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1.
Am J Pathol ; 186(2): 324-36, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26683665

RESUMO

The mammalian target of rapamycin complex 1 (mTORC1) inhibitor rapamycin and its analogs are being increasingly used in solid-organ transplantation. A commonly reported side effect is male subfertility to infertility, yet the precise mechanisms of mTOR interference with male fertility remain obscure. With the use of a conditional mouse genetic approach we demonstrate that deficiency of mTORC1 in the epithelial derivatives of the Wolffian duct is sufficient to cause male infertility. Analysis of spermatozoa from Raptor fl/fl*KspCre mice revealed an overall decreased motility pattern. Both epididymis and seminal vesicles displayed extensive organ regression with increasing age. Histologic and ultrastructural analyses demonstrated increased amounts of destroyed and absorbed spermatozoa in different segments of the epididymis. Mechanistically, genetic and pharmacologic mTORC1 inhibition was associated with an impaired cellular metabolism and a disturbed protein secretion of epididymal epithelial cells. Collectively, our data highlight the role of mTORC1 to preserve the function of the epididymis, ductus deferens, and the seminal vesicles. We thus reveal unexpected new insights into the frequently observed mTORC1 inhibitor side effect of male infertility in transplant recipients.


Assuntos
Proliferação de Células/efeitos dos fármacos , Fertilidade/efeitos dos fármacos , Complexos Multiproteicos/efeitos dos fármacos , Glândulas Seminais/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Sirolimo/farmacologia , Serina-Treonina Quinases TOR/efeitos dos fármacos , Animais , Masculino , Mamíferos , Alvo Mecanístico do Complexo 1 de Rapamicina , Camundongos Transgênicos , Fosforilação , Glândulas Seminais/metabolismo , Fatores de Transcrição/metabolismo
2.
Biol Reprod ; 89(3): 59, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23843239

RESUMO

Uropathogenic Escherichia coli (UPEC)-associated epididymitis is commonly diagnosed in outpatient settings. Although the infection can be successfully cleared using antimicrobial medications, 40% of patients unexplainably show persistent impaired semen parameters even after treatment. Our aim was to investigate whether pathogenic UPEC and its associated virulence factor hemolysin (hlyA) perturb the structural and functional integrity of both the epididymis and sperm, actions that may be responsible for the observed impairment and possibly a reduction of fertilization capabilities. Semen collected from patients diagnosed with E. coli-only related epididymitis showed that sperm counts were low 14 days postantimicrobial treatment regardless of hlyA status. At Day 84 following treatment, hlyA production correlated with approximately 4-fold lower sperm concentrations than in men with hlyA-negative strains. In vivo experiments with the hlyA-producing UPEC CFT073 strain in a murine epididymitis model showed that just 3 days postinfection, structural damage to the epididymis (epithelial damage, leukocyte infiltration, and edema formation) was present. This was more severe in UPEC CFT073 compared to nonpathogenic E. coli (NPEC 470) infection. Moreover, pathogenic UPEC strains prematurely activated the acrosome in vivo and in vitro. Raman microspectroscopy revealed that UPEC CFT073 undermined sperm integrity by inducing nuclear DNA damage. Consistent with these observations, the in vitro fertilization capability of hlyA-treated mouse sperm was completely abolished, although sperm were motile. These findings provide new insights into understanding the possible processes underlying clinical manifestations of acute epididymitis.


Assuntos
Epididimite/microbiologia , Epididimite/patologia , Infecções por Escherichia coli/patologia , Espermatozoides/microbiologia , Espermatozoides/ultraestrutura , Infecções Urinárias/patologia , Escherichia coli Uropatogênica/patogenicidade , Adulto , Animais , Embrião de Mamíferos/microbiologia , Feminino , Humanos , Infertilidade Masculina/microbiologia , Infertilidade Masculina/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Pessoa de Meia-Idade , Análise do Sêmen , Adulto Jovem
3.
Cell Tissue Res ; 354(2): 623-32, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23873629

RESUMO

TCam-2 cells are the main in vitro model for investigations into seminomatous tumors. However, despite their widespread use, questions remain regarding the cells' homogeneity and consequently how representative they are of seminomas. We assess the TCam-2 cell line using routine and novel authentication methods to determine its homogeneity, identify any cellular sub-populations and resolve whether any changes could be due to generational differentiation. TCam-2, embryonal carcinoma cells (2102EP) and breast cancer cell (MCF7) lines were assessed using qRT-PCR, immunocytochemistry, flow cytometry and short tandem repeat analyses. Raman maps of individual cells (minimum of 10) and single scan spectra from 200 cells per culture were obtained. TCam-2s displayed the characteristic marker gene expression pattern for seminoma, were uniform in size and granularity and short tandem repeat analysis showed no contamination. However, based only on physical parameters, flowcytometry was unable to differentiate between TCam-2 and 2102EPs. Raman maps of TCam-2s comprised three equally distributed, distinct spectral patterns displaying large intercellular single spectral variation. All other cells showed little variation. Principal component, cluster and local spectral angle analyses indicated that the TCam-2s contained two different types of cells, one of which comprised two subgroups and was similar to some 2102EP cells. Protein expression corroborated the presence of different cells and generational differences. The detailed characterization provided by the Raman spectra, augmented by the routine methods, provide substantiation to the long-held suspicion that TCam-2 are not homogeneous but comprise differing cell populations, one of which may be embryonal carcinoma in origin.


Assuntos
Seminoma/diagnóstico , Análise Espectral Raman/métodos , Neoplasias Testiculares/diagnóstico , Neoplasias da Mama/química , Neoplasias da Mama/diagnóstico , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Feminino , Humanos , Masculino , Seminoma/química , Seminoma/patologia , Neoplasias Testiculares/química , Neoplasias Testiculares/patologia
4.
Reproduction ; 146(6): R249-58, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24062567

RESUMO

At present, evaluation of male reproductive function consists primarily of routine semen analysis, a collection of conventional microscopic assessments ideally performed following the guidelines set by the World Health Organization. While providing some insight into testicular function, these long-performed tests are limited in the information that they impart; more specifically, they are unable to predict true fertility potential. As a consequence, there is a need for the appraisal and consideration of newer semen parameters that may be more indicative of reproductive success. Although various novel assays have been introduced that broaden the scope of information available to both researcher and clinician, the utility of these tests remains limited due to the lack of standardisation of protocols and the absence of clinically established, dependable reference ranges. As such, it is not surprising that most of these parameters and their associated methods remain recommended for 'research purposes only'. With the burgeoning 'omics' revolution, nanotechnology and the development of new analytical instruments, there is now an opportunity for the identification and measurement of previously unknown features that may prove to be more indicative of each sperm's true functional status and capability. Once optimised, simplified, clinically validated and made more readily accessible, these new approaches hold the promise of forming the fulcrum upon which andrological investigations can enter a new era.


Assuntos
Necessidades e Demandas de Serviços de Saúde , Análise do Sêmen/métodos , Análise do Sêmen/tendências , Animais , Antioxidantes/uso terapêutico , DNA/análise , Genômica/métodos , Necessidades e Demandas de Serviços de Saúde/tendências , Humanos , Infertilidade Masculina/diagnóstico , Infertilidade Masculina/tratamento farmacológico , Infertilidade Masculina/etiologia , Masculino , Estresse Oxidativo/fisiologia , Valor Preditivo dos Testes
5.
J Assist Reprod Genet ; 29(9): 943-50, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22692281

RESUMO

PURPOSE: Assess short- and mid-term impact of cryopreservation on DNA methylation status of different genes in spermatozoa. METHODS: Semen samples from 10 healthy normozoospermic men were collected at the Department of Clinical Andrology of the Centre of Reproductive Medicine and Andrology (Muenster, Germany). Each was divided into four equal aliquots: 1) untreated, 2) diluted in cryoprotectant, 3) short term (2 days) cryopreserved and 4) mid term (4 weeks) cryopreserved. Samples were "swim-up" purified prior to analysis. DNA fragmentation was measured using comet assay and Flow cytometric evaluation with Acridine Orange (FCEAO). The degree of methylation of nine genes was determined by bisulfite pyrosequencing of genomic DNA. RESULT(S): Analysis of three maternally imprinted genes (LIT1, SNRPN, MEST), two paternally imprinted genes (MEG3, H19), two repetitive elements (ALU, LINE1), one spermatogenesis-specific gene (VASA) and one gene associated with male infertility (MTHFR) in semen samples demonstrated no alteration in methylation pattern regardless of duration of cryopreservation. CONCLUSION(S): The lack of any changes in the sub-fraction of the genome examined in our study, implies that sperm DNA methylation is unaffected by cryopreservation and suggests that this daily clinical routine is safe in terms of DNA methylation.


Assuntos
Criopreservação/métodos , Metilação de DNA , Espermatozoides/citologia , Laranja de Acridina/química , Elementos Alu , Ensaio Cometa , Criopreservação/normas , Crioprotetores/química , RNA Helicases DEAD-box/genética , Fragmentação do DNA , Citometria de Fluxo , Genoma Humano , Impressão Genômica , Humanos , Infertilidade Masculina/genética , Masculino , Metilenotetra-Hidrofolato Redutase (NADPH2)/genética , Canais de Potássio de Abertura Dependente da Tensão da Membrana/genética , Reprodutibilidade dos Testes , Análise do Sêmen/métodos , Sensibilidade e Especificidade , Contagem de Espermatozoides , Fatores de Tempo
6.
Reproduction ; 142(1): 63-71, 2011 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-21464116

RESUMO

The synergistic effect of the co-morbidities that comprise metabolic syndrome (MetS) is increasingly being recognised as an important contributor in the pathology of a broad spectrum of seemingly disparate conditions. However, in terms of male reproductive function, beyond erectile dysfunction, little is known about the influence of this cohort (collectively or separately) on spermatogenesis and sperm quality. The aims of this study were to assess the reproductive tract of a MetS animal model for detrimental changes, to determine whether a group of compounds (advanced glycation end products and their receptor) known to cause cell dysfunction and DNA damage was present and assess whether hypogonadotropic hypogonadism was the main contributing factor for the changes seen. Animals fed a high-fat diet were found to have significantly increased cholesterol, triglycerides, blood glucose, mean arterial pressure and visceral fat levels. Although serum testosterone was decreased, no changes were seen in either testicular or epididymal histology. Immunolocalisation of N(ε)-carboxymethyl-lysine and the receptor for advanced glycation end products was found in the testes, epididymides and sperm of the two treated groups of animals; however, ELISA did not show any difference in protein levels. Similarly, assessment of sperm nuclear DNA (nDNA) fragmentation by acridine orange test did not find significant differences in nDNA integrity. We conclude that the minimal effect on spermatogenesis and sperm quality seen in our model is probably due to the moderate increase of blood glucose rather than the hypogonadism.


Assuntos
Modelos Animais de Doenças , Hipogonadismo/etiologia , Síndrome Metabólica/fisiopatologia , Espermatogênese , Espermatozoides/metabolismo , Espermatozoides/patologia , Animais , Fragmentação do DNA , Gorduras na Dieta/efeitos adversos , Epididimo/metabolismo , Epididimo/patologia , Produtos Finais de Glicação Avançada/metabolismo , Hormônio Liberador de Gonadotropina/análogos & derivados , Hiperglicemia/etiologia , Hipogonadismo/induzido quimicamente , Lisina/análogos & derivados , Lisina/metabolismo , Masculino , Síndrome Metabólica/sangue , Síndrome Metabólica/metabolismo , Síndrome Metabólica/patologia , Coelhos , Distribuição Aleatória , Receptor para Produtos Finais de Glicação Avançada , Receptores Imunológicos/metabolismo , Análise do Sêmen , Espermatozoides/efeitos dos fármacos , Testículo/metabolismo , Testículo/patologia , Pamoato de Triptorrelina/toxicidade
7.
Reprod Biomed Online ; 22(2): 215-9, 2011 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-21227754

RESUMO

The long-held view that diabetes has little effect on male reproductive function has been challenged by findings that the condition influences fertility in numerous previously undetected ways. This retrospective chart review of 3000 couples determined the incidence of couples with a male diabetic seeking assisted reproduction treatment and assessed any relationship between male diabetes and IVF/intracytoplasmic sperm injection (ICSI) outcome. Eight (2.7%) couples were found with a diabetic male partner, of which 18 couples underwent assisted reproduction treatment (five IVF, 12 ICSI, one both), with fertilization rates (IVF 68%, ICSI 62%) similar to non-diabetic patients (IVF 70%, ICSI 71%) and no difference in embryo quality. Two men had retrograde ejaculation and two were azoospermic. Other than reduced sperm motility, the remaining 14 had normal World Health Organization semen parameters. Embryo transfers produced one pregnancy (5% combined IVF/ICSI pregnancy rate/cycle) giving a lower-than-expected rate (28.8%). The pregnancy rate from seven FETs (29%) was comparable to the expected (21.3%). Compared with non-diabetics, approximately three times more couples with diabetic men sought treatment, with a larger percentage having 'unexplained' infertility. Fertilization rates and embryo quality did not differ but pregnancy rates were lower in couples with a diabetic male.


Assuntos
Complicações do Diabetes/terapia , Fertilização in vitro , Infertilidade Masculina/terapia , Complicações do Diabetes/epidemiologia , Feminino , Humanos , Infertilidade Masculina/complicações , Masculino , Gravidez , Taxa de Gravidez , Estudos Retrospectivos , Resultado do Tratamento
9.
Eur J Endocrinol ; 170(4): K11-7, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24394723

RESUMO

CONTEXT: Classical congenital adrenal hyperplasia (CAH), a genetic disorder characterized by 21-hydroxylase deficiency, impairs male fertility, if insufficiently treated. PATIENT: A 30-year-old male was referred to our clinic for endocrine and fertility assessment after undergoing unilateral orchiectomy for a suspected testicular tumor. Histopathological evaluation of the removed testis revealed atrophy and testicular adrenal rest tumors (TARTs) and raised the suspicion of underlying CAH. The remaining testis was also atrophic (5 ml) with minor TARTs. Serum 17-hydroxyprogesterone levels were elevated, cortisol levels were at the lower limit of normal range, and gonadotropins at prepubertal levels, but serum testosterone levels were within the normal adult range. Semen analysis revealed azoospermia. CAH was confirmed by a homozygous mutation g.655A/C>G (IVS2-13A/C>G) in CYP21A2. Hydrocortisone (24 mg/m(2)) administered to suppress ACTH and adrenal androgen overproduction unmasked deficient testicular testosterone production. As azoospermia persisted due to sustained hypogonadotropic hypogonadism, a combined s.c. gonadotropin replacement with human chorionic gonadotropin (hCG) (1500 IU twice weekly) and FSH (human menopausal gondadotropin (hMG) 150 IU three times weekly) was initiated. RESULTS: Normalization of testosterone levels and a stable low sperm concentration (0.5 mill/ml) with good sperm motility (85% A+B progressive) were achieved within 21 months of treatment. Despite persisting TARTs, while receiving treatment, the patient successfully impregnated his wife twice, the latter impregnation leading to the birth of a healthy girl. CONCLUSIONS: TARTs in unrecognized (simple virilizing) CAH may lead to unnecessary orchiectomy. In hypogonadotropic, azoospermic CAH, a combined treatment with oral corticosteroids and subcutaneously administered hCG and FSH can successfully restore testicular testosterone production and fertility, even if only one hypoplastic and atrophic testis with adrenal rest tumors is present.


Assuntos
Hiperplasia Suprarrenal Congênita/complicações , Tumor de Resto Suprarrenal/cirurgia , Azoospermia/tratamento farmacológico , Gonadotropina Coriônica/uso terapêutico , Terapia de Reposição Hormonal/métodos , Menotropinas/uso terapêutico , Substâncias para o Controle da Reprodução/uso terapêutico , Neoplasias Testiculares/cirurgia , Tumor de Resto Suprarrenal/complicações , Adulto , Azoospermia/etiologia , Humanos , Hipogonadismo , Masculino , Orquiectomia , Neoplasias Testiculares/complicações
10.
Hum Reprod Update ; 20(3): 403-14, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24144514

RESUMO

BACKGROUND The last 20 years have seen an enormous upsurge in the number of publications reporting findings obtained by Raman spectroscopy, a non-invasive, non-destructive method which uses the inelastic scattering of light to provide a 'fingerprint' of the sample's chemical composition and constituents. Long neglected because of practical difficulties, the technique has been transformed by recent technological advances into a powerful analytical tool capable of opening avenues of investigation that were previously out of the reach of biomedical scientists. Beyond introducing the approach and describing its relative merits and weaknesses, the aim of this review is to provide a spur for discussion of what may become an invaluable tool for biomedical investigations. METHODS A comprehensive review of the literature was conducted searching PubMed and Ovid databases using numerous MeSH terms associated with reproductive medicine. Furthermore, the reference lists of all reported literature were explored. The searches were restricted to English language articles published in the last 50 years. RESULTS Beginning with simple characterizations of biologically and medically important substances, aided by increasing technological sophistication, the use of Raman spectroscopy in biomedicine has quickly expanded to the investigation of complex biochemical interactions, the assessment of organelles and now the evaluation of living cells and tissue. The first Raman investigations of reproductive organs were primarily oncological in nature; however, the past few years have seen an increase in the application of the technique for the assessment and evaluation of both male and female gametes. In particular, progress has been made in the characterization, identification and localization of sperm nuclear DNA damage. CONCLUSIONS The use of Raman spectroscopy has already provided many tantalizing glimpses into the potential that the technique has to answer many of the unresolved issues in investigative and therapeutic reproductive medicine. However, without stringent assessment and the clear representation of the methods' findings, their true meaning cannot be revealed nor should any conclusions be hastily derived. For the potential of Raman microspectroscopy to be truly realized, the dependability and reliability of the technique and its results can only be ascertained by multidisciplinary collaborations that undertake carefully conducted, controlled and analysed studies.


Assuntos
Medicina Reprodutiva/métodos , Análise Espectral Raman/métodos , DNA/análise , Dano ao DNA , Feminino , Humanos , Infertilidade/diagnóstico , Masculino , Reprodutibilidade dos Testes , Análise do Sêmen/métodos , Espermatozoides/química , Neoplasias Urogenitais/diagnóstico
11.
Fertil Steril ; 98(3): 611-616.e4, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22633256

RESUMO

OBJECTIVE: To gauge the performance of laboratories and impact of the German semen analysis external quality control program (QuaDeGA) over its first 10 years. DESIGN: Retrospective analysis of QuaDeGA's twice yearly distribution of fixed semen samples and electronic material documenting sperm motility. Ranking of each participant's responses was determined according to their relation to a "target window." SETTING: Multicenter. PAITENT(S): Healthy donors. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Laboratory performance, World Health Organization (WHO) adherence. RESULT(S): Over 19 runs, there was a steady increase of participants (280 laboratories), the largest group being private urologic practices. Although use of WHO-recommended Neubauer chamber (from 33% to 55%) and diluent (from 11% to 32%) increased, the opposite occurred with morphology staining protocols (from 41% to 19%). Overall, <8% of laboratories truly followed WHO guidelines. Median-based comparisons, replacing reference laboratories, resulted in a merging of performance rankings regardless of the protocols used. CONCLUSION(S): Adherence to WHO recommendations is low, with the majority of laboratories using methods expressly opposed by the guidelines. Participation in QuaDeGA was found to improve the performance of the laboratories involved in the program. However, the use of median-based ranking, while decreasing the extent of variance between laboratories, brings into question the significance of the rankings.


Assuntos
Controle de Qualidade , Análise do Sêmen/normas , Fidelidade a Diretrizes , Humanos , Masculino , Estudos Retrospectivos , Contagem de Espermatozoides , Organização Mundial da Saúde
12.
Fertil Steril ; 98(5): 1124-9.e1-3, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22835447

RESUMO

OBJECTIVE: To determine whether Raman microspectroscopy can identify different levels of oxidative sperm nDNA damage and to corroborate the findings using an established method and an alternative but complementary spectroscopic technique. DESIGN: Three-way comparison of Raman profiles, Fourier transform infrared spectroscopy (FTIR) spectra, and flow-cytometric assessments of sperm nDNA damage. SETTING: University-based research laboratory. PATIENT(S): Thirty-eight men attending the infertility clinic at the Centre of Reproductive Medicine and Andrology. INTERVENTION(S): Induction of oxidative damage by Fenton's reaction on semen samples. MAIN OUTCOME MEASURE(S): Raman profiles, FTIR spectra, and flow-cytometric analysis of DNA fragmentation. RESULT(S): Raman and FTIR spectra contained distinctive differences between untreated and fragmented nDNA sperm that were indicative of oxidative attack. The changes in Raman profiles were similar to those previously seen and corresponded to the DNA backbone. The peak attributions were corroborated by the FTIR spectra. Principal component analysis of the entire Raman spectra distinguished samples with varying degrees of damage. After determination of a cutoff value (0.63), estimation of the percentage of sperm with nDNA damage using the intensity ratio of Raman peaks (1,050/1,095 cm(-1)) correlated linearly to the flow-cytometric assessment. CONCLUSION(S): Raman microspectroscopy still requires further validation but may potentially provide a means of assessing the nDNA status of a living sperm.


Assuntos
Dano ao DNA , DNA/análise , Infertilidade Masculina/diagnóstico , Microespectrofotometria , Estresse Oxidativo , Análise do Sêmen/métodos , Análise Espectral Raman , Espermatozoides/química , Biomarcadores/análise , Citometria de Fluxo , Humanos , Peróxido de Hidrogênio , Infertilidade Masculina/genética , Infertilidade Masculina/patologia , Ferro , Modelos Lineares , Masculino , Oxirredução , Valor Preditivo dos Testes , Análise de Componente Principal , Reprodutibilidade dos Testes , Espectroscopia de Infravermelho com Transformada de Fourier , Espermatozoides/patologia
13.
Fertil Steril ; 92(6): 2085-7, 2009 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-19589518

RESUMO

Routine semen analysis found no differences in diabetic men; however, mRNA profiles showed changes in the expression of genes involved in oxidative stress.


Assuntos
Diabetes Mellitus Tipo 1/genética , Perfilação da Expressão Gênica , Infertilidade Masculina/genética , Estresse Oxidativo/genética , Espermatogênese/genética , Fertilidade/genética , Humanos , Masculino , RNA Mensageiro/metabolismo , Espermatozoides/fisiologia
14.
Hum Reprod ; 22(8): 2169-77, 2007 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-17588956

RESUMO

BACKGROUND: Diabetics have a significantly higher percentage of sperm with nuclear DNA (nDNA) fragmentation and increased levels of advanced glycation end products (AGEs), in their testis, epididymis and sperm. As the receptor for AGEs (RAGE) is important to oxidative stress and cell dysfunction, we hypothesise, that it may be involved in sperm nDNA damage. METHODS: Immunohistochemistry was performed to determine the presence of RAGE in the human testis and epididymis. A comparison of the receptor's incidence and localization on sperm from 10 diabetic and 11 non-diabetic men was conducted by blind semi-quantitative assessment of the immunostaining. Enzyme-linked immunosorbent assay analysis ascertained RAGE levels in seminal plasma and sperm from 21 diabetic and 31 non-diabetic subjects. Dual labelling immunolocalization was employed to evaluate RAGE's precise location on the sperm head. RESULTS: RAGE was found throughout the testis, caput epididymis, particularly the principle cells apical region, and on sperm acrosomes. The number of sperm displaying RAGE and the overall protein amount found in sperm and seminal plasma were significantly higher in samples from diabetic men (P < 0.01, P < 0.0001 and P < 0.0001, respectively). CONCLUSIONS: The presence of RAGE implies that it may play a central role in sperm nDNA damage particularly in diabetic men where the levels are elevated.


Assuntos
Diabetes Mellitus Tipo 1/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Epididimo/química , Receptores Imunológicos/análise , Sêmen/química , Testículo/química , Adolescente , Adulto , Ensaio de Imunoadsorção Enzimática , Produtos Finais de Glicação Avançada , Humanos , Masculino , Pessoa de Meia-Idade , Receptor para Produtos Finais de Glicação Avançada
15.
Am J Physiol Endocrinol Metab ; 285(2): E363-71, 2003 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-12721153

RESUMO

The mechanisms by which excessive glucocorticoids cause muscular atrophy remain unclear. We previously demonstrated that dexamethasone increases the expression of myostatin, a negative regulator of skeletal muscle mass, in vitro. In the present study, we tested the hypothesis that dexamethasone-induced muscle loss is associated with increased myostatin expression in vivo. Daily administration (60, 600, 1,200 micro g/kg body wt) of dexamethasone for 5 days resulted in rapid, dose-dependent loss of body weight (-4.0, -13.4, -17.2%, respectively, P < 0.05 for each comparison), and muscle atrophy (6.3, 15.0, 16.6% below controls, respectively). These changes were associated with dose-dependent, marked induction of intramuscular myostatin mRNA (66.3, 450, 527.6% increase above controls, P < 0.05 for each comparison) and protein expression (0.0, 260.5, 318.4% increase above controls, P < 0.05). We found that the effect of dexamethasone on body weight and muscle loss and upregulation of intramuscular myostatin expression was time dependent. When dexamethasone treatment (600 micro g. kg-1. day-1) was extended from 5 to 10 days, the rate of body weight loss was markedly reduced to approximately 2% within this extended period. The concentrations of intramuscular myosin heavy chain type II in dexamethasone-treated rats were significantly lower (-43% after 5-day treatment, -14% after 10-day treatment) than their respective corresponding controls. The intramuscular myostatin concentration in rats treated with dexamethasone for 10 days returned to basal level. Concurrent treatment with RU-486 blocked dexamethasone-induced myostatin expression and significantly attenuated body loss and muscle atrophy. We propose that dexamethasone-induced muscle loss is mediated, at least in part, by the upregulation of myostatin expression through a glucocorticoid receptor-mediated pathway.


Assuntos
Glucocorticoides/efeitos adversos , Músculo Esquelético/química , Atrofia Muscular/induzido quimicamente , Fator de Crescimento Transformador beta/genética , Animais , Peso Corporal/efeitos dos fármacos , Dexametasona/efeitos adversos , Dexametasona/antagonistas & inibidores , Dexametasona/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Cinética , Masculino , Mifepristona/farmacologia , Músculo Esquelético/patologia , Miostatina , Tamanho do Órgão/efeitos dos fármacos , RNA Mensageiro/análise , Ratos , Ratos Sprague-Dawley , Receptores de Glucocorticoides/fisiologia
16.
J Cell Physiol ; 190(2): 170-9, 2002 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-11807821

RESUMO

Myostatin is a negative regulator of skeletal muscle growth. We have previously reported that recombinant myostatin protein inhibits DNA and protein synthesis in C2C12 cells. Our objective was to assess if C2C12 cells express myostatin, determine its sub-cellular localization and the developmental stage of C2C12 cells in which myostatin mRNA and protein are expressed. To study the endogenous expression of myostatin, C2C12 myoblasts were allowed to progress to myotubes, and changes in the levels of endogenous myostatin mRNA expression were determined by RT-PCR. The myostatin protein and the two major myosin heavy chain (MHC) isoforms (MHC-I and -II) were determined by Western blot. Confirmation of the relative MHC expression patterns was obtained by a modified polyacrylamide gel electropheretic (PAGE) procedure. Imunofluorescence staining was employed to localize the site of myostatin expression and the relative distribution of the MHC isoforms. Co-expression of these proteins was studied using a dual staining approach. Expression of myostatin mRNA was found in myotubes but not in myoblasts. Myostatin protein was seen in most but not all, of the nuclei of polynucleated fibers expressing MHC-II, and myostatin was detected in the cytoplasm of myotube. The localization of myostatin protein in myotube nuclei was confirmed by Western blot of isolated nuclear and cytoplasmic fractions. Incubation of C2C12 myotubes with graded doses of dexamethasone dose-dependently increased the intensity of nuclear myostatin immunostaining and also resulted in the appearance of cytoplasmic expression. In conclusion, myostatin was expressed mostly in C2C12 myotubes nuclei expressing MHC-II. Its predominant nuclear localization suggests that it may play a role in transcriptional regulation.


Assuntos
Músculo Esquelético/metabolismo , Cadeias Pesadas de Miosina/metabolismo , Fator de Crescimento Transformador beta/metabolismo , Animais , Northern Blotting , Western Blotting , Linhagem Celular , Núcleo Celular/metabolismo , Dexametasona/farmacologia , Glucocorticoides/farmacologia , Antígenos de Histocompatibilidade Classe II/metabolismo , Imuno-Histoquímica , Camundongos , Camundongos Endogâmicos C3H , Músculo Esquelético/citologia , Músculo Esquelético/efeitos dos fármacos , Miostatina , RNA Mensageiro/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Coloração e Rotulagem , Frações Subcelulares/metabolismo , Distribuição Tecidual , Fator de Crescimento Transformador beta/genética
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