 43.5 +/- 3.5 nmol/liter for v/v (n = 2)] than was the wild-type W allele [31.1 +/- 16.1 nmol/liter (n = 249); P = 0.039]. Multivariate analysis showed that BMI, PCOS status, and D327N polymorphism influenced plasma SHBG concentrations, each of these parameters contributing independently of the others. Investigating the role of each allele of the TAAAA repeat polymorphism on SHBG levels was more complex because of the number of different genotypes (as many as 18 in our population) and the low frequency of some of them. Moreover, a strong disequilibrium linkage was found between D327N allele v and the eight-TAAAA repeat allele (P < 0.0001). This could mask the effect of the TAAAA repeat polymorphism on SHBG concentration in vivo. Nevertheless, SHBG levels in patients who were homozygous for six repeats (34.9 +/- 16.2 nmol/liter; n = 21) were significantly (P = 0.043) higher than in nine-repeat homozygous patients (21.5 +/- 13.0 nmol/liter; n = 8), and lay between the two for eight-repeat homozygous patients (28.5 +/- 15.8 nmol/liter; n = 44). Delineating the precise role of this PNRP polymorphism will need further investigation in a large healthy population. In summary, although BMI and PCOS status have a major influence on circulating SHBG levels in hirsute women, the present results support the notion that polymorphism(s) within the coding sequence and, potentially, in the regulatory sequence of the SHBG gene are associated with circulating SHBG levels and may represent part of the genetic background of sex steroid hormone activity in humans.


Assuntos
Hirsutismo/sangue , Hirsutismo/genética , Repetições de Microssatélites , Polimorfismo Genético , Globulina de Ligação a Hormônio Sexual/genética , Globulina de Ligação a Hormônio Sexual/metabolismo , Adulto , Alelos , Asparagina/genética , Ácido Aspártico/genética , Índice de Massa Corporal , Feminino , Frequência do Gene , Hirsutismo/complicações , Homozigoto , Humanos , Análise Multivariada , Obesidade/complicações , Obesidade/patologia , Concentração Osmolar , Síndrome do Ovário Policístico/complicações , Polimorfismo Genético/genética
11.
Biol Reprod ; 67(6): 1699-707, 2002 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-12444043

RESUMO

Study of the multidrug resistance phenomenon in tumor cell lines has led to the discovery of the product of the multidrug resistance (MDR) type 1 genes, the plasma membrane P-glycoprotein (P-gp) that functions as an energy-dependent pump for the efflux of diverse anticancer drugs. P-gp was also recently identified in normal epithelial cells with secretory/excretory functions and in the endothelial cells of the capillary blood vessels in the brain and the testis. These endothelial cells are key elements of the blood-brain and blood-testis barriers, respectively. The aim of this study, in the rat, mouse, guinea pig, and human, was to determine whether testicular cells other than the capillary endothelial cells could express MDR type I genes. Immunohistochemistry on testicular sections revealed that P-gp is present in interstitial cells in the mouse, rat, and human testes, in early and late spermatids in guinea pig testis, and in late spermatids in the rat, mouse, and human. Reverse transcription-polymerase chain reaction analysis on isolated mouse, rat, and human cells showed that all somatic testicular cells (Leydig cells, macrophages, peritubular cells, and Sertoli cells) and the cytoplasmic lobes from rat late spermatids expressed MDR type I mRNAs, whereas spermatogonia, pachytene spermatocytes, and early spermatids did not. An ontogenesis study in the mouse reveals that type I MDR gene expression begins at 13.5 days postcoitum at the time when the seminiferous cords and the blood vessels appear and are maintained thereafter. Finally, two functional tests on isolated rat cells, the doxorubicin and rhodamine uptake assays, demonstrated that rat testicular macrophages, Leydig cells, peritubular cells, and Sertoli cells displayed a multidrug-resistance activity, whereas spermatogonia, pachytene spermatocytes, and early spermatids did not. Western blot experiments have revealed that a P-gp of 175 kDa is present in the human testis as well as in the rat Leydig cells, testicular macrophages, peritubular cells, and Sertoli cells, but is absent in spermatogonia, spermatocytes, and early spermatids. We conclude that P-gp is involved in the self-protection of the somatic cells and is most probably one of the molecules that confers its functionality to the blood-testis barrier. The absence of expression of MDR type I genes in mitotic and meiotic germ cells probably explains their particular vulnerability to various anticancer drugs. In contrast, expression of the P-gp in the haploid cells most likely reflects the ability of spermatozoa to assume their own antidrug defense.


Assuntos
Membro 1 da Subfamília B de Cassetes de Ligação de ATP/análise , Genes MDR/genética , Testículo/química , Animais , Barreira Hematotesticular , Western Blotting , Capilares/química , Membrana Celular/química , Endotélio Vascular/química , Cobaias , Humanos , Immunoblotting , Células Intersticiais do Testículo/química , Macrófagos/química , Masculino , Camundongos , RNA Mensageiro/análise , Ratos , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Células de Sertoli/química , Espermátides/química , Espermatozoides/química , Testículo/irrigação sanguínea
12.
Steroids ; 67(7): 637-45, 2002 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-11996937

RESUMO

Bisphenol A, an environmental compound with estrogenic activity, has been shown to bind human sex steroid hormone-binding globulin (hSHBG), the main plasma transport protein which regulates the metabolism of androgens and estrogens and limits their access to target organs. The present study was conducted to determine whether physiologically relevant concentrations of hSHBG can influence the blood clearance rate of bisphenol A and its accumulation in the testes. A radioactive [2-125I]iodobisphenol tracer was synthesized with an association constant (Ka) for binding to hSHBG of 0.14 +/- 0.01 x 10(6) M(-1) at 37 degrees C, a value much lower than for [2-125I]iodoestradiol, which was also synthesized. We used i.v. injection of immunopurified hSHBG in adult male mice to maintain hSHBG levels within the physiologically possible range for humans (27-267 nM) before gavage administration of [2-125I]iodobisphenol or [2-125I]iodoestradiol, for measuring the blood clearance rate of radioactive signal in blood samples taken during the following 120 min. Testicular accumulation of radioactivity was measured 24 h and 48 h after gavage of [2-125]iodobisphenol A. In mice receiving immunopurified hSHBG or vehicle, the time-dependent blood clearance of radioactivity exhibited a bi-exponential decrease which indicated alpha-diffusion and beta-elimination phases for both radioactive ligands. The presence of circulating hSHBG significantly and dose-dependently lowered the clearance rate of radioactivity. However, much higher circulating levels of hSHBG were required to retard the blood clearance of [2-125I]iodobisphenol A as compared to those required for [2-125I]iodoestradiol, in keeping with the important difference in their respective Ka value for binding to SHBG. In addition, mice treated with hSHBG exhibited significantly (P = 0.036) reduced testicular accumulation of radioactivity 24 h and 48 h after ingestion of [2-125I]iodobisphenol A. Provided that the binding properties of bisphenol A for hSHBG are not substantially different from those measured for [2-125I]iodobisphenol A, these findings suggest that, although hSHBG binds 2-mono-iodobisphenol A with a relatively low binding affinity, high enough concentrations of circulating hSHBG (range concentrations between 85 and 267 nM) are potentially able to exert a protective effect against exposure to bisphenol A.


Assuntos
Fenóis/farmacologia , Fenóis/farmacocinética , Globulina de Ligação a Hormônio Sexual/administração & dosagem , Globulina de Ligação a Hormônio Sexual/farmacologia , Testículo/efeitos dos fármacos , Testículo/metabolismo , Administração Oral , Animais , Compostos Benzidrílicos , Ligação Competitiva , Estradiol/análogos & derivados , Humanos , Injeções Intravenosas , Masculino , Taxa de Depuração Metabólica/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos BALB C , Fenóis/administração & dosagem , Fenóis/metabolismo , Ligação Proteica , Globulina de Ligação a Hormônio Sexual/metabolismo , Distribuição Tecidual
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