Gravedad de COVID-19 atribuible a obesidad según IMC y CUN-BAE / Severity of COVID-19 attributable to obesity according to BMI and CUN-BAE

Introducción La obesidad es considerada un factor de riesgo en casos graves de la COVID-19, habiendo sido analizada mediante el índice de masa corporal (IMC), estimador que no correlaciona adecuadamente con el porcentaje de grasa corporal (GC). El objetivo de este estudio ha sido analizar la fracción atribuible poblacional a la GC en formas graves de COVID-19 atendiendo al IMC y al CUN-BAE. Material y métodos Estudio multicéntrico observacional de prevalencia. Se recogió información sociodemográfica, antecedentes personales, IMC y CUN-BAE, de casos positivos SARS-CoV-2, de las provincias de León y La Rioja. Mediante modelos de regresión logística se calcularon odds ratio con sus respectivos intervalos de confianza del 95% ajustando por edad y antecedentes personales, así como la fracción atribuible poblacional a la GC. Resultados Participaron 785 pacientes, 123 (15,7%) fueron graves. Se detectaron como factores de riesgo la edad, la obesidad (tanto por IMC como por CUN-BAE) y los antecedentes personales. Un 51,6% de casos graves podrían ser atribuidos a un exceso de IMC y un 61,4% a exceso de GC estimada según CUN-BAE, observándose una mayor infraestimación del riesgo en mujeres. Conclusiones El exceso de GC es un factor de riesgo para formas graves de la COVID-19 junto con la edad avanzada y la presencia de enfermedades cardiovasculares, respiratorias crónicas u oncohematológicas. El IMC infraestima el riesgo, especialmente en mujeres, siendo el CUN-BAE el predictor seleccionado por su mejor estimación del porcentaje de GC (AU)

Introduction Obesity is considered a risk factor in severe cases of COVID-19, which has been analysed using body mass index (BMI), an estimator that does not correlate adequately with body fat (BF) percentage. The aim of this study was to analyse the population attributable fraction to BF in severe forms of COVID-19 based on BMI and CUN-BAE. Material and methods Multicentre observational prevalence study. Sociodemographic information, personal history, BMI and CUN-BAE were collected in SARS-CoV-2 positive cases from the provinces of León and La Rioja. Logistic regression models were used to calculate odds ratios with their respective 95% confidence intervals adjusting for age and personal history, as well as the population attributable fraction to BF. Results Seven hundred eighty-five patients participated, 123 (15.7%) were severe. Age, obesity (both by BMI and CUN-BAE) and personal history were detected as risk factors. 51.6% of severe cases could be attributed to excess BMI and 61.4% to excess BF estimated according to CUN-BAE, with a higher underestimation of risk in women. Conclusions Excess BF is a risk factor for severe forms of COVID-19 together with advanced age and the presence of cardiovascular, chronic respiratory or oncohematological diseases. BMI underestimates the risk especially in women, being CUN-BAE the predictor selected for its better estimation of the percentage of BF (AU)

[Severity of COVID-19 attributable to obesity according to BMI and CUN-BAE]. / Gravedad de COVID-19 atribuible a obesidad según IMC y CUN-BAE.

INTRODUCTION: Obesity is considered a risk factor in severe cases of COVID-19, which has been analysed using body mass index (BMI), an estimator that does not correlate adequately with body fat (BF) percentage. The aim of this study was to analyse the population attributable fraction to BF in severe forms of COVID-19 based on BMI and CUN-BAE. MATERIAL AND METHODS: Multicentre observational prevalence study. Sociodemographic information, personal history, BMI and CUN-BAE were collected in SARS-CoV-2 positive cases from the provinces of León and La Rioja. Logistic regression models were used to calculate odds ratios with their respective 95% confidence intervals adjusting for age and personal history, as well as the population attributable fraction to BF. RESULTS: Seven hundred eighty-five patients participated, 123 (15.7%) were severe. Age, obesity (both by BMI and CUN-BAE) and personal history were detected as risk factors. 51.6% of severe cases could be attributed to excess BMI and 61.4% to excess BF estimated according to CUN-BAE, with a higher underestimation of risk in women. CONCLUSIONS: Excess BF is a risk factor for severe forms of COVID-19 together with advanced age and the presence of cardiovascular, chronic respiratory or oncohematological diseases. BMI underestimates the risk especially in women, being CUN-BAE the predictor selected for its better estimation of the percentage of BF.

The influence of interferon ß-1b on gut microbiota composition in patients with multiple sclerosis.

INTRODUCTION: The association between gut microbiota and animal models of multiple sclerosis has been well established; however, studies in humans are scarce. METHODS: We performed a descriptive, cross-sectional study comparing the relative composition of gut microbiota in 30 patients with multiple sclerosis (15 treated with interferon ß-1b, 15 not receiving this treatment) and 14 healthy controls using next generation sequencing. RESULTS: Patients with multiple sclerosis and controls showed differences in the proportion of Euryarchaeota, Firmicutes, Proteobacteria, Actinobacteria, and Lentisphaerae phyla and in 17 bacterial species. More specifically, we found significant differences in the proportion of Firmicutes, Actinobacteria, and Lentisphaerae and 6 bacteria species between controls and untreated patients; however, these differences disappeared when compared with treated patients. Untreated patients showed a significant reduction in the proportion of Prevotella copri compared to controls, while the bacteria was significantly more abundant in patients treated with interferon ß-1b than in untreated patients, with levels resembling those observed in the healthy control group. CONCLUSION: We observed differences in gut microbiota composition between patients with multiple sclerosis and controls, and between patients treated and not treated with interferon ß-1b. In most cases, no differences were observed between treated patients and healthy controls, particularly for P. copri levels. This suggests that the clinical improvements observed in patients with multiple sclerosis receiving interferon ß-1b may result from the effect of the drug on gut microbiota. Longitudinal and functional studies are necessary to establish a causal relationship.

Composición de la microbiota intestinal en pacientes con esclerosis múltiple. Influencia del tratamiento con interferón B-1b / The influence of interferon B–1b on gut microbiota composition in patients with multiple sclerosis

Introducción. El papel de la microbiota en los modelos animales de esclerosis múltiple está bien establecido; por el contrario, los estudios en humanos son escasos.MétodosEstudio transversal descriptivo que compara la composición relativa de la microbiota intestinal en 30 pacientes con esclerosis múltiple (15 tratados con interferón β-1b, 15 sin tratamiento) y 14 controles sanos utilizando la secuenciación de última generación.ResultadosLos sujetos control y los pacientes con esclerosis múltiple presentaron diferente abundancia de los filos Euryarchaeota, Firmicutes, Proteobacteria, Actinobacteria, y Lentisphaerae y 17 especies bacterianas. Concretamente, la abundancia en Firmicutes, Actinobacteria y Lentisphaerae y 6 especies mostró diferencias al comparar los grupos control y sin tratamiento, desapareciendo esta diferencia cuando se compararon con los pacientes tratados. Se observó reducción estadísticamente significativa en la abundancia de Prevotella copri en pacientes sin tratamiento en comparación con controles, mientras que los tratados con interferón β-1b presentaron un aumento significativo frente a pacientes sin tratamiento, asemejándose al grupo de pacientes sanos control.ConclusiónLa composición de la microbiota intestinal fue diferente entre los pacientes con esclerosis múltiple y los controles, y entre los pacientes sin tratamiento y los tratados con interferón β-1b. En la mayoría de los casos, no se encontraron diferencias entre los pacientes tratados y los controles sanos, siendo especialmente evidente con P. copri. Esto podría indicar que la influencia del interferón β-1b sobre la microbiota intestinal podría subyacer en los beneficios clínicos observados en pacientes con esclerosis múltiple que siguen este tratamiento. Serán necesarios estudios longitudinales y funcionales para poder mostrar causalidad. (AU)

Introduction: The association between gut microbiota and animal models of multiple sclerosis has been well established; however, studies in humans are scarce.MethodsWe performed a descriptive, cross-sectional study comparing the relative composition of gut microbiota in 30 patients with multiple sclerosis (15 treated with interferon β–1b, 15 not receiving this treatment) and 14 healthy controls using next generation sequencing.ResultsPatients with multiple sclerosis and controls showed differences in the proportion of Euryarchaeota, Firmicutes, Proteobacteria, Actinobacteria, and Lentisphaerae phyla and in 17 bacterial species. More specifically, we found significant differences in the proportion of Firmicutes, Actinobacteria, and Lentisphaerae and 6 bacteria species between controls and untreated patients; however, these differences disappeared when compared with treated patients. Untreated patients showed a significant reduction in the proportion of Prevotella copri compared to controls, while the bacteria was significantly more abundant in patients treated with interferon β–1b than in untreated patients, with levels resembling those observed in the healthy control group.ConclusionWe observed differences in gut microbiota composition between patients with multiple sclerosis and controls, and between patients treated and not treated with interferon β–1b. In most cases, no differences were observed between treated patients and healthy controls, particularly for P. copri levels. This suggests that the clinical improvements observed in patients with multiple sclerosis receiving interferon β–1b may result from the effect of the drug on gut microbiota. Longitudinal and functional studies are necessary to establish a causal relationship. (AU)

Impact of dietary lipoic acid supplementation on liver mitochondrial bioenergetics and oxidative status on normally fed Wistar rats.

The aim of this study was to examine the effects of α-lipoic acid (α-LA) on liver mitochondrial bioenergetics and oxidative status for 8 weeks in normal-healthy animals. A pair-fed group was included to differentiate between α-LA direct effects and those changes due to reduced food intake. α-LA decreased body weight gain, liver weight and insulin levels with no differences compared to its pair-fed group. α-LA significantly reduced energy efficiency, the activity of the electron transport chain complexes and induced a lower efficiency of oxidative phosphorylation with reduced ATP production. α-LA supplementation directly decreased plasma triglycerides (TGs), free fatty acids and ketone bodies levels. A significant reduction in hepatic TG content was also observed. A significant up-regulation of Cpt1a, Acadl and Sirt3, all ß-oxidation genes, along with a significant deacetylation of the forkhead transcription factor 3a (FOXO3A) was found in α-LA-treated animals. Thus, α-LA along with a standard chow diet has direct actions on lipid metabolism and liver by modulating mitochondrial function in normal-weight rats. These results should be taken into account when α-LA is administered or recommended to a healthy population.

Limited beneficial effects of piceatannol supplementation on obesity complications in the obese Zucker rat: gut microbiota, metabolic, endocrine, and cardiac aspects

Resveratrol is beneficial in obese and diabetic rodents. However, its low bioavailability raises questions about its therapeutic relevance for treating or preventing obesity complications. In this context, many related natural polyphenols are being tested for their putative antidiabetic and anti-obesity effects. This prompted us to study the influence of piceatannol, a polyhydroxylated stilbene, on the prevention of obesity complications in Zucker obese rats. A 6-week supplementation was followed by the determination of various markers in plasma, liver, adipose tissue and heart, together with a large-scale analysis of gut microbiota composition. When given in doses of 15 or 45 mg/kg body weight/day, piceatannol did not reduce either hyperphagia or fat accumulation. It did not modify the profusion of the most abundant phyla in gut, though slight changes were observed in the abundance of several Lactobacillus, Clostridium, and Bacteroides species belonging to Firmicutes and Bacteroidetes. This was accompanied by a tendency to reduce plasma lipopolysaccharides by 30 %, and by a decrease of circulating non-esterified fatty acids, LDL-cholesterol, and lactate. While piceatannol tended to improve lipid handling, it did not mitigate hyperinsulinemia and cardiac hypertrophy. However, it increased cardiac expression of ephrin-B1, a membrane protein that contributes to maintaining cardiomyocyte architecture. Lastly, ascorbyl radical plasma levels and hydrogen peroxide release by adipose tissue were similar in control and treated groups. Thus, piceatannol did not exhibit strong slimming capacities but did limit several obesity complications (AU)

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Limited beneficial effects of piceatannol supplementation on obesity complications in the obese Zucker rat: gut microbiota, metabolic, endocrine, and cardiac aspects.

Resveratrol is beneficial in obese and diabetic rodents. However, its low bioavailability raises questions about its therapeutic relevance for treating or preventing obesity complications. In this context, many related natural polyphenols are being tested for their putative antidiabetic and anti-obesity effects. This prompted us to study the influence of piceatannol, a polyhydroxylated stilbene, on the prevention of obesity complications in Zucker obese rats. A 6-week supplementation was followed by the determination of various markers in plasma, liver, adipose tissue and heart, together with a large-scale analysis of gut microbiota composition. When given in doses of 15 or 45 mg/kg body weight/day, piceatannol did not reduce either hyperphagia or fat accumulation. It did not modify the profusion of the most abundant phyla in gut, though slight changes were observed in the abundance of several Lactobacillus, Clostridium, and Bacteroides species belonging to Firmicutes and Bacteroidetes. This was accompanied by a tendency to reduce plasma lipopolysaccharides by 30 %, and by a decrease of circulating non-esterified fatty acids, LDL-cholesterol, and lactate. While piceatannol tended to improve lipid handling, it did not mitigate hyperinsulinemia and cardiac hypertrophy. However, it increased cardiac expression of ephrin-B1, a membrane protein that contributes to maintaining cardiomyocyte architecture. Lastly, ascorbyl radical plasma levels and hydrogen peroxide release by adipose tissue were similar in control and treated groups. Thus, piceatannol did not exhibit strong slimming capacities but did limit several obesity complications.

Gut microbiota: a key player in health and disease. A review focused on obesity

Gut microbiota, its evolutive dynamics and influence on host through its protective, trophic and metabolic actions, has a key role in health and opens unique opportunities for the identification of new markers of the physiopathological state of each individual. Alterations in gut microbiota composition have been associated with plenty disorders. Of interest, the vast number of studies demonstrates the role of microbiota in obesity, a serious public health problem that has reached epidemic proportions in many developed and middle-income countries. The economic and health costs of this condition and its comorbidities such as fatty liver, insulin resistance/diabetes, or cardiovascular events are considerable. Therefore, every strategy designed to reduce obesity would imply important savings. Targeting microbiota, in order to restore/modulate the microbiota composition with antibiotics, probiotics, prebiotics, or even fecal transplants, is considered as a promising strategy for the development of new solutions for the treatment of obesity. However, there is still lot to do in this field in order to identify the exact composition of microbiota in “health” and the specific mechanisms that regulate the host-microbiotal crosstalk. In addition, it is important to note that changes not only in the gut microbiota profile (abundance) but also in its metabolism and functions need to be taken into account in the context of contribution in the physiopathology of obesity and related disorders

Gut microbiota: a key player in health and disease. A review focused on obesity.

Gut microbiota, its evolutive dynamics and influence on host through its protective, trophic and metabolic actions, has a key role in health and opens unique opportunities for the identification of new markers of the physiopathological state of each individual. Alterations in gut microbiota composition have been associated with plenty disorders. Of interest, the vast number of studies demonstrates the role of microbiota in obesity, a serious public health problem that has reached epidemic proportions in many developed and middle-income countries. The economic and health costs of this condition and its comorbidities such as fatty liver, insulin resistance/diabetes, or cardiovascular events are considerable. Therefore, every strategy designed to reduce obesity would imply important savings. Targeting microbiota, in order to restore/modulate the microbiota composition with antibiotics, probiotics, prebiotics, or even fecal transplants, is considered as a promising strategy for the development of new solutions for the treatment of obesity. However, there is still lot to do in this field in order to identify the exact composition of microbiota in "health" and the specific mechanisms that regulate the host-microbiotal crosstalk. In addition, it is important to note that changes not only in the gut microbiota profile (abundance) but also in its metabolism and functions need to be taken into account in the context of contribution in the physiopathology of obesity and related disorders.

Role of mitochondria in HIV infection and associated metabolic disorders: focus on nonalcoholic fatty liver disease and lipodystrophy syndrome.

Highly active antiretroviral therapy (HAART) has considerably improved the prognosis of HIV-infected patients. However, prolonged use of HAART has been related to long-term adverse events that can compromise patient health such as HIV-associated lipodystrophy syndrome (HALS) and nonalcoholic fatty liver disease (NAFLD). There is consistent evidence for a central role of mitochondrial dysfunction in these pathologies. Nucleotide reverse transcriptase inhibitors (NRTIs) have been described to be mainly responsible for mitochondrial dysfunction in adipose tissue and liver although nonnucleoside transcriptase inhibitors (NNRTIs) or protease inhibitors (PIs) have also showed mitochondrial toxicity, which is a major concern for the selection and the long-term adherence to a particular therapy. Several mechanisms explain these deleterious effects of HAART on mitochondria, and evidence points to other mechanisms beyond the "Pol- γ hypothesis." HIV infection has also direct effects on mitochondria. In addition to the negative effects described for HIV itself and/or HAART on mitochondria, HIV-infected patients are more prone to develop a premature aging and, therefore, to present an increased oxidative state that could lead to the development of these metabolic disturbances observed in HIV-infected patients.

Lipoic acid prevents body weight gain induced by a high fat diet in rats: effects on intestinal sugar transport.

Several studies have suggested that oxidative stress might cause and aggravate the inflammatory state associated with obesity and could be the link between excessive weight gain and its related disorders such as insulin resistance and cardiovascular diseases. Thus, antioxidant treatment has been proposed as a therapy to prevent and manage obesity and associated complications. Therefore, the aim of the present study was to investigate the effects of supplementation of a standard or high fat diet with the antioxidant lipoic acid (LA) during 56 days, on body weight gain, adiposity, feed efficiency and intestinal sugar absorption, in male Wistar rats. LA supplementation induced a lower body weight gain and adipose tissue size in both control or high fat fed rats accompanied by a reduction in food intake. The group fed on a high fat diet and treated with LA (OLIP group) showed a lower body weight gain than its corresponding Pair-Fed (PF) group (P < 0.05), which received the same amount of food than LA-treated animals but with no LA. In fact, LA induced a reduction on feed efficiency and also significantly decreased intestinal alpha-methylglucoside (alpha-MG) absorption both in lean and obese rats. These results suggest that the beneficial effects of dietary supplementation with LA on body weight gain are mediated, at least in part, by the reduction observed in food intake and feed efficiency. Furthemore, the inhibitory action of LA on intestinal sugar transport could explain in part the lower feed efficiency observed in LA-treated animals and therefore, highlighting the beneficial effects of LA on obesity.

El ácido lipoico reduce la ganancia de peso inducida por dieta alta en grasa: efectos sobre el transporte intestinal de azúcares / Lipoic acid prevents body weight gain induced by a high fat diet in rats: Effects on intestinal sugar transport

Several studies have suggested that oxidative stress might cause and aggravate theinflammatory state associated with obesity and could be the link between excessiveweight gain and its related disorders such as insulin resistance and cardiovascular diseases.Thus, antioxidant treatment has been proposed as a therapy to prevent andmanage obesity and associated complications. Therefore, the aim of the present studywas to investigate the effects of supplementation of a standard or high fat diet withthe antioxidant lipoic acid (LA) during 56 days, on body weight gain, adiposity, feedefficiency and intestinal sugar absorption, in male Wistar rats. LA supplementationinduced a lower body weight gain and adipose tissue size in both control or high fatfed rats accompanied by a reduction in food intake. The group fed on a high fat dietand treated with LA (OLIP group) showed a lower body weight gain than its correspondingPair-Fed (PF) group (P<0.05), which received the same amount of foodthan LA-treated animals but with no LA. In fact, LA induced a reduction on feedefficiency and also significantly decreased intestinal α-methylglucoside (α-MG)absorption both in lean and obese rats. These results suggest that the beneficial effectsof dietary supplementation with LA on body weight gain are mediated, at least inpart, by the reduction observed in food intake and feed efficiency. Furthemore, theinhibitory action of LA on intestinal sugar transport could explain in part the lowerfeed efficiency observed in LA-treated animals and therefore, highlighting the beneficialeffects of LA on obesity(AU)

Varios estudios han sugerido que el estresoxidativo podria actuar como desencadenantey agravante del estado inflamatorio asociado ala obesidad y podria ser un potencial nexo deunion entre la excesiva ganancia de peso y lasco-morbilidades asociadas. Asi, se ha propuestoel tratamiento con antioxidantes naturalescomo posible terapia contra el desarrollo deobesidad asi como sus complicaciones asociadas.Por ello, el objeto del presente trabajo fueinvestigar en ratas Wistar macho los efectos dela suplementacion de una dieta estandar o altaen grasa con un antioxidante, el acido lipoico(AL) (0,25g/ 100g de comida) durante 56 diassobre la ganancia de peso corporal, la adiposidad,la eficiencia metabolica y la absorcionintestinal de azucares. La suplementacion de ladieta con AL indujo una menor ganancia depeso corporal y redujo el tamano del tejidoadiposo blanco total, tanto en ratas alimentadascon dieta control como alta en grasa. Ademas,disminuyo la ingesta. La ganancia de pesoen el grupo alimentado con dieta alta en grasay AL fue menor que la de su correspondientegrupo Pair-Fed (P<0,05), el cual recibia lamisma cantidad de comida que los animalestratados con AL pero sin este acido. De hecho,la suplementacion con acido lipoico redujo laeficiencia metabolica y disminuyo significativamentela absorcion intestinal de ƒ¿-metilglucosido(ƒ¿-MG) tanto en ratas control comoobesas. Estos resultados sugieren que los efectosbeneficiosos de la suplementacion de ladieta con AL sobre la ganancia de peso corporalestan mediados, al menos en parte, por lareduccion observada en la ingesta de comida yen la eficiencia metabolica. Ademas, la accioninhibitoria del AL sobre el transporte intestinalde azucares podria explicar, en parte, la menoreficiencia metabolica observada en los animalestratados con AL justificando, por consiguiente,los efectos beneficiosos del AL sobre la obesidad(AU)

Linoleic acid decreases leptin and adiponectin secretion from primary rat adipocytes in the presence of insulin.

Obesity rates have dramatically increased over the last few decades and, at the same time, major changes in the type of fatty acid intake have occurred. Linoleic acid, an n-6 polyunsaturated fatty acid, is an essential fatty acid occurring in high amounts in several western diets. A potential role of this fatty acid on obesity has been suggested. Controversial effects of linoleic acid on insulin sensitivity have also been reported. Thus, the aim of this study was to examine the direct effects of linoleic acid on leptin and adiponectin production, two adipokines known to influence weight gain and insulin sensitivity. Because insulin-stimulated glucose metabolism is an important regulator of leptin production, the effects of linoleic acid on adipocyte metabolism were also examined. For this purpose, isolated rat adipocytes were incubated with linoleic acid (1-200 microM) in the absence or presence of insulin. Linoleic acid (1-200 microM) significantly decreased insulin-stimulated leptin secretion and expression (P < 0.05), however, no changes in basal leptin production were observed. Linoleic acid also induced a significant decrease (approximately 20%) in adiponectin secretion (P < 0.05), but only in the presence of insulin and at the highest concentration tested (200 microM). This fatty acid did not modify either glucose uptake or lactate production and the percentage of glucose metabolized to lactate was not changed either. Together, these results suggest that linoleic acid seems to interfere with other insulin signalling pathway different from those controlling glucose uptake and metabolism, but involved in the regulation of leptin and adiponectin production.

Conjugated linoleic acid inhibits glucose metabolism, leptin and adiponectin secretion in primary cultured rat adipocytes.

Conjugated linoleic acid (CLA) supplementation has been reported to induce insulin resistance in animals and humans, however, the underlying mechanisms remain unclear. The aim of this study was to examine the direct effects of CLA on leptin and adiponectin secretion, two hormones with actions known to influence insulin sensitivity. Isolated rat adipocytes were incubated with CLA (1-200microM) in the absence and presence of insulin (1.6nM). CLA inhibited both basal and insulin-stimulated leptin gene expression and secretion (-30 to -40%, P<0.05-0.01). CLA also inhibited basal adiponectin production (-20 to -40%, P<0.05-0.01), but not in the presence of insulin. CLA (50-200muM) decreased basal glucose uptake (P<0.05-0.01) and significantly increased the proportion of glucose metabolized to lactate (P<0.01). Insulin treatment partially prevented the inhibitory effects of CLA on glucose uptake and induced a significant increase (P<0.05-0.01) in the percentage of glucose metabolized to lactate. A strong inverse relationship was observed between the increase in the anaerobic utilization of glucose and the decreases of both leptin and adiponectin secretion. In addition, lipolysis and the expression of the adipogenic transcription factor PPARgamma were decreased by CLA. These results indicate that CLA inhibits leptin and adiponectin secretion and suggest that increased anaerobic metabolism of glucose may be involved in these effects. The inhibition of PPARgamma could also mediate the inhibition of adiponectin induced by CLA. Furthermore, the inhibition of leptin and adiponectin production induced by CLA may contribute to insulin resistance observed in CLA-treated animals and humans.

Effects of eicosapentaenoic acid (EPA) on adiponectin gene expression and secretion in primary cultured rat adipocytes.

Adiponectin, a hormone produced by adipocytes, is involved in glucose metabolism and insulin sensitivity. The production of this adipokine is impaired in obesity and insulin resistance. Eicosapentaenoic acid (EPA) is a dietary n-3 polyunsaturated fatty acid that improves insulin sensitivity in several models of obesity and diabetes, which has been suggested to be related to adiponectin induction. An increase in adiponectin production has been also associated with an up-regulation of the transcriptional factor PPARgamma. The aim of this trial was to evaluate the direct effects of EPA on adiponectin gene expression and protein secretion in isolated rat adipocytes as well as to explore the potential mechanisms involved. A comparative study with troglitazone, a PPARgamma agonist, was also performed. For these purposes, primary rat adipocytes were cultured with EPA (100 and 200 microM) and with troglitazone (10 microM) for 96 hours. Both EPA and troglitazone improved glucose utilization by adipocytes. As expected, troglitazone enhanced adiponectin secretion and increased PPARgamma gene expression. However, EPA significantly decreased adiponectin gene expression and protein secretion and reduced PPARy mRNA levels, suggesting that the inhibition of adiponectin by EPA is likely to be secondary to the down-regulation of this adipogenic transcription factor. Moreover, these results suggest that other mechanisms different from the direct stimulation of adiponectin by the fatty acid are underlying the insulin-sensitizing properties observed after EPA treatment in vivo.

Serum and gene expression levels of leptin and adiponectin in rats susceptible or resistant to diet-induced obesity.

The aim of the present study was to identify the role of leptin and adiponectin in the development of resistance or susceptibility to diet-induced obesity in rats. For this purpose, male Wistar rats were fed with standard laboratory diet (control group) or cafeteria diet. After 15 days, two groups of rats with different response respect to the cafeteria diet were identified, and were assigned as diet-induced obesity (DIO) and diet resistant (DR) rats. The high-fat diet induced a very significant increase in both body and fat mass weight in DIO group. However, DR rats, gained even less weight than control-fed animals. Food intake was increased in cafeteria-fed rats (both DIO and DR) in comparison to control group; but hyperphagia was higher in DIO rats. In addition, feed efficiency (the ratio of weight gained to calories consumed) was significantly decreased in DR as compared to DIO rats. Regarding leptin, a significant increase in both adipose tissue gene expression and serum levels was observed in DIO rats in comparison with other groups (control and DR). A significant increase in both adiponectin circulating levels and adipose tissue mRNA expression was also observed in DIO animals as compared with the other groups. These data suggest that the susceptibility to obesity of DIO rats might be secondary, at least in part, to an earlier development of leptin resistance, which could lead to alterations in food intake (hyperphagia) and energetic metabolism. However, neither changes in leptin or adiponectin seem to be involved in the adaptive mechanisms that confer resistance to high fat intake.

Effects of arachidonic acid on leptin secretion and expression in primary cultured rat adipocytes.

Leptin, a hormone produced in adipocytes, is a key signal in the regulation of food intake and energy expenditure. Several studies have suggested that leptin can be regulated by macronutrients intake. Arachidonic acid is a dietary fatty acid known to affect cell metabolism. Controversial effects of this fatty acid on leptin have been reported. The aim of this experimental trial was to evaluate the effect of the arachidonic acid on basal and insulin-stimulated leptin secretion and expression in isolated rat adipocytes. Because insulin-stimulated glucose metabolism is an important regulator of leptin expression and secretion by the adipocytes, the effects of the arachidonic acid on indices of adipocyte metabolism were also examined. Isolated adipocytes were incubated with arachidonic acid (1-200 microM) in the absence and presence of insulin (1.6 nM). Leptin secretion and expression, glucose utilization and lactate production were determined at 96 h. The arachidonic acid (200 microM) inhibited both the basal and insulin stimulated leptin secretion and expression. Glucose utilization was not affected by the acid. Basal lactate production was increased by the fatty acid at the highest concentration used (200 microM), however lactate production in presence of insulin was not modified. Finally, the percentage of glucose carbon released as lactate was significantly increased (200 microM). These results suggest that the inhibitory effect of the arachidonic acid on leptin secretion and expression may be due, al least in part, to the increase in the anaerobic utilization of glucose.