RESUMO
Endurance training may lead to different hormonal alterations e. g., exercised induced hypothalamic ovarian/testicular dysfunction. The aim of this study was to reveal new connections between physical exercise, leptin and hormonal responses. 36 male participants of the Berlin-Marathon had their blood samples taken 2 days before the marathon. Hormones of the hypothalamic-pituitary axis and leptin were correlated with the training status and the achieved marathon time. Leptin correlated with the achieved marathon time after being adjusted for age and BMI (r=0.607, p<0.001) and was lowest in the best trained runners. Additionally, when the group was divided into quartiles of their achieved marathon time, significantly increased cortisol, fT4, cortisol/DHEAS ratio and decreased IGF-1 levels were observed in the slowest group. In the better trained group, a decrease of testosterone/DHT ratio and an increase of testosterone/cortisol ratio were observed. Our study supports the thesis of a linear relationship between physical fitness and leptin variations in the physiological range. We found an increased anabolic hormonal response in well trained marathon runners and hormonal reactions of increased stress in less trained runners. As the stress-induced neuroendocrine adaptations in our study group are associated with more higher leptin values, the pathophysiological role of decreased leptin values seems to be limited to overtrained athletes.
Assuntos
Desempenho Atlético/fisiologia , Leptina/sangue , Resistência Física/fisiologia , Corrida/fisiologia , Adulto , Atletas , Hormônios/sangue , Humanos , Sistema Hipotálamo-Hipofisário/fisiologia , Masculino , Pessoa de Meia-Idade , Sistema Hipófise-Suprarrenal/fisiologia , Fatores de TempoRESUMO
DESIGN: Testosterone treatment is essential for the induction and maintenance of virilization of female-to-male (FTM) transsexuals. Aim To test the safety of a novel testosterone preparation for this purpose. METHODS: Parenteral long-acting testosterone undecanoate (TU) was administered to 17 FTM transsexuals over 36 months. Observations were made while subjects received treatment. RESULTS: Serum testosterone rose from 0.50+/-0.25 to 6.2+/-1.3 ng/ml at 6 months and remained stable thereafter. The testosterone profiles were largely identical with those in hypogonadal receiving TU. There were no side effects. Over the 36 months of the study, there was a small but significant decrease in plasma cholesterol (from 218+/-47 to 188+/-42 mg/dl) and low-density lipoprotein-cholesterol (from 139+/-48 to 139+/-48 mg/dl), while plasma levels of high-density lipoprotein-cholesterol and triglycerides did not change significantly. Liver enzymes did not change during treatment. There was an increase of both levels in hemoglobin (from 13.6+/-1.2 to 16.0+/-1.5 g/dl) and hematocrit (from 41+/-4 to 46+/-4) upon administration but they remained almost without exception within the physiological range. No special measures were needed. Breast and gonads/internal genitalia did not show pathological changes over the observation period. CONCLUSION: This study reports that TU is suited for induction of virilization in FTM transsexuals without significant side effects over a longer term.
Assuntos
Testosterona/análogos & derivados , Transexualidade/tratamento farmacológico , Adulto , Alanina Transaminase/sangue , Aspartato Aminotransferases/sangue , Colesterol/sangue , Feminino , Hemoglobinas Glicadas/metabolismo , Hematócrito , Humanos , Injeções Intramusculares , Pessoa de Meia-Idade , Estatísticas não Paramétricas , Testosterona/administração & dosagem , Congêneres da Testosterona/administração & dosagem , Transexualidade/sangue , Triglicerídeos/sangue , Adulto JovemRESUMO
OBJECTIVE: We evaluated the German Acromegaly Register for clinical variables associated with the initial biochemical activity of patients with acromegaly. DESIGN: Retrospective analysis of data in the registry. PATIENTS: A total of 1485 patients with acromegaly (males 45.6%, females 54.4%) were treated in 42 German endocrine centres until November 2005. Linear regression models were used to estimate the influence of various parameters on biochemical activity. RESULTS: Male patients with acromegaly were significantly younger at the time of diagnosis than female patients (41 vs. 47 years, P < 0.0001) and had significantly higher random GH levels than females (21 vs. 14 ng/ml, P < 0.005) and IGF-1 levels (773 vs. 679 ng/ml, P < 0.0001), respectively. Age at initial presentation turned out to be the most important independent risk factor associated with random GH levels, oral glucose tolerance test-suppressed GH levels, IGF-1 levels, body mass index (BMI), tumour size and prevalence of hypopituitarism. Sex was an independent risk factor for IGF-1 levels, BMI and prevalence of hypopituitarism. Tumour size was an independent risk factor for both GH and IGF-1 levels. CONCLUSIONS: In summary, initial biochemical activity of acromegaly is influenced by patient's age and to a lesser degree by patient's sex. Male patients are on an average 6 years younger than females.
Assuntos
Acromegalia/metabolismo , Adolescente , Adulto , Fatores Etários , Idade de Início , Idoso , Idoso de 80 Anos ou mais , Índice de Massa Corporal , Criança , Feminino , Alemanha , Hormônio do Crescimento Humano/metabolismo , Humanos , Fator de Crescimento Insulin-Like I/metabolismo , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Fatores Sexuais , Adulto JovemRESUMO
BACKGROUND: The polycystic ovarian syndrome (PCOS) is characterized by hyperandrogenism and associated with obesity and impaired glucose metabolism. Despite the high prevalence of PCOS and the considerable clinical impact, the precise interplay between metabolism and hyperandrogenemia is not entirely clear. OBJECTIVE: The objective of the study was to analyze the effects of iv lipid and heparin infusion on circulating androgen levels in healthy women. DESIGN: This was a randomized, controlled, crossover trial. SETTING: The study was conducted at an endocrinology center. PATIENTS: Patients included 12 healthy young women during the early follicular phase of two subsequent cycles. INTERVENTION: After an overnight fast, a 20% lipid/heparin or a saline/heparin infusion was administered in random order for 330 min. MAIN OUTCOME MEASURES: A detailed characterization of androgen metabolism was performed. RESULTS: Elevations in free fatty acids and triglycerides, induced by lipid/heparin infusion, elevates the levels of androstenedione, dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEAS), testosterone, 5alpha-dihydrotestosterone, estrone, and 17beta-estradiol. Urinary excretion of DHEA, DHEAS, 5-androstene-3beta,17beta-diol, and the sum of urinary excreted DHEA and its 16-hydroxylated downstream metabolites, 16alpha-hydroxy-DHEA and 5-androstene-3beta,16alpha,17beta-triol, were reduced. CONCLUSION: The mechanism of iv lipid and heparin infusion-induced elevation of circulating androgens described here might contribute to the development of hyperandrogenism in women with PCOS and suggests that lowering of hyperlipidemia might be a potential therapeutic target in patients with PCOS to treat hyperandrogenemia.
Assuntos
Androgênios/sangue , Ácidos Graxos não Esterificados/sangue , Heparina/administração & dosagem , Lipídeos/administração & dosagem , Síndrome do Ovário Policístico/tratamento farmacológico , Triglicerídeos/sangue , Adulto , Androgênios/metabolismo , Androstenodiona/sangue , Androstenodiona/metabolismo , Estudos Cross-Over , Desidroepiandrosterona/sangue , Desidroepiandrosterona/metabolismo , Sulfato de Desidroepiandrosterona/sangue , Sulfato de Desidroepiandrosterona/metabolismo , Di-Hidrotestosterona/sangue , Di-Hidrotestosterona/metabolismo , Feminino , Humanos , Infusões Intravenosas , Síndrome do Ovário Policístico/sangue , Síndrome do Ovário Policístico/metabolismo , Cloreto de Sódio/administração & dosagem , Testosterona/sangue , Testosterona/metabolismo , Fatores de TempoRESUMO
Urocortin (UCN) is a 40 amino acid peptide which is closely related to corticotropin-releasing hormone and binds with high affinity to both CRH type 1 and type 2 receptors. UCN is expressed in human reproductive tissues including endometrium, ovary, and placenta. This study was designed to investigate the cellular localization of UCN at the implantation site of the human blastocyst, as well as the regulation of the UCN promoter by two major intracellular signaling pathways, the cAMP/PKA and diacylglycerol/PKC pathways, in cells of placental origin. For this reason, immunohistochemistry was performed on tissue sections from paraffin-embedded human first trimester placentas and freshly isolated human invasive extravillous trophoblast cells (EVT) were analyzed for UCN expression using RT-PCR and immunofluorescence. Finally, UCN promoter activity was analyzed in the JEG3 human choriocarcinoma cell line. Immunohistochemistry revealed expression of UCN in the cytotrophoblast, the EVT and decidual cells. Both UCN mRNA and peptide were detectable in freshly isolated EVT. Finally, a human UCN promoter luciferase reporter construct transfected into JEG3 cells was significantly inducible by phorbol ester plus ionomycin, but not by phorbol ester alone or by forskolin. Collectively, the present study reports the expression of UCN in EVT and the activation of the UCN gene promoter by the diacylglycerol/PKC pathway. The functional significance of urocortin for the physiology of EVT requires further investigation.
Assuntos
Hormônio Liberador da Corticotropina/metabolismo , Implantação do Embrião/fisiologia , Gravidez/metabolismo , Trofoblastos/metabolismo , Feminino , Regulação da Expressão Gênica , Humanos , Ionomicina , Regiões Promotoras Genéticas , RNA Mensageiro/metabolismo , Transdução de Sinais/fisiologia , Acetato de Tetradecanoilforbol , UrocortinasRESUMO
Somatostatin receptor subtype 5 (sst5) has been linked to inhibition of PRL and insulin secretion. We characterized the genomic structure of the human sst5. The transcription start site was located 94 nucleotides upstream of the initiator ATG codon. Sequence analysis of 5'-inverse PCR products revealed the presence of a 6.1-kb intron in the 5'-untranslated region. RT-PCR analysis indicated tissue-specific activation of the newly identified upstream promoter in pituitary, but not in small intestine, lung, or placenta. A -1741 promoter directed significant levels of luciferase expression in GH(4) rat pituitary cells, Skut-1B endometrium cells, and JEG3 chorion carcinoma cells, which was absent in COS-7 monkey kidney cells. A minimal -101 promoter was sufficient to allow tissue-specific expression. Its activity in COS-7 cells was not enhanced by cotransfection of the pituitary-specific transcription factor Pit-1. Analysis of deletion constructs revealed a GC-rich region immediately upstream of the transcription start site, which is necessary for promoter activity. Somatostatin led to a significant inhibition, and forskolin and thyroid hormone to a significant stimulation of pituitary-specific promoter activity. Further mapping suggested a cAMP-responsive element located between -101 and the transcription start site, and thyroid hormone-responsive elements between -1741 and -1269 and between -317 and -101. These studies identified an upstream promoter of the sst5 gene with tissue-specific activity.
Assuntos
Regiões Promotoras Genéticas/genética , Receptores de Somatostatina/biossíntese , Animais , Sequência de Bases , Células Cultivadas , Clonagem Molecular , Colforsina/farmacologia , Regulação da Expressão Gênica/fisiologia , Vetores Genéticos , Humanos , Luciferases/biossíntese , Luciferases/genética , Dados de Sequência Molecular , Hipófise/citologia , Hipófise/metabolismo , Ratos , Receptores de Somatostatina/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Proteínas Cotransportadoras de Sódio-Fosfato , Proteínas Cotransportadoras de Sódio-Fosfato Tipo III , Somatostatina/farmacologia , Simportadores/genética , Hormônios Tireóideos/farmacologia , Transcrição Gênica/genéticaRESUMO
Somatostatin (SRIF) exerts inhibitory effects on virtually all endocrine and exocrine secretions. Five distinct SRIF receptor subtypes (sst 1-5) have been identified. In contrast to the other subtypes, very little is known about specific functions of sst4. We investigated structure and regulation of the human sst4 gene. A genomic clone containing the 5' region of the sst4 gene was isolated. 1.5 kb of the promoter was sequenced and putative transcription factor binding sites were identified. The transcription start site was located 88 nucleotides upstream of the translation start site. A -984 sst4 promoter directed significant levels of luciferase expression in GH4 rat pituitary cells, Skut-1B endometrium cells, and BEAS-2B human bronchial epithelial cells, whereas only low activity was detected in JEG3 chorion carcinoma cells or COS-7 monkey kidney cells. A minimal -209 promoter allowed cell specific expression, its activity in COS-7 cells is not enhanced by co-transfection of the pituitary-specific transcription factor Pit-1. An enhancer element was localized between nt -459 and -984. We did not find any regulation of the sst4 promoter region analyzed by SRIF, forskolin, TPA, IGF-1, EGF, T3, glucocorticoids or 17beta-estradiol. These studies identify the 5' region of the sst4 gene. Furthermore, specific activity of the promoter in various cell lines is demonstrated.
Assuntos
Regiões Promotoras Genéticas/genética , Receptores de Somatostatina/genética , Regiões 5' não Traduzidas/genética , Animais , Sequência de Bases , Células Cultivadas , Clonagem Molecular , Códon de Iniciação , Primers do DNA/química , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Deleção de Genes , Regulação da Expressão Gênica , Biblioteca Genômica , Hormônios/farmacologia , Humanos , Luciferases/metabolismo , Proteínas de Membrana , Dados de Sequência Molecular , Plasmídeos , Reação em Cadeia da Polimerase , Regiões Promotoras Genéticas/efeitos dos fármacos , Análise de Sequência de DNA , Fator de Transcrição Pit-1 , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Transcrição Gênica/genéticaRESUMO
Adrenal computed tomography with determination of Hounsfield units has proved to be sensitive and specific in the differential diagnosis of benign vs. malign adrenal lesions. On the other hand, computed tomography may fail in patients with small adrenal masses of less than 1.0 cm. However, especially in patients with diagnosed malignancies and small adrenal masses which were discovered during the diagnostic staging procedure it is important to determine the origin of the adrenal lesion. An augmented increase in 17alpha-hydroxyprogesterone (17-OHP) levels following corticotropin (1-24) stimulation has been noted in incidentally discovered adrenal masses by several groups. Therefore, we tested the hypothesis that elevated ACTH-stimulated 17-OHP (delta > 2.6 ng/mL) can predict primary adrenal lesions. We evaluated the use of the ACTH test in 85 patients with adrenocortical tumors and in 16 patients who underwent abdominal imaging for staging of a carcinoma other than of adrenal origin. We found an augmented 17-OHP response in 70 (>82%) of patients with known adrenocortical tumors and in 10 (>62%) of patients with adrenal masses and diagnosed malignancies. Results in the latter group have been confirmed in histological studies after operation or puncture. In the group of patients who suffered from a solid malignant tumor and had an adrenal mass, it was thus possible to separate primary from secondary adrenal lesions in 100%. In the group of patients with known adrenocortical tumors, it failed to differentiate between benign and malignant adrenocortical lesion in one case. We therefore think that the ACTH test is a valuable biochemical tool to distinguish primary adrenal tumors from adrenal metastasis derived from other malignancies.
Assuntos
Adenoma/diagnóstico , Neoplasias das Glândulas Suprarrenais/diagnóstico , Hormônio Adrenocorticotrópico , Carcinoma/diagnóstico , 17-alfa-Hidroxiprogesterona/sangue , Adenoma/sangue , Adenoma/metabolismo , Neoplasias das Glândulas Suprarrenais/sangue , Neoplasias das Glândulas Suprarrenais/metabolismo , Neoplasias das Glândulas Suprarrenais/secundário , Adulto , Idoso , Idoso de 80 Anos ou mais , Aldosterona/biossíntese , Carcinoma/sangue , Carcinoma/secundário , Diagnóstico Diferencial , Feminino , Humanos , Hidrocortisona/biossíntese , Masculino , Pessoa de Meia-IdadeRESUMO
Serum dehydroepiandrosterone declines with age. Whether this represents a harmful deficiency or an age-related adaptation is not known. Dehydroepiandrosterone replacement in adrenal insufficiency, a state of pathological loss of dehydroepiandrosterone production, improves well-being, mood, and sexuality. To determine the effects of dehydroepiandrosterone in healthy men with a physiological, age-related decline in serum dehydroepiandrosterone sulfate, we conducted a double blind cross-over study in 22 healthy male volunteers (age range, 50-69 yr) with endogenous dehydroepiandrosterone sulfate levels below 4.1 micromol/liter (1500 ng/ml) receiving 4 months of dehydroepiandrosterone (50 mg/d) and 4 months of placebo treatment in random order, with a 1-month washout period. Dehydroepiandrosterone treatment increased serum dehydroepiandrosterone and dehydroepiandrosterone sulfate to concentrations usually found in young men. Circulating androgen levels did not change; however, androgen metabolites increased, indicating enhanced peripheral androgen synthesis. At baseline, psychometric assessment revealed normal well-being and sexuality scores. After 4 months of dehydroepiandrosterone, no effect on sexuality was observed, whereas some mood scores improved slightly, but were not significantly different from scores after placebo. Compared with placebo, dehydroepiandrosterone had no effect on serum lipids, bone markers, body composition, or exercise capacity. Thus, in contrast to previous findings in adrenal insufficiency, we found no obvious benefit of 4 months of dehydroepiandrosterone supplementation in healthy men with a physiological decline of dehydroepiandrosterone production.
Assuntos
Desidroepiandrosterona/uso terapêutico , Terapia de Reposição Hormonal , Afeto , Idoso , Composição Corporal , Estudos Cross-Over , Desidroepiandrosterona/efeitos adversos , Desidroepiandrosterona/sangue , Método Duplo-Cego , Humanos , Proteína 3 de Ligação a Fator de Crescimento Semelhante à Insulina/sangue , Lipídeos/sangue , Masculino , Pessoa de Meia-Idade , Globulina de Ligação a Hormônio Sexual/análiseRESUMO
Synthetic GH secretagogues stimulate GH release through binding to a recently cloned specific GH secretagogue receptor (GHS-R). The endogenous ligand of this receptor may be part of a new endocrine pathway controlling GH secretion. Two different receptor variants, type 1a and 1b, have been described that differ in their 3'-terminal amino acids. We investigated the genomic structure and transcriptional regulation of the human GHS-R. An 18-kb genomic clone including sequences encoding for the two GHS-R variants was isolated. Sequencing revealed that the two variants originate from specific RNA processing of a single gene that spans approximately 4.1 kb. The transcription start site was defined by 5'-inverse PCR analysis at position -227. RT-PCR analysis points to differential transcriptional initiation and processing. Type 1a is encoded by two exons; 2152 bp of intronic sequence are removed by splicing at position 796/797 relative to the translation start site. Type 1b is encoded by a single exon. A putative polyadenylation signal consensus motif was identified at position +4118; 2.7 kb of the 5'-flanking region were sequenced, and putative transcription factor binding sites were identified. Transcriptional regulation was investigated by transient transfections using promoter fragments ranging in size from 168-1745 bp; 1745 bp of the GHS-R promoter directed significant levels of luciferase expression in GH(4) rat pituitary cells, whereas no activity was detected in monkey kidney COS-7 cells, human endometrium Skut-1B cells, mouse hypothalamic LHRH neuronal GT1-7 cells, or mouse corticotroph pituitary AtT20 cells. A minimal 309-bp promoter allowed pituitary-specific expression. Its activity in COS-7 cells was enhanced by cotransfection of the pituitary-specific transcription factor Pit-1. We did not find any regulation of the GHS-R promoter by forskolin, somatostatin, insulin-like growth factor I, or 12-O-tetraphorbol 12-myristate 13-acetate. Thyroid hormone and estrogen lead to a significant stimulation; glucocorticoids lead to a significant inhibition. Further mapping suggests a thyroid hormone-responsive element, an estrogen-responsive element, and a glucocorticoid-responsive element located between -309 and the translation start codon. These studies demonstrate the nature of the human GHS-R gene and identify its 5'-flanking region. Furthermore, pituitary-specific activity of the promoter and regulation by various hormones are demonstrated.
Assuntos
Regulação da Expressão Gênica , Receptores de Superfície Celular/genética , Receptores Acoplados a Proteínas G , Sequência de Aminoácidos , Animais , Sequência de Bases , Linhagem Celular , Códon , Proteínas de Ligação a DNA/farmacologia , Estradiol/farmacologia , Expressão Gênica , Regulação da Expressão Gênica/efeitos dos fármacos , Glucocorticoides/farmacologia , Haplorrinos , Humanos , Luciferases/genética , Camundongos , Dados de Sequência Molecular , Regiões Promotoras Genéticas , Biossíntese de Proteínas , Ratos , Receptores de Superfície Celular/química , Receptores de Superfície Celular/fisiologia , Receptores de Grelina , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Análise de Sequência de DNA , Fator de Transcrição Pit-1 , Fatores de Transcrição/farmacologia , Transcrição Gênica , Transfecção , Tri-Iodotironina/farmacologiaRESUMO
While progesterone is a known differentiation-inducing factor in the human endometrium, for the breast epithelium both proliferation-inducing and -inhibiting effects have been described. Cyclin D1, which is required for cell cycle progression in G1 and has been shown to play an important role in the pathogenesis of breast cancer has been implicated as a possible mediator of such effects. In the present study we thus investigated the effects of the progestin agonist MPA (medroxy-progesterone acetate) on proliferation of T47D breast cancer cells. In parallel experiments, the regulation of the human cyclin D1 promoter as well as cyclin D1 protein levels under the influence of MPA were studied. Our results show an increase of proliferative activity in T47D cells after 24 and 48 h of MPA treatment followed by inhibition of proliferation after 72 h. In Western blot analysis an increased expression level of cyclin D1 protein can be observed after 24h of MPA stimulation, while at 72h the protein levels are barely detectable. Transient transfection experiments with a luciferase reporter plasmid containing the human cyclin D1 promoter showed an induction of the promoter after 24 and 36h of MPA treatment followed by a reduction in promoter activity. In conclusion, our results confirm the existence of a biphasic response of T47D cell proliferation in response to MPA treatment, consisting of stimulation of proliferation followed by inhibition, and further implicate cyclin D1 as a mediator of these effects, since the cyclin D1 promoter shows a similar biphasic response in this context.
Assuntos
Antineoplásicos Hormonais/farmacologia , Neoplasias da Mama/tratamento farmacológico , Ciclina D1/genética , Acetato de Medroxiprogesterona/farmacologia , Western Blotting , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Divisão Celular/efeitos dos fármacos , Feminino , Humanos , Regiões Promotoras Genéticas , Transcrição Gênica/efeitos dos fármacos , Células Tumorais CultivadasRESUMO
HLA-G is a non-classic class I MHC molecule specifically expressed by human invasive cytotrophoblast cells, which has been suggested to play a role in facilitating the immune tolerance of the conceptus. So far, very little is known about the regulation of the human HLA-G gene. The present study was, thus, designed to investigate the regulation of the human HLA-G promoter. JEG3 choriocarcinoma cells, which express HLA-G endogenously, were used as a model. A 890 bp fragment of the human HLA-G promoter was amplified by nested PCR from genomic DNA, cloned into pCR-Script and, after sequencing, subcloned into pGL3-Luc in front of the luciferase reporter gene. This vector was then used in transient transfection experiments in JEG3 cells. Parallel transfection experiments were performed using an alpha subunit (alphaSU)-Luc reporter plasmid as a control. Using this system, several potential modulating substances were tested in different concentrations and for different periods of time: phorbol ester (TPA), cAMP, IFNgamma, IL-1, and leukemia inhibitory factor (LIF), with only LIF administration resulting in induction of the HLA-G promoter. LIF treatment also resulted in induction of HLA-G mRNA. JEG3 cells are shown to possess LIF receptors. LIF is a pleiotropic cytokine produced at the maternal-fetal interface which has been shown to play an essential role in implantation in mice. LIF is produced in high amounts by the human endometrium and the trophoblast itself, and LIF receptors are present on cytotrophoblast cells. LIF could, thus, play a role in modulating HLA-G production and immune tolerance at the maternal-fetal interface.
Assuntos
Coriocarcinoma/metabolismo , Inibidores do Crescimento/farmacologia , Antígenos HLA/biossíntese , Antígenos de Histocompatibilidade Classe I/biossíntese , Interleucina-6 , Linfocinas/farmacologia , Regiões Promotoras Genéticas/genética , Neoplasias Uterinas/metabolismo , Animais , Northern Blotting , Clonagem Molecular , Feminino , Antígenos HLA-G , Humanos , Fator Inibidor de Leucemia , Luciferases/genética , Camundongos , RNA Mensageiro/biossíntese , RNA Mensageiro/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transfecção , Células Tumorais CultivadasRESUMO
It is well established that steroidogenesis in the adrenal cortex is regulated by extraadrenal factors, such as ACTH and angiotensin II. However, over the last years, it has become increasingly clear that paracrine and autocrine mechanisms are also important for steroid synthesis in the adrenal gland. The current study was designed to analyze whether the pleiotropic cytokine leukemia inhibitory factor (LIF) and/or its receptor (LIF-R) are expressed in the normal human adrenal cortex, and whether they may play a role in regulating steroidogenesis. Using LIF- and LIF-R-specific primers, we show by RT-PCR that both mRNAs are expressed in this tissue, as well as in the NCI-H295 adrenal carcinoma cell line. The correct sequences of the PCR products were verified by restriction enzyme analysis and DNA sequencing. Immunohistochemistry, employing specific antibodies against LIF and LIF-R, reveals expression of both proteins in the normal human adrenal cortex. Finally, we show that LIF can significantly enhance basal and ACTH-induced production of cortisol and aldosterone in NCI-H295 cells. In summary, we show for the first time that LIF and its receptor are expressed in the normal human adrenal cortex. Our stimulation experiments indicate that the intraadrenal LIF/LIF-R system may participate in regulating adrenal steroidogenesis.
Assuntos
Córtex Suprarrenal/metabolismo , Inibidores do Crescimento/metabolismo , Interleucina-6 , Linfocinas/metabolismo , Receptores de Citocinas/metabolismo , Esteroides/biossíntese , Neoplasias das Glândulas Suprarrenais/genética , Neoplasias das Glândulas Suprarrenais/metabolismo , Aldosterona/biossíntese , Sequência de Bases , Primers do DNA/genética , Expressão Gênica , Inibidores do Crescimento/genética , Humanos , Hidrocortisona/biossíntese , Fator Inibidor de Leucemia , Subunidade alfa de Receptor de Fator Inibidor de Leucemia , Linfocinas/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Receptores de Citocinas/genética , Receptores de OSM-LIF , Células Tumorais CultivadasRESUMO
Growth-hormone-releasing hormone (GHRH) stimulates growth hormone (GH) secretion and GH synthesis and is also thought to cause somatotroph proliferation. Specific high-affinity binding sites for GHRH have been demonstrated on pituitary membranes using iodinated GHRH analogs. The complementary DNA encoding for the human GHRH receptor (GHRH-R) was recently cloned. The open reading frame was shown to extend 1269 bp and thus to encode a protein of 423 amino acids with a predicted molecular weight of 47 kDa. Expression is restricted to specific tissues. Analysis of the genomic structure revealed that the human GHRH-R gene spans 15 kb and consists of 13 exons. The 5'-flanking region of the human GHRH-R gene was recently characterized. Transcriptional regulation of the GHRH-R is discussed in this review. Mechanisms of signal transduction for control of GH transcription and secretion are presented. Furthermore, the role of the GHRH-R in proliferation and differentiation of the somatotrophic pituitary cell as well as in disease is examined.
Assuntos
Hormônio Liberador de Hormônio do Crescimento/fisiologia , Hormônio do Crescimento Humano/fisiologia , Receptores de Somatostatina/fisiologia , Sequência de Aminoácidos , Regulação da Expressão Gênica , Glucocorticoides/fisiologia , Hormônios Esteroides Gonadais/fisiologia , Hormônio do Crescimento Humano/metabolismo , Humanos , Dados de Sequência Molecular , Hipófise/metabolismo , Hipófise/fisiologia , Receptores de Somatostatina/química , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Transdução de Sinais/fisiologia , Hormônios Tireóideos/fisiologiaRESUMO
OBJECTIVE: Somatostatin, acting via specific receptors in the anterior pituitary, tonically inhibits pituitary growth hormone secretion and somatotroph proliferation. Reduction of growth hormone secretion and tumour regression in GH-secreting pituitary adenomas treated with long-acting somatostatin analogues varies widely. In 30-40% of these tumours dominant somatic mutations of the Gsalpha gene (gsp) have been demonstrated leading to constitutive adenylyl cyclase induction. A relationship between somatostatin sensitivity and tumour pathogenesis in some tumours has been suggested. Changes in the function of the somatostatin receptor or intracellular signal elements may be of relevance. Somatostatin receptor type 2 A (sst2A) and Gi2 are proposed to mediate selectively the inhibition of GH release in the somatotroph. We therefore investigated the presence of sst2A mutations and gip oncogene in somatotrophic pituitary adenomas. DESIGN: Tumour samples from 15 patients with pituitary somatotroph adenomas were obtained. RNA was isolated and used for reverse transcription and subsequent polymerase chain reaction. All samples were screened for the presence of sst2A mutations and of the gip oncogene by SSCP analysis and sequencing. For comparison, the gsp oncogene was examined. The relationship between clinical data and molecular analysis results was investigated. RESULTS: Seven of the tumours harboured a gsp mutation. No mutations affecting the sst2A protein were found in any of the tumours analysed. Furthermore, gip oncogene was absent in all tumours. CONCLUSION: Mutations of the somatostatin receptor type 2 A and the gip oncogene are unlikely to be involved in the pathogenesis of acromegaly.
Assuntos
Adenoma/metabolismo , Hormônio do Crescimento Humano/metabolismo , Neoplasias Hipofisárias/secundário , Receptores de Somatostatina/genética , Adenoma/genética , Análise Mutacional de DNA , Hormônio do Crescimento Humano/genética , Humanos , Oncogenes , Neoplasias Hipofisárias/genética , Polimorfismo Conformacional de Fita Simples , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
A number of primary diseases of the pituitary with adrenocorticotropin dysregulation have been recognized. A few genetic defects have been identified as causes of secondary adrenocortical insufficiency. Much less is known about the ontogeny of corticotrophic tumours leading to a hypercorticolaemic state. To improve the diagnosis and treatment of these disorders, a better understanding of the mechanisms of corticotrophic pituitary cell differentiation and regulation is of clear interest. Studies using molecular tools have enhanced our knowledge over recent years, and a few reports of considerable relevance are summarized in this review.
Assuntos
Hormônio Adrenocorticotrópico/metabolismo , Interleucina-6 , Adeno-Hipófise/citologia , Animais , Diferenciação Celular , Inibidores do Crescimento/fisiologia , Humanos , Fator Inibidor de Leucemia , Linfocinas/fisiologia , Receptores de Hormônio Liberador da Corticotropina/fisiologiaRESUMO
BACKGROUND: Glucocorticoids mediate their effects on target cells via transactivation and transrepression of certain target genes. While conventional glucocorticoids do not distinguish between transactivation and transrepression, new glucocoticoids should be able to dissociate these effects, thus lowering the potential of unwanted side-effects of glucocorticoids in clinical use. In this study, we developed a new experimental system to test potentially selective glucocorticoids in normal lymphocytes. MATERIALS AND METHODS: Following pretreatment with phytohaemagglutinin, normal lymphocytes were transfected, using electroporation, with pGL3 luciferase reporter vectors under the control: (1) of the human IL-2 promoter; and (2) of a glucocorticoid response element (GRE). Luciferase activity was measured in response to various steroid compounds, including the potentially dissociative glucocorticoid medroxyprogesterone acetate (MPA). RESULTS: The IL-2 promoter was induced 267.2 +/- 27.5-fold (mean +/- SD) by phorbol ester and ionomycin. In these cells, hydrocortisone and dexamethasone caused a 22.9 +/- 3.6% and a 38.4 +/- 10% reduction in luciferase activity, respectively. Under GRE control, hydrocortisone stimulated luciferase activity 6.4 +/- 0.50-fold and dexamethasone 8.2 +/- 0.4-fold. MPA-induced transrepression was 73.3 +/- 7.2% for the IL-2 promoter, and transactivation was 2.4 +/- 0.4-fold with the GRE-driven construct. The natural progestin progesterone did not have significant effects on either construct. CONCLUSIONS: This is the first system that allows efficient analysis of glucocorticoid-dependent transactivation and transrepression in normal human lymphocytes. Compared to conventional glucocorticoids, MPA can be referred to as a dissociative glucocorticoid, its transrepression/transactivation ratio being 6.6 (transrepression 1.91/transactivation 0.29), with dexamethasone being the standard (transrepression 1/transactivation 1). We conclude that MPA is a highly promising substance for the treatment of autoimmune/inflammatory diseases.
Assuntos
Glucocorticoides/farmacologia , Ativação Transcricional/efeitos dos fármacos , Humanos , Imunossupressores/farmacologia , Interleucina-2/genética , Acetato de Medroxiprogesterona/farmacologia , Regiões Promotoras Genéticas , TransfecçãoRESUMO
In the present study, we used Western blot analysis to determine the expression of the progesterone receptor (PR) isoforms, PR-B and PR-A, in breast tumors (n = 53), and correlated the expression patterns of the two isoforms with the clinicopathological parameters of these tumors and with expression of the AP-1 family of transcription factors. Expression of the two PR isoforms correlated significantly with each other, indicating that the expression of the two isoforms is probably regulated in a correlated fashion. Expression of both isoforms correlated significantly with expression of the estrogen receptor (ER). Furthermore, expression of PR-B was found to correlate significantly with the absence of ErbB2/neu. For the AP-1 factors, Fra-1 expression showed an inverse correlation with PR-B expression. In contrast, expression of FosB correlated significantly with expression of both isoforms, and the association was stronger with PR-B expression. An analysis of the ratio of expression of the two isoforms showed that most of the tumors expressed PR-A levels which were equal or higher than the corresponding PR-B expression levels (together 94% of the analyzed tumors) indicating that, in mammary carcinomas, a predominance of the PR-A isoform over the PR-B isoform seems to be the case. While there was no statistically significant correlation with age, staging and histological type, expression of both isoforms correlated with a more differentiated phenotype (G1/G2 grading). However, this association was stronger for PR-B. Also, a PR-A < or = PR-B expression level was associated with G1/G2 grading, while a PR-A > PR-B expression level showed an association with a more undifferentiated phenotype (G3 grading). The expression level of the two PR isoforms might prove to be of prognostic and/or predictive value, especially since the two isoforms have been shown to be functionally different and to modulate the response of tumor cells to progestins and antiprogestins differently.
Assuntos
Neoplasias da Mama/química , Neoplasias da Mama/patologia , Carcinoma/química , Receptores de Progesterona/análise , Western Blotting , Neoplasias da Mama Masculina/química , Neoplasias da Mama Masculina/patologia , Carcinoma/patologia , Feminino , Humanos , Imuno-Histoquímica , Masculino , Pessoa de Meia-Idade , Isoformas de Proteínas/análise , Proteínas Proto-Oncogênicas c-fos/análise , Receptor ErbB-2/análise , Receptores de Estrogênio/análise , Células Tumorais CultivadasRESUMO
The immunosuppressive effects of glucocorticoids (GC) have led to their wide application in the treatment of inflammatory and autoimmune states. However, long term GC treatment is associated with severe side-effects. The development of agents displaying a more favorable ratio of wanted and unwanted GC effects, is, therefore, a major goal of pharmacological and clinical research. In this study, the progesterone receptor agonist medroxyprogesterone acetate (MPA), which also binds to the glucocorticoid receptor (GR), was tested with regard to its immunosuppressive properties. Using a recently established electroporation protocol, we show that MPA (but not progesterone) can suppress a human interleukin-2 (IL-2) promoter-luciferase construct to the same extent as the synthetic GC dexamethasone in normal human lymphocytes. MPA also markedly suppressed IL-2 (as well as IL-1 and IL-6) release, as assessed by specific enzyme-linked immunosorbent assays. In contrast, a highly dexamethasone-inducible glucocorticoid response element-driven promoter construct was only marginally stimulated by MPA in both normal human lymphocytes and HeLa cells. RT-PCR and Western blot analysis of normal human lymphocytes revealed that they do not express progesterone receptor messenger ribonucleic acid and protein, respectively. In contrast, the GR protein was clearly detectable in all samples and was shown to mediate the effects of MPA in transfected Jurkat T lymphoma cells. Our data indicate that 1) MPA can transrepress the human IL-2 gene in normal human lymphocytes in the absence of significant trans-activation; and 2) this effect is mediated by GR. Because of its dissociative GC activity, MPA is a highly promising substance for the treatment of inflammatory/autoimmune states.
Assuntos
Glucocorticoides/farmacologia , Linfócitos/efeitos dos fármacos , Acetato de Medroxiprogesterona/farmacologia , Western Blotting , Células Cultivadas , Expressão Gênica/efeitos dos fármacos , Glucocorticoides/efeitos adversos , Células HeLa , Humanos , Interleucina-2/biossíntese , Interleucina-2/genética , Interleucina-6/biossíntese , Células Jurkat , Linfócitos/imunologia , Acetato de Medroxiprogesterona/metabolismo , Regiões Promotoras Genéticas , RNA Mensageiro/análise , Receptores Androgênicos/fisiologia , Receptores de Glucocorticoides/genética , Receptores de Glucocorticoides/metabolismo , Receptores de Progesterona/genética , Receptores de Progesterona/fisiologia , Proteínas Recombinantes de Fusão , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Ativação Transcricional/efeitos dos fármacos , TransfecçãoRESUMO
BACKGROUND: The physiologic role of dehydroepiandrosterone in humans is still unclear. Adrenal insufficiency leads to a deficiency of dehydroepiandrosterone; we therefore, investigated the effects of dehydroepiandrosterone replacement, in patients with adrenal insufficiency. METHODS: In a double-blind study, 24 women with adrenal insufficiency received in random order 50 mg of dehydroepiandrosterone orally each morning for four months and placebo daily for four months, with a one-month washout period. We measured serum steroid hormones, insulin-like growth factor I, lipids, and sex hormone-binding globulin, and we evaluated well-being and sexuality with the use of validated psychological questionnaires and visual-analogue scales, respectively. The women were assessed before treatment, after one and four months of treatment with dehydroepiandrosterone, after one and four months of placebo, and one month after the end of the second treatment period. RESULTS: Treatment with dehydroepiandrosterone raised the initially low serum concentrations of dehydroepiandrosterone, dehydroepiandrosterone sulfate, androstenedione, and testosterone into the normal range; serum concentrations of sex hormone-binding globulin, total cholesterol, and high-density lipoprotein cholesterol decreased significantly. Dehydroepiandrosterone significantly improved overall well-being as well as scores for depression and anxiety. For the global severity index, the mean (+/-SD) change from base line was -0.18+/-0.29 after four months of dehydroepiandrosterone therapy, as compared with 0.03+/-0.29 after four months of placebo (P=0.02). As compared with placebo, dehydroepiandrosterone significantly increased the frequency of sexual thoughts (P=0.006), sexual interest (P=0.002), and satisfaction with both mental and physical aspects of sexuality (P=0.009 and P=0.02, respectively). CONCLUSIONS: Dehydroepiandrosterone improves well-being and sexuality in women with adrenal insufficiency.