Saciación vs saciedad: reguladores del consumo alimentario / Satiation and satiety in the regulation of energy intake

The study of the factors that regulate high energy food intake is especially relevant nowadays due to the high prevalence of overweight and obesity. Food intake regulation can be divided in two basic processes, namely satiation and satiety. Satiation is the process that determines the moment in which feeding stops and regulates the amount of ingested food during a single meal. Satiety is the interval between meals and regulates the time elapsed between two meals. The longer the interval, the lower energy intake. Each of these processes are regulated by different factors, which are here reviewed.

A new approach to feed frequency studies and protein intake regulation in juvenile pirarucu

ABSTRACT This study aimed to investigate pirarucu's (Arapaima gigas) ability to trigger a self-feeding system to regulate protein intake between two standard diets that contained 39% and 49% of crude protein. The same system allowed the evaluation of daily feeding and locomotor activity rhythms. Eighteen fish (654.44±26.85g) were distributed into six 250 L tanks (3 fish/tank). Fish had free access to both diets (39% vs. 49% protein) by feeders (2 per tank), adapted to be activated by fish themselves. This system was connected to a computer system. After an adaptation period, fish learned to activate feeders and the mean food intake recorded was 2.14% of their body weight on a daily basis. Fish showed feeding (72.48%) and locomotor (72.49%) activity predominantly during the daytime, and daily variations of choice between diets, but fixed a protein intake feeding target at 44.53%. These results should be considered when discussing feeding behavior, feeding schedules and diet intake regulations.

Sinalização cerebral do apetite: [revisão] / Appetite brain sinalization: [review]

JUSTIFICATIVA E OBJETIVOS: Os mecanismos de controle do apetite têm sido estudados, focados principalmente nas funções hipotalâmicas, regulando o aspecto metabólico da alimentação. O objetivo deste estudo foi demonstrar alguns dos principais mecanismos reguladores centrais do apetite, incluindo suas conexões com centros corticais superiores. CONTEÚDO: Os sistemas de controle do apetite estão muito mais voltados para o armazenamento energético do que para a perda de peso. O desejo de comer, os estímulos olfatórios, visuais, de memória e de recompensa passam por centros superiores, em regiões de córtex órbitofrontal, núcleo accumbens, pálido ventral, dentre outras numerosas estruturas, modulando assim o apetite. CONCLUSÃO: A compreensão desses mecanismos não só hipotalâmicos, mas também corticais do apetite abrem novos alvos terapêuticos para o tratamento da obesidade.

BACKGROUND AND OBJECTIVES: The mechanisms that control the appetite have been studied mainly focusing on the hypothalamic functions, which regulates the metabolic aspects of feeding. We will describe others cerebral connections in foodintake regulation. CONTENTS: Systems appetite control is much more focused on the energy storage than for weight loss. The desire to eat, olfactorystimuli, visual, memory and reward go through highercenters in regions of orbitofrontal cortex, nucleus accumbens, ventral pallidum, among numerous other structures, thereby modulating the appetite. CONCLUSION: Understanding these mechanisms not only hypothalamic but also cortical, opens new therapeutic targets for the treatment of obesity.

Hypothalamic regulation of food intake and clinical therapeutic applications: [review] / Regulação hipotalâmica da ingestão alimentar e suas aplicações terapêuticas clínicas: [revisão]

Current estimates suggest that over 1 billion people are overweight and over 300 million people are obese. Weight gain is due to an imbalance between energy expenditure and dietary intake. This review discusses the hypothalamic control of appetite and highlights key developments in research that have furthered our understanding of the complex pathways involved. Nuclei within the hypothalamus integrate peripheral signals such as adiposity and caloric intake to regulate important pathways within the central nervous system controlling food intake and energy expenditure. Firmly established pathways involve the orexigenic NPY/AgRP and the anorexigenic POMC/CART neurons in the arcuate nucleus (ARC) of the hypothalamus. These project from the ARC to other important hypothalamic nuclei, including the paraventricular, dorsomedial, ventromedial and lateral hypothalamic nuclei. In addition there are many projections to and from the brainstem, cortical areas and reward pathways, which modulate food intake.

As estimativas atuais sugerem que mais de 1 bilhão de pessoas apresentam sobrepeso e 300 milhões são obesas. O ganho de peso representa um desequilíbrio entre o gasto energético e o consumo alimentar. Esta revisão discute o controle hipotalâmico do apetite e destaca os pontos-chave no desenvolvimento de pesquisas para ampliar o nosso entendimento dos complexos mecanismos envolvidos nesta regulação. Núcleos situados no hipotálamo integram uma série de sinais com o sistema nervoso central controlando a ingestão alimentar e o gasto energético. As vias mais estabelecidas envolvem os neurônios orexigênicos NPY/AgRP e os neurônios anorexigênicos POMC/CART no núcleo arqueado (ARC) do hipotálamo. Esses neurônios se projetam do ARC para outros importantes núcleos hipotalâmicos, tais quais: paraventricular, dorsomedial, ventromedial e lateral. Além disso, existem várias projeções que vão e vem do tronco cerebral, das áreas corticais e das vias de retroalimentação que modulam o consumo alimentar.

Rol del estómago en la regulación del apetito: la ghrelina en condiciones fisiológicas y en patología digestiva / Role of the stomach in the regulation of the appetite: ghrelin in physiologic conditions and digestive disorders

El cerebro regula la homeostasis energética en respuesta a señales del tracto gastrointestinal y adiposo. La vía de ingesta y el gasto energético se ajustan constantemente, manteniéndose así el peso de manera estable. La ghrelina es una hormona peptídica que estimula el apetito actuando a nivel del núcleo arquato, región conocida por controlar la ingesta de alimento. Se secreta desde el estómago y circula en el plasma bajo condiciones de ayuno. Su regulación depende de varios mecanismos como son, hormonas, control autonómico, nutrientes sanguíneos y el ejercicio. Además la ghrelina juega un rol importante para mantener la secreción de la hormona de crecimiento. Se analizan cambios observados en varias patologías gastroduodenales.

The brain regulates energy homeostasis in response to signals from both adipose and the gastrointestinal tract. The drive to eat and energy expenditure are adjusted so that over time, body weight remains stable. Ghrelin is a peptide hormone that stimulates appetite by acting on the arquate nucleus, a region known to control food intake. It is secreted from the stomach and circulates in the bloodstream under fasting conditions. Its regulation depends on a variety of mechanisms such as, hormones, autonomic control, bloodstream nutrients and exercise. Ghrelin also play an important role in growth hormone release. Ghrelin changes observed in several gastro duodenal disorders are analyzed.

Tabagismo e variação ponderal: a fisiopatologia e genética podem explicar esta associação?: [revisão] / Smoking and changes in body weight: can physiopathology and genetics explain this association?: [review]

O tabagismo é a principal causa de morte prevenível na maioria dos países, inclusive no Brasil. Parar de fumar é uma estratégia importante para reduzir a morbidade e mortalidade associada às doenças tabaco-relacionadas. Sabe-se da relação inversa entre uso de nicotina e peso corporal, onde o índice de massa corporal tende a ser menor em fumantes quando comparados aos não fumantes. Além disso, abstinência tabágica resulta em aumento de peso, sendo que ex-fumantes geralmente aumentam de 5 a 6 kg, mas cerca de 10 por cento adquirem mais de 10 kg. O tratamento farmacológico para a cessação do tabagismo pode atenuar este ganho de peso. O aumento de peso na cessação do tabagismo como contributório à epidemia de obesidade é pouco estudado. Nos EUA, calcula-se que a fração do problema atribuível à cessação do tabagismo seja de 6 por cento para homens e 3,2 por cento para mulheres. Os mecanismos não são claros, mas há evidências mostrando que a dopamina e serotonina diminuem a ingestão alimentar. A administração de nicotina por qualquer via eleva agudamente os níveis destes neurotransmissores no cérebro, causando menor necessidade de ingestão energética e diminuindo o apetite. Além disso, a nicotina tem efeito direto no metabolismo do tecido adiposo, influenciando a taxa de ganho ponderal após a cessação do tabagismo. A leptina, grelina e neuropeptídio Y são peptídeos que podem contribuir para esta relação inversa entre nicotina e índice de massa corporal, em um papel ainda não determinado como conseqüente ou causador das variações ponderais.

Tobacco use is the leading preventable cause of death in most countries, including Brazil. Smoking cessation is an important strategy for reducing the morbidity and mortality associated with tobacco-related diseases. An inverse relationship between nicotine use and body weight has been reported, in which body weight tends to be lower among smokers than among nonsmokers. Smoking abstinence results in an increase in body weight for both males and females. On average, sustained quitters gain from 5 to 6 kg, although approximately 10 percent gain more than 10 kg. Pharmacological treatment for smoking cessation attenuates weight gain. The importance of smoking cessation as a contributing cause of the current obesity epidemic has been little studied. In the USA, the rate of obesity attributable to smoking cessation has been estimated at approximately 6.0 and 3.2 percent for males and females, respectively. Although the mechanisms are unclear, there is evidence that dopamine and serotonin are appetite suppressants. The administration of nicotine, regardless of the delivery system, acutely raises the levels of these neurotransmitters in the brain, reducing the need for energy intake and consequently suppressing appetite. In addition, nicotine has a direct effect on adipose tissue metabolism, influencing the rate of weight gain following smoking cessation. Leptin, ghrelin and neuropeptide Y are substances that might constitute factors involved in the inverse relationship between nicotine and body mass index, although their roles as determinants or consequences of this relationship have yet to be determined.

Effect of food on immature development, consumption rate, and relative growth rate of Toxorhynchites splendens ( Diptera: Culicidae ), a predator of container breeding mosquitoes

Food utilization by the larvae of Toxorhynchites splendens (Wiedemann) was studied in the laboratory by offering larvae of Aedes aegypti Linnaeus, Anopheles stephensi (Liston), and Culex quinquefasciatus (Say). Quantitative analyses of data indicated that immature development was significantly faster with increase in food availability. The regression analysis showed that the degrees of the relationship between immature duration (Id) and food availability were higher when offered early instars of prey (first and second instars) than late instars. Consumption rate (Cr) of the predator increased with increase in food availability and this relationship was highly significant when larvae of An. stephensi were offered as food. Consumption rate to food level decreased with increase in the age class of the prey. There was a significant negative correlation between Id and Cr. This aspect helps to increase population turnover of T. splendens in a shorter period when the prey is abundant. Conversely, the predator compensated the loss in daily food intake at low food level by extending Id thereby attains the minimum threshold pupal weight for adult emergence. There was an increase in the relative growth rate (RGR) of the predator when An. stephensi was offered as prey and this was related to the high protein content of the prey per body weight. There was a positive correlation between Cr and RGR. This adaptive life characteristic strategy of this predator is useful for mass-rearing for large scale field release programmes in the control of container breeding mosquitoes is discussed.

Determinantes dietéticos da ingestão alimentar e efeito na regulação do peso corporal / Dietetic determinants on food intake and effects in body weight regulation

Obesity is a multifactorial pathology currently considered one of the main public health problems. Its prevalence is increasing dramatically in the last decades, reaching huge rates in Brazil and many other countries. Regardless of the factors associated with genetic predisposition, this pathology is often associated with abnormal food intake, and also with high consumption of caloric foods and sedentary habits. Thus, obesity is the result of an imbalance between food intake and energy expenditure. One of the greatest research interests in nutrition has currently been the dietetic determinants that may exert an influence on the process of food intake, as well as the role of foods on physiological, physical and chemical factors most related to the processes of satiation and satiety. Based on these aspects, this paper analyzes several research works to gain a better insight of the dietetic factors affecting food intake and body weight regulation.

Leptina: o diálogo entre adipócitos e neurônios / Leptine: the dialog between adipocytes and neurons

A descoberta da leptina trouxe consigo um interesse renovado sobre o estudo do controle homeostático da energia. Sabe-se agora que o tecido adiposo branco é o maior sítio de produção da leptina. Uma vez na circulação sangüínea ela se liga a receptores específicos no cérebro, levando ao sistema nervoso central um sinal de saciedade que reflete a quantidade existente de energia em forma de gordura no organismo. Agindo por intermédio de receptores que fazem uso da via JAK/SAT de transdução do sinal intracelular, a leptina modifica a expressão e a atividade de inúmeros peptídeos hipotalâmicos que regulam o apetite e o gasto de energia. Além disso, a leptina sinaliza o estado nutricional do organismo a outros sistemas fisiológicos, modulando a função de várias glândulas alvo. Mais recentemente, a leptina recombinante foi administrada com sucesso numa paciente obesa com deficiência do hormônio devido a uma mutação do gene ob. Por outro lado, os efeitos da leptina recombinante no único estudo em pacientes com obesidade e concentrações elevadas de leptina foram menos impressionantes. Nesta revisão, discutiremos a complexidade das ações da leptina com ênfase no seu papel integrativo de sinalizadora do estado nutricional para o organismo.

Nuevos fármacos para el tratamiento de la obesidad / New drugs in obesity treatment

Obesity is an increasingly prevalent health problem. Since 1995 there has been an explosion of research focosed on the regulation of energy balance and fat mass. Characterization of obesity gene products has revealed new biochemical pathways and molecular targets for pharmacological intervention that will lead to new treatments. We hope these will be viewed as adjuncts to behavioral and lifestyle changes aimed at maintenance of wight loss

Evaluación del consumo de leche humana por dilución con deuterio y detección por espectroscopia de infrarrojo / Assessment of human milk consumption by dilution with deuterium and detection by infrared spectroscopy

Objetivo. Adaptar la metodología de evaluación de ingestión de leche humana con isótopos estables utilizando un espectroscopio infrarrojo en lugar de un espectrómetro de masas. Material y métodos. Previo consentimiento informado, 12 mujeres que estaban amamantando recibieron 30 g de D2O por vía oral. a las 4 horas y 1, 3, 6, 9 y 14 días depués de la dosificación, se les tomó una muestra de saliva. Las muestras de saliva de los bebés se tomaron a los 1,2,5,6,13 y 14 días. Todas las muestras fueron preparadas por sublimación y centrifucación y la determinación de la concentración de D2O se determinó por espectroscopía de infrarrojo. Resultados. La recuperación del sistema de sublimación fue superior al 95 por ciento del volumen total tanto de agua sola como de saliva. Se encontró que con tres evaluaciones se alcanza la misma confiabilidad que con 5 evaluaciones. Los volúmenes de ingestión de leche humana fueron similares a los informados por otros autores

Physiological, biochemical and molecular mechanisms of salt appetite control by mineralocorticoid action in brain

Adrenocortical hormone effects in the central nervous system depend on steroid interaction with intracellular receptors, which belong to a superfamily of ligand-activated transcription factors. Using a combination of biochemical and molecular biology techniques, we have demonstrated: 1. the localization of mineralocorticoid receptors in the brain, with highest density present in hippocampus, lateral septum and some amygdaloid nuclei; 2. the arousal of a mineralocorticoid-specific behavior such as salt appetite, coincident with inhibition of the biosynthesis/activity of (Na+K)ATPase in some amygdaloid and hypothalamic nuclei; 3. the modulation of the biosynthesis/activity of the sodium pump by glucocorticoids, although for these hormones changes are stimulatory, as shown in the spinal cord and brain; 4. the reported steroid effects on the (Na+K)ATPase constitute an important mechanism of control of nervous system function, involving behavior, changes in excitability and neurotropism

Possible action of intracerebroventricular thyrotropin on Brobeck's hypothesis.

The effect of ICV administered TSH on Brobeck's thermostatic hypothesis was evaluated by recording chronological changes in electrical activity of precise loci (POA, VMN and CO) coupled by rectal temperature changes in dogs. The study revealed 1. TSH action on thermoregulation is biphasic in nature. 2. This action of TSH is not an independent act but depends on the reaction of satiety centre.