Site-specific circadian expression of leptin and its receptor in human adipose tissue / Expresión circadiana específica de la localización de leptina y su receptor en tejido adiposo humano

Introduction: Circadian variability of circulating leptin levels has been well established over the last decade. However, the circadian behavior of leptin in human adipose tissue remains unknown. This also applies to the soluble leptin receptor. Objective: We investigated the ex vivo circadian behavior of leptin and its receptor expression in human adiposetissue (AT). Subjects and methods: Visceral and subcutaneous abdominal AT biopsies (n = 6) were obtained from morbid obese women (BMI 40 kg/m2). Anthropometric variables and fasting plasma glucose, leptin, lipids and lipoprotein concentrations were determined. In order to investigate rhythmic expression pattern of leptin and its receptor, A Texplants were cultured during 24-h and gene expression was analyzed at the following times: 08:00, 14:00, 20:00, 02:00 h, using quantitative real-time PCR. Results: Leptin expression showed an oscillatory pattern that was consistent with circadian rhythm in cultured AT. Similar patterns were noted for the leptin receptor. Leptin showed its achrophase (maximum expression) during the night, which might be associated to a lower degree of fat accumulation and higher mobilization. When comparing both fat depots, visceral A Tanticipated its expression towards afternoon and evening hours. Interestingly, leptin plasma values were associated with decreased amplitude of LEP rhythm. This association was lost when adjusting for waist circumference. Conclusion: Circadian rhythmicity has been demonstrated in leptin and its receptor in human AT cultures ina site-specific manner. This new knowledge paves the way for a better understanding of the autocrine/paracrine role of leptin in human AT (AU)

Introducción: La variabilidad circadiana de los niveles de leptina circulante se ha establecido en la última década, pero actualmente se desconoce el comportamiento circadiano de leptina y su receptor en tejido adiposo (TA) humano. Objetivo: Investigar si existe un comportamiento circadiano en la expresión de leptina y su receptor en TA humano. Sujetos y métodos: Se obtuvieron biopsias de TA visceral y subcutáneo abdominal de mujeres (n = 6) obesas mórbidas (IMC 40 kg/m2). Se determinaron variables antropométricas y concentraciones plasmáticas en ayunas de glucosa, leptina, lípidos y lipoproteínas. Para investigar los patrones de expresión rítmica de los genes, se cultivaron explantes de TA durante 24-h y se analizó la expresión génica a diferentes horas: 08:00, 14:00, 20:00,02:00 h, usando PCR cuantitativa a tiempo real. Resultados: La leptina mostró un patrón oscilatorio de expresión comparable a un ritmo circadiano en TA cultivado. LEPR expresó patrones circadianos similares. Laleptina presentó su acrofase (máxima expresión) durante la noche, pudiendo asociarse al bajo grado de acumulación y elevada movilización de grasa. Cuando se comparan ambos depósitos grasos, en el TA visceral se anticipóla expresión hacia la tarde/noche. Fue interesante comprobar, cómo los valores plasmáticos de leptina se asociaron con una disminución de amplitud del ritmo de LEP, pero al ajustar para la circunferencia de cintura, dicha asociación desapareció. Conclusión: Demostramos ritmicidad circadiana deleptina y su receptor en TA humano, siendo específica de la localización adiposa. Estos descubrimientos preparan el terreno para una mejor comprensión del papel autocrino/paracrino de la leptina en el TA humano (AU)

Dehydroepiandrosterone-sulphate replacement improves the human plasma fatty acid profile in plasma of obese women.

DHEA-S treatment is used as an anti-aging and anti-obesity hormone therapy in adults; however, it mechanisms of action are not clearly elucidated. The objective of the present work was to analyze the effect of a replacement therapy, which included a daily single oral dose of DHEA-S for three months, on the composition of human plasma fatty acids (FAs) in obese women. In the first study, a randomized, double-blind, placebo-controlled trial was conducted involving 61 postmenopausal women, who were assigned to receive 100mg/day of DHEA-S (n = 41) or placebo (n = 20) orally for 3 months. In a second study, the effect of DHEA-S treatment on postmenopausal obese women (n = 41) was compared to that in premenopausal obese women (n = 20). Blood samples were collected at the beginning and at the end of the treatment. Plasma FAs were analyzed by gas chromatography. DHEA-S treatment produced significant changes in plasma FAs of both post- and premenopausal women with a reduction of total saturated FAs (SFA) as well as an increase in n-6 polyunsaturated FA (PUFA). Particularly, in premenopausal women the DHEA-S treatment also increased the plasma n-3 PUFA percentage. Regarding estimation of desaturase activity, our data showed that Δ6-desaturase was significantly decreased in postmenopausal women after DHEA-S treatment, whereas Δ5-desaturase was increased in the premenopausal group. In conclusion, DHEA-S treatment in obese women modifies plasma FA composition towards a potentially better metabolic profile, mainly by decreasing SFA and increasing n-6 PUFA in both postmenopausal and premenopausal women.

Site-specific circadian expression of leptin and its receptor in human adipose tissue.

INTRODUCTION: Circadian variability of circulating leptin levels has been well established over the last decade. However, the circadian behavior of leptin in human adipose tissue remains unknown. This also applies to the soluble leptin receptor. OBJECTIVE: We investigated the ex vivo circadian behavior of leptin and its receptor expression in human adipose tissue (AT). SUBJECTS AND METHODS: Visceral and subcutaneous abdominal AT biopsies (n = 6) were obtained from morbid obese women (BMI ≥ 40 kg/m²). Anthropometric variables and fasting plasma glucose, leptin, lipids and lipoprotein concentrations were determined. In order to investigate rhythmic expression pattern of leptin and its receptor, AT explants were cultured during 24-h and gene expression was analyzed at the following times: 08:00, 14:00, 20:00, 02:00 h, using quantitative real-time PCR. RESULTS: Leptin expression showed an oscillatory pattern that was consistent with circadian rhythm in cultured AT. Similar patterns were noted for the leptin receptor. Leptin showed its achrophase (maximum expression) during the night, which might be associated to a lower degree of fat accumulation and higher mobilization. When comparing both fat depots, visceral AT anticipated its expression towards afternoon and evening hours. Interestingly, leptin plasma values were associated with decreased amplitude of LEP rhythm. This association was lost when adjusting for waist circumference. CONCLUSION: Circadian rhythmicity has been demonstrated in leptin and its receptor in human AT cultures in a site-specific manner. This new knowledge paves the way for a better understanding of the autocrine/paracrine role of leptin in human AT.

Circadian expression of adiponectin and its receptors in human adipose tissue.

Adiponectin is one of the most clinically relevant cytokines associated with obesity. However, circadian rhythmicity of adiponectin in human adipose tissue (AT) has not been analyzed. To assess whether the mRNA levels of adiponectin and its receptors (ADIPOR1 and ADIPOR2) might show daily circadian rhythms in visceral and sc fat explants obtained from morbid obese women, visceral and sc abdominal AT biopsies (n = 6) were obtained from morbidly obese women (body mass index >or=40 kg/m(2)). Anthropometric variables were measured and fasting plasma glucose, lipid, and lipoprotein concentrations were analyzed. To investigate rhythmic expression pattern, AT explants were cultured during 24 h, and gene expression was analyzed at the following times: 0800, 1400, 2000, and 0200 h, using quantitative real-time PCR. All genes investigated showed a circadian rhythmicity and oscillated accurately and independently of the suprachiasmatic nucleus in both AT explants (P < 0.05). Adiponectin gene expression fluctuated in the same phase as its receptors. Correlation analyses between the genetic circadian oscillation and components of the metabolic syndrome revealed that adiposity and abdominal obesity correlated with a decrease in adiponectin and adiponectin receptors ADIPOR1 and ADIPOR2 amplitude (P < 0.05). Visceral fat showed a trend toward a phase delay and dampening of the mRNA amplitude of adiponectin as compared with sc fat. The mRNA expression of adiponectin and its receptors showed 24-h rhythmicity in human AT from morbidly obese patients.

Expression of cortisol metabolism-related genes shows circadian rhythmic patterns in human adipose tissue.

OBJECTIVE: To analyze, in morbid obese patients, the expression of several human genes regulating cortisol metabolism, such as glucocorticoid receptor (GR), 11beta-hydroxysteroid dehydrogenase type 1 (11betaHSD1), 11beta-hydroxysteroid dehydrogenase type 2 (11betaHSD2), stearoyl-acute regulatory protein (StAR), 5alpha-reductase type I (5alpha-R) and peroxisome proliferator-activated receptor-gamma (PPARgamma) in two different adipose depots. A second objective was to characterize the circadian rhythmicity of these genes in both adipose tissue (AT) regions. DESIGN: Visceral and subcutaneous abdominal AT biopsies were obtained from obese patients (body mass index >or=40 kg m(-2)). To carry out rhythmic expression analysis, AT explants were cultured for 24 h and gene expression at times (T) 0, 6, 12 and 18 h, was performed with quantitative real-time PCR. RESULT: GR, 11betaHSD1 and PPARgamma genes were highly expressed in both subcutaneous and visceral depots. StAR and 5alpha-R genes were detected at lower levels. The expression of 11betaHSD2 was quantified in both AT depots with a higher expression in the visceral depot (P=0.032). Both sexes had similar gene expression levels, except for 5alpha-R (P=0.002). The genes studied showed circadian rhythmicity being more robust in visceral than in subcutaneous AT. Genes ranged in anti-phase between both depots (P=0.002). This rhythmicity was maintained in an AT culture. CONCLUSION: We have shown for the first time circadian rhythmicity in glucocorticoid-related gene expression in human AT ex vivo. These results may have potential therapeutic implications with respect to the pathogenesis and treatment of diseases, such as obesity, type 2 diabetes and cardiovascular diseases.

The decrease of NAD(P)H has a prominent role in dopamine toxicity.

We characterized dopamine toxicity in human neuroblastoma SH-SY5Y cells as a direct effect of dopamine on cell reductive power, measured as NADH and NADPH cell content. In cell incubations with 100 or 500 microM dopamine, the accumulation of dopamine inside the cell reached a maximum after 6 h. The decrease in cell viability was 40% and 75%, respectively, after 24 h, and was not altered by MAO inhibition with tranylcypromine. Dopamine was metabolized to DOPAC by mitochondrial MAO and, at 500 microM concentration, significantly reduced mitochondrial potential and oxygen consumption. This DA concentration caused only a slight increase in cell peroxidation in the absence of Fe(III), but a dramatic decrease in NADH and NADPH cell content and a concomitant decrease in total cell NAD(P)H/NAD(P)+ and GSH/GSSG and in mitochondrial NADH/NAD+ ratios. Dopaminechrome, a product of dopamine oxidation, was found to be a MAO-A inhibitor and a strong oxidizer of NADH and NADPH in a cell-free system. We conclude that dopamine may affect NADH and NADPH oxidation directly. When the intracellular concentrations of NAD(P)H and oxidized dopamine are similar, NAD(P)H triggers a redox cycle with dopamine that leads to its own consumption. The time-course of NADH and NADPH oxidation by dopamine was assessed in cell-free assays: NAD(P)H concentration decreased at the same time as dopamine oxidation advanced. The break in cell redox equilibrium, not excluding the involvement of free oxygen radicals, could be sufficient to explain the toxicity of dopamine in dopaminergic neurons.