PA and OA induce abnormal glucose metabolism by inhibiting KLF15 in adipocytes

Mechanism of fibroblast growth factor 1 regulating fatty liver disorder in mule ducks

Mule ducks tend to accumulate abundant fat in their livers via feeding, which leads to the formation of a fatty liver that is several times larger than a normal liver. However, the mechanism underlying fatty liver formation has not yet been elucidated. Fibroblast growth factor 1 (FGF1), a member of the FGF superfamily, is involved in cellular lipid metabolism and mitosis. This study aims to investigate the regulatory effect of FGF1 on lipid metabolism disorders induced by complex fatty acids in primary mule duck liver cells and elucidate the underlying molecular mechanism. Hepatocytes were induced by adding 1,500:750 µmol/L oleic and palmitic acid concentrations for 36 h, which were stimulated with FGF1 concentrations of 0, 10, 100, and 1000 ng/mL for 12 h. The results showed that FGF1 significantly reduced the hepatic lipid droplet deposition and triglyceride content induced by complex fatty acids; it also reduced oxidative stress; decreased reactive oxygen species fluorescence intensity and malondialdehyde content; upregulated the expression of antioxidant factors nuclear factor erythroid 2 related factor 2 (Nrf2), HO-1, and NQO-1; significantly enhanced liver cell activity; promoted cell cycle progression; inhibited cell apoptosis; upregulated cyclin-dependent kinase 1 (CDK1) and BCL-2 mRNA expression; and downregulated Bax and Caspase-3 expression. In addition, FGF1 promoted AMPK phosphorylation, activated the AMPK pathway, upregulated AMPK gene expression, and downregulated the expression of SREBP1 and ACC1 genes, thereby alleviating excessive fat accumulation in liver cells induced by complex fatty acids. In summary, FGF1 may alleviate lipid metabolism disorders induced by complex fatty acids in primary mule duck liver cells by activating the AMPK signaling pathway.

The role of free fatty acid receptor-1 in gastric contractions in Suncus murinus

Motilin is an important hormonal regulator in the migrating motor complex (MMC). Free fatty acid receptor-1 (FFAR1, also known as GPR40) has been reported to stimulate motilin release in human duodenal organoids. However, how FFAR1 regulates gastric motility in vivo is unclear. This study investigated the role of FFAR1 in the regulation of gastric contractions and its possible mechanism of action using Suncus murinus. Firstly, intragastric administration of oleic acid (C18:1, OA), a natural ligand for FFAR1, stimulated phase II-like contractions, followed by phase III-like contractions in the fasted state, and the gastric emptying rate was accelerated. The administration of GW1100, an FFAR1 antagonist, inhibited the effects of OA-induced gastric contractions. Intravenous infusion of a ghrelin receptor antagonist (DLS) or serotonin 4 (5-HT4) receptor antagonist (GR125487) inhibited phase II-like contractions and prolonged the onset of phase III-like contractions induced by OA. MA-2029, a motilin receptor antagonist, delayed the occurrence of phase III-like contractions. In vagotomized suncus, OA did not induce phase II-like contractions. In addition, OA promoted gastric emptying through a vagal pathway during the postprandial period. However, OA did not directly act on the gastric body to induce contractions in vitro. In summary, this study indicates that ghrelin, motilin, 5-HT, and the vagus nerve are involved in the role of FFAR1 regulating MMC. Our findings provide novel evidence for the involvement of nutritional factors in the regulation of gastric motility.