glucagon-like-peptide-2 and Fatty-Liver

A glucagon-like peptide-2 (GLP-2) analog is used in individuals with intestinal failure who are at risk for liver disease, yet the hepatic actions of GLP-2 are not understood. Treatment of high-fat diet-fed (HFD-fed) mice with GLP-2 did not modify the development of hepatosteatosis or hepatic inflammation. In contrast, Glp2r-/- mice exhibited increased hepatic lipid accumulation, deterioration in glucose tolerance, and upregulation of biomarkers of hepatic inflammation. Both mouse and human liver expressed the canonical GLP-2 receptor (GLP-2R), and hepatic Glp2r expression was upregulated in mice with hepatosteatosis. Cell fractionation localized the Glp2r to hepatic stellate cells (HSCs), and markers of HSC activation and fibrosis were increased in livers of Glp2r-/- mice. Moreover, GLP-2 directly modulated gene expression in isolated HSCs ex vivo. Taken together, these findings define an essential role for the GLP-2R in hepatic adaptation to nutrient excess and unveil a gut hormone-HSC axis, linking GLP-2R signaling to control of HSC activation.

Topics: Animals; Diet, High-Fat; Fatty Liver; Glucagon-Like Peptide 2; Glucagon-Like Peptide-2 Receptor; Hepatic Stellate Cells; Humans; Mice; Mice, Inbred C57BL; Mice, Knockout; Signal Transduction

Fundamental complications of insulin resistance and type 2 diabetes include the development of nonalcoholic fatty liver disease and an atherogenic fasting dyslipidemic profile, primarily due to increases in hepatic very-low-density lipoprotein (VLDL) production. Recently, central glucagon-like peptide-2 receptor (GLP2R) signaling has been implicated in regulating hepatic insulin sensitivity; however, its role in hepatic lipid and lipoprotein metabolism is unknown. We investigated the role of glucagon-like peptide-2 (GLP-2) in regulating hepatic lipid and lipoprotein metabolism in Syrian golden hamsters, C57BL/6J mice, and Glp2r-/- mice consuming either a normal chow or high-fat diet (HFD). In the chow-fed hamsters, IP GLP-2 administration significantly increased fasting dyslipidemia, hepatic VLDL production, and the expression of key genes involved in hepatic de novo lipogenesis. In HFD-fed hamsters and chow-fed mice, GLP-2 administration exacerbated or induced hepatic lipid accumulation. HFD-fed Glp2r-/- mice displayed reduced glucose tolerance, VLDL secretion, and microsomal transfer protein lipid transfer activity, as well as exacerbated fatty liver. Thus, we conclude that GLP-2 plays a lipogenic role in the liver by increasing lipogenic gene expression and inducing hepatic steatosis, fasting dyslipidemia, and VLDL overproduction. In contrast, the lack of Glp2r appears to interfere with VLDL secretion, resulting in enhanced hepatic lipid accumulation. These studies have uncovered a role for GLP-2 in maintaining hepatic lipid and lipoprotein homeostasis.

Topics: Animals; Dyslipidemias; Fatty Liver; Gene Expression; Glucagon-Like Peptide 2; Glucagon-Like Peptide-2 Receptor; Lipogenesis; Lipoproteins; Lipoproteins, VLDL; Liver; Male; Mesocricetus; Mice; Mice, Knockout; Non-alcoholic Fatty Liver Disease

Nonalcoholic steatohepatitis (NASH) is part of the spectrum of nonalcoholic fatty liver disease. However, there are few suitable animal models to study the pathogenesis of NASH or very limited advances in the prevention. Our aims were to establish a mouse model of NASH by intraperitoneally injecting lipopolysaccharide (LPS) at a dose of 1.5 mg per kg body weight per day for 6 weeks and to investigate the potential inhibitory effects of oat β-glucan (1%, 5%, or 10%) added to a specific pathogen-free diet. Intraperitoneal injection of LPS for 6 weeks increased serum LPS levels; decreased serum glucagon-like peptide-2 levels; triggered abnormal aminotransferase activity, glucose intolerance, and insulin resistance; and increased hepatic proinflammatory cytokines (tumor necrosis factor-α, interleukin-6, interleukin-1β), triglyceride, and malonyl dialdehyde levels; but reduced hepatic superoxide dismutase activity. Histologic evaluation revealed evidence of hepatic steatosis, inflammation, and mild necrosis in LPS-treated mice. Dietary supplementation of oat β-glucan prevented most of the LPS-induced metabolic disorders, and improved hepatic steatosis and inflammation, although a dose-dependent effect was not observed. In conclusion, oat β-glucan could inhibit LPS-induced NASH in mice.

Topics: Animals; Avena; beta-Glucans; Disease Models, Animal; Dose-Response Relationship, Drug; Endotoxemia; Fatty Liver; Glucagon-Like Peptide 2; Glucose Intolerance; Inflammation; Insulin Resistance; Interleukin-1beta; Interleukin-6; Lipopolysaccharides; Liver; Male; Malondialdehyde; Mice; Mice, Inbred C57BL; Non-alcoholic Fatty Liver Disease; Oxidative Stress; Superoxide Dismutase; Transaminases; Triglycerides; Tumor Necrosis Factor-alpha; Weight Gain

We previously showed that parenteral nutrition (PN) compared with formula feeding results in hepatic insulin resistance and steatosis in neonatal pigs. The current aim was to test whether the route of feeding (intravenous [IV] vs enteral) rather than other feeding modalities (diet, pattern) had contributed to the outcome.. Neonatal pigs were fed enterally or parenterally for 14 days with 1 of 4 feeding modalities as follows: (1) enteral polymeric formula intermittently (FORM), (2) enteral elemental diet (ED) intermittently (IEN), (3) enteral ED continuously (CEN), and (4) parenteral ED continuously (PN). Subgroups of pigs underwent IV glucose tolerance tests (IVGTT) and hyperinsulinemic-euglycemic clamps (CLAMP). Following CLAMP, pigs were euthanized and tissues collected for further analysis.. Insulin secretion during IVGTT was significantly higher and glucose infusion rates during CLAMP were lower in CEN and PN than in FORM and IEN. Endogenous glucose production rate was suppressed to zero in all groups during CLAMP. In the fed state, plasma glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide (GLP)-1, and GLP-2 were different between feeding modalities. Insulin receptor phosphorylation in liver and muscle was decreased in IEN, CEN, and PN compared with FORM. Liver weight was highest in PN. Steatosis and myeloperoxidase (MPO) activity tended to be highest in PN and CEN. Enterally fed groups had higher plasma GLP-2 and jejunum weight compared with PN.. PN and enteral nutrition (EN) when given continuously as an elemental diet reduces insulin sensitivity and the secretion of key gut incretins. The intermittent vs continuous pattern of EN produced the optimal effect on metabolic function.

Topics: Administration, Intravenous; Animals; Animals, Newborn; Blood Glucose; Endpoint Determination; Enteral Nutrition; Fatty Liver; Female; Food, Formulated; Glucagon-Like Peptide 1; Glucagon-Like Peptide 2; Incretins; Inflammation; Insulin; Insulin Resistance; Insulin Secretion; Intestine, Small; Liver; Metabolic Diseases; Nonlinear Dynamics; Organ Size; Parenteral Nutrition; Swine