Frühbeck, G. (Gema)
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- Deletion of inducible nitric-oxide synthase in leptin-deficient mice improves brown adipose tissue function(Public Library Science, 2010-05-16) Collantes, M. (María); Peñuelas-Sanchez, I. (Ivan); Ramirez, B. (Beatriz); Catalan, V. (Victoria); Becerril, S. (Sara); Frühbeck, G. (Gema); Gomez-Ambrosi, J. (Javier); Rodriguez, A. (Amaia); Sainz, N. (Neira)Abstract Background: Leptin and nitric oxide (NO) on their own participate in the control of non-shivering thermogenesis. However, the functional interplay between both factors in this process has not been explored so far. Therefore, the aim of the present study was to analyze the impact of the absence of the inducible NO synthase (iNOS) gene in the regulation of energy balance in ob/ob mice. Methods and Findings: Double knockout (DBKO) mice simultaneously lacking the ob and iNOS genes were generated, and the expression of molecules involved in the control of brown fat cell function was analyzed by real-time PCR, western-blot and immunohistochemistry. Twelve week-old DBKO mice exhibited reduced body weight (p,0.05), decreased amounts of total fat pads (p,0.05), lower food efficiency rates (p,0.05) and higher rectal temperature (p,0.05) than ob/ob mice. Ablation of iNOS also improved the carbohydrate and lipid metabolism of ob/ob mice. DBKO showed a marked reduction in the size of brown adipocytes compared to ob/ob mutants. In this sense, in comparison to ob/ob mice, DBKO rodents showed an increase in the expression of PR domain containing 16 (Prdm16), a transcriptional regulator of brown adipogenesis. Moreover, iNOS deletion enhanced the expression of mitochondria-related proteins, such as peroxisome proliferatoractivated receptor c coactivator-1 a (Pgc-1a), sirtuin-1 (Sirt-1) and sirtuin-3 (Sirt-3). Accordingly, mitochondrial uncoupling proteins 1 and 3 (Ucp-1 and Ucp-3) were upregulated in brown adipose tissue (BAT) of DBKO mice as compared to ob/ob rodents. Conclusion: Ablation of iNOS improved the energy balance of ob/ob mice by decreasing food efficiency through an increase in thermogenesis. These effects may be mediated, in part, through the recovery of the BAT phenotype and brown fat cell function improvement.
- The obestatin receptor (GPR39) is expressed in human adipose tissue and is down-regulated in obesity-associated type 2 diabetes mellitus(Society for Endocrinology, 2007) Rotellar, F. (Fernando); Catalan, V. (Victoria); Álvarez-Cienfuegos, J. (Javier); Frühbeck, G. (Gema); Silva, C. (Camilo); Gomez-Ambrosi, J. (Javier); Salvador, J. (Javier); Rodriguez, A. (Amaia); Gil, M.J. (María José)The G protein-coupled receptor 39 (GPR39) has recently been identified as the receptor for obestatin, a peptidic hormone involved in energy homeostasis. However, the expression levels of this receptor in human adipose tissue in obesity and obesity-associated type 2 diabetes mellitus (T2DM) remain unknown. Therefore, we evaluated the actual presence of GPR39 mRNA in human adipose tissue and whether GPR39 expression levels are altered in obesity and obesity-associated T2DM. DESIGN: Omental adipose tissue biopsies obtained from 15 women were used in the study. Patients were classified as lean (body mass index 20.8 +/- 1.0 kg/m(2)), obese normoglycaemic (body mass index 48.4 +/- 2.1 kg/m(2)) and obese T2DM patients (body mass index 52.6 +/- 4.9 kg/m(2)). Anthropometric measurements and biochemical profiles were assessed for each subject. Real-time RT-PCR analyses were performed to quantify transcript levels of GPR39 and adiponectin. RESULTS: Obese T2DM patients exhibited significantly lower GPR39 expression levels compared to lean (P = 0.016) and obese normoglycaemic subjects (P = 0.008), while no differences between lean and obese normoglycaemic patients were observed. The mRNA expression levels of GPR39 were negatively correlated to fasting glucose concentrations (r = -0.581, P = 0.023), while exhibiting a positive correlation to adiponectin mRNA expression levels (r = 0.674, P = 0.006). CONCLUSION: GPR39 is expressed in human adipose tissue. The reduced expression levels of GPR39 in omental adipose tissue observed in obese patients with T2DM suggest an involvement of obestatin signalling in glucose homeostasis and T2DM development.
- Leptin inhibits the proliferation of vascular smooth muscle cells induced by angiotensin II through nitric oxide-dependent mechanisms(Hindawi Publishing Corporation, 2010) Fortuño, A. (Ana); Catalan, V. (Victoria); Frühbeck, G. (Gema); Gomez-Ambrosi, J. (Javier); Rodriguez, A. (Amaia)OBJECTIVE: This study was designed to investigate whether leptin modifies angiotensin (Ang) II-induced proliferation of aortic vascular smooth muscle cells (VSMCs) from 10-week-old male Wistar and spontaneously hypertensive rats (SHR), and the possible role of nitric oxide (NO). METHODS: NO and NO synthase (NOS) activity were assessed by the Griess and (3)H-arginine/citrulline conversion assays, respectively. Inducible NOS (iNOS) and NADPH oxidase subutnit Nox2 expression was determined by Western-blot. The proliferative responses to Ang II were evaluated through enzymatic methods. RESULTS: Leptin inhibited the Ang II-induced proliferative response of VSMCs from control rats. This inhibitory effect of leptin was abolished by NOS inhibitor, NMMA, and iNOS selective inhibitor, L-NIL, and was not observed in leptin receptor-deficient fa/fa rats. SHR showed increased serum leptin concentrations and lipid peroxidation. Despite a similar leptin-induced iNOS up-regulation, VSMCs from SHR showed an impaired NOS activity and NO production induced by leptin, and an increased basal Nox2 expression. The inhibitory effect of leptin on Ang II-induced VSMC proliferation was attenuated. CONCLUSION: Leptin blocks the proliferative response to Ang II through NO-dependent mechanisms. The attenuation of this inhibitory effect of leptin in spontaneous hypertension appears to be due to a reduced NO bioavailability in VSMCs.
- Leptin Inhibits Angiotensin II-Induced Intracellular Calcium Increase and Vasoconstriction in the Rat Aorta(Endocrine Society, 2002-09) Fortuño, A. (Ana); Diez-Martinez, J. (Javier); Frühbeck, G. (Gema); Gomez-Ambrosi, J. (Javier); Salvador, J. (Javier); Rodriguez, A. (Amaia); Muñiz, P. (Paula)Besides its role in body weight control leptin may also act as a vasoactive hormone. This study was designed to investigate whether leptin modifies angiotensin II (ANG II)-induced vascular responses. The expression of functional leptin receptors (OB-Rb) was detected in vascular smooth muscle cells (VSMCs) from adult Wistar rats by RT-PCR. Immunocytochemistry and Western blot analysis further showed the expression of OB-R protein in VSMCs. The ANG II (10(-7) mol/liter)-induced increase in intracellular Ca(2+) was blocked (P < 0.01) by leptin (10(-8) mol/liter). Moreover, in calcium-free buffer leptin was able to inhibit 65% of the ANG II-induced calcium release from intracellular stores. In endothelium-denuded aortic rings from adult Wistar rats no effect of leptin on basal tension was observed. However, the ANG II-induced isometric contraction was reduced (P < 0.05) by leptin (10(-8) mol/liter). The experiments were also performed in age- and sex-matched Zucker rats, in which no effect of leptin on ANG II-induced calcium increase and vasoconstriction was observed. It is concluded that leptin blocks the vasoconstrictor action of ANG II and inhibits the ANG II-induced increase in intracellular Ca(2+) in VSMCs through OB-Rb. These findings provide new insight into the physiological effects of leptin on blood pressure regulation.
- The ‘new normality’ in research? What message are we conveying our medical students?(Wiley, 2021) Unamuno, X. (Xabier); Catalan, V. (Victoria); Mentxaka, A. (Amaia); Becerril, S. (Sara); Frühbeck, G. (Gema); Gomez-Ambrosi, J. (Javier); Rodriguez, A. (Amaia)The impact of COVID-19 on medical education has been mainly viewed from the perspective of the imposed transition from face-to- face to online delivery of information and the inforced stopping of practical teaching in hospitals.1-5 However, unfortunately, the deleterious effects of COVID-19 on how research findings are obtained, communicated and valued needs also careful consideration. Whilst teaching students that it is a genuinely exciting and unique time to be in medicine, as teachers of a subject entitled ‘Introduction to Research’ to second-year medical students, we feel particularly worried about what the handling of the pandemia is transmitting our future physicians. Now, more than ever before, scholars need to reaffirm the importance on how research findings are obtained and communicated.
- Obesity and prostate cancer: gene expression signature of human periprostatic adipose tissue(BioMed Central, 2012) Principe, P. (Paulo); Pina, F. (Francisco); Monteiro, C. (Cátia); Medeiros, R. (Rui); Sanches-Magalhães, J. (José); Catalan, V. (Victoria); Fraga, A. (Avelino); Morais, A. (Antonio); Oliveira, J. (Jorge); Ribeiro, R. (Ricardo); Frühbeck, G. (Gema); Lobato, C. (Carlos); Gomez-Ambrosi, J. (Javier); Lobo, F. (Francisco); Rodriguez, A. (Amaia); Cunha, V. (Virginia); Lopes, C. (Carlos); Hu, P. (Pingzhao); Silva, V. (Vitor)Obesity and excess adiposity modified the expression of PP adipose tissue genes to ultimately foster fat mass growth. In patients with prostate cancer the expression profile of PP adipose tissue accounted for hypercellularity and reduced immunosurveillance. Both findings may be liable to promote a favorable environment for prostate cancer progression.
- Impact of nutritional changes on nonalcoholic fatty liver disease(MDPI AG, 2019) Perdomo-Zelaya, C.M. (Carolina M.); Frühbeck, G. (Gema); Escalada, J. (Javier)Non-alcoholic fatty liver disease (NAFLD) is a major global health threat due to its growing incidence and prevalence. It is becoming the leading cause of liver disease in addition to its strong association with cardio-metabolic disease. Therefore, its prevention and treatment are of strong public interest. Therapeutic approaches emphasize lifestyle modifications including physical activity and the adoption of healthy eating habits that intend to mainly control body weight and cardio-metabolic risk factors associated with the metabolic syndrome. Lifestyle interventions may be reinforced by pharmacological treatment in advanced stages, though there is still no registered drug for the specific treatment of NAFLD. The purpose of this review is to assess the evidence available regarding the impact of dietary recommendations against NAFLD, highlighting the effect of macronutrient diet composition and dietary patterns in the management of NAFLD.
- Uroguanylin prevents hepatic steatosis, mitochondrial dysfunction and fibrosis in obesity-associated NAFLD(Elsevier, 2023) Valenti, V. (Víctor); Colina, I. (Inmaculada); Catalan, V. (Victoria); Becerril, S. (Sara); Frühbeck, G. (Gema); Fernández-Sáez, E.M. (Eva M.); Losarcos, M. (Maite); Burrell, M.A. (María Ángela); Martín, M. (Mariana); Moncada, R. (Rafael); Mugueta, C. (Carmen); Silva, C. (Camilo); Gomez-Ambrosi, J. (Javier); Rodriguez, A. (Amaia); Escalada, J. (Javier)Background: The biological mediators supporting the resolution of liver steatosis, inflammation and fibrosis after bariatric surgery in patients with obesity and NAFLD remain unclear. We sought to analyze whether uroguanylin and guanylin, two gut hormones involved in the regulation of satiety, food preference and adiposity, are involved in the amelioration of obesity-associated NAFLD after bariatric surgery. Methods: Proguanylin (GUCA2A) and prouroguanylin (GUCA2B) were measured in 214 participants undergoing bariatric surgery with biopsy-proven NAFLD diagnosis. Pathways involved in lipid metabolism, mitochondrial network and fibrogenesis were evaluated in liver biopsies (n = 137). The effect of guanylin and uroguanylin on these metabolic functions was assessed in HepG2 hepatocytes and LX-2 hepatic stellate cells (HSC) under lipotoxic and profibrogenic conditions. Results: Plasma and hepatic expression of GUCA2B were decreased in obesity-associated NAFLD. Both GUCA2A and GUCA2B levels were increased after sleeve gastrectomy and Roux-en-Y gastric bypass in parallel to the improved liver function. The liver of patients with type 2 diabetes showed impaired mitochondrial β-oxidation, biogenesis, dynamics as well as increased fibrosis. Uroguanylin diminished the lipotoxicity in palmitate-treated HepG2 hepatocytes, evidenced by decresased steatosis and lipogenic factors, as well as increased mitochondrial network expression, AMPK-induced β-oxidation and oxygen consumption rate. Additionally, uroguanylin, but not guanylin, reversed HSC myofibroblast transdifferentiation as well as fibrogenesis after TGF-β1 stimulation. Conclusions: Uroguanylin constitutes a protective factor against lipotoxicity, mitochondrial dysfunction and fibrosis. Increased GUCA2B levels might contribute to improve liver injury in patients with obesity-associated NAFLD after bariatric surgery.
- High body adiposity drives glucose intolerance and increases cardiovascular risk in normoglycemic subjects(Wiley, 2018) Diaz-Gutierrez, J. (Jesús); Pérez-Pevida, B. (Belén); Frühbeck, G. (Gema); Silva, C. (Camilo); Salvador, J. (Javier); Romero, S. (Sonia); Escalada, J. (Javier); Dimitri-Miras, A. (Alexander)Objective: The objective of this study was to assess the utility of the 2-hour oral glucose tolerance test (OGTT) value to discriminate between different cardiometabolic profiles and examine the role of body composition in predicting the associated increased risk for glucose impairment, beta-cell dysfunction, and cardiovascular disease (CVD). Methods: Subjects with normal fasting glucose completed a 2-hour OGTT and were categorized to the carbohydrate metabolism alterations (CMAs) or the control group based on a 2-hour glucose threshold of 7.8 mmol/L. Body composition, visceral adipose tissue, OGTT-based parameters, and cardiovascular risk factors (CVRFs) such as hypertension, dyslipidemia, obstructive sleep apnea, nonalcoholic fatty liver disease, and smoking status were measured. Results: Subjects with CMAs exhibited a significantly higher 1-hour postload glucose level and a greater decline in beta-cell function and CVRF profiles. After multivariate adjustment, an excess of total body and visceral fat was associated with an increased risk of CMAs, beta-cell dysfunction, CVRFs, and lower whole-body insulin sensitivity. Conclusions: These data support the etiopathogenic role of body and visceral fat in the development of glucose derangements and CVRFs early on in the metabolic dysregulation process. Thus, body composition analysis and OGTT assessment performed in individuals with normal fasting glucose enable a better identification of patients at risk of developing type 2 diabetes and CVD.
- Rapid in vivo PGC-1 mRNA upregulation in brown adipose tissue of Wistar rats by a beta(3)-adrenergic agonist and lack of effect of leptin.(Elsevier, 2001) Martinez, J.A. (José Alfredo); Frühbeck, G. (Gema); Gomez-Ambrosi, J. (Javier)Peroxisome proliferator-activated receptor-γ coactivator-1 (PGC-1) is highly expressed in brown adipose tissue (BAT) and plays an important role in adaptive thermogenesis. The aim of this study was to assess the acute effect of a β3-adrenergic agonist (Trecadrine) and leptin on the expression of PGC-1 and PPARγ2 mRNA in BAT. Trecadrine produced a marked increase (4.5-fold) in PGC-1 mRNA compared to controls (P<0.001) without changes in PPARγ2 mRNA, whereas leptin administration did not alter either PGC-1 or PPARγ2 expression. These results show that selective stimulation of the β3-adrenoceptor rapidly upregulates the expression of PGC-1 in brown adipocytes without a concomitant increase in PPARγ2. Moreover, our results show that PGC-1 and PPARγ2 expression in BAT seems not to be acutely regulated by leptin.