Temporary sensory separation of lamb groups from ewes affects behaviors and serum levels of stress-related indicators of small-tailed Han lambs.

Under the current meat sheep breeding system, newborn lambs usually live with their mothers until weaning, and in daily management, they often need to be separated from their ewes for a short period due to dehorning, disease treatment, etc. Such short-term separation was considered to be a high-intensity stress for the lambs. This study aimed to explore the effects of 1 h sensory separations on behaviors and the concentration of stress-related indicators of small-tailed Han lambs. Lambs were assigned to four groups: auditory, visual, and tactile separation (AVT) group; visual and tactile separation (VT) group; tactile separation (T) group; and control (C) group. Then they were separated from their mothers for one hour on postnatal days 14, 21, 28, 35 and 42. Results showed the separated lambs (AVT, VT, and T groups) spent less time lying down relaxing and more time looking around, exploring, vocalizing, and attempting to escape (P < 0.05). Lambs separated by lack of tactile contact only exhibited the most escaping and moving behavior. Twin-born lambs showed less moving, escaping, and vocalizing than single-born lambs (P < 0.05). The separation also led to a rise in serum globulin levels and a decrease in tetraiodothyronine. In conclusion, this study showed that temporary 1 h ewe-lamb separations could affect behaviors and the serum levels of stress indicators of lambs. The behavioral responses were more obvious when lambs were separated by lack of tactile contact only, and in single-born lambs. It can conclude that indicated that when lambs need to be temporarily separated from ewes in daily management production, it would be better to let them stay together with their littermates, and make them avoid hearing or seeing the ewes, such management may partially reduce the separation stress, thereby improving the welfare and breeding efficiency of sheep.

Oleic Acid Promotes the Biosynthesis of 10-Hydroxy-2-decenoic Acid via Species-Selective Remodeling of TAGs in Apis mellifera ligustica.

This study aimed to assess the impact of oleic acid (OA) supplementation on the biosynthesis of 10-hydroxy-2-decenoic acid (10-HDA) in Apis mellifera ligustica. In experiment 1, varying concentrations of OA (2%, 4%, 6% and 8%) were added to an artificial diet for newly emerged bees reared in cages. Analysis of 10-HDA content and gene expression in the mandibular gland (MG) revealed that the 8% OA treatment had the greatest impact on promoting the synthesis of 10-HDA. Subsequent investigations utilized RNA-seq and lipidomics to characterize the molecular signature in the MG after feeding the 8% OA diet. Phosphatidylcholine (PC) and triacylglycerol (TAG) were found to be the predominant lipids in the MG of worker bees. A total of 154 TAGs were identified, with TAG (18:1-18:1-18:1) exhibiting the highest abundance, which increased by 1.5 times. The major TAG species contained palmitic acid (16:0) and oleic acid (18:1) in their structure, which was associated with fatty acid composition of diet. The increase in abundance of main TAGs may be attributed to the upregulation of glycerol-3-phosphate acyltransferase (Gpat) and glycerol kinase (GK) gene expression at the transcriptional level. The upregulation of differentially expressed genes (DEGs) related to carbohydrate metabolism may contribute to meeting the heightened metabolic demands of the MGs in worker bees. Royal jelly (RJ) samples from bee colonies fed with the 8% OA diet exhibited higher 10-HDA level than RJ collected from bee colonies fed with the artificial diet. These results indicate that 8% OA addition in the diet enhanced biosynthesis of 10-HDA in the mandibular gland, which was accompanied by significant and highly species-selective remodeling of TAGs.

Glucose metabolism enhancement by 10-hydroxy-2-decenoic acid via the PI3K/AKT signaling pathway in high-fat-diet/streptozotocin induced type 2 diabetic mice.

10-Hydroxy-2-decenoic acid (10-HDA) is a principal active ingredients of royal jelly. Several recent studies demonstrated that 10-HDA has potential anti-type 2 diabetes mellitus (T2DM) properties. To evaluate the anti-T2DM effect of 10-HDA and explore its underlying molecular mechanisms, we used high fat diet (HFD) combined with streptozotocin (STZ) injection to establish a diabetes model. Mice were randomly divided into four groups (8 mice per group): control group, 10-HDA group, T2DM group, and T2DM + 10-HDA group. The 10-HDA and T2DM + 10-HDA groups were administered intragastric 10-HDA (100 mg per kg body weight), while the control and T2DM groups were administered a vehicle, daily for 4 weeks. Our analysis indicated that there was no significant difference in body weight between T2DM + 10-HDA and control group mice (P > 0.05). Treatment with 10-HDA reduced fasting blood glucose and increased insulin levels in diabetic mice (P < 0.05), as well as increasing the area of pancreatic islets (P < 0.05), and alleviating vacuolar degeneration in the liver. Further, 10-HDA intervention increased superoxide dismutase, catalase, and glutathione peroxidase activities in diabetic mouse liver, alleviated lipid peroxidation, inhibited liver NF-κB nuclear translocation, decreased IL-6 and TNF-α content, and increased P-PI3K, P-AKT, and P-GSK3ß protein levels (all P < 0.05). Fifteen potential biomarkers were screened by analysis of liver metabolomics data, of which hexadecanamide, stearamide, pentadecanoic acid, and fatty acid esters of hydroxy fatty acids (16:0/18:1) were highly abundant. In conclusion, 10-HDA has clear hypoglycemic effects on diabetic mice, through the PI3K/AKT/GSK3ß signaling pathway.

Activation of STIM1/Orai1­mediated SOCE in sepsis­induced myocardial depression.

Unbalanced Ca2+ homeostasis serves an essential role in the occurrence and development of septic myocardial injury. However, the mechanism of Ca2+ homeostasis in septic myocardial depression is poorly understood due to the complexity of Ca2+ transporters in excitable cells. It was therefore hypothesized that cardiac dysfunction, myocardial injury and cardiac apoptosis in septic myocardial depression are associated with elevated intracellular Ca2+ concentrations caused by stromal interaction molecule 1 (STIM1)/Orai calcium release­activated calcium modulator 1 (Orai1)­mediated store­operated Ca2+ entry (SOCE). A septic myocardial depression model was established using the cecal ligation and puncture operation (CLP) in mice and was simulated in H9C2 cells via lipopolysaccharide (LPS) stimulation. Cardiac function, myocardial injury, cardiac apoptosis and the expression levels of Bax, Bcl­2, STIM1 and Orai1 were quantified in vivo at 6, 12 and 24 h. Changes in the intracellular Ca2+ concentration, SOCE and the distribution of STIM1 were assessed in vitro within 6 h. The morphological changes of heart tissue were observed by hematoxylin­eosin staining. Myocardial cellular apoptosis was determined by TUNEL method. The expression of Bax, Bcl­2, STIM1 and Orai1 were visualized by western blot. Cytosolic calcium concentration and SOCE were evaluated by confocal microscopy. The results demonstrated that cardiac contractile function was significantly reduced at 6 h and morphological changes in cardiac tissues, as well as the myocardial apoptosis rate, were markedly increased at 6, 12 and 24 h following CLP. mRNA and protein expression levels of Bax/Bcl­2 were significantly enhanced at 6 and 12 h and glycosylation of Orai1 in the myocardium of septic mice was significantly increased at 6 h following CLP. The intracellular Ca2+ concentration, SOCE, was significantly increased at 1­2 h and the clustering and distribution of STIM1 were markedly changed in H9C2 cells at 1 and 2 h. These findings suggested that myocardial dysfunction, cardiac injury and myocardial depression may be related to increased intracellular Ca2+ concentration resulting from STIM1/Orai1­mediated SOCE, which may provide a potential method to alleviate septic myocardial depression.

Non-targeted lipidomics and transcriptomics analysis reveal the molecular underpinnings of mandibular gland development in Apis mellifera ligustica.

The mandibular gland is an important exocrine gland of worker bees, which mainly secretes fatty acids and pheromones. Lipids have important roles in energy storage, membrane structure stabilization, and signaling. However, molecular underpinnings of mandibular gland development and lipid remodeling at the different physiological stages of worker bees is still lacking. In this study, we used scanning and transmission electron microscopy to reveal the morphological changes in secretory cells, and liquid chromatography-mass spectrometry and RNA-seq to investigate the lipidome and gene transcripts during development. The morphology of secretory cells was flat in newly emerged workers, becoming vacuolated and turgid when they were activated in nurse bees and foragers. Transport vesicles became denser from newly emerged bees to 21-day worker bees. Concentrations of 10-HDA reached a maximum within 15d workers and changes in genes expression were consistent with 10-HDA content. Non-targeted lipidomics analysis of newly emerged, 6d, and 15d worker bees revealed that PC and TAG were the main lipids in mandibular gland, and lipids dramatically altered across developmental stages. TAG 54:4 was increased most strongly at 6d and 15d worker bees, meanwhile, the abundances of TAG 54:1 and TAG 54:2 were decreased sharply. Further, transcriptomics analysis showed that differentially expressed genes were significantly enriched in key nutrient metabolic pathways, particularly lipid metabolism, in 6d and 15d bees. This multi-omic perspective provides a unique resource and deeper insight into bee mandibular gland development and baseline data for further study of the mandibular gland in worker bees.

Selenium-rich royal jelly inhibits hepatocellular carcinoma through PI3K/AKT and VEGF pathways in H22 tumor-bearing mice.

Royal jelly (RJ) and selenium (Se)-rich foods have well-known health benefits that are attributable to a broad range of pharmacological effects including antioxidant, anti-tumor, and immunoregulatory activities. However, the physiological effects of Se-rich RJ, which is produced by feeding Apis mellifera (Hymenoptera: Apidae) sodium selenite sucrose solution, are not well understood. The anti-hepatoma activity and mechanism of Se-rich RJ in H22 tumor-bearing mice were investigated in the current study. The findings showed that the content of organic and inorganic Se in Se-rich RJ was significantly higher than that in RJ. Furthermore, interleukin-2 (IL-2) levels and tumor necrosis factor-α (TNF-α) production in serum were increased and the malondialdehyde (MDA) content in liver was decreased in mice fed RJ and Se-rich RJ. 16SrRNA sequencing and serum untargeted metabolomics showed that RJ and Se-rich RJ could modulate the gut microbiota, and fisetin and L-glutathione oxidized were the main anti-tumor components in RJ and Se-rich RJ. Further analysis showed 11-deoxy prostaglandin F1ß was the specific anti-tumor metabolite in mice treated with Se-rich RJ compared with RJ. The results indicated that RJ and Se-rich RJ could inhibit the expression of PI3K and phosphorylation of AKT, induce cell apoptosis through the activation of caspase-9 and caspase-3, and regulate Bcl-2/Bax expression. RJ and Se-rich RJ also inhibited the expression of COX-2 and VEGF. To summarize, the findings clearly demonstrate that Se-rich RJ could inhibit tumor growth by inducing apoptosis and inhibiting angiogenesis as well as exhibit anti-tumor effects by improving immune function and antioxidant activities. The results indicated that Se-rich RJ could be a potential functional food for the management and prevention of cancer.

Effects of Dietary Energy Level on Performance, Plasma Parameters, and Central AMPK Levels in Stressed Broilers.

This study aimed to characterize the effects of diets with different energy levels on the growth performance, plasma parameters, and central AMPK signaling pathway in broilers under dexamethasone (DEX)-induced stress. A total of 216 1-day-old male broiler chickens were allocated to groups fed with high (HED), National Research Council-recommended (control), or low (LED) energy diets. At 10 days old, chickens were treated with or without dexamethasone (DEX, 2 mg/kg body weight) for 3 consecutive days. HED increased broiler average daily gain (ADG) at 10 days old, compared with the LED (P < 0.05), while average daily feed intake (ADFI) and feed conversion rate (FCR) decreased as the dietary energy level increased (P < 0.05). Chickens fed a HED had higher total protein (TP) content, albumin (ALB), glucose (GLU), total cholesterol (TCHO), high-density lipoprotein (HDL) cholesterol, and low-density lipoprotein (LDL) cholesterol, compared with the control group (P < 0.05). At 13 days old, DEX decreased ADG and increased FCR in broilers fed with different energy diets (P < 0.05). The DEX-HED group had a higher ADFI than non-DEX treated HED group chickens. In addition, TP, ALB, triglycerides (TG), TCHO, HDL, and LDL content levels in the DEX group were higher than those in the control group (P < 0.05). The uric acid (UA) content of the LED group was higher than that of the HED group (P < 0.05). Further, gene expression levels of liver kinase B1, AMP-activated protein kinase α1, neuropeptide Y, and GC receptor in the hypothalamus were increased in chickens treated with DEX (P < 0.05). There was a trend toward interaction between plasma TCHO and hypothalamic LKB1 expression (0.05 < P < 0.1). In conclusion, this study suggests that HED improves growth performance, plasma glucose and total cholesterol at 10 days old broilers, but had no significant effect on performance, plasma parameters, and central AMPK in stressed broilers.

The AMPK-mTOR signaling pathway is involved in regulation of food intake in the hypothalamus of stressed chickens.

Glucocorticoids (GCs) can stimulate the appetite and AMPK in broilers. The activation of hypothalamic mTOR has been proposed as an important anorexigenic signal. However, inhibitory effect of AMPK activity on appetite and AMPK downstream signaling pathway under stress has not been reported. In this study, we performed an intracerebroventricular (icv) injection of compound C, an AMPK inhibitor, in GC-treated birds to explore the regulatory mechanism on appetite and AMPK downstream signaling pathway. A total of 48 7-day-old broilers, which had received an icv cannula, were randomly subjected to one of two treatments: subcutaneous injection of dexamethasone (DEX) or saline. After 3 days of continuous DEX injection, chicks of each group received an icv injection with either compound C (6 µg/2 µL) or vehicle (dimethyl sulfoxide, 2 µL). The results showed that body weight gain was reduced by the DEX treatment. Compared with the control, icv injection of compound C reduced feed intake at 0.5-1.5 h. In the DEX-treated group, the inhibitory effect of compound C on appetite remained apparent at 0.5-1 h. The DEX treatment increased the gene expression of liver kinase B1 (LKB1), neuropeptide Y (NPY), and decreased p-mTOR protein level. In stressed broilers, inhibition of AMPK relieved the decreased mTOR activity. A significant interaction was noted in DEX and compound C on protein expression of phospho-AMPK. Taken together, in stressed broilers, the central injection of compound C could inhibit central AMPK activity and reduce appetite, in which the AMPK/mTOR signaling pathway might be involved.

Association of Brain-Derived Neurotrophic Factor rs6265 G>A polymorphism and Post-traumatic Stress Disorder susceptibility: A systematic review and meta-analysis.

BACKGROUND: Previous studies have shown that the brain-derived neurotrophic factor (BDNF) rs6265 G > A polymorphism is closely related post-traumatic stress disorder (PTSD) risk. However, the results were not consistent. We therefore conducted a meta-analysis to explore the underlying relationships between BDNF rs6265 G > A polymorphism and PTSD risk. MATERIALS AND METHODS: Five online databases were searched, and all related studies were reviewed up to July 1, 2020. Odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were calculated to examine the statistical power of each genetic model. In addition, heterogeneity, sensitivity accumulative analysis, and publication bias were examined to check the statistical power. RESULT: Overall, 16 publications involving 5,369 subjects were included in this systematic review and 11 case-control studies were analyses in meta-analysis. The pooled results indicated an increasing risk of A allele mutations with PTSD risk. Moreover, the sequential subgroup analysis also demonstrated some similar situations in Asian populations and other groups. CONCLUSION: Current meta-analysis suggests that the BDNF rs6265 G > A polymorphism might be involved in PTSD susceptibility.

The mixed application of organic and inorganic selenium shows better effects on incubation and progeny parameters.

This experiment aims to study the effects of dietary selenium (Se) sources on the production performance, reproductive performance, and maternal effect of breeder laying hens. A total of 2,112 Hyline brown breeder laying hens of 42 wk of age were selected and randomly divided into 3 groups, with 8 repeats in each group and 88 chickens per repeat. The sources of dietary Se were sodium selenite (SS, added at 0.3 mg/kg), L-selenomethionine (L-SM, added at 0.2 mg/kg), and combination of SS and L-SM (SS 0.15 mg/kg + L-SM 0.15 mg/kg). The pretest period was 7 d, and the breeding period was 49 d. Compared with 0.3 mg/kg SS, the addition of 0.2 mg/kg L-SM in the diet significantly increased the hatchability (P < 0.05) and the Se content (P < 0.05) in egg yolk and chicken embryo tissues and improved the activity of yolk glutathione peroxidase (GSH-px) effectively (P < 0.05). Treatment with 0.2 mg/kg L-SM also reduced the content of yolk malondialdehyde (P < 0.05) and significantly improved the antioxidant performance of 1-day-old chicks, as manifested by increased activity of antioxidant enzymes (GSH-px, total antioxidant capacity and the ability to inhibit hydroxyl radicals) in serum, pectoral, heart, and liver (P < 0.05). This treatment decreased the malondialdehyde content (P < 0.05) and increased the expression of liver glutathione peroxidase 4 and deiodinase 1 mRNA (P < 0.05). Adding L-SM to the diets of chickens increased the hatchability of breeder eggs as well as the amount of Se deposited and antioxidant enzyme activity in breeder eggs and embryos. Compared with SS, L-SM was more effectively transferred from the mother to the embryo and offspring, showing efficient maternal nutrition. For breeder diets, the combination of organic and inorganic Se (0.15 mg/kg SS + 0.15 mg/kg L-SM) is an effective nutrient supplementation technology program for effectively improving the breeding performance of breeders and the antioxidant performance and health level of offspring chicks.

Effects of dietary corticosterone on the central adenosine monophosphate-activated protein kinase (AMPK) signaling pathway in broiler chickens.

Glucocorticoids (GCs) induce the activation of the central adenosine 5'-monophosphate-activated protein kinase (AMPK) signaling pathway in birds. In this study, we aimed to investigate the effects of corticosterone (CORT) supplemented in diet on the central AMPK signaling pathway in broilers. The average daily gain was reduced by CORT treatment, and the average daily feed intake remained unchanged. Plasma glucose, triglyceride, total cholesterol, and CORT contents were increased by CORT administration. In addition, CORT treatment decreased the relative weights of heart, spleen, and bursa and increased the relative weights of liver and abdominal fat. The glycogen contents in the liver and breast muscle were higher in the chicks treated with CORT. CORT treatment upregulated the gene expression of mammalian target of rapamycin, glucocorticoid receptor, AMPKα2, neuropeptide Y(NPY), liver kinase B1 (LKB1), AMPKα1, and fatty acid synthase in the hypothalamus. Moreover, CORT treatment increased the protein levels of acetyl-coenzyme A carboxylase (ACC) phosphorylation and total AMPK and phosphorylated AMPK in the hypothalamus. Hence, CORT administration in the diet activated the LKB1-AMPK-NPY/ACC signaling pathway in the hypothalamus of broiler.

Effects of dietary energy level on appetite and central adenosine monophosphate-activated protein kinase (AMPK) in broilers.

Adenosine monophosphate-activated protein kinase (AMPK) acts as a sensor of cellular energy changes and is involved in the control of food intake. A total of 216 1-d-old broilers were randomly allotted into 3 treatments with 6 replicates per treatment and 12 broilers in each cage. The dietary treatments included 1) high-energy (HE) diet (3,500 kcal/kg), 2) normal-energy (NE) diet (3,200 kcal/kg), and 3) low-energy (LE) diet (2,900 kcal/kg). The present study was conducted to investigate the effects of dietary energy level on appetite and the central AMPK signal pathway. The results showed that a HE diet increased average daily gain (ADG), whereas a LE diet had the opposite effect (P < 0.05, N = 6). The average daily feed intake (ADFI) of the chickens fed the LE diet was significantly higher than that of the control (P < 0.05, N = 6). Overall, the feed conversion rate gradually decreased with increasing dietary energy level (P < 0.05, N = 6). Moreover, the chickens fed the LE and HE diets demonstrated markedly improved urea content compared with the control group (P < 0.0001, N = 8). The triglyceride (TG) content in the LE group was obviously higher than that in the HE group but showed no change compared with the control (P = 0.0678, N = 8). The abdominal fat rate gradually increased with increased dietary energy level (P = 0.0927, N = 8). The HE group showed downregulated gene expression levels of liver kinase B1 (LKB1), neuropeptide Y (NPY), cholecystokinin (CCK), and glucocorticoid receptor (GR) in the hypothalamus compared with the control group (P < 0.05, N = 8). However, LE treatment significantly increased the mRNA level of AMP-activated protein kinase α2 (AMPKα2) compared with other groups (P = 0.0110, N = 8). In conclusion, a HE diet inhibited appetite and central AMPK signaling. In contrast, a LE diet activated central AMPK and appetite. Overall, the central AMPK signal pathway and appetite were modulated in accordance with the energy level in the diet to regulate nutritional status and maintain energy homeostasis in birds.

Gas6 attenuates lipopolysaccharide­induced TNF­α expression and apoptosis in H9C2 cells through NF­κB and MAPK inhibition via the Axl/PI3K/Akt pathway.

Therapeutic agents used to treat sepsis­induced cardiac dysfunction are designed to suppress tumor necrosis factor (TNF)­α release and inhibit cell apoptosis. Exogenous administration of growth arrest­specific 6 (Gas6) exerts several biological and pharmacological effects; however, the role of Gas6 in sepsis­induced myocardial dysfunction remains unclear. In this study, H9C2 cardiomyocytes were stimulated with LPS (10 µg/ml) to mimic septic cardiac dysfunction and Gas6 (100 ng/ml) was applied exogenously. Subsequently, mitogen­activated protein kinase (MAPK) and nuclear factor (NF)­κB activation, TNF­α expression, and apoptosis in the presence or absence of TP­0903 (15 nM) and Wortmannin (3 nM) were evaluated. The morphological alterations of H9C2 cells were visualized by phase­contrast microscopy. Cell viability was determined using the Cell Counting kit 8 assay and lactate dehydrogenase release, and TNF­α release was analyzed by ELISA analysis. Cell apoptosis was analyzed by flow cytometry and TUNEL assay. Nuclear morphological alterations were detected by Hoechst staining and caspase­3 activity was measured using biochemical methods. The expression levels of Bax and Bcl­2, and the phosphorylation and expression levels of Axl, Akt, IκB­α, p65, c­Jun N­terminal protein kinase (JNK), extracellular signal­regulated kinase (ERK) and p38 were determined by western blotting. Furthermore, immunofluorescence analysis was performed to visualize translocation of NF­κB p65. The results demonstrated that Gas6 suppressed TNF­α release and inhibited cell apoptosis, and attenuated nuclear factor (NF)­κB and mitogen­activated protein kinase (MAPK) activation via the Axl/PI3K/Akt pathway. Furthermore, the cardioprotective properties of Gas6 on the suppression of LPS­induced TNF­α release and apoptosis were abolished by treatment with TP­0903 (an Axl inhibitor) and Wortmannin (a PI3K inhibitor). Pretreatment with TP­0903 and Wortmannin abrogated the effects of Gas6 on phosphorylated­IκB­α, IκB­α, NF­κB, ERK1/2, JNK and p38 MAPK. These findings suggested that activation of Axl/PI3K/Akt signaling by Gas6 may inhibit LPS­induced TNF­α expression and apoptosis, as well as MAPK and NF­κB activation.

Effects of glucocorticoids on lipid metabolism and AMPK in broiler chickens' liver.

Adenosine monophosphate-activated protein kinase (AMPK) plays a pivotal role in the regulation of carbohydrate, lipid, and protein metabolism in animals. In this study, we examined whether any cross talk exists between glucocorticoids and AMPK in the regulation of the liver bile acid biosynthesis pathway. Dexamethasone treatment decreased the growth performance of broiler chickens. The liver mRNA levels of fatty acid transport protein (FATP-1), farnesoid X receptor (FXR), AMPK alpha 1 subunit (AMPKα1), and glucocorticoid receptor were significantly upregulated in DEX-treated broilers; the gene expression of liver cholesterol 7 alpha-hydroxylase (CYP7A1) was significantly downregulated. The protein level of liver CYP7A1 was significantly decreased by DEX treatment at both 24 and 72 h, while the protein level of p-AMPK/ t-AMPK stayed unchanged. In the in vitro cultured hepatocytes, compound C pretreatment blocked the increase in CYP7A1 protein level by DEX and significantly suppressed FATP-1, SREBP-1c, FXR, and CYP7A1 gene expression stimulated by DEX. Compound C treatment significantly reduces the protein level of p-AMPK, and the combination of compound C and DEX significantly reduces the protein level of t-AMPK. Thus, glucocorticoids affected liver AMPK and the bile acid synthesis signal pathway, and AMPK might be involved in the glucocorticoid effect of liver bile acid synthesis.

Effects of feed deprivation on the AMPK signaling pathway in skeletal muscle of broiler chickens.

The 5'-adenosine monophosphate-activated protein kinase (AMPK) plays a key role in rapid metabolic adaptations to maintain energy homeostasis in poultry. It remains unclear if AMPK is involved in muscular energy metabolism in broiler chickens. Hence, in the present study, seven-day-old male broilers were equally divided into three groups: fed ad libitum (control); feed-deprived for 24h (S24); feed-deprived for 24h and then refed for 24h (S24R24). Compared to the control group, the plasma levels of glucose, insulin, T3 and triglycerides in the S24 group were significantly lower (P<0.05), whereas the uric acid levels were significantly higher (P<0.01). Except for glucose, refeeding for 24h reversed the fasting-induced alterations in plasma metabolite. Fasting decreased the liver kinase B1 (LKB1), AMPK alpha 2 subunit (AMPKα2), and fatty acid synthase (FAS) mRNA levels (P<0.05) in M. pectoralis major (PM). Feed deprivation did not affect the phosphorylated AKT, mammalian target of rapamycin (mTOR) and ribosomal protein S6 kinase (p70S6K) in PM (P>0.05), but upregulated carnitine palmitoyltransferase 1 (CPT1) gene expression and increased phosphorylated LKB1 (0.050.05). However, refeeding after 24h of fasting increased the phosphorylated mTOR level in BF muscle which was in parallel with increased plasma insulin concentration. It was likely that increased phospho-mTOR level in the BF muscle was due to the higher sensitivity of BF to insulin. Together, the results suggested that the AMPK signaling pathway might be involved in the energy metabolism alterations in the skeletal muscles of broiler chickens and was also dependent upon the muscle fiber type. Furthermore, the regulatory effects of AMPK on energy metabolism in muscles of broiler chickens might be mediated by the AMPK/FAS pathway.

Effect of Zinc on Appetite Regulatory Peptides in the Hypothalamus of Salmonella-Challenged Broiler Chickens.

The effects of dietary Zinc (Zn) supplementation on the gene expression of appetite regulatory peptides were investigated in Salmonella-infected broiler chickens. Broiler chickens (Arbor Acres, 1 day old) were allocated randomly into 24 pens of 10 birds. The chickens from 12 pens were fed with basal diet and the other with basal diet supplemented with Zn (ZnSO4·H2O, 120 mg/kg). At 5 days of age, the chickens were divided into 4 treatments with 6 pens: basal diet; basal diet and Salmonella challenge; Zn-supplemented diet; Zn-supplemented diet and Salmonella challenge. At 42 days of age, the hypothalamus from 6 chickens per treatment (1 chicken per pen) was individually collected for gene expression determination. Results showed that dietary supplementation of Zn reduced the gene expression of hypothalamic ghrelin and tumor necrosis factor alpha (TNF-α) (P < 0.05). Salmonella infection upregulated the messenger RNA (mRNA) levels of hypothalamic neuropeptide Y (NPY) and TNF-α. Zn supplementation and Salmonella inoculation were significantly correlated with the mRNA levels of toll-like receptor 2-1 (P < 0.05). However, neither dietary Zn supplementation nor Salmonella inoculation had significant effect on hypothalamic agouti-related protein, cocaine- and amphetamine-regulated transcript, and pro-opiomelanocortin. This study shows that dietary Zn supplementation promoted orexigenic appetite regulatory peptides and reduced the expression of the inflammatory cytokine TNF-α in the hypothalamus of Salmonella-challenged broilers.