Brain morphometry and estimation of aging brain in subjects with congenital untreated isolated GH deficiency.

PURPOSE: Individuals with isolated GH deficiency (IGHD) due to a mutation in the GHRH receptor gene have a normal life expectancy and above 50 years of age, similar total cognitive performance, with better attention and executive function than controls. Our objectives were to evaluate their brain morphometry and brain aging using MRI. METHODS: Thirteen IGHD and 14 controls matched by age, sex, and education, were enrolled. Quantitative volumetric data and cortical thickness were obtained by automatic segmentation using Freesurfer software. The volume of each brain region was normalized by the intracranial volume. The difference between the predicted brain age estimated by MRI using a trained neuronal network, and the chronological age, was obtained. p < 0.005 was considered significant and 0.005 < p < 0.05 as a suggestive evidence of difference. RESULTS: In IGHD, most absolute values of cortical thickness and regional brain volumes were similar to controls, but normalized volumes were greater in the white matter in the frontal pole and in the insula bilaterally, and in the gray matter, in the right insula and in left Caudate (p < 0.005 for all comparisons) We also noticed suggestive evidence of a larger volume in IGHD in left thalamus (p = 0.006), right thalamus (p = 0.025), right caudate (p = 0.046) and right putamen (p = 0.013). Predicted brain ages were similar between groups. CONCLUSION: IGHD is primarily associated with similar absolute brain measurements, and a set of larger normalized volumes, and does not appear to alter the process of brain aging.

Set7 Deletion Prevents Glucose Intolerance and Improves the Recovery of Cardiac Function After Ischemia and Reperfusion in Obese Female Mice.

BACKGROUND/AIMS: An obesogenic diet (high fat and sugar, low fiber) is associated with an increased risk for metabolic and cardiovascular disorders. Previous studies have demonstrated that epigenetic changes can modify gene transcription and protein function, playing a key role in the development of several diseases. The methyltransferase Set7 methylates histone and non-histone proteins, influencing diverse biological and pathological processes. However, the functional role of Set7 in obesity-associated metabolic and cardiovascular complications is unknown. METHODS: Wild type and Set7 knockout female mice were fed a normal diet or an obesogenic diet for 12 weeks. Body weight gain and glucose tolerance were measured. The 3T3-L1 cells were used to determine the role of Set7 in white adipogenic differentiation. Cardiac morphology and function were evaluated by histology and echocardiography. An ex vivo Langendorff perfusion system was used to model cardiac ischemia/reperfusion (I/R). RESULTS: Here, we report that Set7 protein levels were enhanced in the heart and perigonadal adipose tissue (PAT) of female mice fed an obesogenic diet. Significantly, loss of Set7 prevented obesogenic diet-induced glucose intolerance in female mice although it did not affect the obesogenic diet-induced increase in body weight gain and adiposity in these animals, nor did Set7 inhibition change white adipogenic differentiation in vitro. In addition, loss of Set7 prevented the compromised cardiac functional recovery following ischemia and reperfusion (I/R) injury in obesogenic diet-fed female mice; however, deletion of Set7 did not influence obesogenic diet-induced cardiac hypertrophy nor the hemodynamic and echocardiographic parameters. CONCLUSION: These data indicate that Set7 plays a key role in obesogenic diet-induced glucose intolerance and compromised myocardial functional recovery after I/R in obese female mice.

The orphan receptor GPR68 is expressed in the hypothalamus and is involved in the regulation of feeding.

Currently, up to 35% off all drugs approved for the treatment of human diseases belong to the G-protein-coupled receptor (GPCR) family. Out of the almost 800 existing GPCRs, 25% have no known endogenous ligands and are regarded as orphan receptors; many of these are currently under investigation as potential pharmacological targets. Here, we hypothesised that orphan GPCRs expressed in the hypothalamus could be targets for the treatment of obesity and other metabolic diseases. Using bioinformatic tools, we identified 78 class A orphan GPCRs that are expressed in the hypothalamus of mice. Initially, we selected two candidates and determined their responsivities to nutritional interventions: GPR162, the GPCR with highest expression in the hypothalamus, and GPR68, a GPCR with intermediate expression in the hypothalamus and that has never been explored for its potential involvement in metabolic regulation. GPR162 expression was not modified by fasting/feeding or by the consumption of a high-fat diet, and was therefore not subsequently evaluated. Conversely, GPR68 expression increased in response to the consumption of a high-fat diet and reduced under fasting conditions. Using immunofluorescence, GPR68 was identified in both proopiomelanocortin-expressing and agouti-related peptide-expressing neurons in the hypothalamic arcuate nucleus. Acute inhibition of GPR68 with an allosteric modulator promoted an increase in the expression of the orexigenic agouti-related peptide and neuropeptide Y, whereas 4- and 12-h inhibition of GPR68 resulted in increased caloric intake. Thus, GPR68 has emerged as an orphan GPCR that is expressed in the hypothalamus and is involved in the regulation of feeding.

Interleukin-17 acts in the hypothalamus reducing food intake.

Interleukin-17 (IL-17) is expressed in the intestine in response to changes in the gut microbiome landscape and plays an important role in intestinal and systemic inflammatory diseases. There is evidence that dietary factors can also modify the expression of intestinal IL-17. Here, we hypothesized that, similar to several other gut-produced factors, IL-17 may act in the hypothalamus to modulate food intake. We confirm that food intake increases IL-17 expression in the mouse ileum and human blood. There is no expression of IL-17 in the hypothalamus; however, IL-17 receptor A is expressed in both pro-opiomelanocortin (POMC) and agouti-related peptide (AgRP) neurons. Upon systemic injection, IL-17 promoted a rapid increase in hypothalamic POMC expression, which was followed by a late increase in the expression of AgRP. Both systemic and intracerebroventricular injections of IL-17 reduced calorie intake without affecting whole-body energy expenditure. Systemic but not intracerebroventricular injection of IL-17 increase brown adipose tissue temperature. Thus, IL-17 is a gut-produced factor that is controlled by diet and modulates food intake by acting in the hypothalamus. Our findings provide the first evidence of a cytokine that is acutely regulated by food intake and plays a role in the regulation of eating.

Resilient hepatic mitochondrial function and lack of iNOS dependence in diet-induced insulin resistance.

Obesity-derived inflammation and metabolic dysfunction has been related to the activity of the inducible nitric oxide synthase (iNOS). To understand the interrelation between metabolism, obesity and NO., we evaluated the effects of obesity-induced NO. signaling on liver mitochondrial function. We used mouse strains containing mitochondrial nicotinamide transhydrogenase activity, while prior studies involved a spontaneous mutant of this enzyme, and are, therefore, more prone to oxidative imbalance. Wild-type and iNOS knockout mice were fed a high fat diet for 2, 4 or 8 weeks. iNOS knockout did not protect against diet-induced metabolic changes. However, the diet decreased fatty-acid oxidation capacity in liver mitochondria at 4 weeks in both wild-type and knockout groups; this was recovered at 8 weeks. Interestingly, other mitochondrial functional parameters were unchanged, despite significant modifications in insulin resistance in wild type and iNOS knockout animals. Overall, we found two surprising features of obesity-induced metabolic dysfunction: (i) iNOS does not have an essential role in obesity-induced insulin resistance under all experimental conditions and (ii) liver mitochondria are resilient to functional changes in obesity-induced metabolic dysfunction.

Combined treatment with melatonin and insulin improves glycemic control, white adipose tissue metabolism and reproductive axis of diabetic male rats.

AIMS: Melatonin treatment has been reported to be capable of ameliorating metabolic diabetes-related abnormalities but also to cause hypogonadism in rats. We investigated whether the combined treatment with melatonin and insulin can improve insulin resistance and other metabolic disorders in rats with streptozotocin-induced diabetes during neonatal period and the repercussion of this treatment on the hypothalamic-pituitary-gonadal axis. MAIN METHODS: At the fourth week of age, diabetic animals started an 8-wk treatment with only melatonin (0.2 mg/kg body weight) added to drinking water at night or associated with insulin (NHP, 1.5 U/100 g/day) or only insulin. Animals were then euthanized, and the subcutaneous (SC), epididymal (EP), and retroperitoneal (RP) fat pads were excised, weighed and processed for adipocyte isolation for morphometric analysis as well as for measuring glucose uptake, oxidation, and incorporation of glucose into lipids. Hypothalamus was collected for gene expression and blood samples were collected for biochemical assays. KEY FINDINGS: The treatment with melatonin plus insulin (MI) was capable of maintaining glycemic control. In epididymal (EP) and subcutaneous (SC) adipocytes, the melatonin plus insulin (MI) treatment group recovered the insulin responsiveness. In the hypothalamus, melatonin treatment alone promoted a significant reduction in kisspeptin-1, neurokinin B and androgen receptor mRNA levels, in relation to control group. SIGNIFICANCE: Combined treatment with melatonin and insulin promoted a better glycemic control, improving insulin sensitivity in white adipose tissue (WAT). Indeed, melatonin treatment reduced hypothalamic genes related to reproductive function.

The PI3K signaling pathway mediates the biological effects of leptin / A via de sinalização intracelular da PI3K medeia os efeitos biológicos da leptina

The activation of the leptin receptor recruits several intracellular signaling pathways, including the phosphatidylinositol 3-kinase (PI3K) pathway. While some of the leptin-induced signaling pathways, such as the JAK2/STAT3 pathway, induce cellular responses primarily through changes in gene expression, the PI3K pathway affects cellular properties more rapidly, through post-translational changes such as protein phosphorylation. Accordingly, several studies have shown that the PI3K pathway is required for the acute effects of leptin, such as a leptin-induced decrease in food intake. Leptin signaling through PI3K also affects the electrophysiological properties of neurons, including changes in their membrane potential and firing rates. In this review, we summarize the recent advances in our understanding of the role played by the PI3K signaling pathway in controlling food intake and energy balance. In particular, we focus on the importance of the PI3K signaling pathway as a mediator of the effects of leptin on hypothalamic neurons.

A ativação do receptor de leptina recruta diversas vias de sinalização intracelular, entre elas a via da fosfatidilinositol 3-quinase (PI3K). Enquanto algumas dessas vias, como a sinalização pelo JAK2/STAT3, induzem respostas celulares por meio de mudanças na transcrição gênica, a via da PI3K altera propriedades celulares de forma rápida, via fosforilação de proteínas. Em concordância, estudos mostraram que a via da PI3K é necessária para que a leptina induza seus efeitos agudos, como redução da ingestão alimentar, após administração de leptina. A ativação da PI3K pela leptina também afeta as propriedades fisiológicas de neurônios, incluindo mudanças no potencial de membrana e no potencial de ação. Nesta revisão, resumimos os recentes avanços na compreen-são do papel desempenhado pela via de sinalização da PI3K no controle da ingestão alimentar e do balanço energético. Discutimos, principalmente, como a via da PI3K é importante para mediar os efeitos da leptina sobre os neurônios hipotalâmicos.

Dieta rica em proteína na redução do peso corporal / High-protein diet for body weight loss

A proporção ideal dos macronutrientes em dietas de emagrecimento é atualmente bastante discutida. Existem evidências de que dietas com maior proporção de proteína aumentam a perda de peso e de gordura corporal e diminuem a perda de massa corporal magra durante o emagrecimento. Todavia, os mecanismos responsáveis por estes efeitos não estão totalmente esclarecidos. Além disso, existem poucas conclusões a respeito dos possíveis efeitos colaterais dessas dietas na função renal e no estado nutricional relativo ao cálcio. Assim, este artigo objetiva trazer informações atuais sobre os efeitos de dietas ricas em proteína na perda de peso e na composição corporal e dos mecanismos envolvidos, bem como seus efeitos na função renal e no estado nutricional relativo ao cálcio.

The ideal proportion of macronutrients in weight loss diets is currently under debate. There are evidences indicating that a higher proportion of protein during weight loss diets enhances the loss of body weight and fat mass, and reduces the loss of lean body mass. Nevertheless, the responsible mechanisms for these effects have not yet been fully elucidated. Furthermore, studies that evaluated the possible side effects of these diets on the renal function and on the nutritional state of calcium have shown inconclusive results. Therefore, this article has the objective to convey recent information about the effects of high-protein diets in the regulation of the body weight and body composition, besides its involved mechanisms, and its effects on the renal function and on the calcium nutritional status.

Hormônio do crescimento e exercício físico: considerações atuais: [revisão] / Growth hormone and physical exercise: current considerations: [revision]

Embora o hormônio do crescimento (GH) seja um dos hormônios mais estudados, vários de seus aspectos fisiológicos ainda não estão integralmente esclarecidos, incluindo sua relação com o exercício físico. Estudos mais recentes têm aumentado o conhecimento a respeito dos mecanismos de ação do GH, podendo ser divididos em: 1) ações diretas, mediadas pela rede de sinalizações intracelulares, desencadeadas pela ligação do GH ao seu receptor na membrana plasmática; e 2) ações indiretas, mediadas principalmente pela regulação da síntese dos fatores de crescimento semelhantes à insulina (IGF). Tem sido demonstrado que o exercício físico é um potente estimulador da liberação do GH. A magnitude deste aumento sofre influência de diversos fatores, em especial, da intensidade e do volume do exercício, além do estado de treinamento. Atletas, normalmente, apresentam menor liberação de GH induzida pelo exercício que indivíduos sedentários ou pouco treinados. Evidências experimentais demonstram que o GH: 1) favorece a mobilização de ácidos graxos livres do tecido adiposo para geração de energia; 2) aumenta a capacidade de oxidação de gordura e 3) aumenta o gasto energético.

Although growth hormone (GH) is one of the most extensively studied hormones, various aspects related to this hormone have not been completely established, including its relationship with physical exercise. Recent studies have contributed to the understanding of the mechanisms of action of GH, which can be divided into 1) direct actions mediated by intracellular signals that are triggered by the binding of GH to its receptor on the plasma membrane, and 2) indirect actions mediated mainly by the regulation of the synthesis of insulin-like growth factors (IGF). Physical exercise has been shown to be a potent stimulator of GH release, especially in young men and women. The magnitude of this increase is influenced by several factors, especially the intensity and volume of exercise, in addition to training status. In this respect, athletes normally present a lower exercise-induced GH release than sedentary or poorly trained individuals. Experimental evidence indicates that GH may 1) favor the mobilization of free fatty acids from adipose tissue for energy generation, 2) increase the capacity of fat oxidation, and 3) increase energy expenditure.

Leptina: aspectos sobre o balanço energético, exercício físico e amenorréia do esforço / Leptin: aspects on energetic balance, physical exercise and athletic amenorhea

O presente manuscrito teve por objetivo realizar uma revisão bibliográfica acerca do papel da leptina no balanço energético, no exercício físico e na incidência da amenorréia do esforço. A leptina é um hormônio secretado pelo tecido adiposo, reconhecido principalmente por sua ação adipostática sobre o sistema nervoso central. Esse hormônio sinaliza o hipotálamo a respeito das reservas energéticas, modulando o funcionamento dos eixos hormonais que envolvam o hipotálamo e a hipófise. A leptina tem ainda ações periféricas importantes, incluindo seu papel sobre o tecido ovariano. Os mecanismos de sinalização intracelular desse hormônio foram identificados no hipotálamo, porém em tecidos periféricos há necessidade de maiores investigações. Existe certo consenso de que quando o exercício e a ingestão alimentar são capazes de promover um balanço energético negativo, as concentrações plasmáticas de leptina diminuem, alterando conseqüentemente: a liberação hipotalâmica de GnRH (fator hipotalâmico de liberação de gonadotrofinas); a liberação hipofisária de LH (hormônio luteinizante) e FSH (hormônio folículo-estimulante). Como resultado, há menor liberação de estrógenos ovarianos. Esse processo pode iniciar a chamada amenorréia hipotalâmica funcional, com repercussões na saúde da mulher. Nessa perspectiva, a avaliação do gasto energético e a elaboração de um plano alimentar adequado em atletas são fundamentais.

The aim of this manuscript was to review the knowledge about leptin, detailing its relationship with energetic intake and physical activity. Leptin is an adipocyte hormone, recognized mainly for its putative role in control of energy expenditure, food intake, body weight and reproductive function. Leptin has still important peripheral actions, including its role on the ovarian tissue. The intracellular signaling mechanisms are recognized in hypothalamus, but in peripheral tissue are not fully understood. The exercise, when practiced by women, if not appropriately planned according to food intake, can modify the leptin release. When energy imbalances induced by exercise and/or deficient food ingestion occurs, low leptin levels are observed, leading to a reduction in GnRH (gonadotropin-release hormone), in LH (luteinizing hormone) and FSH (follicle-stimulating hormone) in pituitary, and consequently a minor release of ovarian estrogens. This process is named hypothalamic amenorrhea, and has repercussions in the woman's health. In this perspective, it is important to emphasize the need to evaluate the energy expenditure from exercise and to formulate adequate alimentary plans to these individuals.

Aspectos atuais da regulação do peso corporal: ação da leptina no desequilíbrio energético / Recent aspects of body weight regulation: leptin's action on the enrgetic misbalance

A obesidade já é considerada epidemia global, com taxas de insucesso em seu tratamento a longo prazo de mais de 90 por cento. A descoberta da leptina, um peptídeo sintetizado principalmente pelos adipócitos, abriu novas fronteiras no estudo do tratamento da obesidade. Constatou-se que a leptina, por meio do controle de sua concentração na circulação, poderia ser um sinalizador do estado energético e do tamanho das reservas de gordura, ao atuar em um circuito de retroalimentação, cuja função é de manter o peso corporal estável, independentemente de variações diárias no consumo de energia. Porém, esse circuito apresenta falhas na maioria dos indivíduos que se tornam obesos (baixa responsividade pela alta concentração de leptina que esses indivíduos apresentam), o que levou à hipótese da ®resistência à leptina¼...