Vitamina D y cáncer: acción antineoplásica de la 1α, 25(OH)2 -vitamina D3 / Vitamin D and cancer: antineoplastic effects of 1α,25(OH)2-vitamin D3

La forma hormonalmente activa de la vitamina D, 1α,25(OH)2-vitamina D3 (1α,25(OH)2D3), además de desempeñar un rol crucial en el mantenimiento de la homeostasis de calcio en el cuerpo, también regula el crecimiento y la diferenciación de diferentes tipos celulares, incluyendo células cancerosas. Actualmente hay numerosos estudios que investigan los efectos de la hormona en estas células, debido al interés en el uso terapéutico del 1α,25(OH)2D3 y de análogos con menor actividad calcémica para el tratamiento o prevención del cáncer. En este trabajo de revisión se describe el sistema endocrino de la vitamina D, su mecanismo de acción, su acción antineoplásica y se provee información sobre los últimos avances en el estudio de nuevos análogos de la hormona con menos actividad calcémica para el tratamiento del cáncer.

The hormonal form of vitamin D, 1α,25(OH)2-vitamin D3 (1α,25(OH)2D3), in addition of playing a central role in the control of calcium homeostasis in the body, regulates the growth and differentiation of different cell types, including cancer cells. At present several epidemiologic and clinical studies investigate the effect of the hormone in these cells due to the interest in the therapeutic use of 1α,25(OH)2D3 and analogues with less calcemic activity for prevention or treatment of cancer. This review describes vitamin D endocrine system, its mechanism of action, its antineoplastic activity and provides information about the latest advances in the study of new hormone analogues with less calcemic activity for cancer treatment.

El tejido graso como modulador endocrino: Cambios hormonales asociados a la obesidad / Adipose tissue as an endocrine modulator: Hormonal changes associated with obesity

Adipose tissue not only stores fat, but secretes factors and hormones, which modify the regulation, metabolism and secretion of several other hormones. The objective of this review is to describe the hormonal disorders associated with increased adipose tissue, which acts as a modulator or disruptor of the endocrine physiology, with special reference to cortisol, androgens, growth hormone and thyroid axis, and discuss the implications for the management and treatment of these patients.

The physiology of vitamin D : current concepts.

The vitamin D endocrine system, besides playing pivotal roles in calcium homeostasis & bone mineral metabolism, is now recognized to subserve a wide range of fundamental biological functions in cell differentiation, inhibition of cell growth as well as immuno modulation. Vitamin D is a prohormone which is converted into its active hormonal form 1, 25 (OH)D2 D, 1, 25 (OH)D2 D activates its cellular receptor (VDR) which activate target genes to engender its biological actions. This review provides a summary of recent understanding of the complex actions of the vitamin D hormone 1, 25 (OH)2 D which is a final product of 1alpha hydroxylation in the proximal tubular cells of kidneys. Emerging evidence also indicates both 1, 25 (OH)2 D3 independent as well as depended action of vitamin D receptor (VDR). Thus, the vitamin D system action may involve more than one single receptor and legand. The presence of 1alpha hydroxylase in many target cells other than proximal renal tubular cells indicates autocrine and paracrine functions for 1, 25 (OH)2 D3 in the control of cell proliferation and differentiation. Vitamin D and related molecules belong to a elaborate endocrine system that acts on target genomic receptors in several organ systems to control cell proliferation and differentiation.

Fatores relacionados com as respostas da testosterona e do cortisol ao treinamento de força / Factors concerned with the testosterone and cortisol response to strength training

Esse artigo visa revisar os resultados encontrados na literatura a respeito dos diversos fatores relacionados com a resposta hormonal aguda e crônica ao treinamento de força. Foi observado que existe uma estreita relação entre a treinabilidade de indivíduos submetidos ao treinamento de força e os níveis circulantes de testosterona nesses sujeitos. Além disso, outros parâmetros hormonais, tais como as razões entre a testosterona e sua proteína carreadora e entre a testosterona com o cortisol, também foram relacionados com a capacidade de aumento de força. Diversos fatores ligados à sessão de treino, além das características da população investigada, influenciam a resposta hormonal aguda e crônica ao treinamento. Entre esses fatores, o volume e a intensidade são as principais variáveis ligadas à magnitude dessa resposta. A determinação de quais fatores possam estar estreitamente relacionados com a resposta hormonal ao treinamento de força pode ser importante para o estabelecimento de uma sessão de treino e uma periodização que otimizem o ambiente anabólico determinado pelas concentrações de testosterona e cortisol, e, dessa forma, maximizar os ajustes neuromusculares decorrentes desse tipo de treinamento.

This study aims to review the results found in the literature concerning a variety of factors related to the acute and chronic hormonal response to strength training. It has been observed that there is a close relationship between the trainability of individuals submitted to strength training and the circulating testosterone levels in these subjects. Moreover, other hormonal parameters, such as the ratios between testosterone and its binding protein and between testosterone and cortisol, were also related to the ability to increase strength. Besides the characteristics of the population investigated, several factors associated with the training session affect the acute and chronic hormonal response to training. Among them, volume and intensity are the main variables associated with the magnitude of this response. Determining which factors might be closely related to the hormonal response to strength training may be important to establish a training session and a periodization that optimize the anabolic environment determined by the testosterone and cortisol concentrations, and thus enhance the neuromuscular adaptations resulting from this type of training.

Estimulação tátil-cinestésica: uma integração entre pele e sistema endócrino? / Tactile-kinesthetic stimulation: integration between skin and endocrine system?

Apresenta-se uma revisão da literatura sobre os aspectos neuroendócrinos da pele e as conseqüências da estimulação tátil-cinestésica sobre o córtex adrenal. Os artigos foram identificados a partir das bases de dados MEDLINE e LILACS, usando as palavras-chave "córtex supra-renal", "pele", "massagem", "lactentes", "glicocorticóide" e "ritmo circadiano". O período pesquisado foi de 1990 a 2003. Foram também consultados artigos de destaque publicados antes desse período. Estudos reconhecem o hipotálamo, a hipófise e a glândula adrenal como órgãos dinâmicos durante o desenvolvimento fetal e neonatal, e que respostas de estresse estão presentes ao nascer. A maioria dos estudos revisados, utilizando a estimulação tátil-cinestésica, seja em humanos ou animais, evidencia a capacidade da pele em metabolizar, coordenar e organizar estímulos externos, procurando manter a homeostase interna e externa, demonstrando a interação entre sistema neuroendócrino e a pele. A estimulação tátil-cinestésica parece ter um efeito sobre a reatividade hormonal, porém essa questão merece uma investigação mais aprofundada.

A literature review on skin neuroendocrine aspects and the consequences of the tactile- kinesthetic stimulation on the adrenal cortex are presented. The articles were identified through MEDLINE and LILACS data bases, using the keywords "suprarenal cortex", "skin", "massage", "infants", "glucocorticoid" and "circadian rhythm". Single articles published between 1990 and 2003 were considered, as well as outstanding ones prior to this period. Studies recognize that the hypothalamus, the pituitary and the adrenal gland are dynamic organs during fetal and neonatal development, and that stress responses are active at birth. Most of the studies reviewed, using tactile-kinesthetic stimulation, both in humans and animals, confirm skin's ability to metabolize, coordinate and organize external stimuli, attempting to maintain both external and internal homeostasis, demonstrating an interaction between the neuroendocrine system and tactile stimulation. Tactile-kinesthetic stimulation seems to have an effect on hormonal reactivity, although the issue demands further investigation.

Endocrine characteristics of polycystic ovary syndrome (PCOS).

Polycystic ovary syndrome (PCOS) is probably the most prevalent endocrinopathy in women and the most common cause of anovulatory infertility. Patients with PCOS have clinical and biochemical features consistent with the ultrasound diagnosis and they are likely to face the problems of hyperandrogenism, subfertility and recurrent miscarriage. The aim of the present review is to summarize our present knowledge on the hormonal background of this very prevalent syndrome and to give some clinical examples how the present knowledge can be applied to treat PCOS patients according to their current problem, such as menstrual cycle disorder, hirsutism, infertility or to prevent late consequences as diabetes mellitus. The etiology and pathogenesis of PCOS is still a matter of controversies, but it is apparent that inappropriate gonadotropin secretion, obesity, hyperinsulinism and insulin resistance are the major determining factors in the development of ovarian hyperandrogenism an chronic anovulation. Reversal of insulin resistance in PCOS constitutes the fundamental goal in the management of hyperandrogenic anovulatory infertility and in the prevention of long-term consequences. The value of the insulin sensitizer metformin therapy awaits further evaluation and it should be integrated in the spectrum of therapeutical options that include the discussed surgical methods and GnRH analogues as well.

The neuroimmune-endocrine axis: pathophysiological implications for the central nervous system cytokines and hypothalamus-pituitary-adrenal hormone dynamics

Cytokines are molecules that were initially discovered in the immune system as mediators of communication between various types of immune cells. However, it soon became evident that cytokines exert profound effects on key functions of the central nervous system, such as food intake, fever, neuroendocrine regulation, long-term potentiation, and behavior. In the 80's and 90's our group and others discovered that the genes encoding various cytokines and their receptors are expressed in vascular, glial, and neuronal structures of the adult brain. Most cytokines act through cell surface receptors that have one transmembrane domain and which transduce a signal through the JAK/STAT pathway. Of particular physiological and pathophysiological relevance is the fact that cytokines are potent regulators of hypothalamic neuropeptidergic systems that maintain neuroendocrine homeostasis and which regulate the body's response to stress. The mechanisms by which cytokine signaling affects the function of stress-related neuroendocrine systems are reviewed in this article.

Estresse: interações neuroendócrinas e imunológicas / Stress: Neuroendocrine and immune interactions

O estresse é fenômeno de crescente interesse científico no qual se evidência a inter-relação entre os sistemas fisiológicos na manutenção da hemeostase. Muitos dados demonstram que informações (na forma de citocinas, neurotransmissores ou mesmo impulsos nervosos) são permutados entre os diveros órgãos durante o estresse. O estresse assim como a resposta imune são mecanismos de adaptação que apresentam elementos comuns na filogênese. são discutidos alguns pontos polêmicos do estresse e a importante interação, observada durante o fenômeno, entre o sistema nervoso, o sistema endócrino e, em particular, o sistema imune. Procura-se demonstrar que além da intuição e do empirismo a relação do estresse com a resposta imune e baseada em evidências sólidas das ciências contemporâneas