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1.
Endocrinol. diabetes nutr. (Ed. impr.) ; 66(1): 4-10, ene. 2019. tab, graf
Artigo em Inglês | IBECS | ID: ibc-175787

RESUMO

Introduction: Patients with HIV+ often present lipid disturbances. The role of ghrelin and obestatin in these lipid disturbances is not clear. The effect of antiretroviral (ART) drugs on those molecules is also unknown. This study measured ghrelin and obestatin levels, as well as metabolic markers, in patients with HIV+ before and after 36 weeks of ART. Material and methods: Twenty HIV-positive, ART-naïve patients who started a scheme consisting of tenofovir/emtricitabine+lopinavir/ritonavir were enrolled. Plasma samples were collected before and after 36 weeks of treatment. Serum ghrelin and obestatin levels were quantitated by ELISA; glucose, cholesterol, and triglyceride levels were measured by colorimetric and enzymatic methods, and cardiovascular risk was calculated by the atherogenic index of plasma (AIP). Results: All patients completed 36 weeks of ART. Total cholesterol (p<0.001), LDL-C (p=0.019), HDL-C (p=0.003), VLDL-C (p=0.002), and triglyceride levels (p=0.021) significantly increased after treatment. AIP revealed increased cardiovascular risk at baseline, which remained high after treatment. There was a statistically significant increase in obestatin level in the unpaired and paired analyses, while ghrelin levels only showed a trend to increase. Changes in ghrelin and obestatin levels positively correlated, but no correlation was seen with any metabolic parameter. Conclusion: After 36 weeks of ART, patients showed an altered lipid profile, but there were no significant changes in cardiovascular risk. Ghrelin and obestatin levels increased after 36 weeks of ART, but the increase was only significant for obestatin. Changes in ghrelin and obestatin positively correlate


Introducción: Los pacientes con VIH+ frecuentemente presentan alteraciones del perfil lípidico. El papel de ghrelina y obestatina en estas complicaciones no está claro. El efecto del tratamiento antirretroviral (TAR) en dichas moléculas es desconocido. Este estudio determinó los niveles de ghrelina y obestatina, así como los parámetros metabólicos en pacientes VIH+ antes y después de 36 semanas del TAR. Material y métodos: Participaron 20 pacientes VIH+, vírgenes a TAR, que iniciaron con un esquema de tenofovir/emtricitabina + lopinavir/ritonavir. Se tomaron muestras de plasma antes y después de 36 semanas de tratamiento. Los niveles séricos de ghrelina y obestatina fueron cuantificados por ELISA, los parámetros bioquímicos fueron determinados por métodos colorimétricos, se evaluó el riesgo cardiovascular por medio del índice aterogénico del plasma (AIP). Resultados: Los pacientes completaron 36 semanas del TAR. Los niveles de colesterol total (p<0,001), c-LDL (p=0,019), c-HDL (p=0,003), c-VLDL (p=0,002) y triglicéridos (p=0,021) mostraron un incremento estadísticamente significativo posterior al tratamiento. El AIP reveló un riesgo cardiovascular alto. Los niveles de obestatina se incrementaron significativamente en el análisis pareado y no pareado; y ghrelina solo mostró tendencia al incremento. Los cambios en ghrelina y obestatina correlacionaron positivamente, sin embargo no correlacionaron con los parámetros metabólicos. Conclusión: Los pacientes VIH+ mostraron un perfil lipídico alterado después de 36 semanas del TAR. Los niveles de ghrelina y obestatina se incrementaron tras 36 semanas del TAR. El riesgo cardiovascular es persistente. Los cambios en ghrelina y obestatina mostraron una correlación positiva


Assuntos
Humanos , Masculino , Feminino , Adulto , Antirretrovirais/farmacologia , HIV , Grelina/sangue , Hormônios Peptídicos/sangue , Antirretrovirais/uso terapêutico , HIV/metabolismo , Grelina/uso terapêutico , Hormônios Peptídicos/uso terapêutico , Dislipidemias/fisiopatologia
2.
Endocrinol. diabetes nutr. (Ed. impr.) ; 66(1): 49-55, ene. 2019. tab
Artigo em Inglês | IBECS | ID: ibc-175793

RESUMO

Background and objective: This randomized crossover clinical trial investigated the effects of substituting legumes for meat consumption in the therapeutic lifestyle change (TLC) diet on leptin and adiponectin concentrations among type 2 diabetic patients. Material and methods: Thirty-one type 2 diabetic patients (24 women, age: 58.1±6.0 years) were randomly assigned to groups designated to consume a legume-free TLC diet or a legume-based TLC diet for 8 weeks. Both diets were similar except for the replacement of two servings of red meat with legumes 3 days per week in the legume-based TLC group. Leptin and adiponectin concentrations were measured at baseline and after the 8-week intervention. Results: The legume-based TLC diet significantly increased adiponectin concentrations in comparison with the legume-free TLC diet. There was no significant change in leptin concentrations after both intervention diets. Conclusions: Legumes increased serum adiponectin concentrations in type 2 diabetic patients. Registration number: IRCT201202251640N7


Antecedentes y objetivo: Este ensayo clínico cruzado aleatorizado investigó los efectos de la sustitución de legumbres por el consumo de carne en la dieta de Cambio Terapéutico en el Estilo de Vida (CTEV) sobre las concentraciones de leptina y adiponectina en pacientes con diabetes tipo 2. Material y métodos: Treinta y un pacientes diabéticos tipo 2 (24 mujeres, edad: 58,1±6,0 años) fueron asignados aleatoriamente a grupos designados para consumir una dieta CTEV libre de legumbres o una dieta CTEV basada en legumbres durante 8 semanas. Ambas dietas fueron similares, excepto por el reemplazo de 2 porciones de carne roja por legumbres 3 días por semana en el grupo de CTEV basado en leguminosas. Las concentraciones de leptina y adiponectina se midieron al inicio y después de la intervención de 8 semanas. Resultados: La dieta de CTEV basada en legumbres aumentó significativamente los niveles de adiponectina en comparación con la dieta de CTEV sin legumbres. No hubo cambios significativos en las concentraciones de leptina después de ambas dietas de intervención. Conclusiones: Las leguminosas aumentaron las concentraciones séricas de adiponectina en pacientes diabéticos tipo 2. Número de registro: IRCT201202251640N7


Assuntos
Humanos , Masculino , Feminino , Pessoa de Meia-Idade , Proteínas de Vegetais Comestíveis , Adiponectina/fisiologia , Diabetes Mellitus Tipo 2/metabolismo , Hormônios Peptídicos/fisiologia , Carne , Proteínas na Dieta , Dieta para Diabéticos , Leptina/fisiologia
3.
Nutr. hosp ; 35(1): 201-210, ene.-feb. 2018. tab, graf
Artigo em Inglês | IBECS | ID: ibc-172109

RESUMO

Introduction: Malnutrition in children with cancer is a significant risk factor for negative outcomes, but in the clinical practice setting, it is difficult to pinpoint which factors operate to cause substantial weight loss and malnutrition in a given patient. Appetite-related hormones like ghrelin and leptin are among possible mediators. However, only few studies have examined the role of these hormones in pediatric patients with cancer to date. Thus, the purpose of this study was to systematically review possible changes in the levels of appetite hormones, specially leptin and ghrelin, in pediatric patients with cancer. Material and methods: We systematically reviewed the literature using PubMed, Lilacs and Scielo, as well as manual bibliographical reference search of the studies. According to the Medical Subject Headings of the National Library of Medicine (MeSH), "childhood cancer", "ghrelin" and "leptin" were used as descriptors. Results: Fifteen studies were included in this systematic review published in English, from 2000 to 2015. A total of 863 patients were evaluated, ages ranging from 0 to 21 years, and most of the studies reported on children and adolescents with acute lymphoblastic leukemia (ALL) survivors. Most studies analyzed leptin levels; only two studies evaluated levels of ghrelin. Conclusion: This review confirms that changes in the responses of the ghrelin and leptin hormones in children and adolescents with cancer are quite diverse, probably due to the different types of cancer observed, different treatments performed and biological characteristics of this age group (AU)


Introducción: la desnutrición en niños con cáncer es un factor de riesgo significativo para resultados negativos, pero en la práctica clínica, es difícil determinar qué factores operan para causar pérdida de peso sustancial y desnutrición en un paciente dado. Entre los posibles mediadores están las hormonas relacionadas con el apetito como la grelina y la leptina. Sin embargo, hasta la fecha, solo unos pocos estudios han examinado el papel de estas hormonas en pacientes pediátricos con cáncer. El propósito de este estudio fue revisar sistemáticamente los posibles cambios en los niveles de hormonas del apetito, especialmente la leptina y la grelina, en pacientes pediátricos con cáncer. Material y métodos: se llevó a cabo una revisión sistemática de la bibliografía empleando PubMed, Lilacs y Scielo, así como la búsqueda bibliográfica manual de referencia de los estudios. Según los encabezamientos médicos de la Biblioteca Nacional de Medicina (MeSH), "cáncer infantil", "grelina" y "leptina" se utilizaron como descriptores. Resultados: en esta revisión sistemática, se incluyeron 15 estudios publicados en ingles de 2000 a 2015. Fueron evaluados un total de 863 pacientes, con edades comprendidas entre 0 y 21 años, y la mayoría de los estudios informaron sobre niños y adolescentes supervivientes de leucemia linfoblastica aguda. La mayoría de los estudios analizaron los niveles de leptina y solo dos estudios evaluaron los niveles de grelina. Conclusión: esta revisión confirma que los cambios en las respuestas hormonales de la grelina y la leptina en niños y adolescentes con cáncer son muy diversos, probablemente debido a los diferentes tipos de cáncer observado, los diferentes tratamientos realizados y las características biológicas de este grupo de edad (AU)


Assuntos
Humanos , Criança , Adolescente , Transtornos da Alimentação e da Ingestão de Alimentos/fisiopatologia , Leucemia-Linfoma Linfoblástico de Células Precursoras/complicações , Hormônios Peptídicos , Apetite/fisiologia , Desnutrição/epidemiologia , Grelina/análise , Leptina/análise
4.
Nefrología (Madr.) ; 36(5): 496-502, sept.-oct. 2016. graf, tab
Artigo em Espanhol | IBECS | ID: ibc-156556

RESUMO

Antecedentes: La irisina es una adipomioquina con posibles efectos antiobesidad y antidiabéticos. Esta hormona ha sido insuficientemente estudiada en pacientes con enfermedad renal crónica (ERC) avanzada. Objetivo: Realizar un análisis exploratorio de los niveles séricos de irisina en pacientes con diferentes modalidades de tratamiento de la ERC. Método: Según diseño transversal, estimamos niveles de irisina en 95 pacientes con ERC manejados conservadoramente (ERCA), con diálisis peritoneal (DP) o con hemodiálisis, comparándolos con un grupo control de 40 individuos sanos. También investigamos las correlaciones entre irisina sérica y variables demográficas, clínicas, metabólicas y de composición corporal. Resultados: Los niveles de irisina fueron más bajos en cualquier grupo de pacientes que en los controles. El análisis univariante desveló correlaciones moderadas entre irisina, por un lado, y masa grasa (pero no magra), filtrado glomerular (GFR) y albúmina y bicarbonato plasmático, por otro. El análisis multivariante confirmó que los pacientes con ERCA (diferencia 111,1ng/mL), en DP (25,9ng/mL) o hemodiálisis (61,4ng/mL) (todos p<0,0005) presentaban niveles ajustados más bajos de irisina que los controles. Asimismo, los pacientes en DP presentaban niveles más altos de la hormona que los de hemodiálisis (diferencia 39,4ng/mL; p=0,002) o ERCA (24,4ng/mL; p=0,036). El análisis multivariante también identificó bicarbonato plasmático (B=3,90 por mM/L; p=0,001) y GFR (B=1,89 por mL/min; p=0,003) como predictores independientes de los niveles de irisina. Por el contrario, no observamos correlación ajustada entre irisina y marcadores de composición corporal. Conclusiones: Los niveles de irisina son bajos en pacientes con ERC, y muestran correlación consistente con GFR y bicarbonato plasmático. Los pacientes en DP presentan niveles más altos de irisina que los manejados conservadoramente o con hemodiálisis. Nuestro estudio confirma una inconsistencia general en los análisis de asociación entre irisina sérica, por un lado, y marcadores metabólicos y de composición corporal, por otro (AU)


Background: Irisin is an adipomyokine with claimed anti-obesity and anti-diabetic effects. This hormone has been insufficiently studied in patients with advanced chronic kidney disease (CKD). Objective: To perform an exploratory analysis of serum irisin levels in patients undergoing different CKD treatments. Method: Following a cross-sectional design, we estimated serum levels of irisin in 95 patients with CKD managed conservatively (advanced CKD), with peritoneal dialysis (PD) or with haemodialysis, and compared our findings with a control group of 40 healthy individuals. We investigated the correlations between serum irisin and demographic, clinical, body composition and metabolic variables. Results: Irisin levels were lower in all the CKD groups than in the control group. The univariate analysis revealed limited correlations between irisin, on the one hand, and fat (but not lean) mass, glomerular filtration rate (GFR) and plasma albumin and bicarbonate, on the other. The multivariate analysis confirmed that advanced CKD patients managed conservatively (difference 111.1ng/ml), with PD (25.9ng/ml) or haemodialysis (61.4ng/ml) (all P<.0005) presented lower irisin levels than the control group. Furthermore, PD patients presented higher serum levels of irisin than those on haemodialysis (difference 39.4ng/ml, P=.002) or those managed conservatively (24.4 ng/ml, P=.036). The multivariate analysis also identified plasma bicarbonate (B=3.90 per mM/l, P=.001) and GFR (B=1.89 per ml/minute,P=.003) as independent predictors of irisin levels. Conversely, no adjusted correlation between irisin and body composition markers was found. Conclusions: Serum irisin levels are low in patients with CKD and show a consistent correlation with GFR and plasma bicarbonate levels. PD patients present higher levels of irisin than those managed conservatively or with haemodialysis. Our study confirms a general inconsistency of the association between serum irisin levels, on the one hand, and body composition and metabolic markers, on the other (AU)


Assuntos
Humanos , Adipocinas/sangue , Insuficiência Renal Crônica/fisiopatologia , Hormônios Peptídicos/sangue , Diálise Renal , Biomarcadores/análise , Composição Corporal/fisiologia , Estudos Transversais , Peptídeo C/sangue , Leptina/sangue
5.
J. physiol. biochem ; 71(3): 559-568, sept. 2015.
Artigo em Inglês | IBECS | ID: ibc-142451

RESUMO

Numerous controversies surround the peptide hormone irisin. Although implicated as a myokine promoting the browning of adipose tissue in rodents, its roles in humans remain unclear. Contradictory results have also been found with respect to the relationships between adiposity or metabolic health and plasma irisin levels in humans. We investigated the relationship between irisin levels and body composition (hydrostatic weighing), insulin sensitivity (hyperinsulinemic-euglycemic clamp), fitness level (ergocycle VO2max) and skeletal muscle metabolic profile in 53 men (aged 34–53 years) from four groups: sedentary non-obese controls (body mass index [BMI] <25 kg/m2), sedentary obese (BMI >30 kg/m2), sedentary obese glucose-intolerant, and non-obese highly trained endurance active. Baseline plasma irisin levels were significantly different between groups, being lowest in trained men (140.6 ± 38.2 ng/mL) and highest in metabolically deteriorated glucose-intolerant subjects (204.0 ± 50.5 ng/mL; ANOVA p = 0.01). Including all subjects, irisin levels were positively associated with adiposity (e.g. fat mass, r = 0.430, p < 0.01) and negatively associated with fitness (r = −0.369, p < 0.01), insulin sensitivity (M/I, r = −0.355, p < 0.01) and muscle citrate synthase (CS) activity (r = −0.482, p < 0.01). Most correlations lost statistical significance when excluding active individuals, except for insulin resistance (r = −0.413, p < 0.01) and CS (r = −0.462,p < 0.01). Multiple regression analyses reveal CS as the strongest independent predictor of irisin levels (r 2 range 0.214 to 0.237). We conclude that muscle oxidative potential is an important factor linked to circulating irisin levels


Assuntos
Adulto , Humanos , Masculino , Pessoa de Meia-Idade , Tecido Adiposo Branco , Hormônios Peptídicos/farmacocinética , Obesidade/fisiopatologia , Resistência à Insulina/fisiologia , Fibronectinas , Estresse Oxidativo/fisiologia , Miosinas , Adipocinas
7.
Eur. j. anat ; 17(2): 59-62, abr. 2013. ilus, tab
Artigo em Inglês | IBECS | ID: ibc-114618

RESUMO

Obestatin, a peptide encoded by the ghrelin precursor gene, is said to exert actions opposite to that of ghrelin. While ghrelin is said to increase appetite and decrease energy expenditure, thus causing weight gain, obestatin acts like an anorexic hormone, decreasing appetite and reducing body weight gain, besides other effects such as reducing serum insulin and glucose levels. However, these actions have been submitted to serious contests with many laboratories opposing each others’ arguments. In our studies on albino rats, obestatin was administered for two different periods of time. One group received intraperitoneal obestatin for one week, while the other got it for two weeks. The control animals received the vehicle alone. It was found that obestatin brought about a reduction in the final body weight, while the control rats continued to gain weight during the period of the experiments. The more the duration of administration of the hormone, more pronounced are the results. There was a fall in the serum glucose and insulin levels in the obestatin-treated rats in comparison with the control rats. Therefore, it was concluded that the anti-obesity hormone obestatin decreases the food intake and the body weight by lessening the appetite in the experimental rats. The study may have implications for its use in obesity (AU)


No disponible


Assuntos
Animais , Ratos , Hormônios Peptídicos/farmacocinética , Apetite/fisiologia , Peso Corporal/fisiologia , Grelina/genética , Glucose , Insulina
8.
Rev. esp. enferm. metab. óseas (Ed. impr.) ; 16(2): 29-33, mar. 2007. ilus
Artigo em Es | IBECS | ID: ibc-057986

RESUMO

La diabetes mellitus es una enfermedad que afecta a unos 200 millones de personas en el mundo. Estudios epidemiológicos y experimentales demuestran la existencia de una pérdida de masa ósea asociada a la diabetes de tipo 1. Esta pérdida parece estar mediada por diversos factores endocrinos y/o locales, entre los que se incluyen: la insulina, el factor similar a la insulina tipo 1 (IGF-1), péptidos pancreáticos (amilina, leptina y preptina), hormonas intestinales (GLP-1 y GLP-2) y la vitamina D. Sin embargo, en la diabetes tipo 2 no existen datos concluyentes que la relacionen con una disminución de la masa ósea


Diabetes mellitus is a disease affecting about 200 million people worldwide. Both epidemiological and experimental studies have demonstrated the existence of a diabetes-related bone loss in type 1 diabetic patients. This relationship seems to be mediated by different endocrine and local factors, namely insulin, insulin-like growth factor 1 (IGF-1), pancreatic peptides (amylin, leptin, and preptin), intestinal hormones (GLP-1 y GLP-2), and vitamin D. However, no such relationship has been demonstrated in type 2 diabetes


Assuntos
Humanos , Diabetes Mellitus/metabolismo , Osteoporose/metabolismo , Densidade Óssea/fisiologia , Fator de Crescimento Insulin-Like I/metabolismo , Insulina/metabolismo , Vitamina D/metabolismo , Hormônios Gastrointestinais/metabolismo , Hormônios Peptídicos/metabolismo
9.
An. sist. sanit. Navar ; 29(2): 207-218, mayo-ago. 2006. tab
Artigo em Es | IBECS | ID: ibc-052113

RESUMO

En nuestra sociedad, la competición deportiva se haconvertido en el espectáculo que moviliza y reúnemayor número de personas en todo el mundo, con lacorrespondiente influencia cultural y económica que deello deriva. Por lo que, los deseos de superación atléticahan llevado a los deportistas a practicar intensos programasde entrenamiento y a recurrir al consumo de sustanciasque mejoren su rendimiento, incurriendo en ocasionesen técnicas de dopaje. Actualmente, el dopaje esel resultado de una combinación de factores sociales,individuales, fisiológicos y culturales, que afecta no sóloa los deportistas profesionales, sino también a los deportistasaficionados. Para que su control y erradicación seaeficaz, es necesario un conocimiento del problema y delas sustancias más utilizadas, dentro de las cuales merecenespecial atención las sustancias hormonales por sucompleja detección y sus posibles repercusiones sobrela salud


Sporting competition in our society has become ;;the spectacle that mobilises and brings together the ;;greatest number of people throughout the world, ;;with the corresponding cultural and economic influence ;;that this implies. As a result, the desire for athletic ;;prowess has led sportspersons to undergo ;;intense training programs and to consume substances ;;that improve their performance, at times ;;having recourse to doping techniques. At present, ;;doping is the result of a combination of social, individual, ;;physiological and cultural factors, which ;;affect not only professional, but also amateur sportspeople. ;;In order for the control and eradication of ;;doping to be efficient, it is necessary to understand ;;the problem and the substances that are most ;;employed, amongst which special mention is merited ;;by hormonal substances due to the complexity of ;;detecting them and their possible repercussions on ;;health


Assuntos
Humanos , Anabolizantes/administração & dosagem , Esteroides/administração & dosagem , Doping nos Esportes , Detecção do Abuso de Substâncias/métodos , Hormônio do Crescimento/administração & dosagem , Eritropoetina/administração & dosagem , Insulina/administração & dosagem , Hormônios Peptídicos/administração & dosagem
10.
Eur. j. anat ; 8(2): 95-99, sept. 2004. ilus
Artigo em Inglês | IBECS | ID: ibc-137847

RESUMO

Leptin is a peptide hormone encoded by the obgene and released by adipocytes. Over the past few years, the synthesis, regulation and effects of leptin have been extensively investigated in view of its pleiotropic role in human (patho)physiology. This work aimed at reviewing current morphological knowledge on leptin synthesis and secretion in adipocytes. It is concluded that the intracellular trafficking of leptin and the structural basis of leptin secretion remain to be defined. Further morphological work, especially at the ultrastructural level, is needed to firmly establish the intracellular distribution and the release pathways of the hormone (AU)


No disponible


Assuntos
Feminino , Humanos , Masculino , Leptina/análogos & derivados , Leptina/administração & dosagem , Tecido Adiposo/anormalidades , Tecido Adiposo , Forma do Núcleo Celular/genética , Hormônios Peptídicos/administração & dosagem , Hormônios Peptídicos , Secreções Corporais/citologia , Leptina , Leptina/metabolismo , Tecido Adiposo/lesões , Tecido Adiposo/metabolismo , Forma do Núcleo Celular/fisiologia , Hormônios Peptídicos/classificação , Hormônios Peptídicos/farmacologia , Secreções Corporais
12.
Nefrología (Madr.) ; 23(supl.2): 12-17, 2003. tab, ilus
Artigo em Espanhol | IBECS | ID: ibc-148518

RESUMO

Desde su descubrimiento en el año 1923, la hormona paratiroidea (PTH) era la única capaz de estimular la resorción ósea, la reabsorción tubular de calcio, la eliminación renal de fósforo y la síntesis de calcitriol. Sin embargo, en 1987 se identificó el PTHrP (PTH-related peptide), el cual ejerce la mayoría de las funciones biológicas de la PTH a través del mismo receptor. Ese receptor, PTH/PTHrP o PTH-R1, fue clonado en el 1992. Las dos moléculas, PTH y PTHrP se ligan a él con gran afinidad y estimulan un sistema de transducción que implica la activación de diferentes proteínas G, la fosfolipasa C y la adenilciclasa. Un tercer miembro de la familia PTH, el TIP-39 (tuberoinfundibular peptide), se liga y activa otro receptor de la PTH, el PTH-R2. También, hay evidencias de la existencia de otros receptores de la PTH (PTH-R3, PTH-R4). Las mutaciones activadoras del PTH-R1 provocan la condrodisplasia metafisaria de tipo Jansen y las mutaciones inactivadoras son responsables de otra condrodisplasia rara, la enfermedad de Blomstrand y de ciertas encondromatosis. La expresión del PTH-R1 aumenta en el riñón y el hueso de ratas deficientes en vitamina D y en respuesta a las endotoxinas, la interleuquina-2, la dexametasona, la T3 y el TGFβ. Al contrario, la PTH, el PTHrP, la angiotensina-II, el IGF-1, la PGE2, la vitamina D y la insuficiencia renal crónica la disminuyen. En conclusión, las implicaciones biológicas del clonaje de los receptores de la PTH son innumerables. El hecho que el PTHrP y el PTH-R1 sean ubicuos y el hecho que hay varios fragmentos circulantes del PTHrP y de la PTH, supone la existencia de otros receptores específicos de esos fragmentos y por supuesto que el metabolismo mineral y óseo es mucho más complejo de lo imaginado (AU)


Since its discovery in 1923, the parathyroid hormone (PTH), was thought to be the sole hormone capable of stimulating bone resorption, renal tubular calcium reabsorption, calcitriol synthesis, and urinary excretion of phosphate. However, in 1987, the PTHrP (PTH-related peptide), was demonstrated to share most of the biological actions of PTH through the activation of the same receptor. This receptor was cloned in 1992 and named PTH/PTHrP receptor or PTH-R1. Both, PTH and PTHrP bind with great affinity to PTH-R1 and stimulate a signal transduction system involving different G-proteins, phospholipase C, and denylate cyclase. A third member of the PTH family, the TIP-39 (tuberoinfundibular peptide), binds and activates another PTH receptor (PTH-R2). There is evidence for other PTH receptors, a PTH-R3, probably specific for PTHrP in keratinocytes, kidney, placenta and a PTH-R4 specific for C-terminal PTH fragments. Activating mutations in the PTH-R1 gene cause Jansen type metaphyseal chondrodysplasia, whereas inactivating mutations are responsible for Blomstrand type rare chondrodysplasia and enchondromatosis. The renal and bone PTH-R1 expression is upregulated in vitamin D deficient rats and by endotoxin, interleukin-2, dexamethasone, T3, and TGFβ. On the contrary, PTH, PTHrP, angiotensin-II, IGF-1, PGE2, vitamin D, and chronic renal failure decrease its expression. In conclusions, the biological implications of the identification and cloning of different PTH receptors are at their beginning. The almost ubiquitous distribution of PTHrP and PTH-R1, the numerous PTHrP and PTH fragments, let us suppose the existence of other PTH-related receptors, and a great complexity of the bone and mineral metabolism (AU)


Assuntos
Humanos , Animais , Ratos , Osso e Ossos/metabolismo , Minerais/metabolismo , Hormônio Paratireóideo/fisiologia , Proteína Relacionada ao Hormônio Paratireóideo , Hormônios Peptídicos/fisiologia , Receptor Tipo 1 de Hormônio Paratireóideo , Receptores de Hormônios Paratireóideos/genética , Receptores de Hormônios Paratireóideos/fisiologia , Encondromatose/genética , Endotoxinas/farmacologia , Regulação da Expressão Gênica , Substâncias de Crescimento/fisiologia , Interleucina-3/fisiologia , Falência Renal Crônica/fisiopatologia , Túbulos Renais/metabolismo , Neuropeptídeos/fisiologia , Osteocondrodisplasias/genética , Conformação Proteica , Distúrbio Mineral e Ósseo na Doença Renal Crônica/fisiopatologia , Transdução de Sinais , Deficiência de Vitamina D/complicações
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