Heparin-releasable Lipoprotein Lipase Research Articles

23-OR: Reduction in Insulin Uncovers a Novel Effect of VEGFB on Cardiac Substrate Utilization

VEGFB is known to up-regulate FA delivery through its effect on EC FA transporters. In its absence, intracellular lipid accumulation was reduced. Paradoxically, cardiac-specific overexpression of VEGFB demonstrated a lowered heparin-releasable lipoprotein lipase (LPL) activity with reduced FA utilization in vivo. Currently, the mechanism behind this in vivo metabolic effect of VEGFB on cardiac LPL is unclear. In transgenic (Tg) hearts, the vectorial transfer of LPL from myocytes to the vascular lumen is obstructed, resulting in LPL buildup within cardiomyocytes. Given that insulin is known to inhibit LPL translocation and thus FA metabolism in the heart, this observation is likely a secondary effect of VEGFB on vascular development with its associated augmentation of insulin delivery. We tested whether lowering of insulin by fasting would validate our hypothesis. WT fasted hearts enhanced their heparin-releasable LPL activity in an attempt to switch substrate utilization to FA. Intriguingly, this increase in LPL activity following fasting was even more dramatic in Tg hearts. Thus, with insulin deficiency following fasting, VEGFB works unimpeded to facilitate LPL movement. This effect occurred through the activation of p38 MAPK. PET imaging using 18FTHA revealed augmented LPL-derived FA and impaired FDG glucose uptake in the Tg fasted heart. Additionally, this increased delivery of LPL-derived FA correlated to augmented mitochondrial oxidation determined by high resolution oxygraphy. We examined whether this property of VEGFB on FA uptake and oxidation could be useful following diabetes, with its attendant loss of metabolic flexibility. Unexpectedly, in Tg hearts, diabetes inhibited myocyte VEGFB gene expression and protein secretion together with its downstream receptor signaling. Our data suggests that following diabetes, loss of VEGFB action may contribute towards the metabolic inflexibility, lipotoxicity and diabetic cardiomyopathy. Disclosure R.Shang: None. C.Lee: None. B.Hussein: None. B.Rodrigues: None. Funding Canadian Institutes of Health Research (PJT180558); Diabetes Canada (OG3215585BR)

Using Synthetic ApoC-II Peptides and nAngptl4 Fragments to Measure Lipoprotein Lipase Activity in Radiometric and Fluorescent Assays.

Lipoprotein lipase (LPL) plays a crucial role in preventing dyslipidemia by hydrolyzing triglycerides (TGs) in packaged lipoproteins. Since hypertriglyceridemia (HTG) is a major risk factor for cardiovascular disease (CVD), the leading cause of death worldwide, methods that accurately quantify the hydrolytic activity of LPL in clinical and pre-clinical samples are much needed. To date, the methods used to determine LPL activity vary considerably in their approach, in the LPL substrates used, and in the source of LPL activators and inhibitors used to quantify LPL-specific activity, rather than other lipases, e.g., hepatic lipase (HL) or endothelial lipase (EL) activity. Here, we describe methods recently optimized in our laboratory, using a synthetic ApoC-II peptide to activate LPL, and an n-terminal Angiopoietin-Like 4 fragment (nAngptl4) to inhibit LPL, presenting a cost-effective and reproducible method to measure LPL activity in human post-heparin plasma (PHP) and in LPL-enriched heparin released (HR) fractions from LPL secreting cells. We also describe a modified version of the triolein-based assay using human serum as a source of endogenous activators and inhibitors and to determine the relative abundance of circulating factors that regulate LPL activity. Finally, we describe how an ApoC-II peptide and nAngptl4 can be applied to high-throughput measurements of LPL activity using the EnzChek™ fluorescent TG analog substrate with PHP, bovine LPL, and HR LPL enriched fractions. In summary, this manuscript assesses the current methods of measuring LPL activity and makes new recommendations for measuring LPL-mediated hydrolysis in pre-clinical and clinical samples.

Antiobesity effect of brewer’s yeast biomass in animal model

Abstract Brewer’s yeast biomass (BYB) is a byproduct of the beer-brewing process. This study explored the inhibition effect of BYB on obesity using an animal model. The prenylflavonoid and hop bitter acid contents of BYB were also evaluated to identify possible active substances. BYB ethanol extract contained four prenylflavonoids and six hop bitter acids. The content of hop bitter acids was higher than that of prenylflavonoids. Feeding Sprague–Dawley rats with 50 or 250 mg/kg BW doses of BYB ethanol extract and 250 mg/kg BW of BYB supernatant was found to significantly reduce tissue fat weight, serum triglyceride and hepatic triglyceride, serum insulin and HOMA-IR, as well as to increase liver antioxidant activity. Moreover, BYB ethanol extract could inhibit increased weight, feed efficiency, heparin-releasable lipoprotein lipase enzyme activity, and thiobarbituric acid reactive substance in liver. In particular, low doses of BYB ethanol extract could enhance lipolysis.

Lipoprotein lipase activity does not predict very low-density lipoprotein-triglyceride fatty acid oxidation during exercise.

Exercise lowers plasma triglyceride levels, but the physiological mechanisms remain not fully elucidated. Lipoprotein lipase (LPL) is a key enzyme in facilitating fatty acid uptake from lipoproteins. As exercise increases the efficiency of very low-density lipoprotein-triglyceride (VLDL-TG) oxidation, we hypothesized that muscle LPL activity would be a rate-limiting step and predict VLDL-TG Fatty acids oxidation during exercise. Sixteen healthy, lean subjects (eight men and eight women) were examined before and during an acute exercise bout (90minutes at 50% of VO2-max). Heparin-releasable LPL activity was measured in muscle and adipose tissue biopsies. Breath 14 CO2 was measured after a primed-constant infusion of ex vivo labeled [14 C]-triolein VLDL-TG. Fractional VLDL-TG storage was measured in adipose tissue biopsies. Exercise did not affect muscle LPL activity (P=.30). No association was observed between muscle LPL activity and VLDL-TG oxidation, neither in the basal state (P=.17) nor during exercise (P=.83). Exercise did not affect upper body or lower body adipose tissue LPL activity (both P=.92). The basal adipose tissue fractional VLDL-TG storage (abdominal.13%±9%; femoral 17%±10% (P=.18)) was not associated with upper body (P=.56) or lower body (P=.44) subcutaneous adipose tissue LPL activity. Muscle LPL activity does not predict VLDL-TG oxidation during rest or exercise. In addition, adipose tissue LPL activity was not associated with VLDL-TG storage during rest. This suggests that LPL activity is present in excess of what is required to facilitate lipid uptake for oxidation during both rest and exercise.

The combination of resveratrol and quercetin enhances the individual effects of these molecules on triacylglycerol metabolism in white adipose tissue.

The aim of this study was to analyze whether the combination of resveratrol and quercetin showed additive or synergic effects on body fat accumulation and triacylglycerol metabolism in adipose tissue from rats fed an obesogenic diet. Rats were divided into four dietary groups: a control group and three groups each treated with either resveratrol (15 mg/kg/day; RSV), quercetin (30 mg/kg/day; Q), or both (15 mg resveratrol/kg/day and 30 mg quercetin/kg/day; RSV + Q) for 6 weeks. White adipose tissues from several anatomical locations were dissected. Serum parameters were analyzed by using commercial kits. The activities of fatty acid synthase and heparin-releasable lipoprotein lipase (HR-LPL) were measured using spectrophotometric and fluorimetric methods, and protein expression of acetyl-CoA carboxylase (ACC), adipose tissue triglyceride lipase (ATGL), and hormone-sensitive lipase (HSL) by western blot. The administration of either resveratrol or quercetin separately did not induce significant reductions in adipose tissue weights. By contrast, the combination of both molecules led to a significant reduction in all the fat depots analyzed. The percentage of reduction in each tissue was greater than the calculated additive effect. HR-LPL activity was reduced in RSV and RSV + Q groups. The activity of HSL was not modified. By contrast, ACC was inhibited and ATGL increased only by the combination of both polyphenols. The results obtained demonstrate a synergistic effect between resveratrol and quercetin and suggest that when these molecules are combined, a great number of metabolic pathways involved in adipose tissue triacylglycerol accumulation are affected.

Abstract 237: CAT-2003 is a Novel Small Molecule That Activates Lipoprotein Lipase and Reduces Fasting and Postprandial Triglycerides

Introduction: Triglycerides from chylomicron and VLDL particles are cleared in the periphery through Lipoprotein lipase (LPL). LPL is negatively regulated by Angiopoietin-like proteins 3 and 4 (Angptl3/4) and Apolipoprotein C3 (apoC3). CAT-2003 is an orally active small molecule that reduces fasting and postprandial triglycerides (TGs) in rat models of hypertriglyceridemia. We hypothesize that CAT-2003 activates LPL by reduction of Angptl3/4 and apoC3. Methods and Results: In vitro addition of CAT-2003 to THP-1 cells increased heparin releasable LPL activity rapidly (28% increase at 2 hr, p=0.01) and was sustained (52% increase at 20 hr, p=.0002). Angptl4 mRNA was decreased, while levels of LPL mRNA remained unchanged. In HepG2 cells CAT-2003 lowers apoC3 (94%, p<0.001) and Angptl3 (99%, p<0.001) mRNA. Secretion of newly made apoC3 protein was significantly inhibited (54%, p=0.004) within 1 hour of CAT-2003 treatment and was reduced by 84% (p<0.0001) after 4 hours. In vivo administration of a single oral dose of CAT-2003 (100 mg/kg) reduced plasma TGs excursion by 80% (p<0.014) at 2 hours and by 91% (p<0.031) at 4 hours following an oral oleate challenge in Sprague-Dawley (SD) rats (n=4 per arm). In a separate SD rat study CAT-2003 (30 mg/kg) was administered as a single oral dose and a time course (0.5 to 4 hrs, n=4 per time point) of PCSK9, apoC3 and Angtpl4 gene regulation in intestine and liver was studied. Expression of these genes was reduced as rapidly as 30 minutes and the reduction was sustained through 4 hours. In a 5-day study in Zucker fa/fa rats with TGs elevated above 900 mg/dL, qd oral dosing with CAT-2003 (10, 30, 100 and 300 mg/kg, n=8 per arm) resulted in dose-dependent reductions in fed and fasted plasma TGs with fasting reductions ranging from 41% (p<0.01) at 10 mg/kg to 67% (p<0.0001) at 300 mg/kg. Conclusion: CAT-2003 inhibits the negative regulators of LPL in vitro and in vivo. The time course of action is rapid and sustained in vitro with a translation to in vivo SD and fa/fa rats. CAT-2003 offers a potential new therapeutic for the treatment of severe hypertriglyceridemia and is being evaluated in Phase 2 clinical studies.

Hyperglycemia-Induced Secretion of Endothelial Heparanase Stimulates a Vascular Endothelial Growth Factor Autocrine Network in Cardiomyocytes That Promotes Recruitment of Lipoprotein Lipase

During diabetes mellitus, coronary lipoprotein lipase increases to promote the predominant use of fatty acids. We have reported that high glucose stimulates active heparanase secretion from endothelial cells to cleave cardiomyocyte heparan sulfate and release bound lipoprotein lipase for transfer to the vascular lumen. In the current study, we examined whether heparanase also has a function to release cardiomyocyte vascular endothelial growth factor (VEGF), and whether this growth factor influences cardiomyocyte fatty acid delivery in an autocrine manner. Acute, reversible hyperglycemia was induced in rats, and a modified Langendorff heart perfusion was used to separate the coronary perfusate from the interstitial effluent. Coronary artery endothelial cells were exposed to high glucose to generate conditioned medium, and VEGF release from isolated cardiomyocytes was tested using endothelial cell conditioned medium or purified active and latent heparanase. Autocrine signaling of myocyte-derived VEGF on cardiac metabolism was studied. High glucose promoted latent and active heparanase secretion into endothelial cell conditioned medium, an effective stimulus for releasing cardiomyocyte VEGF. Intriguingly, latent heparanase was more efficient than active heparanase in releasing VEGF from a unique cell surface pool. VEGF augmented cardiomyocyte intracellular calcium and AMP-activated protein kinase phosphorylation and increased heparin-releasable lipoprotein lipase. Our data suggest that the heparanase-lipoprotein lipase-VEGF axis amplifies fatty acid delivery, a rapid and adaptive mechanism that is geared to overcome the loss of glucose consumption by the diabetic heart. If prolonged, the resultant lipotoxicity could lead to cardiovascular disease in humans.

The combination of resveratrol and conjugated linoleic acid attenuates the individual effects of these molecules on triacylglycerol metabolism in adipose tissue

The combination of resveratrol + conjugated linoleic acid (RSV + CLA) did not show the body fat-lowering effect exhibited by these molecules when administered separately. This study aimed to find metabolic explanations for this situation in an experimental model of diet-induced obesity. Thirty-six male Wistar rats were divided into four groups: rats treated with saline (control), resveratrol (RSV), conjugated linoleic acid (CLA) and a combination of these molecules (RSV + CLA). Rats treated with RSV + CLA did not show the reduction in heparin-releasable lipoprotein lipase (HR-LPL) and fatty acid synthase activities observed in RSV group or the increased HSL expression found in RSV and CLA groups. These animals showed reduced sirtuin 1 expression and CLA isomer amounts in adipose tissue. Finally, intracellular Ca(2+) concentration was increased. The attenuation of the effects induced in adipose tissue triacylglycerol metabolism by RSV and CLA separately, such as the decrease in lipogenesis and fatty acid uptake and the increase in lipolysis, contributes to explain the lack of body fat-lowering effect of the combination RSV + CLA.

Anti-obesity activity of Lactobacillus fermented soy milk products

The anti-obesity activity of Lactobacillus paracasei subsp. paracasei NTU 101 and Lactobacillus plantarum NTU 102 and their soy milk fermented products (SM101 and SM102) were investigated. Results indicated that the inhibition of 3T3-L1 differentiation and the accumulation of free fatty acids markedly increased in rats treated with SM101 and SM102. Moreover, the up-regulation and down-regulation of lipolysis and heparin-releasable lipoprotein lipase, respectively, were observed in the 3T3-L1 adipocytes of the SM101 and SM101 groups, and these effects of SM101 and SM102 were greater than unfermented soy milk (USM). We also found that SM101 and SM102 both improved obesity in Wistar rats fed with a high-fat diet (HFD) and that this improvement was stronger than that observed for USM. The level of serum leptin in HFD-induced rats was significantly elevated by the 5-week administration of SM101 and SM102 (106–1010CFU/mL per rat per day); however, this activity was not promoted by USM. The anti-obesity activity of SM101 and SM102 may result from the increased daidzein and genistein levels that were observed during the fermentation by L. paracasei subsp. paracasei NTU 101 and L. plantarum NTU 102.

Monascus-Fermented Yellow Pigments Monascin and Ankaflavin Showed Antiobesity Effect via the Suppression of Differentiation and Lipogenesis in Obese Rats Fed a High-Fat Diet

Monascus-fermented monascin and ankaflavin are found to strongly inhibit differentiation and lipogenesis and stimulate lipolysis effects in a 3T3-L1 preadipocyte model, but the in vivo regulation mechanism is unclear. This study uses obese rats caused by a high-fat diet to examine the effects of daily monascin and ankaflavin feeding (8 weeks) on antiobesity effects and modulation of differentiation, lipogenesis, and lipid absorption. The results show that monascin and ankaflavin had a significant antiobesity effect, which should result from the modulation of monascin and ankaflavin on the inhibition of differentiation by inhibiting CCAT/enhancer-binding protein β (C/EBPβ) expression (36.4% and 48.3%) and its downstream peroxisome proliferator-activated receptor γ (PPARγ) (55.6% and 64.5%) and CCAT/enhancer-binding protein α (C/EBPα) expressions (25.2% and 33.2%) and the inhibition of lipogenesis by increasing lipase activity (14.0% and 10.7%) and decreasing heparin releasable lipoprotein lipase (HR-LPL) activity (34.8% and 30.5%). Furthermore, monascin and ankaflavin are the first agents found to suppress Niemann-Pick C1 Like 1 (NPC1L1) protein expression (73.6% and 26.1%) associated with small intestine tissue lipid absorption. Importantly, monascin and ankaflavin are not like monacolin K, which increases creatine phosphokinase (CPK) activity, known as a rhabdomyolysis indicator.

Circulating 5α-dihydrotestosterone, abdominal obesity and adipocyte characteristics in women.

Abstract Background: The association between circulating androgen levels and fat distribution in women has been widely inconsistent among existing studies. We sought to investigate the relation between plasma adrenal and gonadal androgen levels and body fat distribution, as well as abdominal adipocyte characteristics. Paired omental and subcutaneous adipose tissue samples were surgically obtained from 60 women (age, 47±5 years; body mass index, 26±5 kg/m2) undergoing gynecological surgery. Body composition and fat distribution were measured by dual-energy X-ray absorptiometry and computed tomography, respectively. Adipocyte diameter, basal lipolysis, and heparin-releasable lipoprotein lipase activity were measured. Steroids were quantified using high-performance gas chromatography and mass spectrometry. Significant negative associations were found between plasma dihydrotestosterone (DHT) levels and total adiposity (body mass index, r=-0.35, p<0.05; fat mass, r=-0.31, p<0.05) as well as computed tomography assessments of abdominal adiposity (r=-0.30, p<0.05 and r=-0.44, p<0.005 for subcutaneous and visceral adipose tissue area, respectively). The association between DHT levels and visceral adipose tissue area was independent of total body fat mass. A significant negative association was also observed between plasma DHT and omental adipocyte diameter (r=-0.27, p<0.05). When expressed as the omental/subcutaneous ratio, heparin-releasable lipoprotein lipase activity was negatively and significantly related to plasma DHT, androstenedione, and dehydroepiandrosterone (DHEA) levels. Abdominally obese women with large, metabolically active omental adipocytes appear to be characterized by reduced endogenous levels of DHT. The assumption that high androgen levels are associated with an android body fat distribution pattern in women should be critically re-examined.

Inactivation of lipoprotein lipase occurs on the surface of THP-1 macrophages where oligomers of angiopoietin-like protein 4 are formed

Lipoprotein lipase (LPL) hydrolyzes triglycerides in plasma lipoproteins causing release of fatty acids for metabolic purposes in muscles and adipose tissue. LPL in macrophages in the artery wall may, however, promote foam cell formation and atherosclerosis. Angiopoietin-like protein (ANGPTL) 4 inactivates LPL and ANGPTL4 expression is controlled by peroxisome proliferator-activated receptors (PPAR). The mechanisms for inactivation of LPL by ANGPTL4 was studied in THP-1 macrophages where active LPL is associated with cell surfaces in a heparin-releasable form, while LPL in the culture medium is mostly inactive. The PPARδ agonist GW501516 had no effect on LPL mRNA, but increased ANGPTL4 mRNA and caused a marked reduction of the heparin-releasable LPL activity concomitantly with accumulation of inactive, monomeric LPL in the medium.Intracellular ANGPTL4 was monomeric, while dimers and tetramers of ANGPTL4 were present in the heparin-releasable fraction and medium. GW501516 caused an increase in the amount of ANGPTL4 oligomers on the cell surface that paralleled the decrease in LPL activity. Actinomycin D blocked the effects of GW501516 on ANGPTL4 oligomer formation and prevented the inactivation of LPL. Antibodies against ANGPTL4 interfered with the inactivation of LPL.We conclude that inactivation of LPL in THP-1 macrophages primarily occurs on the cell surface where oligomers of ANGPTL4 are formed.

Low doses of grape seed procyanidins reduce adiposity and improve the plasma lipid profile in hamsters

Procyanidins are polyphenolic compounds with beneficial effects on health in relation to cardiovascular disease and metabolic syndrome. In this study, we evaluated the potential beneficial effects of low doses of a grape seed procyanidin extract (GSPE) on body weight and fat deposition. Four groups of hamsters were fed either a standard diet (STD) or a high-fat diet (HFD) for 30 days and supplemented with either GSPE at 25 mg per kg of body weight per day (STD-GSPE and HFD-GSPE groups) or vehicle (STD and HFD groups) during the last 15 days of the study. A significant decrease in body weight gain was observed in both GSPE-treated animals at the end of the experiment. GSPE treatment significantly reduced the adiposity index and the weight of all the white adipose tissue depots studied (retroperitoneal (RWAT), mesenteric (MWAT), epididymal (EWAT) and inguinal (IWAT)) in both GSPE-treated groups. GSPE administration reversed the increase in plasma phospholipids induced by the HFD feeding. In the RWAT, GSPE treatment increased the mRNA expression of genes related to β-oxidation and the glycerolipid/free fatty acid (GL/FFA) cycle, mainly in HFD-GSPE animals. In the MWAT, the effects of GSPE at the transcriptional level were not as evident as in the RWAT. Moreover, GSPE treatment induced heparin-releasable lipoprotein lipase activity in the RWAT and MWAT depots. The alterations in the lipid metabolic pathways induced by GSPE were accompanied by lower FFA levels in the plasma and decreased lipid and triglyceride accumulation in the MWAT. The use of GSPE at low doses protects against fat accumulation and improves the plasma lipid profile in hamsters. We suggest that GSPE exerts these effects in part through the activation of both β-oxidation and the GL/FFA cycle, mainly in the RWAT.

Lipoprotein lipase deficiency in chronic kidney disease is accompanied by down-regulation of endothelial GPIHBP1 expression

Chronic renal failure (CRF) is associated with hypertriglyceridemia and impaired clearance of very low density lipoprotein (VLDL) and chylomicrons which are largely due to lipoprotein lipase (LPL) deficiency/dysfunction. After its release from myocytes and adipocytes, LPL binds to the endothelium in the adjacent capillaries where it catalyzes hydrolysis of triglycerides in VLDL and chylomicrons. The novel endothelium-derived molecule, glycosylphosphatidylinositol-anchored binding protein 1 (GPIHBP1), plays a critical role in LPL metabolism and function by anchoring LPL to the endothelium and binding chylomicrons. GPIHBP1-deficient mice and humans exhibit severe hypertriglyceridemia and diminished heparin-releasable LPL, pointing to the critical role of GPIHBP1 in regulation of LPL activity. Given its central role in regulation of LPL activity and triglyceride metabolism, we explored the effect of chronic kidney disease (CKD) on GPIHBP1 expression. Expression of GPIHBP1 and LPL were determined by reverse transcriptase-polymerase chain reaction, Western blot and immunohistochemical analyses in the adipose tissue, skeletal muscle and myocardium of rats 12weeks after 5/6 nephrectomy (CRF) or sham-operation (control). Compared to the controls, the CRF group exhibited severe hypertriglyceridemia, significant reduction of the skeletal muscle, myocardium and adipose tissue LPL mRNA and protein abundance. This was accompanied by parallel reductions of GPIHBP1 mRNA abundance and immunostaining in the tested tissues. LPL deficiency in CKD is associated with and compounded by GPIHBP1 deficiency. Together these abnormalities contribute to impaired clearance of triglyceride-rich lipoproteins, diminished availability of lipid fuel for energy storage in adipocytes and energy production in myocytes and consequent hypertriglyceridemia, cachexia, muscle weakness and atherosclerosis.

Changes in white adipose tissue metabolism induced by resveratrol in rats

BackgroundA remarkable range of biological functions have been ascribed to resveratrol. Recently, this polyphenol has been shown to have body fat lowering effects. The aim of the present study was to assess some of the potential underlying mechanisms of action which take place in adipose tissue.MethodsSixteen male Sprague-Dawley rats were randomly divided into two groups: control and treated with 30 mg resveratrol/kg body weight/d. All rats were fed an obesogenic diet and after six weeks of treatment white adipose tissues were dissected. Lipoprotein lipase activity was assessed by fluorimetry, acetyl-CoA carboxylase by radiometry, and malic enzyme, glucose-6P-dehydrogenase and fatty acid synthase by spectrophotometry. Gene expression levels of acetyl-CoA carboxylase, fatty acid synthase, lipoprotein lipase, hormone-sensitive lipase, adipose triglyceride lipase, PPAR-gamma, SREBP-1c and perilipin were assessed by Real time RT-PCR. The amount of resveratrol metabolites in adipose tissue was measured by chromatography.ResultsThere was no difference in the final body weight of the rats; however, adipose tissues were significantly decreased in the resveratrol-treated group. Resveratrol reduced the activity of lipogenic enzymes, as well as that of heparin-releasable lipoprotein lipase. Moreover, a significant reduction was induced by this polyphenol in hormone-sensitive lipase mRNA levels. No significant changes were observed in other genes. Total amount of resveratrol metabolites in adipose tissue was 2.66 ± 0.55 nmol/g tissue.ConclusionsIt can be proposed that the body fat-lowering effect of resveratrol is mediated, at least in part, by a reduction in fatty acid uptake from circulating triacylglycerols and also in de novo lipogenesis.

Fasting and post-prandial adipose tissue lipoprotein lipase and hormone-sensitive lipase in obesity and Type 2 diabetes

Fasting and post-prandial abnormalities of adipose tissue (AT) lipoprotein lipase (LPL) and hormone- sensitive lipase (HSL) activities may have pathophysiological relevance in insulin-resistant conditions. The aim of this study was to evaluate activity and gene expression of AT LPL and HSL at fasting and 6 h after meal in two insulin-resistant groups - obese with Type 2 diabetes and obese without diabetes - and in non-diabetic normal-weight controls. Nine obese subjects with diabetes, 10 with obesity alone, and 9 controls underwent measurements of plasma levels of glucose, insulin, and triglycerides before and after a standard fat-rich meal. Fasting and post-prandial (6 h) LPL and HSL activities and gene expressions were determined in abdominal subcutaneous AT needle biopsies. The diabetic obese subjects had significantly lower fasting and post-prandial AT heparin-releasable LPL activity than only obese and control subjects (p<0.05) as well as lower mRNA LPL levels. HSL activity was significantly reduced in the 2 groups of obese subjects compared to controls in both fasting condition and 6 h after the meal (p<0.05), while HSL mRNA levels were not different. There were no significant changes between fasting and 6 h after meal measurements in either LPL or HSL activities and gene expressions. Lipolytic activities in AT are differently altered in obesity and Type 2 diabetes being HSL alteration associated with both insulin-resistant conditions and LPL with diabetes per se. These abnormalities are similarly observed in the fasting condition and after a fat-rich meal.

대두, 청국장 및 된장이 고지방-고콜레스테롤식이를 급여한 흰쥐의 콜레스테롤 함량 및 체중감소에 미치는 영향

This study was conducted to investigate the cholesterol lowering effect and weight reduction of autoclaved soy flour, cheonggulgang and doenjang, which are fermented using Bacillus subtilis DJI, in rats fed a high-fat/high-cholesterol diet. Male Sprague-Dawley rats weighing 250 g, were divided into five groups; a normal diet group (N), a high-fat/high-cholesterol diet group (HFC), a high-fat/high-cholesterol diet with 5% autoclaved soy flour group (HFC-S), a high-fat/high-cholesterol diet with 5% cheonggulgang group (HFC-CJ), and a high-fat/high-cholesterol diet with 5% deonjang group (HFC-DJ). The body weight gain and adipose tissues weights increased in rats fed a high-fat/high-cholesterol diet, but decreased significantly in rats fed autoclaved soy flour, cheonggulgang and doenjang, compared with the HFC group. Food intake was lower in the all HFC groups (HFC, HFC-S.HFC-CJ and HFC-DJ) than that of the N group, However, there was no differences in the food intake between HFC diet groups. Serum triglyceride level increased with a high-fat/high-cholesterol dietgroup whereas HFC-CJ and HFC-DJ groups were markedly decreased serum triglyceride levels compared with N group. Levels of serum total cholesterol and LDL-cholesterol, and level of total cholesterol in the liver were significantly lower in the HFC-S group, the HFC-CJ group and the HFC-DJ group than that of the HFC group, but exerted no significant change between the HFC groups on levels of total lipid and triglyceride in the liver. Fecal total lipid content increased in the HFC-CJ group and the HFC-DJ group than those of the HFC group and HFC-S group. The activities of heparin-releasable lipoprotein lipase (HR-LPL) and total-extractable LPL in adipose tissues decreased in the HFC-S group, the HFC-CJ group and the HFC-DJ group compared with the HFC group. These results suggest that dietary cheonggulgang and doenjang may exert cholesterol-lowering effect and prevent obesity.

모시잎이 고지방-고콜레스테롤 식이 흰쥐의 지질대사 개선 및 항비만 효과에 미치는 영향

본 연구는 모시잎의 혈청, 간 및 지방조직의 체내 지질대사 개선 및 항비만 효과를 살펴보기 위하여 in vivo에서 5주령 된 흰쥐 수컷 24마리를 1주일간 적응시킨 후 정상 식이군(N), 고지방-고콜레스테롤 식이군(HFC), 고지방-고콜레스테롤 식이와 5% 모시잎 분말 첨가군(HFC-RL) 및 고지방-고콜레스테롤 식이와 10% 모시잎 분말 첨가군(HFC-RH)으로 나누어 4주간 실시하였다. 고지방-고콜레스테롤 식이로 인하여 체중이 유의적으로 증가하였으나, 모시잎 분말의 첨가 수준이 증가할수록 체중이 유의하게 감소하였다. 식이섭취량은 대조군(HFC)이 가장 낮았으며, 모시잎 분말 급여로 감소하는 경향이었다. 식이효율은 10% 모시잎 분말첨가로 유의하게 감소하여 정상 식이군(N)의 식이효율 수준과 유사하였다. 장간막지방조직과 부고환지방조직의 무게는 10% 모시잎 분말 첨가로 유의하게 감소하여 정상 식이군(N)보다 오히려 더 감소하는 경향을 보였다. 고지방-고콜레스테롤 식이로 증가되어진 혈청 중 AST, ALT, ALP 및 LDH 활성은 모시잎 분말 급여로 저하되었다. 혈청 중 중성지방 함량과 총콜레스테롤 함량도 고지방-고콜레스테롤 식이 급여로 증가되었으나, 모시잎 분말 첨가에 따라 농도 의존적으로 감소하였다. 고지방-고콜레스테롤 식이로 감소되어진 혈청 중 HDL-콜레스테롤 함량은 모시잎 분말 급여로 모두 유의하게 증가하였으며, 증가되어진 혈청 중 LDL-콜레스테롤 함량은 모두 유의하게 감소하였다. 동맥경화지수와 심혈관위험지수는 5%와 10%의 모시잎 분말 급여로 모두 유의하게 감소하였으며, 특히 10% 모시잎 분말을 급여하였을 경우 감소효과가 커 정상 식이군(N)과 유사한 경향이었다. 간조직 중 중성지방과 총콜레스테롤 함량은 모시잎 분말 급여로 모두 대조군(HFC)에 비하여 유의하게 감소하였다. 장간막지방조직과 부고환 지방조직의 중성지방 및 총콜레스테롤 함량도 모시잎 분말 급여로 유의하게 감소하였다. 지방조직의 HR-LPL과 TE-LPL 활성은 모시잎 분말의 첨가 급여로 농도 의존적으로 유의하게 감소하였다. 이상의 실험 결과 고지방-고콜레스테롤 식이와 함께 급여한 모시잎 분말은 체중, 간 및 지방조직의 무게 감소와 더불어 혈청 및 지방조직의 지질대사 개선에 긍정적인 영향을 미치는 것으로 나타났다. 이러한 결과는 모시잎 분말에 다량 함유된 식이섬유소와 클로로필 등의 생리활성 물질이 지질대사를 개선시키고 지방축적을 억제하여 고지혈증의 예방 및 치료효과와 비만을 억제하는 효과를 나타내 대사성 합병률과 심혈관계 질환의 발생을 감소시키는데 효과가 있을 것으로 생각되어진다. 그 외에 어떠한 생리활성 성분이 어떻게 작용을 하는지에 대해서는 추후 더 체계적인 연구가 필요할 것으로 사료된다. This study was performed to investigate the effects of ramie (Boehmeria nivea) leaf powder on improvements in lipid metabolism in serum, liver and adipose tissue, and the anti-obesity effect in rats fed a high fat/high cholesterol diet for 4 weeks to induce a hyperlipidemic and obese model rat. Male Sprague-Dawley rats weighting 210 g were divided into four groups; a normal diet group (N), a high fat/high cholesterol diet group (HFC), a high fat/high cholesterol diet with 5% ramie leaf powder group (HFC-RL), and a high fat/high cholesterol diet with 10% ramie leaf powder group (HFC-RH). The body weight gain increased with a high fat/high cholesterol diet, but gradually decreased in the ramie leaf powder fed groups compared with the HFC group. The liver index in the HFC group was highest among the four groups, although the difference was not significant compared with the ramie leaf powder fed groups. The adipose tissues weight in the HFC group was heavier than that of the N group, whereas those of groups fed ramie leaf powder decreased gradually. Alkaline phosphatase activity was not different between the HFC groups, but serum alkaline aminotransferase and lactate dehydrogenase activities decreased significantly after ramie leaf powder feeding. Levels of serum triglyceride, total cholesterol, LDL-cholesterol, atherogenic index and cardiac risk factors tended to decrease in the ramie leaf powder fed groups compared with the HFC group, whereas serum HDL-cholesterol level decreased in the HFC group and markedly increased in the ramie leaf powder fed groups. Levels of triglyceride and total cholesterol in the liver were significantly lower in the ramie leaf powder fed groups than in the HFC group. Levels of triglyceride and total cholesterol in adipose tissues were also lower in the ramie leaves powder fed groups than in the HFC group. The activities of heparinreleasable lipoprotein lipase (LPL) and total-extractable LPL in adipose tissues increased in the HFC group compared to that of the N group, but those of the ramie leaf powder fed groups decreased significantly. These results suggest that ramie leaf powder may improve lipid metabolism in serum, liver and adipose tissue and potentially reduce lipid storage.

Adiponectin Increases LPL Activity via RhoA/ROCK-Mediated Actin Remodelling in Adult Rat Cardiomyocytes

Cardiomyocyte substrate utilization is important in maintaining optimal cardiac function. Adiponectin has been shown to confer cardioprotective effects in part via regulating glucose and fatty acid uptake and oxidation in cardiomyocytes. Here we investigated mechanisms whereby adiponectin mediates a particular metabolic effect by focusing on lipoprotein lipase (LPL), an enzyme that increases free fatty acid availability to the heart by breakdown of chylomicrons and very-low-density lipoproteins in circulation. We used primary adult rat cardiomyocytes and demonstrate that adiponectin increased LPL translocation to the cell surface where it could be released at least partly in its active form, as evidenced by measuring basal and heparin-releasable LPL activity. Furthermore, these effects of adiponectin were mediated via remodeling of the actin cytoskeleton. We quantitatively assessed the filamentous to globular actin ratio and show that increased stress fiber formation, visualized by rhodamine-phalloidin immunofluorescence, in response to adiponectin, is achieved via stimulating Ras homolog gene family A (RhoA) activity, determined using G-LISA RhoA activation assay kit. We also demonstrate that adiponectin induces phosphorylation and inhibition of cofilin, leading to a reduction in actin treadmilling. Increased cofilin phosphorylation and stress fiber formation in response to adiponectin were prevented by inhibition of either RhoA or its downstream kinase Rho-associated protein kinase. Importantly, inhibition of cytoskeletal remodeling prevented adiponectin-stimulated plasma membrane LPL content detected by immunofluorescence and also subsequent LPL activity. In summary, we show that adiponectin mediates actin cytoskeleton remodeling to translocate LPL and allow subsequent activation.

The Effect of Monascus Secondary Polyketide Metabolites, Monascin and Ankaflavin, on Adipogenesis and Lipolysis Activity in 3T3-L1

The aim of the present work is to investigate the effects of Monascus secondary metabolites, monascin (MS) and ankaflavin (AK), on cell proliferation, adipogenesis, lipolysis and heparin-releasable lipoprotein lipase (HR-LPL) in 3T3-L1 preadipocyte. MS and AK inhibit the proliferation of 3T3-L1 cells in a dose-dependent fashion. At 8 μg/mL concentration MS inhibits proliferation for 80.5% after 48 h, whereas the value for AK is 69.2%. Adipogenesis is inhibited by MS and AK without dose-dependency. Triglyceride is decreased 37.1% and 41.1% respectively by treating 0.125 μg/mL MS and AK. Adipocyte-specific transcription factors peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer binding protein β (C/EBPβ), C/EBPδ and C/EBPα mRNA levels are measured by real-time polymerase chain reaction. The expression of the four transcriptional factors analyzed (PPARγ, C/EBPβ, C/EBPδ and C/EBPα) is reduced at the initial and the middle period. At the later period, there is no effect on the expression of PPARγ and C/EBPα by treating MS and AK. Furthermore, both MS and AK increase basal lipolysis of mature adipocytes by 113.2% and 278.3% upregulation, respectively. And both MS and AK reduce the activity of HR-LPL, by 45.3% and 58.1% reduction, respectively. This study reveals for the first time that Monascus secondary metabolites, MS and AK, can prevent the differentiation of preadipocyte and stimulate basal lipolysis of mature adipocytes, avoiding the accumulation of lipid.