Dietary Methionine Restriction Improves Gastrocnemius Muscle Glucose Metabolism through Improved Insulin Secretion and H19/IRS-1/Akt Pathway in Middle-Aged Mice.

Methionine restriction (MR) improves glucose metabolism. In skeletal muscle, H19 is a key regulator of insulin sensitivity and glucose metabolism. Therefore, this study aims to reveal the underlying mechanism of H19 upon MR on glucose metabolism in skeletal muscle. Middle-aged mice were fed MR diet for 25 weeks. Mouse islets ß cell line ß-TC6 cells and mouse myoblast cell line C2C12 cells were used to establish the apoptosis or insulin resistance model. Our findings showed that MR increased B-cell lymphoma-2 (Bcl-2) expression, deceased Bcl-2 associated X protein (Bax), cleaved cysteinyl aspartate-specific proteinase-3 (Caspase-3) expression in pancreas, and promoted insulin secretion of ß-TC6 cells. Meanwhile, MR increased H19 expression, insulin Receptor Substrate-1/insulin Receptor Substrate-2 (IRS-1/IRS-2) value, protein Kinase B (Akt) phosphorylation, glycogen synthase kinase-3ß (GSK3ß) phosphorylation, and hexokinase 2 (HK2) expression in gastrocnemius muscle and promoted glucose uptake in C2C12 cells. But these results were reversed after H19 knockdown in C2C12 cells. In conclusion, MR alleviates pancreatic apoptosis and promotes insulin secretion. And MR enhances gastrocnemius muscle insulin-dependent glucose uptake and utilization via the H19/IRS-1/Akt pathway, thereby ameliorating blood glucose disorders and insulin resistance in high-fat-diet (HFD) middle-aged mice.

Eugenol improves high-fat diet/streptomycin-induced type 2 diabetes mellitus (T2DM) mice muscle dysfunction by alleviating inflammation and increasing muscle glucose uptake.

Eugenol has been used in dietary interventions for metabolic diseases such as diabetes and obesity. However, the protective effect of eugenol on muscle function in diabetes is unclear. In this study, a high-fat diet (HFD) with a streptozocin (STZ) injection induced type II diabetes mellitus in a mouse model. Oral eugenol lowered blood glucose and insulin resistance of HFD/STZ-treated mice. Eugenol reduced HFD/STZ-induced muscle inflammation and prevented muscle weakness and atrophy. Eugenol administration significantly increased GLUT4 translocation and AMPK phosphorylation in skeletal muscle, thereby enhancing glucose uptake. By silencing the transient receptor potential vanilloid channel 1 (TRPV1) gene in C2C12 myotube cells, eugenol was found to increase intracellular Ca2+ levels through TRPV1, which then activated calmodulin-dependent protein kinase-2 (CaMKK2) and affected AMPK protein phosphorylation. In conclusion, eugenol is a potential nutraceutical for preventing high-glucose-induced muscle impairments, which could be explained by its mediating effects on glucose absorption and inflammatory responses in the muscle.

Methionine Restriction Improves Cognitive Ability by Alleviating Hippocampal Neuronal Apoptosis through H19 in Middle-Aged Insulin-Resistant Mice.

LncRNA H19 has been reported to regulate apoptosis and neurological diseases. Hippocampal neuron apoptosis damages cognitive ability. Methionine restriction (MR) can improve cognitive impairment. However, the effect of MR on hippocampal neuronal apoptosis induced by a high-fat diet (HFD) in middle-aged mice remains unclear. For 25 weeks, middle-aged mice (C57BL/6J) were given a control diet (CON, 0.86% methionine + 4.2% fat), a high-fat diet (HFD, 0.86% methionine + 24% fat), or an HFD + MR diet (HFMR, 0.17% methionine + 24% fat). The HT22 cells were used to establish the early apoptosis model induced by high glucose (HG). In vitro, the results showed that MR significantly improved cell viability, suppressed the generation of ROS, and rescued HT22 cell apoptosis in a gradient-dependent manner. In Vivo, MR inhibited the damage and apoptosis of hippocampal neurons caused by a high-fat diet, reduced hippocampal oxidative stress, improved hippocampal glucose metabolism, relieved insulin resistance, and enhanced cognitive ability. Furthermore, MR could inhibit the overexpression of H19 and caspase-3 induced by HFD, HG, or H2O2 in vivo and in vitro, and promoted let-7a, b, e expression. These results indicate that MR can protect neurons from HFD-, HG-, or H2O2-induced injury and apoptosis by inhibiting H19.

Development of Drug Carriers with Biocompatibility Based On Human Serum Albumin and ß-Cyclodextrin Molecules and Study of Anticancer Activity.

Herein, a novel molecule S4, which could form a uniform S4 spherical aggregate in water, was synthesized, and the S4 aggregate was used to load Dox to prepare the S4@Dox nanomedicine. The loading efficiency was 80.0 ± 4.5%. The pH response and slow release of Dox were the typical characteristics of the S4@Dox nanomedicine. In vitro experiments showed that cancer cells could successfully phagocytose S4 aggregates and the S4@Dox nanomedicine. The toxicity of S4 aggregates to MCF-7, HepG2, and H22 cells was low, and the S4@Dox nanomedicine had better antitumor activity and specific targeting, especially to the MCF-7 cells. The antitumor activity in vivo and in the tissue section showed that the S4@Dox nanomedicine could significantly reduce Dox toxicity, effectively induce the apoptosis of cancer cells, and effectively inhibit tumor growth, which showed that the nanomedicine had better antitumor activity.

Oxidized Pork Induces Hepatic Steatosis by Impairing Thyroid Hormone Function in Mice.

SCOPE: Recent studies have linked high consumption of red and processed meats to an increased risk of non-alcoholic fatty liver disease, and cooking-induced oxidation of proteins and amino acids might be contributing factors. Herein, this study investigates the influence of oxidized pork and the protein oxidation biomarker dityrosine (Dityr) on hepatic steatosis in mice. METHODS AND RESULTS: Low- and high-oxidative injury pork (LOP and HOP) are freeze-dried to prepare mouse diets. Mice are fed a diet of either the control, LOP, HOP, LOP+Dityr, or Dityr for 12 weeks. HOP and Dityr intake induced oxidative stress and inflammation that impaired thyroid function and peripheral metabolism (reduced type 1 deiodinase activity) of thyroid hormones (THs). These lead to a decrease in the circulating as well as liver THs and induced hepatic steatosis. This process might be regulated through reduced TH levels and altered TH target genes and proteins related to hepatic lipid metabolism that ultimately inhibited hepatic energy metabolism, as indicated by increased hepatic lipid synthesis, decreased hepatic lipid catabolism, and fatty acid oxidation. CONCLUSION: HOP intake could induce hepatic steatosis by impairing TH function. Dityr plays an important role in the HOP-induced harmful effects.

Oxidized Pork Induces Disorders of Glucose Metabolism in Mice.

SCOPE: Consumption of red meat, particularly processed red meat, has been reported to be associated with type 2 diabetes risk, and oxidized proteins and amino acids may be involved in this process. This study explores the effects of pork with varying degrees of oxidative injury caused by cooking on glucose metabolism in mice. METHODS AND RESULTS: Cooked pork is freeze-dried to prepare animal feed. Mice are fed either a control diet (CON), a low- (LOP), or a high-oxidative injury pork diet (HOP) for 12 weeks. Intake of HOP causes hyperglycemia, hypoinsulinemia, and impaired glucose tolerance, indicating a glucose metabolism disorder. Accumulation of oxidation products increases oxidative stress and inflammatory response, which impairs pancreatic islet ß cells function and reduces insulin secretion. Moreover, HOP-mediated hyperglycemia can be partly attributed to elevated hepatic glucose output, as indicated by increased gluconeogenesis and glycogenolysis, and decreased glycolysis and glycogen content. Changes in these processes may be regulated by reduced insulin levels and suppression of the insulin receptor substrate-1 (IRS-1)/phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) signaling pathway and its downstream signaling molecules. CONCLUSION: HOP intake induces disorders of glucose metabolism by impairing pancreatic insulin secretion and increasing hepatic glucose output. Protein oxidation plays a key role in abnormal glucose metabolism induced by HOP.

Sea Cucumber Peptides Improved the Mitochondrial Capacity of Mice: A Potential Mechanism to Enhance Gluconeogenesis and Fat Catabolism during Exercise for Improved Antifatigue Property.

Sea cucumber promotes multifaceted health benefits. However, the mechanisms of sea cucumber peptides (Scp) regulating the antifatigue capacity is still unknown. The present study is aimed at further elucidating the effects and mechanisms of Scp on the antifatigue capacity of mice. At first, C57BL/6J mice were assigned into four groups named Con, L-Scp, M-Scp, and H-Scp and received diets containing Scp (0%, 0.15%, 0.3%, and 0.5%, respectively) for continuous 30 days. On the 21th day, a fore grip test was conducted on mice. On the 25th day, a rotating rod test was conducted on mice. On the 30th day, the quantities of glycogen and mitochondrial DNA (mtDNA) were determined in 8 random mice and another 8 mice were forced to swim for 1 hour before slaughter for detecting biochemical indicators. It was observed that the Scp groups significantly prolonged the running time in rotarod, increased forelimb grip strength, improved lactic acid (LD) and urea nitrogen (BUN) levels in the serum, decreased lactic dehydrogenase (LDH) and glutamic oxalacetic transaminase (GOT) activities in the serum, increased blood glucose (BG) and glycogen (GN) levels in the liver and skeletal muscle after swimming, increased the activity of Na+-K+-ATPase and Ca2+-Mg2+-ATPase in the skeletal muscle and heart, and improved antioxidant capacity. Furthermore, Scp treatment significantly elevated the mRNA and protein relative levels of power-sensitive factors, lipid catabolism, and mitochondrial biogenesis and significantly upregulated mRNA levels of gluconeogenesis. Besides, mtDNA before the swimming test was increased in the three Scp groups. These results show that Scp treatment has antifatigue capacity. Furthermore, these results suggest that improved energy regulation and antioxidant capacity may be the result of improved mitochondrial function.

Dietary Methionine Restriction Ameliorated Fat Accumulation, Systemic Inflammation, and Increased Energy Metabolism by Altering Gut Microbiota in Middle-Aged Mice Administered Different Fat Diets.

Diet greatly influences gut microbiota. Dietary methionine restriction (MR) prevents and ameliorates age-related or high-fat-induced diseases and prolongs life span. This study aimed to reveal the impact of MR on gut microbiota in middle-aged mice with low-, medium-, high-fat diets. C57BL/6J mice were randomly divided into six groups with different MR and fat-content diets. Multiple indicators of intestinal function, fat accumulation, energy consumption, and inflammation were measured. 16S rRNA gene sequencing was used to analyze cecal microbiota. Our results indicated that MR considerably reduced the concentrations of lipopolysaccharide (LPS) and increased short-chain fatty acids (SCFAs) by upregulating the abundance of Corynebacterium and SCFA-producing bacteria Bacteroides, Faecalibaculum, and Roseburia and downregulating the LPS-producing or proinflammatory bacteria Desulfovibrio and Escherichia-Shigella. The effect of MR on LPS and SCFAs further reduced fat accumulation and systemic inflammation, enhanced heat production, and mediated the LPS/LBP/CD14/ TLR4 pathway to strength the intestinal mucosal immunity barrier in middle-aged mice.

Correction: Inhibitory effect of a genistein derivative on pigmentation of Guinea pig skin.

[This corrects the article DOI: 10.1039/C6RA27106E.].