Influence of different types of sugar on overfeeding performance-part of meat quality.

Previous research in our lab showed that 10% glucose, 10% fructose, and 10% sucrose can induce lipid deposition in goose fatty liver formation process more efficiently. However, whether the overfeeding diet supplement with sugar can affect the meat quality is unclear. The aim of this research was to estimate the meat quality of geese overfed with overfeeding diet adding with different types of sugar. The results indicated there were no significant differences in the diameter of muscle fiber, the muscle fiber density, pH0, pH24, the meat color, the cooking loss, the drip loss, the shear force and the dry matter in breast muscle and thigh muscle between corn flour groups and three sugars groups (P > 0.05). The crude fat content of breast muscle in fructose group was significantly higher than that in sucrose group (P < 0.05); the inosinic acid content of leg muscle in fructose group was significantly higher than that in the sucrose group (P < 0.05); the ratios of essential amino acids to total amino acids (EAA/TAA) in the breast muscle of maize flour group, fructose group, sucrose group and glucose group were 42%, 35%, 32% or 34%;57%, 64%, 64%, and 62%, respectively; the ratios of essential amino acids to total amino acids in leg muscle of maize flour group, fructose group, sucrose group and glucose group were 31%, 33%, 35%, and 34%, respectively. The contents of C16:1 and C18:1 n-9c in breast muscle in fructose group were significantly higher than that in sucrose group (P < 0.05). Compared with maize flour group, the contents of C18:0 and C20:0 were lower in leg muscle of sugar group (P < 0.05). Compared with the maize flour group, the activities of hydrogen peroxide (H2O2) and glutathione peroxidase (GSH-PX) in breast muscle were higher than those of sucrose group (P < 0.05), the total antioxidant capacity (T-AOC) levels in breast muscle was higher than that of fructose group and sucrose group (P < 0.05). Cluster analysis and principal component analysis (PCA) showed that there was no difference in meat quality between maize flour and sugar group. In conclusion, the overfeeding with maize flour supplement with 10% sugar had no evident influence on the meat quality.

The Regulation of Lipid Deposition by Insulin in Goose Liver Cells Is Mediated by the PI3K-AKT-mTOR Signaling Pathway.

BACKGROUND: We previously showed that the fatty liver formations observed in overfed geese are accompanied by the activation of the PI3K-Akt-mTOR pathway and an increase in plasma insulin concentrations. Recent studies have suggested a crucial role for the PI3K-Akt-mTOR pathway in regulating lipid metabolism; therefore, we hypothesized that insulin affects goose hepatocellular lipid metabolism through the PI3K-Akt-mTOR signaling pathway. METHODS: Goose primary hepatocytes were isolated and treated with serum-free media supplemented with PI3K-Akt-mTOR pathway inhibitors (LY294002, rapamycin, and NVP-BEZ235, respectively) and 50 or 150 nmol/L insulin. RESULTS: Insulin induced strong effects on lipid accumulation as well as the mRNA and protein levels of genes involved in lipogenesis, fatty acid oxidation, and VLDL-TG assembly and secretion in primary goose hepatocytes. The stimulatory effect of insulin on lipogenesis was significantly decreased by treatment with PI3K-Akt-mTOR inhibitors. These inhibitors also rescued the insulin-induced down-regulation of fatty acid oxidation and VLDL-TG assembly and secretion. CONCLUSION: These findings suggest that the stimulatory effect of insulin on lipid deposition is mediated by PI3K-Akt-mTOR regulation of lipogenesis, fatty acid oxidation, and VLDL-TG assembly and secretion in goose hepatocytes.

Effects of palmitic acid on lipid metabolism homeostasis and apoptosis in goose primary hepatocytes.

Studies have shown that not only does palmitic acid promote triglyceride (TG) accumulation, but it also affects cell viability in in vitro steatosis models. However, to what degree these effects are mediated by steatosis in goose primary hepatocytes is unknown. In this study, the effects of palmitic acid on the lipid metabolism homeostasis pathway and on apoptosis were determined. The authors measured the mRNA levels of genes involved in TG synthesis, lipid deposition, fatty acid oxidation and the assembly and secretion of VLDL-TG in goose primary hepatocytes. The results indicated that palmitic acid can significantly reduce the activity of goose hepatocytes, and that palmitic acid had a significant effect on TG accumulation; however, with increasing palmitic acid concentrations, the extracellular TG and extracellular VLDL concentration gradually decreased. With increasing palmitic acid concentrations, the gene expression levels of DGAT1, DGAT2, PPARα, CPT-1, FoxO1 and MTTP (which regulate hepatic TG synthesis, fatty acid oxidation and the assembly and secretion of VLDL-TGs) first increased and then decreased; the change in PLIN gene expression was palmitic acid dose-dependent, similar to the regulatory mode of intracellular TG accumulation. In conclusion, this study clearly shows that palmitic acid can promote TG accumulation and induce apoptosis in goose primary hepatocytes, and this effect may be related to the lipid metabolism pathway.