No abstract

Intestinal glucagon-like peptide-1 (GLP-1) is a hormone that stimulates insulin secretion and acts as a neuropeptide to control glucose homeostasis, but little is known whether intestinal GLP-1 has any effect in the control of hepatic glucose production (HGP). Here we found that intraduodenal infusion of GLP-1 activated duodenal PKC-δ, lowered HGP and was accompanied by a decrease in hepatic expression of gluconeogenic enzymes and an increase in hepatic insulin signaling in rats. However, gut co-infusion of either the GLP-1 receptor antagonist Ex-9, or the PKC-δ inhibitor rottlerin with GLP-1, negated the ability of gut GLP-1 to lower HGP and to increase hepatic insulin signaling during clamps. The metabolic and molecular signal effects of duodenal GLP-1 were also negated by co-infusion with tetracaine, pharmacologic inhibition of N-methyl-d-aspartate receptors within the dorsalvagal complex, or hepatic vagotomy in rats. In summary, we identified a neural glucoregulatory function of gut GLP-1 signaling.

The aim of study was to assess the relationship between zinc-α2-glycoprotein (ZAG) and androgen excess with insulin resistance in polycystic ovary syndrome (PCOS) women. 99 PCOS women and 100 healthy controls were recruited. Euglycemic-hyperinsulinemic clamp (EHC) was preformed to assess their insulin sensitivity. Circulating ZAG was determined with an ELISA kit. In healthy subjects, circulating ZAG levels exhibited a characteristic diurnal rhythm in humans, with a major nocturnal rise occurring between midnight and early morning. Circulating ZAG and M-value were much lower in PCOS women than in the controls. In all population, overweight/obese subjects had significantly lower circulating ZAG levels than lean individuals. Multiple linear regression analysis revealed that only M-value and the area under the curve for glucose were independently related factors to circulating ZAG in PCOS women. Multivariate logistic regression analysis showed that circulating ZAG was significantly associated with PCOS even after controlling for anthropometric variables, blood pressure, lipid profile and hormone levels. The PCOS women with high ZAG had fewer MetS, IGT and polycystic ovaries as compared with the low ZAG PCOS women. Taken together, circulating ZAG levels are reduced in women with PCOS and ZAG may be a cytokine associated with insulin resistance in PCOS women.

We conclude that Sfrp5 may be an adipokine that is associated with the pathogenesis of MetS in humans.

The dedicator of cytokinesis 5 (DOCK5) is associated with obesity. However, the mechanism by which DOCK5 contributes to obesity remains completely unknown. Here, we show that hepatic DOCK5 expression significantly decreases at a state of insulin resistance (IR). Deletion of DOCK5 in mice reduces energy expenditure, promotes obesity, augments IR, dysregulates glucose metabolism, and activates the mTOR (Raptor)/S6K1 pathway under a high-fat diet (HFD). The overexpression of DOCK5 in hepatocytes inhibits gluconeogenic gene expression and increases the level of insulin receptor (InsR) and Akt phosphorylation. DOCK5 overexpression also inhibits mTOR/S6K1 phosphorylation and decreases the level of raptor protein expression. The opposite effects were observed in DOCK5-deficient hepatocytes. Importantly, in liver-specific Raptor knockout mice and associated hepatocytes, the effects of an adeno-associated virus (AAV8)-or adenovirus-mediated DOCK5 knockdown on glucose metabolism and insulin signaling are largely eliminated. Additionally, DOCK5-Raptor interaction is indispensable for the DOCK5-mediated regulation of hepatic glucose production (HGP). Therefore, DOCK5 acts as a regulator of Raptor to control hepatic insulin activity and glucose homeostasis.

Over half of those with undiagnosed diabetes had isolated post-load hyperglycaemia. Homeostasis model assessment and high-sensitivity C-reactive protein are useful to identify subjects with isolated post-load hyperglycaemia, with improved performance over fasting plasma glucose or HbA(1c) alone.

The euglycemic–hyperinsulinemic clamp is not available in most clinical settings. An accessible and inexpensive measurement for identifying insulin resistance (IR) is necessary. Our aim is to assess whether the adiponectin (ADI) index (ADI/[FBG × FIns]) is a better surrogate index for the assessment of IR or metabolic syndrome (MetS).A population-based cross-sectional study was conducted including 100 healthy women and 99 polycystic ovary syndrome patients. The euglycemic–hyperinsulinemic clamp was performed. Circulating ADI levels were determined by ELISA.Polycystic ovary syndrome and polycystic ovary syndrome plus MetS subjects had higher products of fasting triglycerides and glucose (TyG), Homeostasis Model Assessment of Insulin Resistance (HOMA-IR), increased ratios of the area under the curve for insulin/the area under the curve for glucose (AUCi/AUCg), but lower ADI index as compared with healthy subjects. Partial correlation analysis in all populations showed that the M-value was significantly negatively correlated with HOMA-IR, TyG, TG/HDL, and AUCi/AUCg, and correlated positively with the ADI index. The r value of Pearson correlation between the ADI index and M-value was greater than that of the correlation between HOMA-IR, TyG, TG/HDL-C, and AUCi/AUCg. The optimal cut-off value of the ADI index for detection of IR was 0.67, with a sensitivity of 89.4% and a specificity of 88.1%, whereas for detection of MetS, it was 0.32, with a sensitivity of 88.7% and a specificity of 71.0%.The ADI index may be a surrogate marker in detecting IR and MetS.

Background: Dickkopf1 (DKK1) isa protein with established links to metabolic diseases. However, its association with polycystic ovary syndrome (PCOS) and insulin resistance (IR) remains ambiguous. Methods: We conducted a cross-sectional study involving 300 participants, including 100 healthy women, 100 women with PCOS, and 100 individuals with IR. We used the STRING database to identify proteins that interact with DKK1 and performed KEGG and GO analyses to determine the biological processes and signaling pathways that are enriched in DKK1-related proteins. Serum DKK1 levels and Adipoq were measured by ELISA kits. The expression of DKK1 in liver tissue wasdetected by western blotting. Results: Relative to the control group, both the IR and PCOS cohorts exhibited markedly elevated serum DKK1 levels and noticeably reduced Adipoq levels. Correlation analyses revealeda positive relationship between serum DKK1 levels and body mass index(BMI), waist-hip ratio (WHR), body fat percentage (FAT%), systolic blood pressure (SBP), triglycerides (TG), fasting plasma glucose (FPG), fasting insulin (FIns), glycosylated hemoglobin (HbA1c), and homeostasis model assessment of insulin resistance (HOMA-IR) and a negative relationship between Adipoq levels and M-value. Multiple regression analysis indicated that BMI, FAT%, TG, and Adipoq were independent factors affecting DKK1. An analysis of multiple stepwise regressions revealed that DKK1 was a risk factor for IR and PCOS. In the euglycemic-hyperinsulinemic clamp (EHC) test, serum DKK1 levels exhibited a significant increase in the PCOS patients and a pronounced decrease in the IR patients at 30 minutes and returned to baseline at 60 minutes. Conclusions: Our research revealedthat an increase in DKK1 levels in the blood was significantly associated with PCOS and IR, thereby highlighting the potential involvement of DKK1 in the pathogenesis of PCOS and IR. This insight paves the way for further investigations into the role of DKK1 in PCOS and IR.