Hormone-sensitive Lipase mRNA Expression Research Articles

Human recombinant relaxin-2 (serelaxin) regulates the proteome, lipidome, lipid metabolism and inflammatory profile of rat visceral adipose tissue

Recombinant human relaxin-2 (serelaxin) has been widely proven as a novel drug with myriad effects at different cardiovascular levels, which support its potential therapeutic efficacy in several cardiovascular diseases (CVD). Considering these effects, together with the influence of relaxin-2 on adipocyte physiology and adipokine secretion, and the connection between visceral adipose tissue (VAT) dysfunction and the development of CVD, we could hypothesize that relaxin-2 may regulate VAT metabolism. Our objective was to evaluate the impact of a 2-week serelaxin treatment on the proteome and lipidome of VAT from Sprague-Dawley rats. We found that serelaxin increased 1 polyunsaturated fatty acid and 6 lysophosphatidylcholines and decreased 4 triglycerides in VAT employing ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS) based platforms, and that regulates 47 phosphoproteins using SWATH/MS analysis. Through RT-PCR, we found that serelaxin treatment also caused an effect on VAT lipolysis through an increase in the mRNA expression of hormone-sensitive lipase (HSL) and a decrease in the expression of adipose triglyceride lipase (ATGL), together with a reduction in the VAT expression of the fatty acid transporter cluster of differentiation 36 (Cd36). Serelaxin also caused an anti-inflammatory effect in VAT by the decrease in the mRNA expression of tumor necrosis factor α (TNFα), interleukin-1β (IL-1β), chemerin, and its receptor. In conclusion, our results highlight the regulatory role of serelaxin in the VAT proteome and lipidome, lipolytic function, and inflammatory profile, suggesting the implication of several mechanisms supporting the potential benefit of serelaxin for the prevention of obesity and metabolic disorders.

Effects of Weight Loss and Aerobic Exercise Training on Adi-Pose Tissue Zinc α2-Glycoprotein and Associated Genes in Obesity.

Zinc α2-glycoprotein (ZAG) has been implicated in fatty acid metabolism and utilization and is lower in obese and higher in cachexic adults compared to those of normal weight. Previous studies suggest that ZAG binds to the beta3-adrenergic receptor (β3AR) to influence fatty acid metabolism in adipose tissue by regulating hormone sensitive lipase (HSL). The purpose of this study is to investigate the effects of a six-month weight loss (WL) or aerobic exercise (AEX) intervention on adipose tissue and skeletal muscle ZAG mRNA levels and protein expression, as well as the expression of β3AR, and HSL. Abdominal adipose tissue (AB) and gluteal adipose tissue (Glut) and vastus lateralis muscle biopsies were performed before and after WL (n = 13) or AEX (n = 13). ZAG, HSL, and β3AR expressions were determined by RT-PCR, and ZAG and HSL plasma levels by ELISA. Body weight decreased by 9.69% (p < 0.001) in WL and did not change with AEX. Maximal oxygen consumption (VO2max) increased by 7.1% (p < 0.005) after WL and by 16.69% (p < 0.001) after AEX. WL significantly decreased body weight with a reduction of percentage of fat, fat mass, fat-free mass (FFM). AEX decreased percent fat and increased VO2max, but did not change fat mass and FFM. Abdominal ZAG and HSL mRNA levels did not change significantly after WL or AEX. There were no changes in plasma ZAG, HSL and adipose tissue β3AR mRNA levels after WL and AEX. ZAG, HSL and β3AR mRNA expressions in adipose tissue are positively associated each other. Adipose tissue abdominal and gluteal HSL are negatively associated with HOMA-IR (Homeostatic Model Assessment for Insulin Resistance), and both ZAG and HSL adipose tissue are negatively associated with fasting glucose and the glucose area under the curve. Further work is needed to elucidate the role of ZAG and HSL in the propensity for weight gain and the ability of exercise to mitigate these responses.

Kaempferia parviflora rhizome extract exerts anti-obesity effect in high-fat diet-induced obese C57BL/6N mice.

Kaempferia parviflora (KP) rhizome, also called black ginger, has been used as a herbal medicine for many centuries. This current study was aimed at exploring whether KP rhizome extract (KPE) had anti-obesity effects and the mechanism involved. Five-week-old C57BL/6N male mice were allocated into five groups for 8-week feeding with control diet (CD), high-fat diet (HFD), HFD + 150 mg/kg body weight (BW)/day KPE (HFD+K150), HFD + 300 mg/kg BW/day KPE (HFD+K300), and HFD + 600 mg/kg BW/day KPE (HFD+K600). KPE decreased BW, body fat mass, adipose tissue weight, adipocyte size, and serum levels of glucose, triglycerides, cholesterol, insulin, and leptin in HFD-induced obese C57BL/6N mice. KPE inhibited adipogenesis by decreasing CCAAT/enhancer binding protein α, peroxisome proliferator-activated receptor γ, sterol regulatory element-binding protein-1c, acetyl-CoA carboxylase 1, ATP-citrate lyase, and fatty acid synthase mRNA expression. KPE improved lipolysis by increasing carnitine palmitoyl transferase 1 and hormone-sensitive lipase mRNA expression. These results suggest that KPE may have inhibited HFD-induced obesity by regulating several pathways involved in decreasing adipogenesis and enhancing lipolysis. Thus, the results suggest that KPE (or KP) may be applicable as an anti-obesity agent.

Cydonia oblonga Miller fruit extract exerts an anti-obesity effect in 3T3-L1 adipocytes by activating the AMPK signaling pathway.

The fruit of Cydonia oblonga Miller (COM) is used traditionally in Mediterranean region medicine to prevent or treat obesity, but its mechanism of action is still unclear. Beyond a demonstrated anti-obesity effect, the fruit was tested for the mechanism of adipogenesis in 3T3-L1 preadipocytes. 3T3-L1 preadipocytes were cultured for 8 days with COM fruit extract (COME) at different concentrations (0-600 µg/mL) with adipocyte differentiation medium. The cell viability was measured using an MTT assay; triglyceride (TG) was stained with Oil Red O. The expression levels of the adipogenesis-related genes and protein expression were analyzed by reverse transcription polymerase chain reaction and Western blotting, respectively. COME inhibited intracellular TG accumulation during adipogenesis. A COME treatment in 3T3-L1 cells induced upregulation of the adenosine monophosphate-activated protein kinase (AMPK)α phosphorylation and downregulation of the adipogenic transcription factors, such as sterol regulatory element-binding protein 1c, peroxisome proliferator-activated receptor γ, and CCAAT/enhancer binding protein α. The COME treatment reduced the mRNA expression of fatty acyl synthetase, adenosine triphosphate-citrate lyase, adipocyte protein 2, and lipoprotein lipase. It increased the mRNA expression of hormone-sensitive lipase and carnitine palmitoyltransferase I in 3T3-L1 cells. COME inhibits adipogenesis via the AMPK signaling pathways. COME may be used to prevent and treat obesity.

Dietary isoleucine affects muscle fatty acid and amino acid profiles through regulating lipid metabolism and autophagy in hybrid catfish (Pelteobagrus vachelli ♀× Leiocassis longirostris ♂).

The present study explored the impacts of Ile on muscle fatty acid and amino acid profiles, lipid metabolism, and autophagy in hybrid catfish. Seven isonitrogenous (387.8g/kg protein) semi-purified diets were formulated to contain 5.0 (control), 7.5, 10.0, 12.5, 15.0, 17.5, and 20.0g Ile/kg diet respectively. The fish (initial weight of 33.11±0.09g) were randomly assigned to 7 groups for a 56-day trial. Each group has 3 replicates with 30 fish per replicate, fed at 08:00 and 18:00 each day. Results showed that muscle protein and lipid, C14:0, C18:0, C22:0, C14:1, C18:1n-9, polyunsaturated fatty acid (PUFA), Arg, Ile, Ala, Cys, Gly, Tyr, essential amino acid (EAA), and total amino acid (TAA) contents and flavor amino acid (FAA)/TAA in muscle had positive linear and/or quadratic responses to dietary Ile levels (P<0.05). Fatty acid synthase (FAS), stearoyl-CoA desaturase (SCD), acetyl-CoA carboxylase (ACC), and lipoprotein lipase (LPL) activities had positive linear and/or quadratic responses, but carnitine palmitoyl transferase 1 (CPT1) activity had a negative response with increasing dietary Ile levels (P<0.05). The mRNA expressions of FAS, SCD, ACC, LPL, fatty acid binding protein 4 (FABP4), FATP1, sterol response element-binding protein 1c (SREBP-1c), sequestosome 1 (SQSTM1), and adenosine 5'-monophosphate-activated protein kinase (AMPK) had positive linear and/or quadratic responses to dietary Ile levels (P<0.05). The mRNA expressions of hormone-sensitive lipase (HSL), CPT1, peroxisome proliferator-activated receptor α (PPARα), PPARγ, uncoordinated 51-like kinase 1 (ULK1), beclin1 (Becn1), autophagy-related protein 9α (Atg9α), Atg4b, Atg7, autophagy marker light chain 3B (LC3B), and SQSTM1 in muscle had negative linear and/or quadratic responses to dietary Ile levels (P<0.05). The p-AMPK and ULK1 protein levels, and p-AMPK/AMPK were decreased by 12.5g Ile/kg in the diet (P<0.05). Finally, SQSTM1 protein level had the opposite effect (P<0.05). The above results indicate that dietary Ile improves fish muscle fatty acid and amino acid profiles potentially via respectively regulating lipid metabolism and autophagy. The Ile requirement of hybrid catfish (33 to 72g) were estimated to be 12.63, 13.77, 13.75, 11.45, 10.50, 12.53 and 12.21g/kg diet based on the regression analysis of protein, lipid, SFA, PUFA, FAA, EAA, and TAA muscle contents, respectively.

Cloning and Molecular Characterization of HSL and Its Expression Pattern in HPG Axis and Testis during Different Stages in Bactrian Camel.

Hormone-sensitive lipase (HSL) is a key enzyme in animal fat metabolism and is involved in the rate-limiting step of catalyzing the decomposition of fat and cholesterol. It also plays an important regulatory role in maintaining seminiferous epithelial structure, androgen synthesis and primordial germ cell differentiation. We previously reported that HSL is involved the synthesis of steroids in Bactrian camels, although it is unclear what role it plays in testicular development. The present study was conducted to characterize the biological function and expression pattern of the HSL gene in the hypothalamic pituitary gonadal (HPG) axis and the development of testis in Bactrian camels. We analyzed cloning of the cDNA sequence of the HSL gene of Bactrian camels by RT-PCR, as well as the structural features of HSL proteins, using bioinformatics software, such as ProtParam, TMHMM, Signal P 4.1, SOPMA and MEGA 7.0. We used qRT-PCR, Western blotting and immunofluorescence staining to clarify the expression pattern of HSL in the HPG axis and testis of two-week-old (2W), two-year-old (2Y), four-year-old (4Y) and six-year-old (6Y) Bactrian camels. According to sequence analysis, the coding sequence (CDS) region of the HSL gene is 648 bp in length and encodes 204 amino acids. According to bioinformatics analysis, the nucleotide and amino acid sequence of Bactrian camel HSL are most similar to those of Camelus pacos and Camelus dromedarius, with the lowest sequence similarity with Mus musculus. In adult Bactrian camel HPG axis tissues, both HSL mRNA and protein expression were significantly higher in the testis than in other tissues (hypothalamus, pituitary and pineal tissues) (p < 0.05). The expression of mRNA in the testis increased with age and was the highest in six-year-old testis (p < 0.01). The protein expression levels of HSL in 2Y and 6Y testis were clearly higher than in 2W and 4Y testis tissues (p < 0.01). Immunofluorescence results indicate that the HSL protein was mainly localized in the germ cells, Sertoli cells and Leydig cells from Bactrian camel testis, and strong positive signals were detected in epididymal epithelial cells, basal cells, spermatocytes and smooth muscle cells, with partially expression in hypothalamic glial cells, pituitary suspensory cells and pineal cells. According to the results of gene ontology (GO) analysis enrichment, HSL indirectly regulates the anabolism of steroid hormones through interactions with various targets. Therefore, we conclude that the HSL gene may be associated with the development and reproduction of Bactrian camels in different stages of maturity, and these results will contribute to further understanding of the regulatory mechanisms of HSL in Bactrian camel reproduction.

Anti-obesity effect of Cydonia oblonga Miller extract in high-fat diet-induced obese C57BL/6 mice

• Cydonia oblonga Miller extract (COME) exerts anti-obesity effect in obese mouse. • COME reduces white adipose tissue deposition in high-fat diet induced obese mice. • COME induces the activation of AMPK in epididymal adipose tissue. • COME modulates adipogenic transcription factors and their target genes expressions. The present study was designed to explore whether Cydonia oblonga Miller extract (COME) had anti-obesity effects and the mechanism involved. COME reduced body weight, fat mass, adipose tissue weight, and serum levels of insulin, triglyceride, and leptin, but increased the serum levels of adiponectin and high-density lipoprotein-cholesterol in high-fat diet (HFD)-induced obese C57BL/6 mice. COME increased AMPK activation. COME suppressed adipogenesis by decreasing CCAAT/enhancer binding protein α, peroxisome proliferator-activated receptor γ, sterol regulatory element-binding protein-1c, acetyl-CoA carboxylase 1, ATP-citrate lyase, fatty acid synthase, and adipocyte protein 2 mRNA expression and enhanced lipolysis by increasing carnitine palmitoyl transferase 1 and hormone sensitive lipase mRNA expression. These results suggest that COME is potentially beneficial in inhibiting HFD-induced obesity by inducing AMPK activation and thereby, regulating several pathways involved in inhibiting adipogenesis, and promoting lipolysis and fatty acid oxidation. Our results suggest that COM may be used as an anti-obesity agent.

Dietary fat content and adipose triglyceride lipase and hormone-sensitive lipase gene expressions in adults’ subcutaneous and visceral fat tissues

IntroductionWe examined the association of adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL) gene expressions, as the key regulators of lipolysis, with dietary fat quantity and composition in subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT). MethodsIn this observational study, samples were collected from patients undergoing elective abdominal surgery. Participants were categorized into two groups based on their body mass index (BMI) status. Dietary, anthropometric, and biochemical data were collected before surgery. Linear regression was performed to determine the association of dietary fat content with ATGL and HSL gene expressions in SAT and VAT. Results152 individuals with a mean ± SD age of 40.7 ± 13.2 years and a median (inter-quartile range) BMI of 39.4 (26.5–45.3 kg/m2) participated in this study, of whom 54 were non-obese (BMI<30 kg/m2), and 98 were obese (BMI≥30 kg/m2). Among non-obese participants, positive associations were observed between ATGL mRNA expression and reported intakes of total fatty acids (TFA) (β=0.306, P = 0.025), myristic (β=0.285, P = 0.038), palmitic (β=0.417, P = 0.002), oleic (β=0.333, P = 0.017), dairy trans (β=0.374, P = 0.006), and other trans FAs (β=0.369, P = 0.006) in SAT. In contrast, inverse associations between HSL mRNA expression and reported intakes of TFAs (β=-0.377, P = 0.005), myristic (β=-0.282, P = 0.039), palmitic (β=-0.372, P = 0.006), stearic (β=-0.314, P = 0.020), and oleic acid (β=-0.372, P = 0.007) were observed in SAT. No associations were observed among obese participants, nor in VAT among non-obese individuals. ConclusionATGL and HSL mRNA expressions in SAT were associated with dietary fat quantity and composition among non-obese adults.

Duration and degree of diet-induced metabolic acidosis prepartum alter tissue responses to insulin in dairy cows

The objective of this experiment was to determine the effects of altering the dietary cation-anion difference (DCAD) fed for the last 21 or 42 d of gestation on glucose metabolism and tissue insulin responsiveness. Ninety parous Holstein cows at 232 d of gestation were assigned randomly to dietary treatments with 2 levels of DCAD (-70 or -180 mEq/kg) fed for 2 durations (short: the last 21 d of gestation; long: the last 42 d of gestation). For the short treatments, a diet with +110 mEq/kg was fed from 232 to 254 d of gestation. Intravenous glucose tolerance tests (IVGTT) were performed at either 250 or 270 d of gestation by infusing 0.25 g of dextrose/kg of body weight within 1 min. The following day, cows underwent an insulin challenge (IC) and received 0.1 IU of insulin/kg of body weight intravenously. Blood was sampled at min -15, -5, and 0 to establish a baseline and from 5 to 180 min relative to infusions; plasma concentrations of glucose, insulin, and fatty acids were determined, and the respective areas under the curves (AUC) were calculated. Liver was sampled after the IVGTT, and adipose tissue was sampled after the IVGTT and IC for quantification of mRNA expression and protein abundance. Reducing the DCAD altered acid-base balance compatible with a compensated metabolic acidosis. At 250 d, reducing the DCAD increased the AUC for glucose and reduced that of insulin following the IVGTT, whereas during the IC, clearance rate decreased and time to half-life of insulin increased with reducing DCAD, resulting in a tendency to a larger AUC for fatty acids. At 270 d, quantitative insulin sensitivity check index and the revised quantitative insulin sensitivity check index were smaller in cows fed the acidogenic diets for the last 42 d of gestation compared with the last 21 d of gestation, thereby suggesting reduced insulin sensitivity. In addition, cows fed for the long duration tended to have greater AUC for glucose but smaller AUC for insulin following an IVGTT than those fed for the short duration, thereby suggesting reduced insulin release and glucose disposal. Treatments did not affect hepatic mRNA expression of G6PC, PCK1, PCK2, and PC or adipose tissue mRNA expression of ATGL, ACC, B2AR, HSL, and PLIN1. On the other hand, for proteins, reducing the DCAD linearly reduced abundance of rabbit anti-mouse protein kinase B (AKT) and tended to reduce rabbit anti-human phosphorylated (Ser-9) glycogen synthase kinase-3 β (pGSK) and the pGSK:rabbit anti-human glycogen synthase kinase-3 β (GSK) ratio in hepatic tissue, whereas a linear increase in rabbit anti-human hormone-sensitive lipase (HSL) and rabbit anti-mouse phosphorylated (Ser-660) hormone-sensitive lipase (pHSL) in adipose tissue was observed after the IVGTT at 250 d. Moreover, reducing the DCAD resulted in a linear reduction of AKT and tended to reduce rabbit anti-human acetyl-CoA carboxylase (ACC) but increased pHSL linearly in adipose tissue after an IC at 250 d. Cows fed acidogenic diets for a short duration tended to have less pHSL in adipose tissue than those fed for a long duration after an IVGTT at 270 d. Associations were observed between blood pH and mRNA and protein abundance in hepatic and adipose tissues. Diet-induced metabolic acidosis altered insulin release and insulin signaling, resulting in a shift in adipose tissue metabolism that would favor lipolysis over lipogenesis.

Infusion of short chain fatty acids in the ileum improves the carcass traits, meat quality and lipid metabolism of growing pigs.

Short chain fatty acids (SCFA) are the main products of indigestible carbohydrates undergoing bacterial fermentation in the hindgut, which are related to some physiological functions. This study was designed to investigate the effects of SCFA infusion by ileum on the carcass traits, meat quality and lipid metabolism of growing pigs. In a 28-day study, 24 growing barrows fitted with a T-cannula in distal ileum were divided into 4 treatments: 1) Control, 2) antibiotics (AB), 3) AB + 300 mL of SCFA1 solution (ABS1), 4) AB + 300 mL of SCFA2 solution (ABS2). The concentrations of acetate, propionate and butyrate in SCFA1 solution were respectively 61.84, 18.62 and 12.55 mmol/L, and in SCFA2 were respectively 40.08, 15.41 and 9.78 mmol/L. The results showed that the SCFA infusion increased the average daily feed intake and average daily gain of pigs (P < 0.05). Meanwhile, the SCFA treatments increased longissimus dorsi area (P < 0.05) and carcass weight (P = 0.058), decreased the drip loss of longissimus dorsi (P = 0.059), and reduced serum concentrations of triglyceride, total cholesterol and urea nitrogen (P < 0.05). Besides, the SCFA administration inhibited the mRNA expressions of fatty acid synthase (FAS) and acetyl-CoA carboxylase in longissimus dorsi (P < 0.05), the mRNA expression of FAS in the liver (P < 0.05), and the mRNA expression of hormone-sensitive lipase in abdominal fat (P < 0.05). Short chain fatty acid infusion also enhanced the mRNA expression of carnitine palmitoyltransferase-1α in the liver (P < 0.05), the mRNA expressions of peroxisome proliferator activated receptor gamma and lipoprotein lipase in abdominal fat (P < 0.05), and the mRNA expressions of free fatty acid receptor 2, glucose-6-phosphatase and phosphoenolpyruvate carboxykinase 1 in the colon (P < 0.05). These results suggested that SCFA administration in the ileum could improve the carcass traits and meat quality of growing pigs, which was possibly due to the fact that SCFA modulated lipid metabolism.

Short-term administration of spexin in rats reduces obesity by affecting lipolysis and lipogenesis: An in vivo and in vitro study

The present study aimed to characterize the role of spexin (SPX) in maintaining glucose and lipid homeostasis in vivo in rats with diet-induced obesity. The in vitro effect of spexin on metabolic and endocrine functions of adipocytes isolated from obese rats was also investigated. The in vivo experiment was conducted on rats with diet-induced obesity and administered with SPX for 7 days. Lipid and carbohydrate parameters, liver markers, and hormonal profile were measured. In in vitro studies, adipocytes isolated from obese rats were used. The effect of SPX on lipolysis, lipogenesis, and leptin secretion from fat cells was assessed. The results showed that short-term administration of SPX causes weight loss, increases insulin sensitivity, and improves the metabolic state of obese rats. The in vitro experiments showed that spexin and its receptors, namely galanin receptor 2 (GALR2) and galanin receptor 3 (GALR3), were expressed in various fat depots and in adipocytes from obese rats. We also found that the addition of spexin increased the basal and isoproterenol-stimulated lipolysis and reduced the basal and insulin-stimulated lipogenesis in adipocytes isolated from obese rats. Molecular analysis showed that SPX activated hormone-sensitive lipase (HSL) phosphorylation and upregulated perilipin and HSL mRNA expression. These results suggest that SPX regulates metabolism of obese rats by affecting lipolysis and lipogenesis in adipocytes. Moreover, the present study for the first time demonstrates that SPX modulates leptin synthesis and secretion from isolated adipocytes.

Expression of Sirtuin 1 in visceral adipose tissue in Tibetan mini-pigs with obesity and insulin resistance induced by high fat/cholesterol diet

To investigate the role of Sirt1 in visceral adipose tissue in Tibetan mini-pigs with obesity and insulin resistance induced by high fat/cholesterol diet. Twelve male Tibetan mini-pigs were divided into 2 groups randomly: normal control (NC) group, high-fat/cholesterol (HFC) diet group, 6 in each group. After 16 weeks of modeling, fasting body weight and body mass index (BMI) were measured. Total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) were measured in anterior venous blood, and atherosclerosis index (AI) was calculated. Meanwhile, intravenous glucose tolerance test was conducted to observe the changes of blood glucose and insulin, and the area under the curve (AUC) was calculated. After euthanasia, visceral fat rate was detected, and visceral fat tissue was taken for histopathological observation and fat cell diameter analysis. RT-PCR was used to observe the mRNA expression levels of Sirtuin1 (Sirt1), insulin-like growth factor-1 (IGF-1), glucose transporter 4 (GLUT4), peroxisome proliferator-activated receptor γ (PPARγ), peroxisome proliferator-activated receptor γ-assisted activator 1α (PGC-1α), forkhead box protein O1 (FoxO1), lipolysis-related gene hormone-sensitive lipase (HSL), and fat synthesis-related gene fatty acid synthase (FASN)changes in adipose tissue. Compared with the NC group, the body weight, BMI, TC, LDL-C, HDL-C, AI and visceral fat rate were significantly increased after 16 weeks of high-fat/cholesterol induction in Tibetan mini-pigs(P＜0.05,P＜0.01). Meanwhile, the glucose tolerance curve was significantly delayed and the area under the curve of blood glucose and insulin was significantly increased (P＜0.05). HE pathological observation and quantitative analysis showed that fat cells were hypertrophy and the average cell diameter was increased significantly (P＜0.01). In addition, the mRNA expression levels of Sirt1,PGC-1α, GLUT4, and HSL were all decreased in varying degrees in adipose tissue, among which the mRNA expressions of Sirt1 and HSL were significantly decreased (P＜0.05), while the mRNA expressions of FOXO1, IGF-1, PPARγ, and FASN were significantly increased (P＜0.05, P＜0.01). Tibetan mini-pigs were induced by high fat/cholesterol diet to form obesity model with phenotypic characteristics such as lipid disorder and insulin resistance, whereas Sirt1 plays a key role in visceral fat deposition and insulin sensitivity reduction in obese Tibetan mini-pigs.

Amino acids regulate energy utilization through mammalian target of rapamycin complex 1 and adenosine monophosphate activated protein kinase pathway in porcine enterocytes.

As major fuels for the small intestinal mucosa, dietary amino acids (AA) are catabolized in the mitochondria and serve as sources of energy production. The present study was conducted to investigate AA metabolism that supply cell energy and the underlying signaling pathways in porcine enterocytes. Intestinal porcine epithelial cells (IPEC-J2) were treated with different concentrations of AA, inhibitor, or agonist of mammalian target of rapamycin complex 1 (mTORC1) and adenosine monophosphate activated protein kinase (AMPK), and mitochondrial respiration was monitored. The results showed that AA treatments resulted in enhanced mitochondrial respiration, increased intracellular content of pyruvic acid and lactic acid, and increased hormone-sensitive lipase mRNA expression. Meanwhile, decreased citrate synthase, isocitrate dehydrogenase alpha, and carnitine palmitoyltransferase 1 mRNA expression were also observed. We found that AA treatments increased the protein levels of phosphorylated mammalian target of rapamycin (p-mTOR), phosphorylated-p70 ribosomal protein S6 kinase, and phosphorylated-4E-binding protein 1. What is more, the protein levels of phosphorylated AMPK α (p-AMPKα) and nicotinamide adenine dinucleotide (NAD)-dependent protein deacetylase sirtuin-1 (SIRT1) were decreased by AA treatments in a time depending manner. Mitochondrial bioenergetics and the production of tricarboxylic acid cycle intermediates were decreased upon inhibition of mTORC1 or AMPK. Moreover, AMPK activation could up-regulate the mRNA expressions of inhibitor of nuclear factor kappa-B kinase subunit beta (Ikbkβ), integrin-linked protein kinase (ILK), unconventional myosin-Ic (Myo1c), ribosomal protein S6 kinase beta-2 (RPS6Kβ2), and vascular endothelial growth factor (VEGF)-β, which are downstream effectors of mammalian target of rapamycin (mTOR). The mRNA expressions of phosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit delta isoform (PIK3CD) and 5′-AMP-activated protein kinase subunit gamma-1 (PRKAG1), which are upstream regulators of mTOR, were also up-regulated by AMPK activation. On the other hand, AMPK activation also down-regulated FK506-binding protein 1A (FKBP1A), serine/threonine-protein phosphatase 2A 55 kDa regulatory subunit B beta isoform, phosphatase and tensin homolog (PTEN), and unc-51 like autophagy activating kinase 1 (Ulk1), which are up-stream regulators of mTORC1. Taken together, these data indicated that AA regulated cellular energy metabolism through mTOR and AMPK pathway in porcine enterocytes. These results demonstrated interactions of AMPK and mTORC1 pathways in AA catabolism and energy metabolism in intestinal mucosa cells of piglets, and also provided reference for using AA to remedy human intestinal diseases.

Propionate alleviates high-fat diet-induced lipid dysmetabolism by modulating gut microbiota in mice.

The aims were to examine whether oral sodium propionate supplementation regulate lipid metabolism through modulating gut microbiota. ICR male mice (26·98±0·30g) were randomly assigned to three groups (n=10) and fed control diet (Con), high-fat diet (HFD) and HFD plus propionate (Pro) respectively. In this study, we found that HFD increased the weight of final body, inguinal white adipose tissues (iWAT), epididymal white adipose tissue (eWAT) and perirenal white adipose tissue (pWAT), as well as the adipocyte mean area of iWAT and eWAT in mice (P<0·05), whereas sodium propionate treatment reduced the weight of iWAT and pWAT as well as adipocyte mean area of iWAT in mice fed a HFD (P<0·05). Moreover, in the iWAT, the mRNA expression of lipogenesis genes, including peroxisome proliferator activated receptor γ, acetyl-CoA carboxylase and carnitine palmitoyl transferase-1β, was upregulated by HFD challenge (P<0·05), and the elevation of these genes was nearly reversed to the level of control diet-fed mice by sodium propionate treatment. Meanwhile, sodium propionate treatment increased the hormone-sensitive lipase mRNA expression in the iWAT of HFD-fed mice (P<0·05). High-throughput pyrosequencing of the 16S rRNA demonstrated that sodium propionate treatment significantly recovered the gut microbiota dysbiosis in HFD-fed mice, including the richness and diversity of microbiota and the ratio of Firmicutes to Bacteroidetes. Furthermore, the HFD-induced reductions in colonic levels of butyrate and valerate were reversed by sodium propionate treatment, which also normalized the serum LPS level seen in HFD-fed mice to the levels of the control diet-fed mice. Collectively, these results indicated that sodium propionate treatment could improve lipid metabolism in HFD-fed mice, and the potential mechanisms might be via regulating gut microbiota. We demonstrated for the first time that oral sodium propionate significantly improved HFD-induced dysbiosis of gut microbiota, indicating that the mitigative effect of propionate for HFD-induced lipid dysmetabolism might be mediated by gut microbiota in mice.

Effects of liraglutide on lipolysis and the AC3/PKA/HSL pathway.

BackgroundLiraglutide reduces blood glucose, body weight and blood lipid levels. Hormone-sensitive lipase (HSL) is a key enzyme in lipolysis. Evidence from our and other studies have demonstrated that adenylate cyclase 3 (AC3) is associated with obesity and can be upregulated by liraglutide in obese mice. In the present study, we investigated whether hepatic HSL activity is regulated by liraglutide and characterized the effect of liraglutide in the AC3/protein kinase A (PKA)/HSL signalling pathway.MethodsObese mice or their lean littermates were treated with liraglutide or saline for 8 weeks. Serum was collected for the measurement of insulin and lipids. We investigated hepatic AC3, HSL and phosphorylated HSL Ser-660 (p-HSL(S660)) protein expression levels andAC3 and HSL mRNA expression levels and cyclic adenosine monophosphate (cAMP), PKA activity in liver tissue.ResultsLiraglutide treatment decreased triglycerides (TGs) and free fatty acids (FFAs), increased glycerol, and upregulated hepatic AC3 and p-HSL(s660) levels and cAMP and PKA activities.ConclusionThe results suggest that liraglutide can upregulates AC3/PKA/HSL pathway and may promotes lipolysis.

Molecular mechanism of non-alcoholic fatty liver disease induced and aggravated by chronic stress through HSL/ATGL-FFA which promotes fat mobilization

Abstract Objective To study the effects of social stress (CS) and social stress combined with high-fat diet on fat mobilization as a candidate mechanism for the induction or aggravation of non-alcoholic fatty liver disease (NAFLD). Methods Thirty-two male Wistar rats (250 ± 10 g) were randomly allocated to a blank control group (BC), a high-fat diet group (HFD), a CS group, and a combined CS and high-fat diet group (CS + HFD). Rats were sacrificed and tissues were collected after 8 weeks. Liver and body mass were measured and used to calculate the liver index. Serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), and free fatty acids (FFAs) were measured. Liver sections were examined microscopically after oil red O and hematoxylin and eosin staining. The relative mRNA expression of acetyl-CoA carboxylase (ACCase), hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase in liver, and hormone-sensitive lipase (HSL), and adipose triglyceride lipase (ATGL) in subcutaneous adipose tissue, were measured by real-time PCR. The liver concentrations of triglyceride, reactive oxygen species, and ACCase were measured by ELISA and HSL activity was determined using turbidimetry. Results NAFLD developed in the CS, HFD, and CS + HFD groups, with the most severe NAFLD being in the CS + HFD group. Serum AST, ALT, and FFA, liver index, and hepatic triglyceride, FFA, and tumor necrosis factor-α were significantly higher in both the CS and CS + HFD groups. However, food intake and ACCase mRNA expression were lower. The mRNA expression of HSL and ATGL in adipose tissue was much higher, and HSL activity was higher in the CS group than in the BC group, and in the CS + HFD group than in the HFD group. Conclusion We have successfully established two models of stress-induced NAFLD, suggesting stress can induce and aggravate NAFLD by promoting fat mobilization through upregulation of HSL and ATGL.

PO-305 An 8-week, low carbohydrate, high fat, ketogenic diet enhanced exercise capacity through improved ketolysis and lipolysis in mice

PO-305 An 8-week, low carbohydrate, high fat, ketogenic diet enhanced exercise capacity through improved ketolysis and lipolysis in mice

Ganoderma lucidum polysaccharides improve insulin sensitivity by regulating inflammatory cytokines and gut microbiota composition in mice

Ectopic lipid accumulation and low-grade chronic inflammation are critical pathogenesis of insulin resistance development. Ganoderma lucidum is a traditional Chinese herb for balancing energy homeostasis. In this research, we determined the effects of G. lucidum polysaccharides (GLP) on high-fat diet (HFD)-induced insulin resistant mice. We observed that GLP treatment decreased plasma insulin concentration and reversed HFD-induced systemic insulin resistance. Meanwhile, GLP ameliorated low-grade chronic inflammation, inducing lipolysis in adipose tissues. GLP decreased plasma triglyceride and non-esterified fatty acid outflux by suppressing mRNA expressions of hormone-sensitive lipase, fatty acid binding protein 4, tumor necrosis factor-α, and interleukin-6 in epididymal fat. Finally, GLP treatment suppressed ectopic lipid accumulation in peripheral tissues and hepatic insulin-regulated lipogenesis. GLP also regulated composition of gut microbiota implicated in type 2 diabetes mellitus development.

Insulin and insulin-like growth factor-1 modulate the lipolytic action of growth hormone by altering signal pathway linkages

Growth hormone (GH) has many actions in vertebrates, including the regulation of two disparate metabolic processes: growth promotion (anabolic) and the mobilization of stored lipids (catabolic). Our previous studies showed that GH stimulated IGF-1 production in hepatocytes from fed rainbow trout, but in cells from fasted fish GH stimulated lipolysis. In this study, we used rainbow trout (Oncorhynchus mykiss) to elucidate regulation of the mechanisms that enable cells to alter their lipolytic responsiveness to GH. In the first experiment, cells were removed from either fed or fasted fish, conditioned in medium containing serum (10%) from either fed or fasted fish, then challenged with GH. GH stimulated the expression of hormone sensitive lipase (HSL), the primary lipolytic enzyme, in cells from fasted fish conditioned with “fasted serum” but not in cells from fasted fish conditioned in “fed serum.” Pretreatment of cells from fed fish with “fasted serum” resulted in GH-stimulated HSL expression, whereas GH-stimulated HSL expression in cells from fasted fish was blocked by conditioning in “fed serum.” The nature of the conditioning serum governed the signaling pathways activated by GH irrespective of the nutritional state of the animals from which the cells were removed. When hepatocytes were pretreated with “fed serum,” GH activated JAK2, STAT5, Akt, and ERK pathways; when cells were pretreated with “fasted serum,” GH activated PKC and ERK. In the second study, we examined the direct effects of insulin (INS) and insulin-like growth factor (IGF-1), two nutritionally-regulated hormones, on GH-stimulated lipolysis and signal transduction in isolated hepatocytes. GH only stimulated HSL mRNA expression in cells from fasted fish. Pretreatment with INS and/or IGF-1 abolished this lipolytic response to GH. INS and/or IGF-1 augmented GH activation of JAK2 and STAT5 in cells from fed and fasted fish. However, INS and/or IGF-1 eliminated the ability of GH to activate PKC and ERK from fasted cells. These results indicate that INS and IGF-1 determine the signaling pathways activated by GH and whether or not a lipolytic response ensues. Such hormone-receptor-signal pathway linkages provide insight into the molecular basis of GH multifunctionality and into how cellular responses to GH can be adjusted to meet physiological (e.g., nutritional), developmental, or other conditions.

Branched-chain amino acid ratios in low-protein diets regulate the free amino acid profile and the expression of hepatic fatty acid metabolism-related genes in growing pigs.

Liver metabolism is affected by nutrients. The aim of this study was to explore the effects of low-protein diets (17% crude protein, CP) supplemented with branched-chain amino acids (BCAAs), including leucine (Leu), isoleucine (Ile) and valine (Val), on hepatic amino acid profile and lipid metabolism in growing pigs. The ratio of Leu:Ile:Val in all groups was 1:0.51:0.63 (20% crude protein, CP), 1:1:1 (17% CP), 1:0.75:0.75 (17% CP), 1:0.51:0.63 (17% CP) and 1:0.25:0.25 (17% CP) respectively. Results revealed that compared to the positive control group (1:0.51:0.63, 20% CP), the low-protein diets significantly augmented the concentrations of most essential amino acids and non-essential amino acids (p<.05), with the greatest values observed in the 1:0.25:0.25 group. Moreover, relative to the control, the low-protein diets with the Leu:Ile:Val ratio ranging from 1:0.75:0.75 to 1:0.25:0.25 markedly downregulated the mRNA abundance of acetyl-CoA carboxylase (ACC), lipoprotein lipase (LPL) and fatty acid-binding protein 4 (FABP-4) (p<.05), and upregulated the mRNA expression of hormone-sensitive lipase (HSL), peroxisome proliferator-activated receptor-g coactivator-1α (PGC-1α), uncoupling protein 3 (UCP3) and liver carnitine palmitoyltransferase 1 (L-CPT-1) (p<.05). Therefore, our data suggest that protein-restricted diets supplemented with optimal BCAA ratio, that is, 1:0.75:0.75-1:0.25:0.25, induce a shift from fatty acid synthesis to fatty acid oxidation in the liver of growing pigs. These effects may be associated with increased mitochondrial biogenesis.