Effects of In Ovo Administration of DHEA on Lipid Metabolism and Hepatic Lipogenetic Genes Expression in Broiler Chickens During Embryonic Development

Effects of yeast cultures with different fermentation times on the growth performance, caecal microbial community and metabolite profile of broilers

The objective of this study was to investigate the effects of yeast culture (YC) on the growth performance, caecal microbial community and metabolic profile of broilers. A total of 350 1-day-old healthy Arbor Acres broilers were randomly assigned to seven treatment groups. The first group received a basal diet without YC supplementation, whereas the remaining groups received a basal diet supplemented with either YC fermented for 12, 24, 36, 48 or 60 hr, or a commercial YC product (SZ2). MiSeq 16S rRNA high-throughput sequencing was used to investigate the bacterial community structure, and gas chromatography-mass spectrometry was used to identify the metabolites in the caeca of broilers. The broilers that received a diet supplemented with YC had a higher average daily gain and average daily feed intake than those received YC-free or SZ2-enriched diets. The feed conversion ratio (FCR) of YCs fermented for 24 hr resulted in the best feed efficiency, whereas the FCR of YC fermented for 60 hr resulted in poor feed efficiency (p < .05). In the caeca of broilers, the bacterial communities were well separated, as determined by principal component analysis, and the proportions of the eight genera were significantly different among the seven groups (p < .05). The genus Akkermansia was the most abundant when the diet supplemented with YC fermented for 24 hr (p < .05). Furthermore, the Firmicutes/Bacteroidetes ratio was positively correlated with the FCR in the caecum (r = .47, p < .005). Five differentially expressed metabolites (i.e., L-alanine, benzeneacetic acid, D-mannose, D-arabitol and cholesterol) were identified in the caeca of broilers that received diets supplemented with YCs fermented for 24 or 60 hr. In summary, the different fermentation times of the YCs can markedly improve the growth performance and FCR of broilers by altering the caecal microbial community, and the growth performance which is related to the changes in key metabolic pathways.

Dehydroepiandrosterone reduced lipid droplet accumulation via inhibiting cell proliferation and improving mitochondrial function in primary chicken hepatocytes

Dehydroepiandrosterone (DHEA) possesses fat-reducing effect, while little information is available on whether DHEA regulates cell proliferation and mitochondrial function, which would, in turn, affect lipid droplet accumulation in the broiler. In the present study, the lipid droplet accumulation, cell proliferation, cell cycle and mitochondrial membrane potential were analysis in primary chicken hepatocytes after DHEA treated. The results showed that total area and counts of lipid droplets were significantly decreased in hepatocytes treated with DHEA. The cell viability was significantly increased, while cell proliferation was significantly inhibited in a dose dependent manner in primary chicken hepatocytes after DHEA treated. DHEA treatment significantly increased the cell population in S phase and decreased the population in G2/M in primary chicken hepatocytes. Meanwhile, the cyclin A and cyclin-dependent kinases 2 (CDK2) mRNA abundance were significantly decreased in hepatocytes after DHEA treated. No significant differences were observed in the number of mitochondria, while the mitochondrial membrane permeability and succinate dehydrogenase (SDH) activity were significantly increased in hepatocytes after DHEA treated. In conclusion, our results demonstrated that DHEA reduced lipid droplet accumulation by inhibiting hepatocytes proliferation and enhancing mitochondrial function in primary chicken hepatocytes.

Dehydroepiandrosterone reduces accumulation of lipid droplets in primary chicken hepatocytes by biotransformation mediated via the cAMP/PKA-ERK1/2 signaling pathway

Dehydroepiandrosterone (DHEA) is commonly used as a nutritional supplement to control fat deposition, but the mechanism of this action is poorly understood. In this study, we demonstrated that DHEA increased phosphorylation of AMP-activated protein kinase (p-AMPK). Elevated p-AMPK levels resulted in reduced expression of sterol regulatory element binding protein-1c, acetyl CoA carboxylase, fatty acid synthase and enhanced expression of peroxisome proliferators-activated receptor α and carnitine palmitoyl transferase-I, ultimately leading to the reduction of lipid droplet accumulation in primary chicken hepatocytes. We found that DHEA activates the cyclic adenosine 3', 5'-monophosphate/protein kinase A - extracellular signal-regulated kinase 1/2 (cAMP/PKA-ERK1/2) signaling pathway, which regulates the conversion of DHEA into testosterone and estradiol by increasing the 17β-hydroxysteroid dehydrogenase and aromatase protein expression. Importantly, the fat-reducing effects of DHEA are more closely associated with the conversion of DHEA into estradiol than with the action of DHEA itself as an active biomolecule, or to its alternative metabolite, testosterone. Taken together, our results indicate that DHEA is converted into active hormones through activation of the cAMP/PKA-ERK1/2 signaling pathway; the fat-reducing effects of DHEA are achieved through its conversion into estradiol, not testosterone, and not through direct action of DHEA itself, which led to the activation of the p-AMPK in primary chicken hepatocytes. These data provide novel insight into the mechanisms underlying the action of DHEA in preventing fat deposition, and suggest potential applications for DHEA treatment to control fat deposition or as an agent to treat disorders related to lipid metabolism in animals and humans.

Tissue lipid metabolism and hepatic metabolomic profiling in response to supplementation of fermented cottonseed meal in the diets of broiler chickens

This study investigated the effects of fermented cottonseed meal (FCSM) on lipid metabolites, lipid metabolism-related gene expression in liver tissues and abdominal adipose tissues, and hepatic metabolomic profiling in broiler chickens. One hundred and eighty 21-d-old broiler chickens were randomly divided into three diet groups with six replicates of 10 birds in each group. The three diets consisted of a control diet supplemented with unfermented cottonseed meal, an experimental diet of cottonseed meal fermented by Candida tropicalis, and a second experimental diet of cottonseed meal fermented by C. tropicalis plus Saccharomyces cerevisae. The results showed that FCSM intake significantly decreased the levels of abdominal fat and hepatic triglycerides (P<0.05 for both). Dietary FCSM supplementation down-regulated the mRNA expression of fatty acid synthase and acetyl CoA carboxylase in liver tissues and the lipoprotein lipase expression in abdominal fat tissues (P<0.05 for both). FCSM intake resulted in significant metabolic changes of multiple pathways in the liver involving the tricarboxylic acid cycle, synthesis of fatty acids, and the metabolism of glycerolipid and amino acids. These findings indicated that FCSM regulated lipid metabolism by increasing or decreasing the expression of the lipid-related gene and by altering multiple endogenous metabolites. Lipid metabolism regulation is a complex process, this discovery provided new essential information about the effects of FCSM diets in broiler chickens and demonstrated the great potential of nutrimetabolomics in researching complex nutrients added to animal diets.

(-)-Hydroxycitric acid reduced fat deposition via regulating lipid metabolism-related gene expression in broiler chickens

BACKGROUND

Chicken 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.

METHODS

A 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.

RESULTS

Body 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.

CONCLUSIONS

Supplemental (-)-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 abstract Mechanism of (-)-HCA effect on hepatic lipids metabolism.

The effects of H3N2 swine influenza virus infection on TLRs and RLRs signaling pathways in porcine alveolar macrophages

Background

Swine influenza is an economically important respiratory disease of swine resulting from infection with influenza A virus. Swine influenza virus (SIV) becomes the focus as pigs have been hypothesized to serve as an intermediate host for the adaptation of avian influenza viruses to humans or as mixing vessels for the generation of genetically reassortant viruses. The ability of the innate immune system to detect and respond to pathogens is important for survival. Therefore, there is a critical need to evaluate the immediate response to viral infection, especially the role of the toll-like receptors (TLRs) and RNA helicase RIG-I-like receptors (RLRs) innate immunity signaling pathways in H3N2 swine influenza virus infection.

Method

In this study, porcine alveolar macrophages (PAMs) were obtained from porcine lungs and were infected with SIV at a multiplicity of infection (MOI) of 5 in vitro. The changes of the related receptors, signaling proteins and effector molecules of TLRs and RLRs signaling pathways post H3N2 virus infection of PAMs were quantified by Real-time quantitative RT-PCR and western blotting.

Results

The results showed that H3N2 SIV infection significantly increased mRNA expression of TLR-3, TLR-7, RIG- I and MDA5 after 4 hpi (P < 0.05). Western blotting showed that the protein levels of TLR-3, TLR-7 and RIG-I also had a significantly increase after PAM exposed to virus. A significant change of MyD88, MAVS, IRF-3 and IRF-7 mRNA expression were present at 8 hpi. More than a 4-fold increase was induced for TNF-α and IL-1β mRNA expression. And the concentration of TNF-α and IL-1β peaked at 12 and 24 hpi, respectively. IFN-α, IFN-β mRNA and protein levels increased after SIV infection and significant differences was observed at 8, 12 and 24 hpi.

Conclusion

These results indicate that H3N2 swine influenza virus infection significantly influences the expression of the receptors, adapter proteins and downstream effector molecules of RLRs and TLRs signaling pathways. This study enhances our understanding of innate immunity signaling pathways in PAM anti-infection of H3N2 SIV.

Identification and characterization of genes that control fat deposition in chickens

BACKGROUND

Fat deposits in chickens contribute significantly to meat quality attributes such as juiciness, flavor, taste and other organoleptic properties. The quantity of fat deposited increases faster and earlier in the fast-growing chickens than in slow-growing chickens. In this study, Affymetrix Genechip® Chicken Genome Arrays 32773 transcripts were used to compare gene expression profiles in liver and hypothalamus tissues of fast-growing and slow-growing chicken at 8 wk of age. Real-time RT-PCR was used to validate the differential expression of genes selected from the microarray analysis. The mRNA expression of the genes was further examined in fat tissues. The association of single nucleotide polymorphisms of four lipid-related genes with fat traits was examined in a F2 resource population.

RESULTS

Four hundred genes in the liver tissues and 220 genes hypothalamus tissues, respectively, were identified to be differentially expressed in fast-growing chickens and slow-growing chickens. Expression levels of genes for lipid metabolism (SULT1B1, ACSBG2, PNPLA3, LPL, AOAH) carbohydrate metabolism (MGAT4B, XYLB, GBE1, PGM1, HKDC1)cholesttrol biosynthesis (FDPS, LSS, HMGCR, NSDHL, DHCR24, IDI1, ME1) HSD17B7 and other reaction or processes (CYP1A4, CYP1A1, AKR1B1, CYP4V2, DDO) were higher in the fast-growing White Recessive Rock chickens than in the slow-growing Xinghua chickens. On the other hand, expression levels of genes associated with multicellular organism development, immune response, DNA integration, melanin biosynthetic process, muscle organ development and oxidation-reduction (FRZB, DMD, FUT8, CYP2C45, DHRSX, and CYP2C18) and with glycol-metabolism (GCNT2, ELOVL 6, and FASN), were higher in the XH chickens than in the fast-growing chickens. RT-PCR validated high expression levels of nine out of 12 genes in fat tissues. The G1257069A and T1247123C of the ACSBG2 gene were significantly associated with abdominal fat weight. The G4928024A of the FASN gene were significantly associated with fat bandwidth, and abdominal fat percentage. The C4930169T of the FASN gene was associated with abdominal fat weight while the A59539099G of the ELOVL 6 was significantly associated with subcutaneous fat. The A8378815G of the DDT was associated with fat band width.

CONCLUSION

The differences in fat deposition were reflected with differential gene expressions in fast and slow growing chickens.

Molecular characterization and tissue expression profile of three novel ovine genes: ATP5O, NDUFA12 and UQCRH from muscle full-length cDNA library of black-boned sheep

Three novel ovine genes were obtained from muscle full-length cDNA library of black-boned sheep. Sequence analysis revealed that nucleotide sequences of these genes were not homologous to any of the known sheep or goat genes, but these genes have high similarity to ATP synthase subunit O (ATP5O), NADH dehydrogenase (ubiquinone) 1 alpha subcomplex, 12 (NDUFA12) and ubiquinol-cytochrome c reductase hinge protein (UQCRH) genes of other mammal animals (accession number: FJ546085, FJ546078 and FJ546083). The alignment analysis showed that the ovine ATP5O, NDUFA12 and UQCRH genes and proteins have closer genetic relationships with the ATP5O, NDUFA12 and UQCRH genes and proteins from cattle. Conserved domain prediction showed that these three genes included OSCP, NDUFA12 superfamily and UCR-hinge superfamily domains respectively. The deduced sequence of ATP5O, NDUFA12 and UQCRH protein had 213, 145 and 91 amino acid residues, with a molecular weight of approximately 23419.66, 17089.50 and 10657.75 Da and a theoretical isoelectric point of 9.90, 9.68 and 4.45. The secondary structure prediction revealed that 60% helix structure in ATP5O, 60% coils in NDUFA12 and no strand in UQCRH. One potential signal peptide structure in ATP5O protein were found. NDUFA12 and UQCRH have the extremely low possibility of signal peptides. Meanwhile, RasMol was used for visualizing the PDB files generated by Swiss-Model in cartoon or three-dimensional format. ATP5O and UQCRH protein were modeled by Swiss-Model. Tissue expression profile indicated that the ovine ATP5O, NDUFA12 and UQCRH genes could be expressed in all detected tissues including muscles, heart, liver, spleen, lung, kidney and adipose tissues, but the expression abundance of these genes were various in the different tissues. Our experiment supplied the primary foundation for further researches on these three ovine genes.

Comparative proteomics and phosphoproteomics analyses of DHEA-induced on hepatic lipid metabolism in broiler chickens

Dehydroepiandrosterone (DHEA) is a precursor of the adrenocorticosteroid hormones that are common to all animals, including poultry. The study described herein was undertaken to investigate the effect of DHEA on lipid metabolism in broiler chickens during embryonic development and to determine the regulatory mechanisms involved in its physiological action. Treatment group eggs were injected with 50mg DHEA diluted in 50 μL dimethyl sulfoxide (DMSO) per kg, while control group eggs (arbor acres [AA] fertilized) were injected with 50 μL DMSO per kg prior to incubation. Liver samples were collected on days 9, 14 and 19 of embryonic development as well as at hatching. Extracted proteins were analyzed by two dimensional gel electrophoresis (2-DE) in combination with western blotting for specific anti-phosphotyrosine. The differential spots were identified by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS) or MALDI-TOF-TOF-MS. Peptide mass fingerprinting (PMF) of the differentially-expressed proteins were performed using the MASCOT, Prospector or proFound server. Thirty-seven proteins and twenty-two tyrosine phosphorylation proteins were successfully identified. All 37 proteins and 22 tyrosine phosphorylation proteins exhibited a significant volume difference from the control group. These results demonstrated that DHEA increased the expression and level of tyrosine phosphorylation and sulfotransferase proteins in broilers (at pI 5.9), therefore promoting the biotransformation of DHEA. The expression of apolipoproteinA-I was increased in the DHEA treatment group, which facilitated the conversion of cholesterol to cholesterol esters. Also, DHEA increased the expression of peroxiredoxin-6 and its tyrosine phosphorylation protein levels, thus enhancing its anti-oxidative activity. Furthermore, pyruvate dehydrogenase expression was decreased and the level of its tyrosine phosphorylation proteins increased in the DHEA treatment group. Take together, those data indicate that DHEA reduces the supply of acetyl-CoA by inhibiting the activity of its target enzyme (i.e., pyruvate dehydrogenase), thus affecting both protein synthesis and phosphorylation level and decreasing fat deposition in broiler chickens during embryonic development, which could reflect a physiologically-relevant DHEA fat-reduction mechanism in the broiler chicken.

Molecular characterization and tissue expression of ovine PSAM6 gene from muscle full-length cDNA library of black-boned sheep

An ovine PSMA6 gene was obtained from muscle full-length cDNA library of black-boned sheep. The sequences for the PSAM6 gene of Romney sheep and Yunling black goat were also generated in this study. Sequence analysis revealed that nucleotide sequence of this gene was not homologous to any of the known sheep genes, and its open reading frame encodes a protein that contains the putative conserved domain of proteasome subunit alpha type 6 (PSAM6). The nucleotide sequence had higher identity with other animals. However, one mutation of A to G at the site of 383 bp, leading to an amino acid mutation of Asn to Ser, was found only in the black-boned sheep. Tissue expression analysis indicated that this gene was generally expressed in most tissues and differently expressed in tissues of black-boned sheep. This the first report of the ovine PSAM6 gene.

Dehydroepiandrosterone activates cyclic adenosine 3',5'-monophosphate/protein kinase A signalling and suppresses sterol regulatory element-binding protein-1 expression in cultured primary chicken hepatocytes

Dehydroepiandrosterone (DHEA), a steroid hormone that is secreted by the adrenal cortex in mammals, has an array of biological actions, including inhibition of fat synthesis, decreasing the number of adipocytes, and a reduction in mammalian metabolic efficiency. Recent studies showed that DHEA may decrease fat deposition in poultry, but the mechanism of action is unclear. In the present study, we demonstrate that DHEA stimulates intracellular cyclic adenosine 3',5'-monophosphate (cAMP) accumulation in chicken hepatocytes during a 30 min incubation period. Increases in intracellular cAMP are evoked by as low as 0.1 microm-DHEA. The cAMP induced by DHEA, while suppressing cAMP-specific phosphodiesterase activity, also activates cAMP-dependent protein kinase A (PKA) in chicken hepatocytes. In addition, the activation of PKA leads to down-regulation of sterol regulatory element-binding protein-1 (SREBP-1). These findings demonstrate that direct action by DHEA leads to activation of the cAMP/PKA signalling system in the modulation of lipid metabolism by repressing SREBP-1, thereby providing a novel explanation for some of the underlying effects proposed for DHEA in the prevention of fat deposition in poultry.

Dehydroepiandrosterone supplement increases malate dehydrogenase activity and decreases NADPH-dependent antioxidant enzyme activity in rat hepatocellular carcinogenesis

Beneficial effects of dehydroepiandrosterone (DHEA) supplement on age-associated chronic diseases such as cancer, cardiovascular disease, insulin resistance and diabetes, have been reported. However, its mechanism of action in hepatocellular carcinoma in vivo has not been investigated in detail. We have previously shown that during hepatocellular carcinogenesis, DHEA treatment decreases formation of preneoplastic glutathione S-transferase placental form-positive foci in the liver and has antioxidant effects. Here we aimed to determine the mechanism of actions of DHEA, in comparison to vitamin E, in a chemically-induced hepatocellular carcinoma model in rats. Sprague-Dawley rats were administered with control diet without a carcinogen, diets with 1.5% vitamin E, 0.5% DHEA and both of the compounds with a carcinogen for 6 weeks. The doses were previously reported to have anti-cancer effects in animals without known toxicities. With DHEA treatment, cytosolic malate dehydrogenase activities were significantly increased by ~5 fold and glucose 6-phosphate dehydrogenase activities were decreased by ~25% compared to carcinogen treated group. Activities of Se-glutathione peroxidase in the cytotol was decreased significantly with DHEA treatment, confirming its antioxidative effect. However, liver microsomal cytochrome P-450 content and NADPH-dependent cytochrome P-450 reductase activities were not altered with DHEA treatment. Vitamin E treatment decreased cytosolic Se-glutathione peroxidase activities in accordance with our previous reports. However, vitamin E did not alter glucose 6-phosphate dehydrogenase or malate dehydrogenase activities. Our results suggest that DHEA may have decreased tumor nodule formation and reduced lipid peroxidation as previously reported, possibly by increasing the production of NADPH, a reducing equivalent for NADPH-dependent antioxidant enzymes. DHEA treatment tended to reduce glucose 6-phosphate dehydrogenase activities, which may have resulted in limited supply for de novo synthesis of DNA via inhibiting the hexose monophophaste pathway. Although both DHEA and vitamin E effectively reduced preneoplastic foci in this model, they seemed to function in different mechanisms. In conclusion, DHEA may be used to reduce hepatocellular carcinoma growth by targeting NADPH synthesis, cell proliferation and anti-oxidant enzyme activities during tumor growth.