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BackgroundChicken as a delicious food for a long history, and it is well known that excess fat deposition in broiler chickens will not only induced metabolic diseases, but also lead to adverse effect in the consumer’s health. (−)-Hydroxycitric acid (HCA), a major active ingredient of Garcinia Cambogia extracts, had shown to suppress fat accumulation in animals and humans. While, the precise physiological mechanism of HCA has not yet been full clarified, especially its action in broiler chickens. Thus, this study aimed to assess the effect of (−)-HCA on lipid metabolism in broiler chickens.MethodsA total of 120 1-day-old broiler chickens were randomly allocated to four groups, with each group was repeated three times with 10 birds. Birds received a commercial diet supplemented with (−)-HCA at 0, 1000, 2000 or 3000 mg/kg, respectively, for a period of 4 weeks ad libitum.ResultsBody weight (BW) in the 2000 and 3000 mg/kg (−)-HCA groups was significantly decreased (P < 0.05) than that in control group. A significantly decreased of serum triglyceride (TG) and density lipoprotein-cholesterol (LDL-C) content were observed in 3000 mg/kg (−)-HCA group (P < 0.05). Broiler chickens supplmented with 2000 and 3000 mg/kg (−)-HCA had pronouncedly higher hepatic lipase (HL) activity, hepatic glycogen and non-esterified fatty acid (NEFA) contents in liver (P < 0.05). Serum free triiodothyronine (FT3) and thyroxin (T4) contents were significantly higher in 3000 mg/kg (−)-HCA group (P < 0.05) compared with the control group. Supplemental (−)-HCA markedly decreased fatty acid synthase (FAS) and sterol regulatory element binding protein-1c (SREBP-1c) (P < 0.05) mRNA levels, while the mRNA abundance of adenosine 5′-monophosphate-activated protein kinaseβ2 (AMPKβ2) (P < 0.05) was significantly increased. In addition, ATP-citrate lyase (ACLY) mRNA level (P < 0.05) was significantly decreased in broiler chickens supplemented with 3000 mg/kg (−)-HCA. No differences was observed on carnitine palmitoyl transferase-I(CPT-I), while peroxisome proliferators-activated receptor α (PPARα) mRNA level (P < 0.05) was significantly increased in broiler chickens supplemented with 2000 and 3000 mg/kg (−)-HCA.ConclusionsSupplemental (−)-HCA inhibited lipogenesis by inhibiting ACLY, SREBP-1c and FAS expression, and accelerated lipolysis through enhancing HL activity and PPARα expression, which eventually led to the reduced abdominal fat deposition in broiler chickens.Graphical abstractMechanism of (−)-HCA effect on hepatic lipids metabolism.

(-)-Hydroxycitric acid (HCA) suppresses fatty acid synthesis in animals, but its biochemical mechanism in poultry is unclear. This study identified the key proteins associated with fat metabolism and elucidated the biochemical mechanism of (-)-HCA in broiler chickens. Four groups (n = 30 each) received a diet supplemented with 0, 1000, 2000 or 3000 mg/kg (-)-HCA for 4 weeks. Of the differentially expressed liver proteins, 40 and 26 were identified in the mitochondrial and cytoplasm respectively. Pyruvate dehydrogenase E1 components (PDHA1 and PDHB), dihydrolipoyl dehydrogenase (DLD), aconitase (ACO2), a-ketoglutarate dehydrogenase complex (DLST), enoyl-CoA hydratase (ECHS1) and phosphoglycerate kinase (PGK) were upregulated, while NADP-dependent malic enzyme (ME1) was downregulated. Biological network analysis showed that the identified proteins were involved in glycometabolism and lipid metabolism, whereas PDHA1, PDHB, ECHS1, and ME1 were identified in the canonical pathway by Ingenuity Pathway Analysis. The data indicated that (-)-HCA inhibited fatty acid synthesis by reducing the acetyl-CoA supply, via promotion of the tricarboxylic acid cycle (upregulation of PDHA1, PDHB, ACO2, and DLST expression) and inhibition of ME1 expression. Moreover, (-)-HCA promoted fatty acid beta-oxidation by upregulating ECHS1 expression. These results reflect a biochemically relevant mechanism of fat reduction by (-)-HCA in broiler chickens.

A cDNA sequence putatively encoding a v v 6 -fatty acid desaturase was isolated from Rhizopus arrhizus using reverse transcription polymerase chain reaction and rapid ampli¢cation of cDNA ends methods. Sequence analysis indicated that this cDNA sequence had an open reading frame of 1377 bp encoding 458 amino acids of 52 kDa. The deduced amino acid sequence showed high similarity to those of fungal v v 6 -fatty acid desaturases which comprised the characteristics of membrane-bound desaturases, including three conserved histidinerich motifs and hydropathy pro¢le. A cytochrome b 5 -like domain was observed at the N-terminus. To elucidate the function of this novel putative desaturase, the coding sequence was expressed heterologously in Saccharomyces cerevisiae strain INVScl. The result demonstrated that the coding product of the sequence exhibited v v 6 -fatty acid desaturase activity by the accumulation of Q Q-linolenic acid. ß

The effects of pyruvate (Pyr), creatine pyruvate (Cr-Pyr) and creatine (Cr) on lipid and protein metabolism were compared in broiler chickens. A total of 400 1-day-old male birds (Aconred) were allocated to four groups, each of which included four replicates (25 birds per replicate). Treatments consisted of unsupplemented basal diet (Control), basal diet containing 2% Pyr, basal diet containing 3% Cr and basal diet containing 5% Cr-Pyr. Cr-Pyr and Pyr significantly decreased the hepatic triglyceride and serum total cholesterol concentration (P , 0.01). Cr-Pyr markedly increased the serum non-esterified fatty acid and highdensity lipoprotein cholesterol concentrations (P , 0.05), whereas the expression of carnitine palmitoyl transferase I (P , 0.05) and peroxisome proliferators-activated receptor-a (P , 0.01) mRNA in the liver were both decidedly enhanced in the Cr-Pyr group. The relative leg muscle weight was higher in the Cr-Pyr group than in the control group, whereas the serum uric acid content and hepatic glutamic-oxaloacetic transaminase activity were lower in the Cr-Pyr and Cr groups (P , 0.05), respectively. Muscle insulin-like growth factor I (P , 0.05) expression was enhanced, and the myostatin (P , 0.01) mRNA level was reduced in both the Cr-Pyr and Cr groups. In addition, Cr-Pyr did not alter body weight or the feed conversion ratio. These results indicate that, compared with Pyr and Cr alone, Cr-Pyr has a bifunctional role in broiler chickens, in that it influences both lipid and protein metabolism.Keywords: creatine pyruvate, pyruvate, creatine, lipolysis, protein synthesis ImplicationsIn this study, the administration of creatine pyruvate (Cr-Pyr, a new compound, which contains pure pyruvic acid molecularly bound to pure pharmaceutical grade creatine at a concentration ratio of 40 : 60) was compared with the administration of Pyr or Cr alone for its effect on lipid and protein metabolism in broilers. The insights gained from this study will provide a better understanding of the mechanisms involved in the Cr-Pyr effect on broiler chickens. Further clarity will help the industry to avoid obesity-related problems during production and explore new ways to improve muscle growth in broilers.

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