El tejido adiposo, ¿solo un almacén de energía? / Adipose Tissue, Just an Energy Storage?

Resumen Cuando los alimentos cubren los requerimientos energéticos, el organismo almacena el exceso de calorías como glucógeno en el hígado y el músculo, y los triacilgliceroles en el tejido adiposo. Morfológica y funcionalmente se clasifica en blanco y pardo. El pardo tiene gran cantidad de mitocondrias, almacena los triacilgliceroles en vacuolas y disipa la energía en forma de calor; el blanco almacena energía en gotas lipídicas que ocupan la mayor parte de su volumen. Después de la ingesta de alimentos se libera insulina, lo que hace que externen GLUT4 para absorber glucosa. Los quilomicrones o las lipoproteínas de muy baja densidad (VLDL) transportan los triacilgliceroles a los depósitos de tejido adiposo. Durante el ayuno, por acción del glucagón, se liberan enzimas que degradarán a los tri, di y monogliceroles para liberar a los ácidos grasos. El tejido adiposo libera citocinas pro y antiinflamatorias, así como leptina, adiponectina que regulan el apetito y la saciedad. La proteína cinasa activada por AMP se activa como respuesta a una baja en la cantidad de energía de la célula y le ayuda a mantener un balance energético. En el adipocito promueve la degradación de los triacilgliceroles para liberar a los ácidos grasos que se emplearán como fuente energética. Se requiere de mayor cantidad de estudios para conocer más sobre la función del tejido adiposo como regulador del metabolismo y no solo como almacén de energía.

Abstract When food meets energy requirements, the body stores in the liver and in the muscle the excess of calories as glycogen and triacylglycerols in the adipose tissue. Morphologically and functionally, it is classified into white and brown tissues. Brown tissue has many large mitochondria and stores triacylglycerols in vacuoles and dissipates energy as heat; white tissue stores energy as lipid droplets that occupy most of the adipocyte's volume. After food intake insulin is released, which causes GLUT4 externalization into the cellular membrane to absorb glucose. Chylomicrons or VLDL transport triacylglycerols to adipose tissue depots. During fasting, by the action of glucagon, enzymes are released that will degrade tri-, di- and mono-glycerols to release fatty acids. Adipose tissue releases pro and anti-inflammatory cytokines, as well as leptin and adiponectin that regulate appetite and satiety. AMPK is activated in response to a decrease in the cell's energy and helps it to maintain its energetic balance. In the adipocyte, it promotes the degradation of triacylglycerols releasing fatty acids to be used as an energy source. More studies are needed to learn more about the function of adipose tissue as a regulator of the metabolism and not only as an energy storage.

Perfil lipídico sérico de ratos tratados com surfactante / Serum lipid levels of rats treated with surfactant

A aterosclerose é uma doença multifatorial, lenta e progressiva e a hiperlipidemia um dos fatores potenciais no desenvolvimento de doenças cardíacas ateroscleróticas. As vantagens da indução das dislipidemias experimentais são a produção de lesões ateromatosas em curto espaço de tempo; adequado controle dietético e fatores ambientais; a possibilidade de estudos sobre a reversibilidade de lesões ateroscleróticas e ensaios pré-clínicos de substâncias hipolipidêmicas. Este estudo visou avaliar o perfil lipídico sérico de ratos tratados com surfactante. Foram utilizados 28 ratos Wistar, machos, albinos, adultos e hígidos. Estes foram distribuídos em quatro grupos experimentais formados por sete animais cada, a saber: Grupo I – (controle); Grupo II – tratado com tyloxapol, na dose de 500 mg/kg de peso corporal, via intraperitoneal a cada 48 horas, durante duas semanas; Grupo III – tratado com tyloxapol na dose de 500 mg/kg de peso corporal, via intraperitoneal a cada 48 horas, durante três semanas; Grupo IV – tratado com tyloxapol na dose de 500 mg/kg de peso corporal, via intraperitoneal a cada 48 horas, durante quatro semanas. Na avaliação do perfil lipídico, os valores de triacilgliceróis e HDL demonstraram que o grupo III diferiu significativamente do grupo I e os valores de colesterol total e LDL indicaram que o grupo I diferiu significativamente dos grupos II, III e IV. Conclui-se que o surfactante tyloxapol foi efetivo na indução da hiperlipidemia.

Atherosclerosis is a multifactorial, progressive and slow disease, and hyperlipidaemia is one of the potential factors in the development of atherosclerotic cardiac diseases. The experimental dyslipidaemia carrying out advantages are the production of atheromatous lesions in a short period of time, an adequate dietetic control and environmental factors, the possibility of studies concerning reversibility of atherosclerotic lesions, and pre-clinic experiments with hypolipidaemic substances. This study aims at evaluating tyloxapol analyzing serum lipid levels. Twenty-eight healthy Wistar adults’ albino male rats, weighing an average of 200 g were utilized. They were distributed into four experimental groups with seven animals each, as follows: Group I – (control); Group II – treated with tyloxapol at a dose of 500mg/kg of body weight, through intraperitoneal via each 48 hours, for two weeks; Group III - treated with tyloxapol at a dose of 500mg/ kg of body weight, through intraperitoneal via each 48 hours, for three weeks; Group IV - treated with tyloxapol at a dose of 500mg/kg of body weight, through intraperitoneal via each 48 hours, for four weeks. As lipid profile evaluation is concerned, the values of triacylglycerols and HDL have indicated that group III has significantly differed from group I and the values of total cholesterol and LDL have indicated that group I has significantly differed from group II, III and IV. It was concluded that for the studied period the surfactant tyloxapol was effective to inducing hyperlipidaemia.

Comparative performance of lab tests and blood testing device to monitor glucose, total cholesterol and triacylglycerol in type 2 diabetic patients / Desempenho comparativo de testes de laboratório e de dispositivos de teste de sangue para monitorar glicose, colesterol total e triglicérides em pacientes diabéticos tipo 2

The performance of lab tests (LT) and blood testing devices (BTD) to monitor glycemia vs. glycated hemoglobin A1c (A1c) were compared. In addition, the performance of blood glucose, total cholesterol (TC) and triacylglycerol measured by LT and BDT were compared. All parameters were measured based on the same blood samples from overnight fasted type 2 diabetic patients (T2DP). Linear regression analysis was used for all comparisons. The results showed that A1c correlated better with LT-glucose (r = 0.58) than BTD-glucose (r = 0.42). Moreover, LT vs. BTD showed r values of 0.90, 0.82 and 0.92 for glucose, TC and triacylglycerol, respectively. It was concluded that the performance of LT-glucose was better than BDT-glucose. Moreover, since triacylycerol and TC measured by BTD correlated better with LT compared to BDT-glucose vs. LT-glucose, the inclusion of BTD-TC and BTD-triacylglycerol for detecting and monitoring hyperlipidemia in T2DP should be considered.

Comparou-se a performance de avaliação da glicemia através de dosagens laboratoriais (DL) ou dispositivo para teste de sangue capilar (DTSC) vs. hemoglobina glicada A1c (A1c). Comparou-se ainda a performance de avaliação da glicemia, colesterol total (CT) e triacilglicerol (DL vs. DTSC). Avaliou-se estes parametros a partir das mesmas amostras de sangue coletadas em pacientes diabéticos tipo 2 (PDT2) em jejum noturno, sendo as comparações realizadas através de análise de regressão linear. A A1c correlacionou-se melhor com a glicemia-DL (r = 0,58) em relação a glicemia-DTSC (r = 0,42). Comparou-se DL vs. DTSC obtendo se r = 0,90, 0,82 e 0,92 para glicemia, CT e triacilglicerol, respectivamente. Concluiu-se que houve melhor performance da glicose-DL em relação a glicose-DTSC. Além disso, considerando que o triacilglicerol e TC avaliado através de DTSC correlaciona-se melhor com DL em comparação a DTSC-glicose vs. DL-glicose, a inclusão de DTSC-TC e DTSC-triacilglicerol visando detectar e monitorar hyperlipidemia in PDT2 deve ser considerada.

Effect of acute dose of alcohol on the biochemical features of syndrome X in different categories of male and female Nigerian drinkers in apparent good health

Background: "Syndrome X", known since the 1980’s is a disease condition precipitated by insulin resistance. Insulin resistance causes glucose and insulin to accumulate in the blood. Syndrome X is characterized by abnormal values of triacylglycerol (TAG), blood pressure (BP), glucose and HDL-cholesterol-all risk factors for heart disease. Insulin resistance may be exacerbated by bad diet, poor lifestyle, absence of physical activity, genetic predisposition and being overweight. However, recent reports have shown that poor lifestyle is likely to be the main cause rather than bad diet or being overweight. Even though heavy consumption of alcohol could be regarded as a poor lifestyle, its relationship to the biochemical features and symptoms of Syndrome X in both genders is yet to be properly documented among Nigerian drinkers of alcohol. Methods: To establish a baseline information on the relationship between alcohol consumption and Syndrome X among Nigerians, two hundred and seventy-four consenting individuals in apparent good health and who were either light (53 male, 44 female), moderate (51 male, 42 female) or heavy (46 male, 38 female) drinkers of alcohol were selected. They had no personal or familial history of CHD, stroke, cancer or related diseases. The drinkers were tested using an acute dose (1 g ethanol/kg body weight) of alcohol. Results: Results show that the administered acute dose (1 g ethanol/kg body weight) increased serum glucose, (p>0.05), TAG (p<0.05) and BP (p<0.05) some biochemical risk factors of Syndrome X in both genders irrespective of the drinking category. However, alcohol-induced changes were highest among the female heavy drinkers. Thus, observations from this study suggest that heavy consumption of alcohol by especially the female folk could alter the pathways that metabolize carbohydrates and lipids and this may increase the risk of Syndrome X.

Antecedentes: Desde la década de 1980 se conoce el síndrome X, entidad patológica que se precipita por la resistencia a la insulina. A su turno, esta resistencia hace que la glucosa y la insulina se acumulen en la sangre. El síndrome X se caracteriza por valores anormales de triacilglicerol (TAG), presión sanguínea (PS), glucosa y colesterol de alta densidad (HDL), que son todos elementos de riesgo para enfermedades cardíacas. La resistencia a la insulina se puede aumentar por malos hábitos dietéticos, falta de actividad física, predisposición genética y sobrepeso. Sin embargo, varios informes recientes demostraron que un estilo de vida poco saludable puede ser también una causa principal del síndrome, quizá más que los malos hábitos dietéticos o el sobrepeso. Aunque el consumo alto de alcohol se podría considerar como un estilo de vida poco saludable, su relación con los factores bioquímicos y los síntomas del síndrome X, en ambos géneros, aún no se ha documentado de manera precisa entre los nigerianos consumidores de alcohol. Métodos: Establecer una información de base acerca de las relaciones entre consumo de alcohol y síndrome X para 264 nigerianos en aparente buen estado de salud que participaron de modo voluntario en el estudio. Aunque todos consumían alcohol, entre ellos había consumidores ligeros (53 hombres, 44 mujeres); consumidores moderados (51 hombres, 42 mujeres); y consumidores pesados (46 hombres, 38 mujeres). Ninguno tenía historia familiar de enfermedad cardíaca coronaria (ECC), accidentes cerebro-vasculares, cáncer, y otras enfermedades relacionadas. A todos se les examinó con una dosis de prueba (1 g de etanol/kg peso corporal) de alcohol. Resultados: Se comprobó que la dosis de prueba administrada (1 g de etanol/kg peso corporal) aumentó los niveles sanguíneos de glucosa (p>0.05) y TAG (p<0.05), así como la PS (p<0.05), factores de riesgo para el Síndrome X en ambos géneros, sin tener en cuenta la categoría del consumidor.