Hepatic Lipogenic Enzyme Activities Research Articles

Exercise Down-Regulates Hepatic Lipogenic Enzymes in Food-Deprived and Refed Rats

The effects of an acute bout of prolonged exercise on the activities of several hepatic lipogenic enzymes and the abundance of fatty acid synthase (FAS) mRNA were evaluated using a food deprivation-refeeding protocol in which diets contained 50% of the energy from either fructose or cornstarch. Food was withheld from male rats for 48 h and refed for 0, 4, 8, 12, 24 or 48 h. At each time point, half of each dietary group was subjected to a single bout of treadmill running until exhaustion and killed immediately. The other half of each group rested without food for the same amount of time before being killed. Exercise significantly decreased FAS activity by 57, 46, 10, 26 and 70% at 4, 8, 12, 24 and 48 h of refeeding, respectively, in the fructose-fed rats; and by 70 and 63% at 24 and 48 h of refeeding, respectively, in the cornstarch-fed rats. Activities of L-type pyruvate kinase and glucose 6-phosphate dehydrogenase were significantly decreased after exercise in the fructose-fed, but not cornstarch-fed rats. In rested rats, FAS mRNA abundance increased ∼fourfold above the unfed levels after 8 and 12 h of refeeding. Exercise attenuated the diet-induced increases in FAS mRNA abundance. At 8 h of refeeding, both cornstarch- and fructose-fed exercised rats had 71% (P < 0.05) of the FAS mRNA levels of their rested counterparts; at 12 h, these exercised rats showed only 46 and 27% (P < 0.05) of FAS mRNA levels compared with rested rats fed the same diet. We conclude that dietary induction of FAS activity and mRNA abundance can be inhibited by prolonged exercise, suggesting that exercise may influence FAS transcription and/or mRNA stability.

Insect meals in feeds for juvenile gilthead seabream (Sparus aurata): Effects on growth, blood chemistry, hepatic metabolic enzymes, body composition and nutrient utilization

Alternative and sustainable fish diets are required by modern aquaculture. We investigated the possibility of using insect (Tenebrio molitor TM, Hermetia illucens HI or Musca domestica MD) larvae meals (as 19.5% of the feed formulation) to replace 30% of the in the fish meal (FM) in a gilthead seabream (Sparus aurata) feed formulated to contain 65% FM. The feeds were isonitrogenous (ca 57% crude protein of dry matter) isolipidic (ca 17% lipid dry matter) and isoenergetic (ca 22 MJ kg−1 dry matter). To achieve similar energy content among the experimental diets, the fish oil inclusion was adjusted. Fish (average initial weight of 29.5 g) were fed up to apparent satiation three times a day, 7 days per week in a 93-days trial. Each diet was assigned to three 500 L tanks with fish density 2 kg m−3. Five fish from the initial population and two fish per tank were taken for whole-body composition analysis. At the end of the experimental period, nine fish per treatment were taken for the analysis of plasma metabolites and liver enzyme activities. Growth performance, feed intake, feed conversion and somatic indices of fish fed the different insect meal diets were similar to the FM fish. However, among the insect meal fish groups, the feeding with the TM diet resulted in higher specific growth rate compared to the HI diet (1.57% and 1.51% per day, respectively). The whole-body proximate composition was similar among experimental groups. Fish fed HI had the lowest fat retention (57.0% compared to 69.3–74.2%). Additionally, the HI group had also lower dry matter and energy retention (30.5% and 36.6%, respectively) compared to the FM group (33.8% and 41.5%, respectively). The whole-body saturated and mono-unsaturated fatty acids content was similar to all the experimental groups. Fish fed diets higher in fish oil (FM and HI) had higher eicosapentaenoic, docosahexaenoic and total ω-3 poly-unsaturated fatty acids content. Whole-body amino acid composition was similar among all experimental groups, while the amino acid retention exhibited significant differences. The plasma metabolites and enzyme activities as well as the hepatic lipogenic enzyme activity were not affected by the different diets. Fish fed the HI diet exhibited higher liver alanine aminotransferase (ALT) activity in comparison to the TM group. Overall, this study shows that FM can be successfully replaced by TM, HI or MD meals in 30% by weight in the diets of gilthead sea bream. Comparing insect meals, HI meal was inferior in terms of growth performance and dry matter-fat retention compared to TM and MD, respectively.

Effect of different carbohydrate-to-lipid ratios elicits growth, feed utilization, lipid deposition and lipogenic enzyme activity in striped catfish (Pangasianodon hypophthalmus, Sauvage, 1878) fingerlings

This study evaluated the effects of diets containing various carbohydrate-to-lipid (CHO L-1) ratios on growth performance, nutrient utilization body indices and hepatic lipogenic enzyme (malic enzyme, 6-phosphogluconate dehydrogenase and fatty acid synthase) activities. Triplicate groups of Pangasianodon hypophthalmus fingerlings were fed eight isoenergetic and isonitrogenous diets with different carbohydrate-to-lipid ratios (0.51, 0.79, 1.12, 1.79, 2.41, 3.24, 4.43 and 7.62). Higher body fat deposition and lower growth performance were observed in P. hypophthalmus fingerlings fed with high-lipid diet than those fed with high-carbohydrate diet. The fish fed the diet with 7.62 CHO L-1 ratio exhibited significantly (p<0.05) higher hepatosomatic index compared to those fed higher lipid diets (0.51 and 0.79). High dietary carbohydrate level significantly increased (p<0.05) the activities of malic, 6-phosphogluconate dehydrogenase and fatty acid synthase enzyme. Based on the second-order polynomial regression analysis of weight gain, the optimal dietary carbohydrate and lipid contents for P. hypophthalmus fingerling were 304 and 103 g kg−1, respectively, which correspond to a dietary CHO L-1 ratio of 2.95.

Supplementation of Sulfur-Containing Amino Acids or Essential Amino Acids Does Not Reverse the Hepatic Lipid-Lowering Effect of a Protein-Rich Insect Meal in Obese Zucker Rats.

The present study tested the hypothesis that the liver lipid-lowering effect of insect meal (IM) is caused by its low methionine concentration. A total of fifty, male obese Zucker rats were randomly assigned to five groups of 10 rats each (casein (C), IM, IM + Met, IM + Cys, and IM + EAA). While group C received a diet with casein, the IM-fed groups received a diet with IM as the protein source. In groups IM + Met, IM + Cys and IM + EAA, the diets were additionally supplemented with methionine, cysteine and essential amino acids (EAA), respectively. Hepatic concentrations of triacylglycerols and cholesterol, and hepatic mRNA levels and activities of lipogenic and cholesterogenic enzymes were markedly lower in the IM-fed groups than in group C (p < 0.05). All of these parameters either did not differ across the IM-fed groups or were only slightly higher in groups IM + Met, IM + Cys and IM+EAA than in the group IM. In conclusion, the results indicate that a difference in the amino acid composition between IM and casein, a low concentration of methionine in IM and a reduced cysteine synthesis secondary to a decreased methionine availability resulting from feeding IM are not causative for the lipid-lowering effect of IM.

Partially Defatted Tenebrio molitor Larva Meal in Diets for Grow-Out Rainbow Trout, Oncorhynchus mykiss (Walbaum): Effects on Growth Performance, Diet Digestibility and Metabolic Responses.

Simple SummaryThe current developments in the aquaculture sector have highlighted the need to find sustainable ingredients to replace fishmeal as a protein source in fish feeds. The use of insect meals may be a valid option, due to their good nutritional values and low ecological footprint. In this study, we evaluated the effects of a progressive fishmeal substitution with increasing concentrations of a partially defatted yellow mealworm meal in rainbow trout diets. We observed that the total substitution of fishmeal with insect meal is feasible and that there are no negative effects on fish growth or on the digestibility of most nutrients. The activities of hepatic enzymes involved in the amino acid metabolism and lipid synthesis were also evaluated. The enzymatic activities were not negatively influenced by insect meal inclusion in the diets. These results are of practical application for feed manufacturers and farmers, as they support the inclusion of insect meals in fish diets to obtain sustainable feeds that able to support an increase in aquaculture production.Insect meals are good candidates to replace fishmeal as new protein sources in aquafeeds. This study evaluated the effects of fishmeal replacement with different dietary inclusion levels of a partially defatted Tenebrio molitor (L.) larva meal (TM) on rainbow trout (Oncorhynchus mykiss Walbaum) growth, diet digestibility, and hepatic intermediary metabolism. A 154-day growth trial was performed with 252 rainbow trout (78.3 ± 6.24 g) randomly divided into twelve tanks and fed four experimental diets containing increasing levels of TM: 0% (TM0), 25% (TM25), 50% (TM50), and 100% (TM100) of fishmeal substitution, corresponding to TM dietary inclusion levels of 0%, 5%, 10%, and 20%, respectively. A digestibility trial was performed feeding 180 rainbow trout (94.6 ± 7.31 g) with the experimental diets used in the growth trial. The growth parameters were not affected by TM dietary inclusion. Regarding the evaluated apparent digestibility coefficients (ADC), only the ADC of crude protein was affected, showing the following trend: TM0 = TM25 > TM50 > TM100. The activities of key hepatic amino acid catabolic and lipogenic enzymes were not affected by the dietary composition. The results suggest that a partially defatted TM could totally replace fishmeal in commercial rainbow trout diets without negative effects on fish performance.

Suppression of abdominal fat and anti-hyperlipidemic potential of Emblica officinalis: Upregulation of PPARs and identification of active moiety.

Since ancient time, Emblica officinalis (E. officinalis) is being used for the management of various ailments. Phytochemical analysis proves that fruit juice of E. officinalis contains high amount gallic acid, which could be responsible for medicinal potentials. Hence in this study, gallic acid and fruit juice of E. officinalis were evaluated for anti-hyperlipidemic potential in various experimental animal models. Experimentally, hyperlipidemia was induced through administration of poloxamer-407, tyloxapol and high-fat-diet supplement in rats. Treatment with gallic acid as well as fruit juice of E. officinalis decreased plasma cholesterol and reduced oil infiltration in liver and aorta. Mechanistically, E. officinalis increased peroxisome proliferator-activated receptors-α (PPARα) expression and increased activity of lipid oxidation through carnitine palmitoyl transferase (CPT) along with decreased activity of hepatic lipogenic enzymes i.e. glucose-6-phosphate dehydrogenase (G6PD), fatty acid synthase (FAS) and malic enzyme (ME). Additionally, E. officinalis increased cholesterol uptake through increased LDL-receptor expressions on hepatocytes and decreased LDL-receptor degradation due to decreased proprotein convertase subtilisin/kexin type 9 (PCSK9) expression. Simultaneously, E. officinalis showed ability to restore glucose homeostasis through increased Glut4 and PPARγ protein expression in adipose tissue. These findings exposed central role of gallic acid in E. officinalis arbitrated anti-hyperlipidemic action through upregulation of PPARs, Glut4 and lipogenic enzymes, and decreased expression of PCSK9 and lipogenic enzymes. Findings from this experiment demonstrated that E. officinalis is a potential therapy for management of hyperlipidemia and gallic acid could be a potential lead candidate.

Effects of blueberry leaf and stem extracts on hepatic lipid levels in rats consuming a high-sucrose diet

Background: Blueberry stems, a by-product of blueberry leaf tea production, are typically discarded. We evaluated the effects of hot-water extracts of rabbiteye blueberry (Vaccinium virgatum Aiton; RB species) leaves and stems on hepatic lipid levels in rats consuming a high-sucrose diet.Methods: Male Sprague-Dawley rats were divided into groups that received a control high-sucrose diet alone or supplementation with 2.0% blueberry leaf extract or 0.5% or 2.0% blueberry stem extract. Blood and hepatic lipid levels, hepatic lipogenic enzyme activity, and hepatic quercetin metabolites were evaluated after 28 days of ad libitum consumption.Results: Supplementation with the extracts did not affect body weight gain, food intake, liver and white adipose tissue weights, or serum lipid levels. Hepatic triglyceride and total cholesterol levels were reduced in the groups that received 2.0% supplementation of either extract. Hepatic malic enzyme activity was also reduced in those groups. Quercetin and its glycosides, the major polyphenols identified in the extracts, accumulated in the liver as quercetin aglycone and quercetin metabolites. Conclusion: We demonstrated how daily consumption of blueberry leaf and stem extracts can decrease hepatic lipid levels, potentially downregulating malic enzyme activity. These effects were intensive in leaf extracts. The active compounds existed in both extracts may be quercetin and its glycosides. Therefore, blueberry stems and leaves may be an attractive candidate novel functional food.Keywords: Blueberry leaf; blueberry stem; quercetin; hepatic lipid; rat; functional food

Intake of phytic acid and myo-inositol lowers hepatic lipogenic gene expression and modulates gut microbiota in rats fed a high-sucrose diet.

Dietary phytic acid (PA) was recently reported by our group to suppress hepatic lipogenic gene expression and modulate gut microbiota in rats fed a high-sucrose (HSC) diet. The present study aimed to investigate whether the modulatory effects of PA depend on the dietary carbohydrate source and are attributed to the myo-inositol (MI) ring of PA. Male Sprague-Dawley rats were fed an HSC or a high-starch (HSR) diet with or without 1.02% sodium PA for 12 days. Subsequently, the rats were fed the HSC diet, the HSC diet containing 1.02% sodium PA or an HSC diet containing 0.2% MI for 12 days. The HSC diet significantly increased the hepatic triglyceride (TG) concentration as well as the activity and expression of hepatic lipogenic enzymes compared with the HSR diet. The increases were generally suppressed by dietary PA with a concomitant increase in the fecal and cecal ratios of Lactobacillus spp. In rats fed the HSR diet, PA intake did not substantially affect the factors associated with hepatic lipid metabolism or gut microbiota composition. The effects of MI intake were similar to that of PA intake on hepatic lipogenesis and gut microbiota in rats fed the HSC diet. These results suggest that dietary PA downregulates hepatic lipogenic gene expression and modulates gut microbiota composition in rats fed an HSC diet but not in rats fed an HSR diet. The MI ring of PA may be responsible for the effects of PA intake on hepatic lipogenic gene expression and gut microbiota.

Rare sugars, d-allulose, d-tagatose and d-sorbose, differently modulate lipid metabolism in rats.

Rare sugars including d-allulose, d-tagatose, and d-sorbose are present in limited quantities in nature; some of these rare sugars are now commercially produced using microbial enzymes. Apart from the anti-obesity and anti-hyperglycaemic activities of d-allulose, effects of these sugars on lipid metabolism have not been investigated. Therefore, we aimed to determine if and how d-tagatose and d-sorbose modulate lipid metabolism in rats. After feeding these rare sugars to rats, parameters on lipid metabolism were determined. No diet-related effects were observed on body weight and food intake. Hepatic lipogenic enzyme activity was lowered by d-allulose and d-sorbose but increased by d-tagatose. Faecal fatty acid excretion was non-significantly decreased by d-allulose, but significantly increased by d-sorbose without affecting faecal steroid excretion. A trend toward reduced adipose tissue weight was observed in groups fed rare sugars. Serum adiponectin levels were decreased by d-sorbose relative to the control. Gene expression of cholesterol metabolism-related liver proteins tended to be down-regulated by d-allulose and d-sorbose but not by d-tagatose. In the small intestine, SR-B1 mRNA expression was suppressed by d-sorbose. Lipid metabolism in rats varies with rare sugars. Application of rare sugars to functional foods for healthy body weight maintenance requires further studies. © 2017 Society of Chemical Industry.

Long-Term Dietary Supplementation with Yerba Mate Ameliorates Diet-Induced Obesity and Metabolic Disorders in Mice by Regulating Energy Expenditure and Lipid Metabolism.

This study evaluated whether long-term supplementation with dietary yerba mate has beneficial effects on adiposity and its related metabolic dysfunctions in diet-induced obese mice. C57BL/6J mice were randomly divided into two groups and fed their respective experimental diets for 16 weeks as follows: (1) control group fed with high-fat diet (HFD) and (2) mate group fed with HFD plus yerba mate. Dietary yerba mate increased energy expenditure and thermogenic gene mRNA expression in white adipose tissue (WAT) and decreased fatty acid synthase (FAS) mRNA expression in WAT, which may be linked to observed decreases in body weight, WAT weight, epididymal adipocyte size, and plasma leptin level. Yerba mate also decreased levels of plasma lipids (free fatty acids, triglycerides, and total cholesterol) and liver aminotransferase enzymes, as well as the accumulation of hepatic lipid droplets and lipid content by inhibiting the activities of hepatic lipogenic enzymes, such as FAS and phosphatidate phosphohydrolase, and increasing fecal lipid excretion. Moreover, yerba mate decreased the levels of plasma insulin as well as the homeostasis model assessment of insulin resistance, and improved glucose tolerance. Circulating levels of gastric inhibitory polypeptide and resistin were also decreased in the mate group. These findings suggest that long-term supplementation of dietary yerba mate may be beneficial for improving diet-induced adiposity, insulin resistance, dyslipidemia, and hepatic steatosis.

Physiological activities of the combination of fish oil and α-lipoic acid affecting hepatic lipogenesis and parameters related to oxidative stress in rats.

We studied the combined effect of fish oil and α-lipoic acid on hepatic lipogenesis and fatty acid oxidation and parameters of oxidative stress in rats fed lipogenic diets high in sucrose. A control diet contained a saturated fat (palm oil) that gives high rate of hepatic lipogenesis. Male Sprague-Dawley rats were fed diets supplemented with 0 or 2.5g/kg α-lipoic acid and containing 0, 20, or 100g/kg fish oil, for 21 days. α-Lipoic acid significantly reduced food intake during 0-8 days but not the later period of the experiment. Fish oil and α-lipoic acid decreased serum lipid concentrations and their combination further decreased the parameters in an additive fashion. The combination of fish oil and α-lipoic acid decreased the activity and mRNA levels of hepatic lipogenic enzymes in an additive fashion. Fish oil increased the parameters of hepatic fatty acid oxidation enzymes. α-Lipoic acid appeared to antagonize the stimulating effects of fish oil of fatty acid oxidation through reductions in the activity of some fatty acid oxidation enzymes. α-Lipoic acid attenuated fish oil-dependent increases in serum and liver malondialdehyde levels, and this compound also reduced the serum 8-hydroxy-2'-deoxyguanosine level. α-Lipoic acid affected various parameters related to the antioxidant system; fish oil also affected some of the parameters. The combination of fish oil and α-lipoic acid effectively reduced serum lipid levels through the additive down-regulation of hepatic lipogenesis. α-Lipoic acid was effective in attenuating fish oil-mediated oxidative stress.

Sea Cucumber Saponin Echinoside A (EA) Stimulates Hepatic Fatty Acid β-Oxidation and Suppresses Fatty Acid Biosynthesis Coupling in a Diurnal Pattern.

Circadian rhythms control aspects of physiological events, including lipid metabolism, showing rhythmic fluctuation over 24 h. Therefore, it is not sufficient to evaluate thoroughly how dietary components regulate lipid metabolism with a single time-point assay. In the present study, a time-course study was performed to analyze the effect of sea cucumber saponin echinoside A (EA) on lipid metabolism over 24 h. Results showed that EA lowered the levels of TC and TG in both serum and liver at most time-points during the 24 h. Activities of hepatic lipogenic enzymes and lipolytic enzymes were inhibited and elevated respectively by EA to varied degrees at different time-points. Meanwhile, parallel variation trends of gene expression involved in fatty acid synthesis and β-oxidation were observed accordingly. The interaction between EA and lipid metabolism showed a time-dependent effect. Overall, EA impaired fatty acid synthesis and enhanced mitochondrial fatty acid β-oxidation in ad libitum feeding over 24 h.

Dietary Fatty Acid Metabolism is Affected More by Lipid Level than Source in Senegalese Sole Juveniles: Interactions for Optimal Dietary Formulation.

This study analyses the effects of dietary lipid level and source on lipid absorption and metabolism in Senegalese sole (Solea senegalensis). Juvenile fish were fed 4 experimental diets containing either 100 % fish oil (FO) or 25 % FO and 75 % vegetable oil (VO; rapeseed, linseed and soybean oils) at two lipid levels (~8 or ~18 %). Effects were assessed on fish performance, body proximate composition and lipid accumulation, activity of hepatic lipogenic and fatty acid oxidative enzymes and, finally, on the expression of genes related to lipid metabolism in liver and intestine, and to intestinal absorption, both pre- and postprandially. Increased dietary lipid level had no major effects on growth and feeding performance (FCR), although fish fed FO had marginally better growth. Nevertheless, diets induced significant changes in lipid accumulation and metabolism. Hepatic lipid deposits were higher in fish fed VO, associated to increased hepatic ATP citrate lyase activity and up-regulated carnitine palmitoyltransferase 1 (cpt1) mRNA levels post-prandially. However, lipid level had a larger effect on gene expression of metabolic (lipogenesis and β-oxidation) genes than lipid source, mostly at fasting. High dietary lipid level down-regulated fatty acid synthase expression in liver and intestine, and increased cpt1 mRNA in liver. Large lipid accumulations were observed in the enterocytes of fish fed high lipid diets. This was possibly a result of a poor capacity to adapt to high dietary lipid level, as most genes involved in intestinal absorption were not regulated in response to the diet.

Hypolipidemic potential of squid homogenate irrespective of a relatively high content of cholesterol.

BackgroundOur previous study has shown that regardless of a relatively high amount of cholesterol, squid homogenate lowers serum and hepatic cholesterol in animals. Since this work, we have developed a new method to inhibit autolysis of squid proteins with sodium citrate. This study aims to investigate how squid homogenate prepared with sodium citrate affects lipid metabolism in Sprague–Dawley rats at the molecular level.MethodsWe prepared squid homogenate with sodium citrate to inhibit autolysis of squid protein. In Experiment 1 (Exp. 1), rats were given a cholesterol-free control diet or a squid diet, with squid homogenate added at the level of 5% as dietary protein for 4 weeks. Blood, the liver and adipose tissue were taken after 6 hours fasting. Serum and hepatic lipids and activities of enzymes related to lipid metabolism were measured. In Experiment 2 (Exp. 2), the above-mentioned diets had cholesterol added at the level of 0.1% and given to rats. Lipid parameters, enzyme activities, and gene expression of proteins involved in lipid metabolism in the liver and the small intestine were determined. In addition, feces were collected for two days at the end of Exp. 2 to measure fecal excretion of steroids.ResultsIn Exp.1, serum triglyceride and cholesterol were ~50% and ~20% lower, respectively, in the squid diet-fed rats than in the control diet-fed animals while hepatic cholesterol was ~290% higher in the squid diet-fed rats. When cholesterol was included into the diets (Exp. 2), serum lipids were significantly lower in the squid group while no difference of hepatic lipid was seen between two groups. Activities of hepatic lipogenic enzymes were significantly lower in rats on the squid diet while the enzyme responsible for fatty acid oxidation was not modified (Expt. 1 and 2). Hepatic level of mRNA of microsomal triglyceride transfer protein was significantly lower in the squid group. In the small intestine, the squid diet exhibited significantly lower gene expression of proteins involved in fatty acid transport and cholesterol absorption. Fecal secretion of acidic steroids, but not neutral steroids, was higher in rats fed the squid diet than in those fed the control diet.ConclusionThese results imply that newly-developed squid homogenate has hypolipidemic potential primarily through decreased absorption of bile acids in the small intestine and suppressed lipogenesis in the liver.

Protein-sparing effect of carbohydrate in diets for juvenile turbot Scophthalmus maximus reared at different salinities

The aim of the present study was to investigate the protein-sparing effect of carbohydrate in diets for juvenile turbot (Scophthalmus maximus) reared at five salinities (12, 18, 24, 30, and 36). The fish were fed three isocaloric and isolipidic diets for 60 days. The results show that specific growth rate (SGR) and feed conversion efficiency (FCE) were higher in fish reared at salinities of 18 and 36, but lower at 12. Fish fed with diet C25P40 (25% carbohydrate and 40% protein) had lower SGR and FCE values compared with those fed with the C5P52 (5% carbohydrate and 52% protein) and C15P46 (15% carbohydrate and 46% protein) diets; however, there was no statistical difference between diet C5P52 and C15P46. SGR and FCE values were unaffected by diet composition in fish reared at salinity 36. Hepatic lipogenic enzyme activities were higher in fish reared at 18 and 36, but lower at 12, while glucokinase (GK) activity was higher in fish reared at 12, and lower at 18 and 36. Dietary starch enhanced GK activity while depressing lipogenic enzyme activity. However, lipogenic enzyme activity increased with increasing dietary starch in fish reared at 36. It is recommended that salinity should be maintained >12 in the farming of juvenile turbot. In addition, an increase in gelatinized starch from 5% to 15% could spare 6% dietary protein in fish reared at salinities of 18–30, while higher salinity (36) could improve dietary carbohydrate use and enhance the protein-sparing effect, which is linked with the induction of lipogenic capacities.

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.

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.

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.

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.