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The main cause of death in obese individuals is cardiovascular disease precipitated by atherosclerosis. Endothelial dysfunction and inflammation are considered early events in the development of the disease.The aim of this study was to identify biomarkers of subclinical atherosclerosis in patients with morbid obesity by comparing clinical, vascular, and biochemical parameters indicative of endothelial dysfunction in patients with and without atheromatous plaque and monitoring changes after bariatric surgery.Multicenter collaboration between Biochemistry and Biomedicine Department in Barcelona University and University Hospital Arnau de Vilanova in Lleida.Plasma samples from 66 patients with morbid obesity were obtained before bariatric surgery and at 6 and 12 months after. Patients were divided into 2 groups based on the presence of atheromatous plaque. We used contrast-enhanced carotid ultrasound, enzyme-linked immunosorbent assay, Griess, and EndoPAT-2000 methods.Patients with plaque showed the worst profile of cardiovascular risk factors. Carotid intima-media thickness and plasminogen activator inhibitor-1 were higher in plaque group (P.0001). After bariatric surgery, vasa vasorum, oxidized low-density lipoprotein, and plasminogen activator inhibitor-1 decreased (P.0001 in all cases).Obesity promotes atherogenesis, leading to vascular endothelial damage. Bariatric surgery reduces cardiovascular risk and the prognosis is better for patients without plaque. The increase in plasminogen activator inhibitor-1, carotid intima-media thickness, and vasa vasorum proliferation might be the first alterations in the atheromatous process in obesity and could serve as good biomarkers of subclinical atherosclerosis.

Morbid obesity is associated with accelerated atherosclerosis, a chronic vascular disease related to oxidative stress (OS) and endothelial dysfunction.We aimed to evaluate the effect of bariatric surgery (BS) on oxidative stress as a cardiovascular risk factor in patients with and without atheromatous plaques.Arnau de Vilanova University Hospital and University of Barcelona.Plasma samples from 66 patients with morbid obesity were obtained before BS and 6 and 12 months after. Patients were divided into 2 groups based on the presence of atheromatous plaques (detected by ultrasonography). OS parameters were measured by enzyme-linked immunosorbent assay.Patients with morbid obesity had OS independently of the presence of an atheroma, but oxidized low-density lipoprotein levels were higher in patients with plaques throughout the study (P = .0430). After surgery, oxidized low-density lipoprotein and malondialdehyde levels decreased significantly (P.0001 in both cases). At the beginning of the study, antioxidant enzyme levels were the same between the groups. After surgery, paraoxonase 1 levels were increased (P.0001) in the group without plaque, being significantly higher (P = .0147). Superoxide dismutase 2 levels were only decreased in patients without plaque (P.0010), while catalase activity was higher in patients with plaque.Morbid obesity may lead to chronic OS, which increases predisposition to atherogenesis. BS improves the antioxidant profile and reduces OS and co-morbidities in both groups. However, the benefits are greater for patients without plaque. Therefore, BS may prevent atheroma formation and also could prevent plaque rupture by decreasing OS.

Purpose Obesity, a worldwide health problem, is linked to an abnormal gut microbiota and is currently most efectively treated by bariatric surgery. Our aim was to characterize the microbiota of high-fat fed Sprague–Dawley rats when subjected to bariatric surgery (i.e., vertical sleeve gastrectomy) and posterior refeeding with either a high-fat or control diet. We hypothesized that bariatric surgery followed by the control diet was more efective in reverting the microbiota modifcations caused by the high-fat diet when compared to either of the two factors alone. Methods Using next-generation sequencing of ribosomal RNA amplicons, we analyzed and compared the composition of the cecal microbiota after vertical sleeve gastrectomy with control groups representing non-operated rats, control fed, high-fat fed, and post-operative diet-switched animals. Rats were fed either a high-fat or control low-fat diet and were separated into three comparison groups after eight weeks comprising no surgery, sham surgery, and vertical sleeve gastrectomy. Half of the rats were then moved from the HFD to the control diet. Using next-generation sequencing of ribosomal RNA amplicons, we analyzed the composition of the cecal microbiota of rats allocated to the vertical sleeve gastrectomy group and compared it to that of the non-surgical, control fed, high-fat fed, and post-operative diet-switched groups. Additionally, we correlated diferent biological parameters with the genera exhibiting the highest variation in abundance between the groups. Results The high-fat diet was the strongest driver of altered taxonomic composition, relative microbial abundance, and diversity in the cecum. These efects were partially reversed in the diet-switched cohort, especially when combined with sleeve gastrectomy, resulting in increased diversity and shifting relative abundances. Several highly-afected genera were correlated with obesity-related parameters. Conclusions The dysbiotic state caused by high-fat diet was improved by the change to the lower fat, higher fber control diet. Bariatric surgery contributed signifcantly and additively to the diet in restoring microbiome diversity and complexity. These results highlight the importance of dietary intervention following bariatric surgery for improved restoration of cecal diversity, as neither surgery nor change of diet alone had the same efects as when combined. This work was supported by the Ministerio de Sanidad y Consumo, Instituto de Salud Carlos III (ISCIII) (PI11/01159, PI15/00190 and PI15/00332 to JAB-F and JP-O), was co-fnanced by European Union Funds, Fondo Europeo de Desarrollo Regional (FEDER) “Una manera de hacer Europa”. Additional funding from the Stockholm Health Authority grant # SLL 20160933 was awarded to KIU

Background To date, laparoscopic adjustable gastric banding remains the third most commonly performed surgical procedure for weight loss. Some patients fail to get acceptable outcomes and undergo revisional surgery at rates ranging from 7% to 60%. Roux-en-Y gastric bypass (RYGB), one anastomosis gastric bypass (OAGB), and sleeve gastrectomy (SG) are among the most common salvage options for failed laparoscopic adjustable gastric banding. Objective To compare the outcomes of converting failed laparoscopic adjustable gastric banding to RYGB, OAGB, or SG. Methods Data collected from 7 experienced bariatric centers around the world were retrospectively collected, reviewed, and analyzed. Final body mass index (BMI), change in BMI, percentage excess BMI loss, and major complications with particular attention to leaks, hemorrhage, and mortality were reported. Results Of 1219 patients analyzed, 74% underwent RYGB, 16% underwent OAGB, and 10% underwent SG after banding failure. The mean age was 38 years (±10 yr), and 82% of patients were women. The mean follow-up was 33 months. The follow-up rate was 100%, 87%, and 52% at 1, 3, and 5 years, respectively. At the latest follow-up, percentage excess BMI loss >50% was achieved by 75% of RYGB, 85% of OAGB, and 67% of SG patients. Postoperative complications occurred in 13% of patients after RYGB, 5% after OAGB, and 15% after SG. Conclusion Our data show that it is possible to achieve or maintain significant weight loss with an acceptable complication rate with all 3 surgical options.

Seasonality is a phenomenon that is characterized by changes over the year in sleep, mood, behaviour, appetite and body weight. In humans, seasonal variations have been found in certain variables, such as lipid variables and body mass index. We hypothesize that this rhythm could influence the expected variation of the levels of biochemical variables in cases of body weight loss. Thus, the goal of this study was to observe whether the time of year in which bariatric surgery (BS) took place modulated the changes in several variables related to glucidic and lipid metabolism. Blood samples were obtained from 24 women and 10 men before BS and 1 and 3 months after BS. We calculated the percentage of variation that occurred for each individual and for each variable as a function of the time of the year. Data were adjusted to a 12-month period sinusoidal curve, with significance being set at p 0.05. The results showed that almost all of the studied variables changed due to the BS according to a seasonal rhythm. Most of the variables showed a decrease that was most prominent in winter. In the cases of body mass index (BMI), adrenocorticotropin hormone (ACTH), and cortisol, the highest variation occurred in winter. Insulin and cholesterol in high-density lipoproteins (cHLD) variations were higher in springtime. Glucose variation showed a decrease after surgery with acrophase in summer-fall and plasminogen activator inhibitor-1 (PAI-1) and homeostatic model assessment-insulin resistance (HOMA-IR) in spring-summer. Ghrelin levels showed increases with a rhythm of variation with an acrophase in summer-fall. The seasonal rhythm found in this study fits nearly with the inverse of the endogenous circannual rhythm of the variables studied. The time of the year when the highest variation takes place is related to the circannual rhythm of the variable. The results agree with the manifestation of seasonal rhythm in human biochemical variables, which are reflected in the responses to weight loss after BS.

Background Inflammation and endothelial dysfunction are associated with morbid obesity (MO) and atherosclerosis. Objective To evaluate inflammation and endothelial function as the initial mechanisms underlying subclinical atherosclerosis in patients with MO, with and without atheromas, and their evolution after bariatric surgery (BS). Setting Arnau de Vilanova University Hospital and University of Barcelona. Methods Plasma samples from 66 patients with MO were obtained before BS and 6 and 12 months after BS. Patients were divided into 2 groups based on the presence of atheromatous plaques (detected by ultrasound imaging). Results Inflammation was increased as demonstrated by changes in the levels of fibroblast growth factor 21, adiponectin, leptin, interleukin 6, tumor growth factor α, nonesterified free fatty acids, lipoprotein(a) and C-reactive protein (CRP). Endothelial dysfunction was characterized by impaired angiogenesis (measured through angiopoietin 1 and 2 and brain-derived neurotrophic factor), vascular function (changes in endothelin 1 and thrombomodulin levels), and diapedesis (changes in intercellular and vascular cell adhesion molecules, and E- and P-selectins). Both mechanisms occurred regardless of the presence of atheromas. BS ameliorated both processes even in patients who already had subclinical atherosclerosis. However, CRP, thrombomodulin, and P-selectin levels were higher in patients with atheromas. Conclusions Endothelial dysfunction and inflammation were detected before the appearance of structural changes in vessel walls on ultrasonography images. BS might prevent or slow atherogenesis in the early stages by breaking the vicious circle between inflammation and endothelial dysfunction. CRP, thrombomodulin, and P-selectin may have a critical role in plaque development and, together with the study of endothelial dysfunction, might be useful in assessing early atherosclerosis and its evolution after BS.

BACKGROUND There is growing evidence that oxidative stress (OS) is a critical factor linking obesity with its associated comorbidities, such as cardiovascular diseases. AIM To evaluate the degree of OS in people with morbid obesity and its relationship with glycoproteins, determined using 1H-NMR spectroscopy, before and after bariatric surgery (BS). METHODS In this observational cohort study, plasma from 24 patients with BMI ≥ 40 kg/m2 (age: 21-65 years) was used to measure metabolites implicated in OS. We measured glycoprotein (GlycA, GlycB and GlycF) areas and shape factors (H/W = height/width). RESULTS One year after BS, oxidized low-density lipoprotein had decreased by 49% (P

Bariatric surgery with or without diet change has become one of the most effective treatments for obesity. The objective of this study was to observe the effects of vertical sleeve gastrectomy (VSG) and diet change in Sprague-Dawley rats on both body and tissue weights. Eighteen rats were fed with a standard chow diet (SCD) (C group), and 36 rats were fed with a high-fat diet (HFD) (diet-induced obesity (DIO) group). After 8 weeks, the animals underwent VSG, sham surgery or no surgery (NS). After surgery, a third of the rats fed with the HFD changed to the SCD (DIO + C group). Body weight, food and energy intake were recorded daily during the experiment (12 weeks). Food efficiency (%) (FE) was determined from weekly weight gain and weekly kilocalorie consumed measurements. The DIO group had higher and significant weight gain than the C group at the time of surgery (p

Seasonal variations have been described in humans in several variables such as sleep, mood, appetite, food preferences, or body weight. We hypothesized that these variations could also influence the decrease in body weight rate in patients submitted to body weight loss interventions. Thus, here we tested the variations of weight loss according to the time of the year the surgery took place in a group patients (n = 1322) submitted to bariatric surgery in the Hospital Universitari de la Vall d'Hebron in Barcelona (geographical coordinates: 41°25'41″N 2°8'32″E). For the analysis, the percentage of total body weight loss (%TWL), excess body weight loss (%EWL) and percentage of body mass index loss (%BMIL) were calculated at 3 (n = 1255), 6 (n = 1172), 9 (n = 1002), and 12 months (n = 1076) after surgery. For %EWL and %BMIL a statistically significant seasonal variation was detected when the variables were calculated at 3 months, but not at the other times, with more weight loss in summer-fall. However, seasonal variations were not detected for %TWL (p = 0.09). The mean amplitude of the seasonal rhythm for %EWL was of 1.8%, while for the rhythm of %BMIL was 0.7%. Moreover, a second peak was detected in January-February modulating the seasonal rhythm of the two variables. Results confirm seasonal variations in humans and indicate that short term responses to weight loss can be modulated by the time of year.

Cortisolemia and 11βHSD1 in liver and adipose tissue are altered in obesity. However, their participation in the development of obesity remains unclear. This study analyzed these parameters in the transition from morbid to type 1 obesity after bariatric surgery.

We have investigated the differences in plasma parameters and serum trace elements between "healthy" and unhealthy morbidly obese patients before and after Roux-en-Y gastric bypass surgery.A group of 32 morbidly obese patients undergoing bariatric surgery were divided into three groups. Group 1 subjects were free of dyslipidemia and type II diabetes mellitus (defined as "healthy" obese, DM-DL-); Group 2 subjects had only the presence of dyslipidemia (DM-DL+), while group 3 patients demonstrated the presence of both (DM + DL+). In all patients, we studied haematological, haemostasis, anaemia, coagulation plasma and trace elements parameters before and 1, 6 and 12 months after gastric bypass surgery.We found significant differences in some haematological parameters, including haemostasis (e.g., T-Quick, p = 0.0048) and coagulation (e.g., ATIII and PAI-1, p = 0.001 and p0.0001, respectively) and in anaemia parameters (e.g., folate, cobalamin and transferrin, p = 0.0002, p0.0001 and p = 0.0001, respectively) but also in serum trace elements between the groups. However, the response to bariatric surgery was similar in the three groups.Any healthy morbid obese subject is really metabolically "unhealthy" because he or she has many other haematologic or serum abnormalities that are often not included in the criteria for the definition of "healthy" in these obese subjects.

Although intermediate metabolism is known to follow circadian rhythms, little information is available on the variation in lipase activities (lipoprotein and hepatic lipase, LPL and HL, respectively) and lipids throughout the year. In a cross-sectional study, we collected and analysed blood from 245 healthy students (110 men and 135 women) between 18 and 25 years old from the University of Barcelona throughout the annual campaign (March, May, October and December) of the blood bank. All subjects gave their written informed consent to participate. All blood samples were taken after breakfast at 8:00 and 11:00 am. Plasma glucose, total plasma protein, triacylglycerides (TAG), free fatty acids (FFA), free cholesterol and esterified cholesterol (FC and TC, respectively), cholesterol in low-density lipoproteins (cLDL), cholesterol in high-density lipoproteins (cHDL), phospholipids (PL) and lipase activities (LPL and HL) were determined. Cosinor analysis was used to evaluate the presence (significance of fit cosine curve to data and variance explained by rhythm) and characteristics of possible 12-month rhythms (acrophase, MESOR and amplitude). Statistically significant seasonal rhythms were detected for all the variables studied except proteins, with most of them peaking in the winter season. The lowest value for cLDL and the HL occurs in summer, while for cHDL and the LPL it is in winter. These findings demonstrate for the first time that in physiological conditions, plasma LPL and HL activities and lipids follow seasonal rhythms. The metabolic significance of this pattern is discussed.

Diabesity and fatty liver have been associated with low levels of high-density lipoprotein cholesterol, and thus could impair macrophage-specific reverse cholesterol transport (m-RCT). Liver X receptor (LXR) plays a critical role in m-RCT. Abcg5/g8 sterol transporters, which are involved in cholesterol trafficking into bile, as well as other LXR targets, could be compromised in the livers of obese individuals. We aimed to determine m-RCT dynamics in a mouse model of diabesity, the db/db mice. These obese mice displayed a significant retention of macrophage-derived cholesterol in the liver and reduced fecal cholesterol elimination compared with nonobese mice. This was associated with a significant downregulation of the hepatic LXR targets, including Abcg5/g8. Pharmacologic induction of LXR promoted the delivery of total tracer output into feces in db/db mice, partly due to increased liver and small intestine Abcg5/Abcg8 gene expression. Notably, a favorable upregulation of the hepatic levels of ABCG5/G8 and NR1H3 was also observed postoperatively in morbidly obese patients, suggesting a similar LXR impairment in these patients. In conclusion, our data show that downregulation of the LXR axis impairs cholesterol transfer from macrophages to feces in db/db mice, whereas the induction of the LXR axis partly restores impaired m-RCT by elevating the liver and small intestine expressions of Abcg5/g8.

Objective The possible differences were investigated in 32 morbidly obese patients depending on whether they were “healthy” or had dyslipidemia and/or type 2 diabetes. Methods Lipid metabolism and insulin resistance were analyzed in subcutaneous (SAT) and visceral adipose tissue (VAT) before and during 6 and 12 months after Roux-en-Y gastric bypass. Results Significant differences have been found in lipoprotein lipase (LPL) and hormone-sensitive lipase (HSL) activities in SAT from the different obese group versus normal weight (control) but not between them. The reduced lipase activities in VAT were 43 and 19% smaller (22 and 4% smaller, respectively, vs. control) than the “healthy” obese group for LPL and HSL, respectively, and were accompanied with a reduced expression of these lipases, as well as decreased expression of FAT/CD36, FABP4, and AQ7 in that tissue. In addition, the expression of the other genes measured showed a downregulation not only versus the “healthy” obese but also versus the normal weight group. Conclusions Being obese is not “healthy,” but it is even less so if morbidly obese patients with diabetes and dyslipidemia were considered. The reduced fat accumulation in these patients may be attributed to the decrease of the expression and activity of the lipases of their adipose tissue.

Objective: The purpose of this study was to evaluate the effect of weight loss induced in morbidly obese subjects by Roux-en-Y gastric bypass bariatric surgery on the atherogenic features of their plasma lipoproteins. Methods: Twenty-one morbidly obese subjects undergoing bariatric surgery were followed up for up to 1 year after surgery. Plasma and lipoproteins were assayed for chemical composition and lipoprotein-associated phospholipase A2 (Lp-PLA2) activity. Lipoprotein size was assessed by non-denaturing polyacrylamide gradient gel electrophoresis, and oxidised LDL by ELISA. Liver samples were assayed for mRNA abundance of oxidative markers. Results: Lipid profile analysis revealed a reduction in the plasma concentrations of cholesterol and tri-glycerides, which were mainly associated with a significant reduction in the plasma concentration of circulating apoB-containing lipoproteins rather than with changes in their relative chemical composition. All patients displayed a pattern A phenotype of LDL subfractions and a relative increase in the anti-atherogenic plasma HDL-2 subfraction (> 2-fold; P < 0.001). The switch towards predominantly larger HDL particles was due to an increase in their relative cholesteryl ester content. Excess weight loss also led to a significant decrease in the plasma concentration of oxidised LDL (similar to-25%; P < 0.01) and in the total Lp-PLA2 activity. Interestingly, the decrease in plasma Lp-PLA2 was mainly attributed to a decrease in the apoB-containing lipoprotein-bound Lp-PLA2. Conclusion: Our data indicate that the weight loss induced by bariatric surgery ameliorates the atherogenicity of plasma lipoproteins by reducing the apoB-containing Lp-PLA2 activity and oxidised LDL, as well as increasing the HDL-2 subfraction. (C) 2014 Elsevier Ireland Ltd. All rights reserved.

The objective of this study was to establish the relationship between the plasminogen activator inhibitor-1 (PAI-1), antithrombin-III (ATIII), fibrinogen, and white blood cell (WBC) levels in severely obese patients. We analyzed various plasma parameters implicated in the intrinsic and extrinsic coagulation pathway from 34 severely obese patients before and 1, 6, and 12 months after gastric bypass. In obese people, ATIII, fibrinogen, and WBC levels were in the upper limit of the normal range, and all were higher and significantly different from nonobese people. After bariatric surgery, the ATIII level continued to be high during the first month and increased until 12 months, while fibrinogen decreased only at that time. PAI-1 plasma protein and PAI-1 mRNA levels in liver and adipose tissue show similar profiles and had a strong positive correlation (r = 0.576, P = 0.0003 in liver; r = 0.433, P = 0.0004 in adipose tissue). They were higher in obese patients compared with nonobese control, but tended to recover normal values 1 month after surgery. Thus, the liver and adipose tissue could be an important source of PAI-1 protein in plasma. Gastric bypass surgery leads to a normalization of the hematological profile and a decrease in PAI-1 levels, which entails a decrease of risk for thromboembolism in severely obese.

Increased C-reactive protein (CRP) levels strongly predict inflammatory diseases such as obesity and tissue damage. We wanted to study the CRP in plasma and tissue in morbidly obese patients before and after surgery and relate it with the expression of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) in tissues. We analyzed CRP concentration in plasma, adipose and liver, and the expression of IL-6 and TNF-α, in those tissues, in 34 morbidly obese patients before and 1, 6 and 12 months after gastric bypass. Morbidly obese had a greater amount of CRP in plasma (3 times) and tissues (21, 5 and 7 times more in liver, subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT), respectively) than control subjects. The expression of IL-6 in SAT showed a similar profile to plasma and SAT CRP in both obese patients and after weight loss, despite no significant correlation was found. We were only able to detect IL-6 in the liver of a subset of patients. The expression of TNF-α after surgery showed a no significant slight tendency to decrease in SAT with weight loss, but in the liver, we did not observe any change. IL-6 in SAT, but not in liver, seems to be more closely related to plasma and tissue CRP than TNF-α in both obese patients and after weight loss. Plasma CRP protein perfectly reflects the decrease in inflammation and improves with weight loss in the tissues.

The relationship between C-reactive protein (CRP), nitric oxide (NO), leptin, adiponectin, and insulin growth factor 1 (IGF-1) is poorly defined in morbidly obese patients before and after gastric bypass and, in some cases, is controversial.We examined the plasma of 34 morbidly obese patients before and 1, 6, and 12 months after Roux-en-Y gastric bypass surgery.Obese people had more CRP (21.3 +/- 1.8 microg/ml) and leptin (36.9 +/- 4.0 ng/ml) than those in the control group (nonobese people: CRP = 6.9 +/- 0.9 microg/ml, p0.0001; leptin = 7.5 +/- 0.4 ng/ml, p0.0001). However, they had less NO (30.4 +/- 2.7 nmol/ml), IGF-1 (77.5 +/- 6.6 ng/ml), and adiponectin (11.1 +/- 1.0 microg/ml) than those in the control group (NO = 45.8 +/- 3.9 nmol/ml, p = 0.0059; IGF-1 = 202.0 +/- 12.0 ng/ml, p0.0001; adiponectin = 18.0 +/- 2.0 microg/ml, p0.0001). During weight loss, the amount of CRP and leptin decreased until they reached the nonobese values, but the level of NO remained lower than in nonobese people, even 1 year after surgery. The linear regression slopes were negative and very significant for leptin (p = 0.0005) and CRP (p = 0.0018) but were less significant for NO (p = 0.0221). IGF-1 displayed a very good linear regression (both negative and significant) with some anthropometric parameters, including body mass index (p = 0.0025), total fat (p = 0.0177), and the percentage of fat (p0.0001).For the first time, we report the relationship between IGF-1 and CRP, NO, leptin, and adiponectin. For all these parameters, the best and most widely demonstrated improvements in comorbidities before and during weight loss in morbid obesity were associated with CRP and leptin.

Although bariatric surgery is currently the most common practice for inducing weight loss in morbidly obese patients (BMI > 40 kg/m2), its effect on the lipid content of adipose tissue and its lipases (lipoprotein lipase [LPL] and hormone-sensitive lipase [HSL]) are controversial. We analyzed LPL and HSL activities and lipid content from plasma as well as subcutaneous (SAT) and visceral (VAT) adipose tissue of 34 morbidly obese patients (MO) before and after (6 and 12 months) Roux-en-Y gastric bypass surgery and compare the values with those of normal weight (control) patients. LPL activity was significantly higher in MO (SAT = 32.9 ± 1.0 vs VAT = 36.4 ± 3.3 mU/g tissue; p

Although bariatric surgery is the most common procedure used to induce weight loss in morbidly obese patients, its effect on plasma satiety factors (leptin, ghrelin, and apolipoprotein (apo)-AIV) is controversial. The aim of this work was to analyze these parameters before and at different times after surgery. Plasma was obtained from 34 patients before undergoing Roux-en-Y gastric bypass and during weight loss in the 12 months following surgery. Morbidly obese patients had significantly higher values (147%) of leptin than normal-weight (NW) persons, while their ghrelin levels were 46% less than NW. Apo-AIV levels had approximately the same value in both groups (obese and NW). During weight loss, leptin decreased by 75% and ghrelin increased by 78%. Both parameters reached values less than or near NW, respectively, at 1 year after surgery. During the first month after surgery, apo-AIV plasma levels decreased (47%) but later increased and finally returned to preoperative values. Apo-AIV levels were correlated negatively with leptin and positively with ghrelin. High-density lipoprotein (HDL) levels were positively correlated with those of ghrelin and apo-AIV. During weight loss, plasma leptin and ghrelin could be good markers of total fat decrease. Ghrelin could also indicate gastric mucous improvement, whereas apo-AIV could indicate the recovery of intestinal function. Changes produced in the HDL levels of morbidly obese patients during weight loss suggest a decreased risk of coronary disease.

The oocytes of many fish species accumulate high amounts of neutral lipids as a caloric reserve for embryonic and larval development. We propose that lipoprotein lipase (LPL, EC 3.1.1.34) plays an important role in supplying the oocytes with fatty acids and we have cloned its cDNA from the ovary of sea bass, and determined the patterns of LPL activity and LPL mRNA expression in the ovary. The cDNA obtained was 3051 bp long with an open reading frame encoding 518 amino acids. The amino acid sequence has a high similarity and shows similar structural features to LPL of other species. Northern blot analysis revealed LPL expression in adipose tissue and gonads only. LPL activity and LPL mRNA expression in the ovary was very high in fish with a gonadosomatic index (GSI) above 5, coinciding with the appearance of a high number of lipid droplets in the ooplasm. The LPL mRNA expression was localised to the follicle cells surrounding the oocyte. Our results suggest that LPL is likely to play an important role in the incorporation of neutral lipids into the oocytes, and that follicle cells, in addition to participating in steroidogenesis, also may be important in building up oocyte lipid reserves. © 2008 Elsevier Inc. All rights reserved., This work was supported by grants from the former Spanish Ministry of Science and Technology (grant AGL2000-1983 to F.P., and Ph.D. FPI bursary FP2000-5907 to A.J.I).

Cortisolemia and 11βHSD1 in liver and adipose tissue are altered in obesity. However, their participation in the development of obesity remains unclear. This study analyzed these parameters in the transition from morbid to type 1 obesity after bariatric surgery.A group of 34 patients with morbid obesity and 22 nonobese subjects were recruited. Initial hypothalamus-pituitary-adrenal (HPA) basal activity and 11βHSD1 mRNA expression in liver, subcutaneous (SAT), and visceral adipose tissue (VAT) were evaluated. A year after bariatric surgery (weight loss of 48 kg), these parameters were reappraised in plasma, SAT, and liver.Body weight loss was accompanied by a downshift in basal HPA activity and 11βHSD1 expression in SAT. In patients with morbid obesity, 11βHSD1 expression correlated positively with BMI in VAT and negatively in liver at 6 and 12 months after surgery. In SAT, a correlation was observed with body weight only when patients showed type 1 obesity. Insulin, glucose, and HOMA correlated positively with all the HPA indicators and 11βHSD1 expression in SAT.Body weight loss after bariatric surgery is accompanied by a downshift in basal HPA activity. Hepatic and VAT 11βHSD1 expressions in morbid obesity are predictors of body weight loss.

We have investigated the differences between metabolically "healthy" morbidly obese patients and those with comorbidities.Thirty-two morbidly obese patients were divided by the absence ("healthy": DM-DL-) or presence of comorbidities (dyslipidemic: DM-DL+, or dyslipidemic and with type 2 diabetes: DM+DL+). We have studied various plasma parameters and gene expression adipose tissue, before and after gastric bypass.The group DM+DL+ tends to have lower values than the other two groups for anthropometric parameters. Regarding the satiety parameters, only leptin (p = 0.0024) showed a significant increase with comorbidities. Lipid parameters showed significant differences among groups, except for phospholipids and NEFA. For insulin resistance parameters, only glucose (p 0.0001) was higher in DM+DL+ patients, but not insulin or homeostasis model assessment of insulin resistance (HOMA-IR). The gene expression of adiponectin, insulin receptor (INSR) and glucose receptor-4 (GLUT4), in the subcutaneous fat, decreased in all groups vs. a non-obese control. Interleukin-6 (IL6) and the inhibitor of plasminogen activator type 1 (PAI-1) genes decreased only in DM-DL+ and DM+DL+, but not in "healthy" patients. Leptin increased in all groups vs. the non-obese control. The visceral fat from DM+DL+ patients showed a sharp decrease in adiponectin, GLUT4, IL6 and PAI-1. All parameters mentioned above improved very significantly by surgery, independent of the occurrence of comorbidities.The morbidly obese "healthy" individual is not really metabolically healthy, but morbidly obese individuals with diabetes and dyslipidemia are more metabolically imbalanced.

This paper describes the development of a procedure for measuring total lipid, triacylglyceride, and cholesterol content using small amounts of tissue (50 mg for liver samples and 10 mg for adipose tissue samples). In the first step, total lipids are extracted with an organic solvent mixture of hexane and isopropanol. In the second step, extracted lipids are emulsified by sonication in a buffer containing 1,4-piperazinediethanesulfonic acid (28.75 mM), magnesium chloride.6H(2)O (57.76 mM), free fatty acids-bovine serum albumin (8.76 microM), and sodium dodecyl sulfate (0.1%). Lipid concentrations from the resulting emulsion can then be assessed using commercial enzymatic kits. This method is also suitable for determining direct homogenate triacylglyceride and total cholesterol content in cases where a lipid percentage is not needed. The proposed method increases the yield of lipid recovery from small tissue samples and allows the measurement of both triacylglyceride and cholesterol content from a single starting sample. The methodology described here is the first to accomplish simultaneous determination of both parameters and is potentially useful for animal small tissue samples, particularly human biopsy samples.

C/EBPbeta (CCAAT/enhancer-binding protein beta) is a transcriptional regulator of the UCP1 (uncoupling protein-1) gene, the specific marker gene of brown adipocytes that is responsible for their thermogenic capacity. To investigate the role of C/EBPbeta in brown fat, we studied the C/EBPbeta-null mice. When placed in the cold, C/EBPbeta(-/-) mice did not maintain body temperature. This cold-sensitive phenotype occurred, although UCP1 and PGC-1alpha (peroxisome-proliferator-activated receptor gamma co-activator-1alpha) gene expression was unaltered in brown fat of C/EBPbeta(-/-) mice. The UCP1 gene promoter was repressed by the truncated inhibitory C/EBPbeta isoform LIP (liver-enriched transcriptional inhibitory protein, the truncated inhibitory C/EBPbeta isoform). Since C/EBPbeta-null mice lack both C/EBPbeta isoforms, active LAP (liver-enriched transcriptional activatory protein, the active C/EBPbeta isoform) and LIP, the absence of LIP may have a stronger effect than the absence of LAP upon UCP1 gene expression. Gene expression for UCP2 and UCP3 was not impaired in all tissues analysed. In primary brown adipocytes from C/EBPbeta(-/-) mice, induction of gene expression by noradrenaline was preserved. In contrast, the expression of genes related to lipid storage was impaired, as was the amount of triacylglycerol mobilized after acute cold exposure in brown fat from C/EBPbeta(-/-) mice. LPL (lipoprotein lipase) activity was also impaired in brown fat, but not in other tissues of C/EBPbeta(-/-) mice. LPL protein levels were also diminished, but this effect was independent of changes in LPL mRNA, suggesting that C/EBPbeta is involved in the post-transcriptional regulation of LPL gene expression in brown fat. In summary, defective thermoregulation owing to the lack of C/EBPbeta is associated with the reduced capacity to supply fatty acids as fuels to sustain brown fat thermogenesis.

Hepatic lipase is involved in cholesterol uptake by the liver. Although it is known that catecholamines are responsible for the daily variation of enzyme activity, the mechanisms involved are poorly understood. Rat hepatocytes incubated with adrenaline or other Ca2+-mobilizing hormones were used as an experimental model. Adrenaline reduced in a similar proportion the secretion of both hepatic lipase and albumin. The effect of adrenaline disappeared completely in cells exposed to cycloheximide. Adrenaline decreased incorporation of [35S]Met into cellular and secreted proteins, but it affected neither degradation of [35S]Met-prelabeled proteins nor the abundance of total and specific (albumin, hepatic lipase, beta-actin) mRNA. Other Ca2+-mobilizing agents had the opposite effect on hepatic lipase secretion: it was decreased by vasopressin but was increased by epidermal growth factor. Vasopressin and epidermal growth factor had the opposite effect on [35S]Met incorporation into cellular and secreted proteins, but neither affected hepatic lipase mRNA. The acute effect of adrenaline, vasopressin, and epidermal growth factor on hepatic lipase secretion is the consequence of the effect of these hormones on protein synthesis and is therefore nonspecific.Key words: adrenaline, vasopressin, epidermal growth factor, albumin secretion.

In humans, stress can increase the risk of cardiovascular disease by altering lipoprotein metabolism. Scarce experimental and clinical data are available on this effect. Therefore, we studied the metabolic response to acute and chronic stress following a model of immobilization (IMO) in rats and we evaluated the resulting circulating lipoprotein levels. Repeated IMO treatment (2 hours daily, always between 9:00 AM and 11:00 AM, for 2 periods of 5 and 4 consecutive days, separated by 2 days of rest) daily decreased body weight gain and food intake, increased adrenal weight, and slightly reduced liver glycogen and plasma insulin (without considerable variations of blood glucose), which is characteristic of chronic stress. A single IMO application (30 minutes of an unexpected IMO starting at 2:00 PM immediately before the animals were killed) significantly increased the circulating levels of corticosterone, glucose, insulin, glycerol, and ketone bodies, which is the typical response to acute stress. Both acute and chronic stress decreased the plasmatic triacylglycerol (TAG) concentration, as reflected by the reduction in the number of very-low-density lipoprotein (VLDL) particles. This may be due to an increase in the metabolization of TAG, as suggested by the slightly higher amounts of circulating LDLs. Chronic stress, but not acute stress, significantly increased both the number and the estimated size of circulating high-density lipoprotein (HDLs), as shown by the plasma cholesterol concentration. Acute stress did not have an additive effect over chronic stress on the lipoprotein parameters studied. The metabolic effects of these IMO-induced alterations on lipoprotein profiles are discussed, and future studies in lipidic metabolism are suggested.

Tumor necrosis factor (TNFalpha) has been invoked as an adipostat. Accordingly, the adipose tissue expression of TNFalpha has been shown to be proportional to the degree of adiposity. The regulatory role of TNFalpha in obesity may be controlled by several mechanisms. These include the inhibitory effect on LPL activity, the mediation on glucose homeostasis or the effect on leptin. To assess the role of TNFalpha in obesity we measured adipocyte TNFalpha expression in 96 females with a wide range of adiposity and with or without type 2 diabetes. We analysed the relationship between TNFalpha expression, adipocyte LPL activity, insulin resistance and leptin in this population.The TNFalpha and leptin expression of the adipose tissue in obese and morbid obese patients were significantly higher than in controls. Obese and morbid obese patients had slightly higher levels of LPL activity, but these differences were not significant. We observed a significant relationship between adipose TNFalpha expression and body mass index (r=0.35, P0.001). TNFalpha expression was negatively related to LPL activity (r=-0.28, P0.05) and positively related to leptin expression (r=0.35, P0.001).Our results indicate that obese women, even those with morbid obesity, over-express TNFalpha in subcutaneous adipose tissue in proportion to the magnitude of the fat depot and independently of the presence of type 2 diabetes. The TNFalpha system may be a homeostatic mechanism that prevents further fat deposition by regulating LPL activity and leptin production.

Sequential flotation ultracentrifugation is commonly used in the preparation of plasma lipoproteins. However, protocols often require prolonged centrifugation time (48–72 h) and large plasma volumes (2–20 ml), which makes them unsuitable for studies on small laboratory animals. Although analytical techniques such as FPLC have often small sample requirements, further fraction analysis is often limited to the small fraction volume obtained. A sequential ultracentrifugation micromethod is described to obtain rat lipoprotein fractions from 400 μl of plasma in a cumulative centrifugation time of 7.5 h. Fraction volumes were determined and densities were adjusted to those of rat plasma lipoproteins. Polyacrylamide gel electrophoresis and enzymatic measurements of triglycerides, total cholesterol, and phospholipids were used to assess the purity of the lipoprotein fractions. The results were compared with those obtained from a classical sequential ultracentrifugation protocol. The micromethod presented here can be further adapted to other experimental animal species with little modifications.

The possible differences were investigated in 32 morbidly obese patients depending on whether they were "healthy" or had dyslipidemia and/or type 2 diabetes.Lipid metabolism and insulin resistance were analyzed in subcutaneous (SAT) and visceral adipose tissue (VAT) before and during 6 and 12 months after Roux-en-Y gastric bypass.Significant differences have been found in lipoprotein lipase (LPL) and hormone-sensitive lipase (HSL) activities in SAT from the different obese group versus normal weight (control) but not between them. The reduced lipase activities in VAT were 43 and 19% smaller (22 and 4% smaller, respectively, vs. control) than the "healthy" obese group for LPL and HSL, respectively, and were accompanied with a reduced expression of these lipases, as well as decreased expression of FAT/CD36, FABP4, and AQ7 in that tissue. In addition, the expression of the other genes measured showed a downregulation not only versus the "healthy" obese but also versus the normal weight group.Being obese is not "healthy," but it is even less so if morbidly obese patients with diabetes and dyslipidemia were considered. The reduced fat accumulation in these patients may be attributed to the decrease of the expression and activity of the lipases of their adipose tissue.

Summary Aims Obesity is characterized by dislipoproteinaemia with increased cholesterol and triacylglycerol levels and lower chylomicra disposal rates. We studied here whether these alterations were related to lipoprotein number and/or size and composition. Methods Plasma from lean and obese Zucker rats was fractionated into lipoprotein classes (chylomicra, very low density lipoprotein (VLDL), low density lipoprotein (LDL) and high density lipoprotein (HDL)) by differential centrifugation. The apoprotein and lipid composition of each fraction were measured. Lipoprotein particle size was estimated by dynamic light scattering and used to tabulate the mean diameter and volume of lipoprotein micelles. Particle mass was calculated from the density and volume. The mass of lipids and protein in each fraction/ml of plasma allowed the estimation of mean particle concentration and then the number of molecules of lipid and protein/unit of lipoprotein micelle. Results A large part of hyperlipidaemia of obese rats is due to the accumulation of chylomicra: 1.3 ± 0.2 mg/ml in lean rats [LR] (34% of all lipoproteins) and 8.2 ± 0.9 mg/ml in the obese rats [OR] (66% of all lipoproteins). Lipid percentage composition of lipoproteins was similar in both groups. The particle size of LDL and HDL was much higher in OR than in LR: LDLs weighed 31.1 ± 7.5 ag (LR) vs. 273 ± 81 ag (OR), and HDLs weighed 31.7 ± 12.6 ag (LR) and 375 ± 103 ag (OR). In chylomicra and VLDL there was a relative scarcity of apoproteins in OR compared with LR. The whole architecture of LDLs is altered in OR, with a predominance of surface lipids: phospholipid and free cholesterol, and lower amounts of core lipids: triacylglycerols and cholesterol esters, with surface/core lipids ratios of 0.74 (LR) and 1.89 (OR). The consequences of anomalous LDL and HDL composition, size and overall structure may result in magnified lipoprotein metabolism alterations that hamper their ability to transfer apolipoproteins to larger chylomicra and VLDL, and to alter cholesterol transfer and binding of their apoproteins to cell surface receptors. The smaller number of LDL and HDL particles may further compound these difficulties and thus change the free to esterified cholesterol ratios observed in OR. Conclusions The main conclusions of this study are the key importance of chylomicron analysis for a better understanding of the transfer of lipids, and the altered lipoprotein size and apoprotein distribution in obese rats, which seriously hamper cholesterol interchange, resulting in hypercholesterolaemia, and thus triggering even more far-reaching consequences for the well-being of the obese.

Adult female lean and obese Zucker rats maintained under standard conditions were used for the estimation of plasma, liver and white adipose tissue (WAT) activity of lipoprotein lipase, plasma and liver hepatic lipase and plasma lecithin-cholesterol acyltransferase. No differences in plasma or tissue levels of lipoprotein lipase between lean and obese rats were detected, but the larger WAT size of the obese rats resulted in higher lipase activity per unit of rat weight. Hepatic lipase levels in plasma were higher in the obese, but in liver, the higher activity was found in lean rats. No significant differences were found for lecithin-cholesterol acyltransferase activity, except when the levels in the HDL fraction were expressed per unit of protein weight, showing lower activity in the obese rats. In conclusion, the essentially maintained enzyme activities in obese rat tissues suggest that they cannot explain the deficient lipoproteins processing of obese rats, and, consequently their dislipidaemia.

In recent years, the CD40/CD40L system has been implicated in the pathophysiology of severe chronic inflammatory diseases. Recently, obesity has been described as a low chronic inflammatory disease, so this system could also be involved in the inflammatory process.To study soluble CD40 ligand (sCD40L) and other factors implicated in coagulation (plasminogen activator inhibitor 1, antithrombin III, and fibrinogen) and inflammation (C-reactive protein) in patients with morbid obesity and different body mass indexes (BMIs) (calculated as weight in kilograms divided by height in meters squared), before and after weight loss induced by bariatric surgery.Plasma samples were obtained before and after a bariatric surgery intervention. Several inflammatory markers were then studied (sCD40L, plasminogen activator inhibitor 1, antithrombin III, and C-reactive protein). The values obtained were compared with a control group of nonobese persons.Thirty-four morbidly obese patients undergoing gastric bypass surgery and 22 normal-weight controls matched for age and sex.A Roux-en-Y gastric bypass was performed in morbidly obese patients.Levels of sCD40L, plasminogen activator inhibitor 1, antithrombin III, fibrinogen, and C-reactive protein 12 months after bariatric surgery.Obese men showed a tendency for decreased plasma sCD40L levels 1 year after surgery (mean [SEM], 246.5 [70.4] pg/mL before vs 82.2 [23.2] pg/mL after surgery; P.05), whereas there were not any significant changes in obese women (285.9 [67.5] pg/mL before vs 287.0 [56.9] pg/mL after surgery). Levels of the other markers studied decreased significantly with weight loss in both sexes. However, all other studied markers tend to have higher concentrations in patients with higher BMIs, except for sCD40L, which tended to have lower concentrations in patients with BMIs higher than 55. The decreases with weight loss were lower with higher BMIs for all measurements, except for antithrombin III.Increased BMI, but not sex, influences recovery to normal levels for the markers studied, possibly indicating a worse prognosis.

Variations in hepatic lipase (HL) activity were studied for the first time in liver, plasma and adrenal glands of partially hepatectomized (70%), sham-operated and intact rats. Activity profiles performed during 7 days in liver, plasma and adrenal glands of sham-operated rats were similar to those obtained in intact animals. However, HL activity in intact animals appeared to be slightly higher during the first 24 hours. Following surgery, hepatectomized animals showed a reduction of about 300 U in liver HL activity which persisted for 7 days. Plasma HL activity of hepatectomized rats was undetectable at 6 hours post-surgery but in increased afterwards. A high correlation between liver and adrenal gland HL activity was found in hepatectomized but not in sham-operated animals. HL mRNA levels in hepatectomized rats showed a 40% decrease during the first 24 hours after surgery, but they returned to the normal range later. On the other hand, HL mRNA values increased in sham-operated rats but no increase in HL activity was detected in these animals. To conclude, our results show that HL activity decreases dramatically during hepatic regeneration due to a concomitant decrement in the expression of the gene that encodes the enzyme and to other undetermined factors.

We have cloned the cDNA encoding LPL and studied its mRNA expression and enzyme activity in the ovary of European sea bass in order to investigate a possible role of this enzyme in the incorporation of neutral lipids into the oocytes. The results suggest that LPL is likely to play an important role in this process.

AIM: To evaluate the effects of surgical weight loss (Roux-en-Y gastric bypass with a modified Fobi-Capella technique) on non alcoholic fatty liver disease in obese patients. METHODS: A group of 26 morbidly obese patients aged 45 ± 2 years and with a body mass index > 40 kg/m2 who underwent open surgical weight loss operations had paired liver biopsies, the first at surgery and the second after 16 ± 3 mo of weight loss. Biopsies were evaluated and compared in a blinded fashion. The presence of metabolic syndrome, anthropometric and biochemical variables were also assessed at baseline and at the time of the second biopsy. RESULTS: Percentage of excess weight loss was 72.1% ± 6.6%. There was a reduction in prevalence of metabolic syndrome from 57.7% (15 patients) to 7.7% (2 patients) (P < 0.001). Any significance difference was observed in aspartate aminotransferase or alanine aminotransferase between pre and postsurgery. There were improvements in steatosis (P < 0.001), lobular (P < 0.001) and portal (P < 0.05) inflammation and fibrosis (P < 0.001) at the second biopsy. There were 25 (96.1%) patients with non alcoholic steatohepatitis (NASH) in their index biopsy and only four (15.3%) of the repeat biopsies fulfilled the criteria for NASH. The persistence of fibrosis (F > 1) was present in five patients at second biopsy. Steatosis and fibrosis at surgery were predictors of significant fibrosis postsurgery. CONCLUSION: Restrictive mildly malabsorptive surgery provides significant weight loss, resolution of metabolic syndrome and associated abnormal liver histological features in most obese patients.

We studied the interaction of epidermal growth factor (EGF) and adrenaline in the control of several metabolic functions in isolated hepatocytes from fed rats. EGF did not modulate glucose release, urea production or hepatic lipase secretion, but interfered with the stimulatory effect of adrenaline on both glucose and urea production and also with the inhibitory effect of this hormone on hepatic lipase secretion. EGF also interfered with the effect of both angiotensin II and vasopressin on glucose release and on hepatic lipase secretion. While the effect of EGF interfering with the action of adrenaline on glucose release was potentiated in the absence of extracellular calcium, the effect on the inhibition of hepatic lipase secretion was abolished. These results suggest that EGF interfered with catecholamine actions in the liver at a site distal from the generation of the calcium signal.

Neuregulins (NRG) belong to the EGF family of growth factors, which are ligands of the ErbB receptors. Their expression in the adult heart is essential, especially when the heart is submitted to cardiotoxic stress such as that produced by anthracyclines. It is considered that ErbB4 is the only NRG receptor expressed by the adult heart. Upon binding, ErbB4 may dimerize with ErbB2 to generate signals inside cells. However, here we show the presence of ErbB3 in the mouse heart from birth to adulthood by Western blotting and real-time RT-PCR. The expression level of ErbB3 mRNA was lower than that of ErbB2 or ErbB4, but was more stable throughout postnatal development. In isolated heart myocytes, ErbB3 localized to the Z-lines similarly to ErbB1. Perfusion of isolated hearts with NRG-1β induced phosphorylation of ErbB3, as well as ErbB2 and ErbB4. In adult mice, both ErbB2 and ErbB3, but not ErbB1 or ErbB4, were rapidly down-regulated upon the induction of heart hypertrophy. In conclusion, our results demonstrate that ErbB3, in addition to ErbB4, is a receptor for neuregulin-1β in the adult mouse heart.

Recently, it was shown that lipoprotein lipase (LPL) was produced in neonatal but not in adult rat liver. In an attempt to further define the mechanism involved in liver LPL expression, we identified a neonatal mouse hepatoma cell line, BWTG3, capable of producing LPL. The regulation of LPL expression by various extracellular stimuli was investigated in this cell line. Progesterone caused a rise in LPL production by BWTG3 cells. Other hormones tested, such as insulin, glucagon, adrenalin, testosterone, and thyroid hormone, had no effect on LPL production. The effects of progesterone on LPL production showed slow kinetics reaching a maximum 24 h after addition. Cotransfection of a progesterone receptor expression vector with a 5'-LPL-CAT reporter construct resulted in an induction of CAT activity, suggesting that the increase in LPL accumulation after progesterone was linked to transcriptional induction of the LPL gene. Stimuli causing an elevation of protein kinase A activity in the cells also increased LPL production. Three agents capable of elevating intracellular cAMP levels, i.e., forskolin, dBcAMP, and choleratoxin, caused an elevation of LPL production. The increase in LPL activity caused by forskolin and choleratoxin was paralleled by an elevation of LPL mRNA levels, while dBcAMP only induced a small elevation of LPL mRNA levels. The increase in LPL production was shown to be linked to the stimulation of the PKA signal transduction pathway and was apparently transmitted via the transcription factor CREB. No effect of the stimulation of protein kinase C or calcium/calmodulin-dependent kinase on LPL production was detected. In conclusion, LPL production is regulated by progesterone and agents stimulating protein kinase A in BWTG3 hepatoma cells, making these cells a valuable model to study the regulation of LPL production.

The effect of fasting on hepatic endothelial lipase activity in the liver of adult rats was investigated. We found that, both in male and female rats, fasting produced a progressive decrease of the hepatic endothelial lipase activity. Upon refeeding, the activity returned to control values in 48 h. In isolated livers from fed male rats, a sharp peak of hepatic endothelial lipase activity appeared in the perfusate upon heparin addition. It accounted for 75% of the total activity (heparin-released + residual) of the tissue. Fasting (24 h) decreased the heparin-releasable activity, and this effect was responsible for most of the decrease found in whole tissue. We suggest that the effect might be due to a decreased synthesis and/or secretion of the enzyme by hepatocytes, since isolated hepatocytes from fasted rats, incubated at 37 C, released 65% less activity to the incubation medium than hepatocytes from fed rats. Adrenaline, but not insulin, glucagon, dexamethasone, epidermal growth factor, or T3, decreased the amount of hepatic endothelial lipase activity released by hepatocytes isolated from fed rats. The effect of adrenaline appears to be mediated by alpha 1-receptors since phenylephrine but not isoprenaline reproduced, and prazosin but not propranolol blocked, the effect of the catecholamine. In the presence of cycloheximide, adrenaline also decreased the amount of activity released. We suggest that, in our incubation conditions (up to 3 h), the hormone affects the posttranslational processing of the enzyme. In vivo administration of prazosin blocked the effect of both noradrenaline and fasting on hepatic endothelial lipase activity in whole liver. Those results suggest that catecholamines are involved in the decreased hepatic endothelial lipase activity found in the liver of fasted rats, and points out the role of these hormones in the acute modulation of an enzyme involved in reverse cholesterol transport.