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.

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 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.