Lipogenic Enzyme Activities Research Articles

Ethanol extract of Butea monosperma bark modulates dyslipidemia in streptozotocin-induced diabetic rats

Context: Dyslipidemia is one of the major risk factors for cardiovascular disease in diabetes mellitus (DM). The availability of multiple lipid-lowering drugs and supplements provides new opportunities for patients to regulate lipid levels.Objective: The present study was designed to evaluate the effect of Butea monosperma Lam. (Fabaceae) bark extract in diabetes-induced dyslipidemia.Materials and methods: A daily dose of B. monosperma bark extract (BMBE, 500 mg/kg body weight) was given orally to streptozotocin (STZ)-induced diabetic rats for 60 d. Several indices such as blood glucose, insulin, glycosylated hemoglobin, TC, TG, high-density lipoprotein-cholesterol (HDL-C), apo A1, apo B, activities of lipogenic enzymes in tissues, liver function tests, and histopathology of liver were analyzed to assess the modulation of STZ-induced diabetic dyslipidemia by B. monosperma bark.Results: BMBE significantly reduced blood glucose (40.79%) and increased plasma insulin (37.5%) levels in diabetic rats. Altered levels of serum lipids, lipoproteins, and activities of lipogenic enzymes in tissues were partially restored upon the administration of BMBE in diabetic rats. Liver function tests and histopathological examination revealed that consumption of BMBE at a dose of 500 mg/kg body weight had no toxic effects in experimental rats.Conclusion: The findings suggest that BMBE supplementation could ameliorate dyslipidemia in DM.

Chemical Constituents of Rhododendron formosanum Show Pronounced Growth Inhibitory Effect on Non-Small-Cell Lung Carcinoma Cells

The aim of the present study was to investigate whether Rhododendron formosanum Hemsl. (Ericaceae), an endemic species in Taiwan, exhibits antineoplastic potential against non-small-cell lung carcinoma (NSCLC). R. formosanum was successively extracted with methanol and then separated into dichloromethane (RFL-DCM), ethyl acetate (RFL-EA), n-butanol (RFL-BuOH), and water (RFL-H2O) fractions. Among these extracts, RFL-EA exhibited the most effective antineoplastic effect. This study also demonstrated that fractions 2 and 3 from the RFL-EA extract (RFL-EA-2, RFL-EA-3) possessed the strongest antineoplastic potential against NSCLC cells. The major phytochemical constituents of RFL-EA-2 and RFL-EA-3 were ursolic acid, oleanolic acid, and betulinic acid. This study indicated that ursolic acid demonstrated the most efficient antineoplastic effects on NSCLC cells. Ursolic acid inhibited growth of NSCLC cells in a dose- and time-dependent manner and stimulated apoptosis. Apoptosis was substantiated by activation of caspase-3 and -9, and a decrease in Bcl-2 and an elevation of the Bax were also observed following ursolic acid treatment. Ursolic acid activated AMP-activated protein kinase (AMPK) and then inhibited the mammalian target of rapamycin (mTOR), which controls protein synthesis and cell growth. Moreover, ursolic acid decreased the expression and/or activity of lipogenic enzymes, such as acetyl-CoA carboxylase (ACC) and fatty acid synthase (FASN) via AMPK activation. Collectively, these data provide insight into the chemical constituents and anticancer activity of R. formosanum against NSCLC cells, which are worthy of continued study.

Scopoletin prevents alcohol-induced hepatic lipid accumulation by modulating the AMPK–SREBP pathway in diet-induced obese mice

ObjectiveThis study investigated the effects of scopoletin on alcohol-induced hepatic lipid accumulation in diet-induced obese mice and its mechanism. Material/MethodsAlcohol (25% v/v, 5g/kg body weight) was orally administered once a day for 6 weeks to mice fed with a high-fat diet (35%kcal) with or without scopoletin (0.05%, wt/wt). ResultsScopoletin reduced plasma acetaldehyde, fatty acid, total cholesterol, triglyceride and insulin levels, hepatic lipid and droplets and fasting blood glucose levels that were increased by alcohol. Scopoletin significantly activated hepatic AMPK and inhibited ACC and SREBP-1c and the activities of lipogenic enzymes, such as FAS, PAP and G6PD compared to the alcohol control group. Moreover, scopoletin significantly inhibited hepatic CYP2E1 activity and protein levels but elevated the activities of SOD, CAT, GSH-Px and GST and the levels of GSH compared to the alcohol control group. The hepatic lipid peroxide level was significantly lowered by scopoletin supplementation in alcohol-administered obese mice. ConclusionsTaken together, these results suggested that scopoletin can ameliorate alcohol-induced hepatic lipid accumulation by modulating AMPK–SREBP pathway-mediated lipogenesis in mice fed a high-fat diet.

Hypolipidemic and Body Fat–Lowering Effects of Giant Embryo Brown Rice (Seonong 17 and Keunnunjami) in High‐Fat‐Fed Mice

ABSTRACTThe effects of giant embryo brown rice Seonong 17 and Keunnunjami, in comparison with that of ordinary normal brown rice, on the body weight and lipid profile in mice under a high‐fat diet condition were investigated. The animals were fed with experimental diets for eight weeks: normal control, high fat (HF), and high fat supplemented with normal brown rice, Seonong 17 rice, or Keunnunjami rice powder. Their body and fat weights, lipid profiles, lipogenic enzyme activities, and adipokine concentrations were determined. Significant differences between the animal groups were analyzed with Tukey's test (P < 0.05). A marked increase in the body weight and fat, plasma triglyceride and total cholesterol concentrations, and free fatty acid level were found in HF mice relative to the control group. On the other hand, diet supplementation with rice, particularly the giant embryo rice samples, significantly suppressed this high‐fat‐induced body weight gain and hyperlipidemia via regulation of lipogenesis and adipokine production. Both the Seonong 17 and Keunnunjami exhibited greater hypolipidemic and body fat–lowering effects than the normal brown rice. The results demonstrate that these giant embryo mutants may be beneficial as biomaterials for functional foods with antiobesity and hypolipidemic effects.

The role of estrogen in adipose tissue metabolism: insights into glucose homeostasis regulation [Review

Adipose tissue is an organ with active endocrine function involved in the regulation of energy balance and glucose homeostasis via multiple metabolic signaling pathways targeting the brain, liver, skeletal muscle, pancreas, and other organs. There is increasing evidence demonstrating that the female sex hormone, estrogen, regulates adipose development and improves systemic glucose homeostasis in both males and females. The underlying mechanism linking estrogenic regulation in adipose tissue and systemic glucose metabolism has not been fully elucidated, but is thought to include interactions of estrogen receptor signaling events involving lipolytic and/or lipogenic enzyme activity, free fatty acid metabolism, and adipocytokine production. Thus, understanding the effects of estrogen replacement on adipose tissue biology and metabolism is important in determining the risk of developing obesity-related metabolic disorders in patients undergoing treatment for sex hormone deficiency. In this report, we review literature regarding the role of estrogens and their corresponding receptors in the control of adipose metabolism and glucose homeostasis in both rodents and humans. We also discuss the effects of selective estrogen receptor modulators on glucose metabolism.

Lowering effect of firefly squid powder on triacylglycerol content and glucose-6-phosphate dehydrogenase activity in rat liver.

Effects of dietary firefly squid on serum and liver lipid levels were investigated. Male Wistar rats were fed a diet containing 5% freeze-dried firefly squid or Japanese flying squid for 2 weeks. There was no significant difference in the liver triacylglycerol level between the control and Japanese flying squid groups, but the rats fed the firefly squid diet had a significantly lower liver triacylglycerol content than those fed the control diet. No significant difference was observed in serum triacylglycerol levels between the control and firefly squid groups. The rats fed the firefly squid had a significantly lower activity of liver glucose-6-phosphate dehydrogenase compared to the rats fed the control diet. There was no significant difference in liver fatty acid synthetase activity among the three groups. Hepatic gene expression and lipogenic enzyme activity were investigated; a DNA microarray showed that the significantly enriched gene ontology category of down-regulated genes in the firefly squid group was "lipid metabolic process". The firefly squid group had lower mRNA level of glucose-6-phosphate dehydrogenase compared to the controls. These results suggest that an intake of firefly squid decreases hepatic triacylglycerol in rats, and the reduction of mRNA level and enzyme activity of glucose-6-phosphate dehydrogenase might be related to the mechanisms.

Combined effect of sesamin and soybean phospholipid on hepatic fatty acid metabolism in rats.

We studied the combined effect of sesamin (1:1 mixture of sesamin and episesamine) and soybean phospholipid on lipid metabolism in rats. Male rats were fed diets supplemented with 0 or 2 g/kg sesamin, and containing 0 or 50 g/kg soybean phospholipid, for 19 days. Sesamin and soybean phospholipid decreased serum triacylglycerol concentrations and the combination of these compounds further decreased the parameter in an additive fashion. Soybean phospholipid but not sesamin reduced the hepatic concentration of triacylglycerol. The combination failed to cause a strong decrease in hepatic triacylglycerol concentration, presumably due to the up-regulation of Cd36 by sesamin. Combination of sesamin and soybean phospholipid decreased the activity and mRNA levels of hepatic lipogenic enzymes in an additive fashion. Sesamin strongly increased the parameters of hepatic fatty acid oxidation enzymes. Soybean phospholipid increased hepatic activity of 3-hydroxyacyl-CoA dehydrogenase although it failed to affect the activity of other enzymes involved in fatty acid oxidation. Sesamin strongly increased hepatic concentration of carnitine. Sesamin and soybean phospholipid combination further increased this parameter, accompanying a parallel increase in mRNA expression of carnitine transporter. These changes can account for the strong decrease in serum triacylglycerol in rats fed a diet containing both sesamin and soybean phospholipid.

Quercetin can reduce insulin resistance without decreasing adipose tissue and skeletal muscle fat accumulation

Quercetin exhibits a wide range of biological functions. The first aim of the present work was to analyze the effects of quercetin on fat accumulation in adipose tissue and glycemic control in rats. Any potential involvement of muscle fatty acid oxidation in its effect on glycemic control was also assessed. Animals were fed a high-fat high-sucrose diet either supplemented with quercetin (30mg/kg body weight/day), or not supplemented, for 6weeks. One week before killing, a glucose tolerance test was carried out. Muscle triacylglycerol content, serum glucose, insulin, fructosamine and free fatty acids were measured, and homeostatic model assessment for insulin resistance (HOMA-IR) was calculated. The activities of lipogenic enzymes and lipoprotein lipase in adipose tissue, carnitine palmitoyl transferase-1b (CPT-1b) and citrate synthase in skeletal muscle, and the expression of several genes, ACO, CD36, CPT-1b, PPAR-α, PGC-1α, UCP3, TFAM and COX-2 in skeletal muscle were analyzed. Quercetin caused no significant reduction in body weight or adipose tissue sizes. However, fructosamine, basal glucose and insulin, and consequently HOMA-IR, were significantly reduced by quercetin. No changes were observed in the activity of lipogenic enzymes and lipoprotein lipase. Muscle triacylglycerol content was similar in both experimental groups. The expression of ACO, CD36, CPT-1b, PPAR-α, PGC-1α, UCP3, TFAM and COX-2 remained unchanged. It can be concluded that quercetin is more effective as an anti-diabetic than as an anti-obesity biomolecule. The improvement in insulin resistance induced by this flavonoid is not mediated by a delipidating effect in skeletal muscle.

D-Psicose increases energy expenditure and decreases body fat accumulation in rats fed a high-sucrose diet

We investigated the anti-obesity effects of d-psicose by increasing energy expenditure in rats pair-fed the high-sucrose diet (HSD). Wistar rats were divided into two dietary groups: HSD containing 5% cellulose (C) and 5% d-psicose (P). The C dietary group was further subdivided into two groups: rats fed the C diet ad libitum (C-AD) and pair-fed the C diet along with those in the P group (C-PF). Resting energy expenditure during darkness and lipoprotein lipase activity in the soleus muscle were significantly higher in the P group than in the C-PF group. Serum levels of glucose, leptin and adiponectin; glucose-6-phosphate dehydrogenase activities in the liver and perirenal adipose tissue; and body fat accumulation were all significantly lower in the P group than in the C-PF group. The anti-obesity effects of D-psicose could be induced not only by suppressing lipogenic enzyme activity but also by increasing EE in rats.

Dietary Salba (Salvia hispanica L) seed rich in α-linolenic acid improves adipose tissue dysfunction and the altered skeletal muscle glucose and lipid metabolism in dyslipidemic insulin-resistant rats

This work reports the effect of dietary Salba (chia) seed rich in n-3 α-linolenic acid on the morphological and metabolic aspects involved in adipose tissue dysfunction and the mechanisms underlying the impaired glucose and lipid metabolism in the skeletal muscle of rats fed a sucrose-rich diet (SRD). Rats were fed a SRD for 3 months. Thereafter, half the rats continued with SRD while in the other half, corn oil (CO) was replaced by chia seed for 3 months (SRD+chia). In control group, corn starch replaced sucrose. The replacement of CO by chia seed in the SRD reduced adipocyte hypertrophy, cell volume and size distribution, improved lipogenic enzyme activities, lipolysis and the anti-lipolytic action of insulin. In the skeletal muscle lipid storage, glucose phosphorylation and oxidation were normalized. Chia seed reversed the impaired insulin stimulated glycogen synthase activity, glycogen, glucose-6-phosphate and GLUT-4 protein levels as well as insulin resistance and dyslipidemia.

Effects of dietary non-protein energy source levels on growth performance, body composition and lipid metabolism in herbivorous grass carp (Ctenopharyngodon idellaVal.)

A study was conducted to determine the effects of dietary non-protein energy sources on growth, tissue lipid accumulation and lipid metabolism-related genes expression of grass carp. Triplicate groups of fish were fed for 9 weeks on four isonitrogenous (300 g kg−1) experimental diets with four levels of non-protein energy (6.52 kJ g−1 control diet, 5.32 kJ g−1 high-CEL diet, 8.46 kJ g−1 high-CHO diet and 8.53 kJ g−1 high-LIP diet respectively). Increasing dietary non-protein energy source levels did not improve the growth, and the high-CEL diet reduced the growth of grass carp. The high-CHO diet tended to induce high hepatosomatic index, with high fat and glycogen content of liver. However, the high-LIP diet caused the high mesenteric fat index, but did not increase liver fat. The mRNA abundance and activities of hepatic lipogenic enzymes were significantly increased in the high-CHO diet group, whereas the opposite tendencies were observed in the high-LIP diet group. Peroxisome proliferator-actived receptor-α (PPARα) in liver and PPARγ in mesenteric adipose tissue were up-regulated in the high-CEL diet group. Lipoprotein lipase (LPL) gene expression was significantly increased both in liver and mesenteric adipose tissue of fish fed the high-LIP diet, while the LPL gene expression was up-regulated in liver but down-regulated in mesenteric adipose tissue of fish fed the high-CEL diet. These findings suggest that an increase in dietary non-protein energy sources alters the genes expression of lipid metabolism and increased lipid deposition.

Eicosapentaenoic acid-enriched phospholipid ameliorates insulin resistance and lipid metabolism in diet-induced-obese mice

BackgroundOver the past two decades, a striking increase in the number of people with metabolic syndrome (MS) has taken place worldwide. With the elevated risk of not only diabetes but also cardiovascular morbidity and mortality, there is urgent need for strategies to prevent this emerging global epidemic. The present study was undertaken to investigate the effects of dietary eicosapentaenoic acid-enriched phospholipid (EPA-PL) on metabolic disorders.MethodsMale C57BL/6J mice (n = 7) were fed one of the following 4 diets for a period of 4 weeks: 1) a modified AIN-96G diet with 5% corn oil (control diet); 2) a high fat (20%, wt/wt) and high fructose (20%, wt/wt) diet (HF diet); 3) the HF diet containing 1% SOY-PL (SOY-PL diet); 4) the HF diet containing 1% EPA-PL (EPA-PL diet). The oral glucose tolerance test was performed. Plasma TG, TC, glucose, NEFA, insulin, leptin, adiponectin, TNF-α and IL-6 levels were assessed. In addition, hepatic lipid levels, lipogenic, and lipidolytic enzyme activities and gene expressions were evaluated.ResultsBoth EPA-PL and SOY-PL significantly inhibited body weight gain and white adipose tissue accumulation, alleviated glucose intolerance, and lowered both serum fasting glucose and NEFA levels substantially. Only EPA-PL significantly reduced serum TNF-α and IL-6 levels, and increased serum adiponectin level. EPA-PL was more effective in reducing hepatic and serum TG and TC levels than SOY-PL. Both EPA-PL and SOY-PL reduced the activities of hepatic lipogenic enzymes, such as FAS and G6PDH, but only EPA-PL significantly increased CPT, peroxisomal β-oxidation enzymes activities and CPT-1a mRNA level. Alterations of hepatic lipogenic gene expressions, such as FAS, G6PDH, ACC, SCD-1 and SREBP-1c were consistent with changes in related enzyme activities.ConclusionsAccording to our study, EPA-PL supplementation was efficacious in suppressing body fat accumulation, and alleviating insulin resistance and hepatic steatosis by modulating the secretion of adipocytokines and inflammatory cytokines, suppression of SREBP-1c mediated lipogenesis and enhancement of fatty acid β-oxidation. These results demonstrate that EPA-PL is a novel beneficial food component for the prevention and improvement of metabolic disorders.

Antihyperlipidemic effects of mature coconut water and its role in regulating lipid metabolism in alloxan-induced experimental diabetes

The present study aims to evaluate the antihyperipidemic effects of mature coconut water (MCW), a natural nutritious beverage and its role in regulating lipid metabolism in experimental diabetes. The experimental animals were divided into four groups—normal control, MCW-alone-treated rats, diabetic control, and diabetic rats treated with MCW. Blood glucose, lipid profile, atherogenic index, phospholipids in various tissues, free fatty acids, activities of various lipogenic enzymes, 3-hydroxy-3-methylglutaryl-coenzyme A (HMG CoA) reductase in liver, lecithin–cholesterol acyl transferase (LACT) in plasma, and lipoprotein lipase (LPL) in heart were evaluated in all the experimental groups. The results indicate that in diabetic rats, MCW treatment reduced the blood glucose and lipid levels in blood and other tissues along with reduced activity of HMG CoA reductase and increased activity of LACT and LPL. In addition, levels of triglycerides, phospholipids, and free fatty acids in various tissues and atherogenic index were significantly lowered. In conclusion, MCW significantly reduced hyperlipidemia and regulated the defects in lipid metabolism in diabetic rats, indicating the therapeutic potential of MCW in diabetes and associated atherogenic complications.

Inhibitory Effects of S-Allylmercaptocysteine Derived from Aged Garlic on Cholesterol Biosynthesis in Hepatocytes

마늘 숙성 중 생성되는 S-allylmercaptocysteine의 콜레스테롤 생합성 억제 효과에 대하여 Hepatocytes를 이용하여 조사하였다. HepG2 cells을 Dulbecco`s modified Eagle`s medium(DMEM)에 배양하여 S-allylmercaptocysteine의 농도를 20, 40, 60, 80 및 100 mL 씩 각각 첨가하여 cell viability를 살펴본 결과 20∼40 μg/mL에서는 높았으며, 60 μg/mL 농도에서 약 50%가 유지되었다. S-allylmercaptocysteine을 5, 10, 15 및 20 μg/mL 농도로 [14C]-acetatecholesterol에서 처리하였을 경우 15 μg/mL 농도에서 cholesterol 생합성이 79%로 억제되었다. Fatty acid synthase의 활성은 0.95 nmol에서 19%의 억제효과를 나타내었으나, Glucose 6-phosphate dehydrogenase (G6PDH)의 활성에는 거의 영향을 미치지 않았다. S-allylmercaptocysteine의 3-hydroxy-3-methylglutaryl CoA (HMG-CoA) reductase의 활성은 용량 의존형으로 감소하였다. 이상의 결과로 보아 마늘 숙성 과정에서 생성되는 주요 성분인 S-allylmercaptocysteine은 간 세포에서 cholesterol의 생합성을 억제하는데 기여하는 것으로 나타났다.

Early Diet Dilution with 40% Rice Hull Induces Lower Body Fat and Lipid Metabolic Programming in Peking Ducks

This study was conducted to evaluate the effect of early diet dilution with 40% rice hull on growth performance, carcass characteristic and composition of meat-type ducks, and to reveal the possible mechanism for decreased body fat deposition. 160 1-day-old White Peking ducks with initial body weight of <TEX>$44.5{\pm}1.0$</TEX> g were allotted to two treatments with 8 replicate pens per treatment and 10 ducks per pen (5 male and 5 female). Ducks were fed with the experimental starter diets diluted with 0% (control, RH0), 40% rice hull (RH40) during 8 to 14 d of age, respectively. Thereafter, all ducks were fed with grower diet. Ducks fed with RH40 diet from 8 to 14 d of age increased (p<0.05) feed intake, decreased (p<0.05) body weight, body weight gain and adjusted feed intake (excluded rice hull), abdominal fat, skin with fat, and fat content in carcass, and reduced (p<0.05) activities of hepatic malic dehydrogenase, glucose-6-phosphate dehydrogenase and fatty acid synthetase. When diet dilution was withdrawn in the re-fed period from 15 to 42 d of age, full compensatory growth of body weight, breast meat and leg meat weight were attained. However, ducks were still less (p<0.05) carcass fat content and showed continually lower (p<0.05) hepatic lipogenic enzyme activities at the market age in RH40 ducks than the control. These results indicated that diluting diet with 40% rice hull during 8 to 14 d of age might be a suitable method to improve feed efficiency, and to reduce carcass fat deposition in the production of meat-type ducks.

Demethoxycurcumin Inhibits Energy Metabolic and Oncogenic Signaling Pathways through AMPK Activation in Triple-Negative Breast Cancer Cells

Demethoxycurcumin (DMC), curcumin (Cur), and bisdemethoxycurcumin (BDMC) are major forms of curcuminoids found in the rhizomes of turmeric. This study examined the effects of three curcuminoid analogues on breast cancer cells. The results revealed that DMC demonstrated the most potent cytotoxic effects on breast cancer MDA-MB-231 cells. Compared with estrogen receptor (ER)-positive or HER2-overexpressing breast cancer cells, DMC demonstrated the most efficient cytotoxic effects on triple-negative breast cancer (TNBC) cells. However, nonmalignant MCF-10A cells were unaffected by DMC treatment. The study showed that DMC activated AMPK in TNBC cells. Once activated, AMPK inhibited eukaryotic initiation factor 4E-binding protein-1 (4E-BP1) signaling and mRNA translation via mammalian target of rapamycin (mTOR) and decreased the activity and/or expression of lipogenic enzymes, such as fatty acid synthase (FASN) and acetyl-CoA carboxylase (ACC). DMC also targeted multiple AMPK downstream pathways. Among these, the dephosphorylation of Akt is noteworthy because it circumvents the feedback activation of Akt that results from mTOR inhibition. Moreover, DMC suppressed LPS-induced IL-6 production, thereby blocking subsequent Stat3 activation. In addition, DMC also sustained epidermal growth factor receptor (EGFR) activation by suppressing the phosphatases, PP2a and SHP-2. These results suggest that DMC is a potent AMPK activator that acts through a broad spectrum of anti-TNBC activities.

Hypotriglyceridemic Potential of Fermented Mixed Tea Made with Third-Crop Green Tea leaves and Camellia (Camellia japonica) Leaves in Sprague–Dawley Rats

Fermented mixed tea made with third-crop green tea leaves and camellia leaves by a tea-rolling process has been developed. The objective of this study was to investigate hypotriglyceridemic potential of the mixed tea in rats. The mixed tea contained theasinensins and theaflavins. Rats fed the mixed tea extract at the level of 1% exerted significantly lower body weight and adipose tissue weight compared to animals fed third-crop green tea or camellia tea extract alone for 4 weeks. Serum and hepatic triglyceride was significantly and dose-dependently decreased by the mixed tea. This decrease was associated with lowered lipogenic enzyme activities in the liver. Furthermore, an oral administration of 4 or 8% of the mixed tea extract followed by fat emulsion suppressed the increment of serum triglyceride level. These results suggest that the mixed tea has hypotriglyceridemic action, partially via delaying triglyceride absorption in the small intestine and repressing hepatic lipogenic enzymes.

Intravenous infusions of glucose stimulate key lipogenic enzymes in adipose tissue of dairy cows in a dose-dependent manner

The present study was investigated whether increasing amounts of glucose supply have a stimulatory effect on the mRNA abundance and activity of key lipogenic enzymes in adipose tissue of midlactation dairy cows. Twelve Holstein-Friesian dairy cows in midlactation were cannulated in the jugular vein and infused with either a 40% glucose solution (n=6) or saline (n=6). For glucose infusion cows, the infusion dose increased by 1.25%/d relative to the initial net energy for lactation (NEL) requirement until a maximum dose equating to a surplus of 30% NEL was reached on d 24. This maximum dose was maintained until d 28 and stopped thereafter (between d 29–32). Cows in the saline infusion group received an equivalent volume of 0.9% saline solution. Samples of subcutaneous adipose tissue were taken on d 0, 8, 16, 24, and 32 when surplus glucose reached 0, 10, 20, and 30% of the NEL requirement, respectively. The mRNA abundance of fatty acid synthase, cytoplasmic acetyl-coenzyme A synthetase, cytoplasmic glycerol 3-phosphate dehydrogenase-1, and glucose 6-phosphate dehydrogenase showed linear treatment × dose interactions with increasing mRNA abundance with increasing glucose dose. The increased mRNA abundance was paralleled by a linear treatment × dose interaction for fatty acid synthase and acetyl-coenzyme A synthetase enzymatic activities. The mRNA abundance of ATP-citrate lyase showed a tendency for linear treatment × dose interaction with increasing mRNA abundance with increasing glucose dose. The mRNA abundance of all tested enzymes, as well as the activities of fatty acid synthase and acetyl-coenzyme A synthetase, correlated with plasma glucose and serum insulin levels. In a multiple regression model, the predictive value of insulin was dominant over that of glucose. In conclusion, gradual increases in glucose supply upregulate key lipogenic enzymes in adipose tissue of midlactating dairy cows with linear dose dependency. Insulin appears to be critically involved in this regulation.

Differential induction of enzymes and genes involved in lipid metabolism in liver and visceral adipose tissue of juvenile yellow catfish Pelteobagrus fulvidraco exposed to copper

The present study was conducted to determine the mechanism of waterborne Cu exposure influencing lipid metabolism in liver and visceral adipose tissue (VAT) of juvenile yellow catfish Pelteobagrus fulvidraco. Yellow catfish were exposed to four waterborne copper (Cu) concentrations (2 (control), 24 (low), 71 (medium), 198 (high)μgCu/l, respectively) for 6 weeks. Waterborne Cu exposure had a negative effect on growth and several condition indices (condition factor, viscerosomatic index, hepatosomatic index and visceral adipose index). In liver, lipid content, activities of lipogenic enzymes (6-phosphogluconate dehydrogenase (6PGD), glucose-6-phosphate dehydrogenase (G6PD), malic enzyme (ME), isocitrate dehydrogenase (ICDH), and fatty acid synthase (FAS)) as well as mRNA levels of 6PGD, G6PD, FAS and sterol-regulator element-binding protein-1 (SREBP-1) genes decreased with increasing Cu concentrations. However, activity and mRNA level of lipoprotein lipase (LPL) gene in liver increased. In VAT, G6PD, ME and LPL activities as well as the mRNA levels of FAS, LPL and PPARγ genes decreased in fish exposed to higher Cu concentrations. The differential Pearson correlations between transcription factors (SREBP-1 and peroxisome proliferators-activated receptor-γ (PPARγ)), and the activities and mRNA expression of lipogenic enzymes and their genes were observed between liver and VAT. Thus, our study indicated that reduced lipid contents in liver and VAT after Cu exposure were attributable to the reduced activities and mRNA expression of lipogenic enzymes and their genes in these tissues. Different response patterns of several tested enzymes and genes to waterborne Cu exposure indicated the tissue-specific regulatory effect of lipid metabolism following waterborne Cu exposure. To our knowledge, the present study provides, for the first time, evidence that waterborne chronic Cu exposure can disturb the normal processes of lipid metabolism at both the enzymatic and molecular levels, and in two tissues (the liver and adipose tissue), which serves to increase our understanding of the mechanisms underlying lipid metabolism during Cu exposure.

Effects of Trans-Fatty Acids on Liver Lipid Metabolism in Mice Fed on Diets Showing Different Fatty Acid Composition

Aim: Our aim was to investigate the effects of trans-fatty acids (TFA) on liver lipid metabolism in mice fed on experimental diets rich in either oleic or linoleic acid. Methods: Twenty-two male CF1 mice (22.0 ± 0.1 g) were fed with diets rich in corn oil or olive oil, supplemented or not with TFA (0.75 g TFA/100 g diet), for 4 weeks. Changes in triacylglycerol content, the activity and expression of enzymes involved in lipogenesis and fatty acid oxidation were measured. Results: Supplementation of an olive oil-rich diet with TFA increased liver triacylglycerols, the activity and expression of lipogenic enzymes and sterol regulatory element-binding protein SREBP-1a expression. By contrast, when TFA were added to a corn oil-rich diet, they did not modify these parameters. No significant differences were observed among the experimental groups in the activity and expression of carnitine palmitoyltransferase-Ia, body and liver weights or serum triacylglycerol concentrations. Conclusions: The effect of TFA on liver fat accumulation depends on the dietary fatty acid composition. Steatosis induced by TFA when included in an olive oil diet (but not in a corn oil diet) was associated with an increased lipogenesis but not with a decreased fatty acid oxidation in animals fed on the olive oil diet. This metabolic change is mediated by SREBP-1a but not by SREBP-1c, and seems to be independent of insulin.