Performed Glucose Tolerance Tests Research Articles

Effects of high fat diet on metabolic health vary by age of menopause onset.

Menopause accelerates metabolic dysfunction, including (pre-)diabetes, obesity and visceral adiposity. However, the effects of endocrine vs. chronological aging in this progression are poorly understood. We hypothesized that menopause, especially in the context of middle-age, would exacerbate the metabolic effects of a high fat diet. Using young-adult and middle-aged C57BL/6J female mice, we modeled diet-induced obesity via chronic administration of high fat (HF) diet vs. control diet. We modeled peri-menopause/menopause via injections of 4-vinylcyclohexene diepoxide, which accelerates ovarian failure vs. vehicle. We performed glucose tolerance tests 2.5 and 7 months after diet onset, during the peri-menopausal and menopausal phases, respectively. Peri-menopause increased the severity of glucose intolerance and weight gain in middle-aged, HF-fed mice. Menopause increased weight gain in all mice regardless of age and diet, while chronological aging drove changes in adipose tissue distribution towards more visceral vs. subcutaneous adiposity. These data are in line with clinical data showing that post-menopausal women are more susceptible to metabolic dysfunction and suggest that greater chronological age exacerbates the effects of endocrine aging (menopause). This work highlights the importance of considering both chronological and endocrine aging in studies of metabolic health.

Endoplasmic reticulum stress inhibition ameliorated WFS1 expression alterations and reduced pancreatic islets’ insulin secretion induced by high-fat diet in rats

Endoplasmic reticulum (ER) stress is involved in the development of glucose homeostasis impairment. When ER stress occurs, the unfolded protein response (UPR) is activated to cope with it. One of the UPR components is WFS1 (Wolfram syndrome 1), which plays important roles in ER homeostasis and pancreatic islets glucose-stimulated insulin secretion (GSIS). Accordingly and considering that feeding high-fat food has a major contribution in metabolic disorders, this study aimed to investigate the possible involvement of pancreatic ER stress in glucose metabolism impairment induced by feeding high-fat diet (HFD) in male rats. After weaning, the rats were divided into six groups, and fed on normal diet and HFD for 20 weeks, then 4-phenyl butyric acid (4-PBA, an ER stress inhibitor) was administered. Subsequently, in all groups, after performing glucose tolerance test, the animals were dissected and their pancreases were removed to extract ER, islets isolation and assessment of GSIS. Moreover, the pancreatic ER stress [binding of immunoglobulin protein (BIP) and enhancer-binding protein homologous protein (CHOP)] and oxidative stress [malondialdehyde (MDA), glutathione (GSH) and catalase] biomarkers as well as WFS1 expression level were evaluated. HFD decreased pancreatic WFS1 protein and GSH levels, and enhanced pancreatic catalase activity, MDA content, BIP and CHOP protein and mRNA levels as well as Wfs1 mRNA amount. Accordingly, it increased BIP, CHOP and WFS1 protein levels in the extracted ER of pancreas. In addition, the HFD caused glucose intolerance, and decreased the islets’ GSIS and insulin content. However, 4-PBA administration restored the alterations. It seems that, HFD consumption through inducing pancreatic ER stress, altered WFS1 expression levels, reduced the islets’ GSIS and insulin content and finally impaired glucose homeostasis.

RF01 | PMON44 Absence of Kisspeptin in KNDy Neurons of Mice Causes Sexually Dimorphic Metabolic Dysfunction on a High-Fat Diet

Abstract Kisspeptin neurons in the arcuate nucleus (ARC) of the hypothalamus are considered as the gonadotropin-releasing hormone (GnRH) pulse generator to control the cascade of hormone secretions that constitute the reproductive axis. These neurons typically co-express Neurokinin B and Dynorphin and are thus dubbed KNDy neurons. In addition, KNDy neuron kisspeptin is hypothesized to be a major sensor and regulator of metabolic homeostasis while relaying energy status to the hypothalamic-pituitary-gonad (HPG) axis. However, the direct metabolic impact of KNDy neuron kisspeptin has not been well-characterized. To explore this role, we examined the metabolic profile of our previously established KNDy neuron-specific kisspeptin knock-out mouse model (Pdyn-Cre/Kissfl/fl, or KO). To do so, we performed glucose tolerance tests, EchoMRI body composition analysis, and measured body weight in wild type (WT) control or KO mice fed with either regular chow or a high-fat diet (HFD, 60% kcal fat, Research Diets, New Brunswick, NJ) for 12 weeks post-weaning. At 4 weeks on the HFD, KO females weighed significantly more than HFD WT females, which continued through the remaining 8 weeks. Additionally, we found significantly decreased glucose tolerance and increased fat mass in HFD KO females compared to HFD WT females. However, KO males exhibited no significant differences in body weight, body composition, or glucose tolerance between the genotypes on either diet. This data suggests that KNDy neuron kisspeptin is critical for metabolic homeostasis and preventing metabolic dysfunction when challenged with a high-fat diet. Our findings further suggest a sexual dimorphism whereby KNDy neuron kisspeptin performs this action predominantly in females. Presentation: Saturday, June 11, 2022 1:18 p.m. - 1:23 p.m., Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.

The IGF-1R Inhibitor NVP-AEW541 Causes Insulin-Independent and Reversible Cardiac Contractile Dysfunction.

The antitumor treatment NVP-AEW541 blocks IGF-1R. IGF-1R signaling is crucial for cardiac function, but the cardiac effects of NVP-AEW541 are ill defined. We assessed NVP-AEW541′s effects on cardiac function and insulin response in vivo and in isolated working hearts. We performed a dose–response analysis of NVP-AEW541 in male, 3-week-old rats and assessed the chronic effects of the clinically relevant dose in adult rats. We performed glucose tolerance tests and echocardiography; assessed the expression and phosphorylation of InsR/IGF-1R and Akt in vivo; and measured substrate oxidation, contractile function, and insulin response in the isolated working hearts. NVP-AEW541 caused dose-dependent growth retardation and impaired glucose tolerance in the juvenile rats. In the adults, NVP-AEW541 caused a continuously worsening depression of cardiac contractility, which recovered within 2 weeks after cessation. Cardiac Akt protein and phosphorylation were unchanged and associated with InsR upregulation. An acute application of NVP-AEW541 in the working hearts did not affect cardiac power but eliminated insulin’s effects on glucose and fatty acid oxidation. The systemic administration of NVP-AEW541 caused dose- and time-dependent impairment of glucose tolerance, growth, and cardiac function. Because cardiac insulin signaling was maintained in vivo but absent in vitro and because contractile function was not affected in vitro, a direct link between insulin resistance and contractile dysfunction appears unlikely.

1175-P: Inhibition of FBXO48 Improves Metabolic Changes Associated with NAFLD by Inhibiting Proteasomal Degradation of Phosphorylated AMPKa

Hypothesis: Nonalcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease in developed countries yet there are no FDA-approved therapies for the disease. AMPK is a cellular energy sensor that coordinates metabolic pathways to balance energy demand with production. Growing evidence suggests loss of AMPK activity contributes to NAFLD. We recently identified an orphan F-box protein, FBXO48, which mediates the ubiquitination and proteasomal degradation of phosphorylated AMPKα (pAMPK). We hypothesized that increasing pAMPK levels via inhibition of FBXO48 would improve glucose homeostasis and slow NAFLD progression. Methods: Twelve-week old male wildtype (WT) mice were fed low-fat diet (LFD) or “fast food” diet (FFD) for 24 weeks and then given vehicle (VEH) or a small molecule FBXO48 inhibitor (SMI; 5 mg/kg/d) for 8 weeks. We measured changes in body weight/composition, performed glucose tolerance tests (GTT), and collected plasma and liver for analysis. Results: SMI had no significant effect on body weight or composition, although body weight and fat mass were 2.4 and 2.1 g less in SMI FFD compared with VEH FFD mice, suggesting a modest effect on weight loss. SMI significantly improved glucose homeostasis in FFD mice and restored plasma glucose levels during GTT to those observed in LFD mice. SMI had no effect on liver triglyceride levels in LFD mice and produced a 15% non-significant reduction in FFD mice. Gene expression of inflammation markers Cd68 and Ccl2 were significantly reduced in SMI FFD compared with VEH FFD mice, as were markers of fibrosis Col1a1 and Col3a1. Conclusions: Our data suggest that increasing pAMPK levels through inhibition of FBXO48 may be a viable treatment option for improving glucose homeostasis and reducing inflammation/fibrosis associated with NAFLD. Disclosure A. Murali: None. L. R. Edmunds: None. B. Xie: None. B. Chen: Board Member; Self; Generian, Employee; Self; Generian. Y. Liu: Employee; Self; Generian. M. J. Jurczak: None. Funding National Institute of Diabetes and Digestive and Kidney Diseases (DK007052R01, DK119627)

Hyperandrogenemia alters mitochondrial structure and function in the oocytes of obese mouse with polycystic ovary syndrome

Hyperandrogenemia in an obese PCOS mouse model results in altered glucose/insulin metabolism and mitochondrial structure and function in the oocytes, in part explaining adverse outcomes and inheritance patterns seen in PCOS. To study the oocyte quality by means of mitochondrial structure and function in a well-established classic PCOS mouse model. Animal study using an obese PCOS mouse model compared with control. Animal research facility in a tertiary care university hospital setting. C57/B6J mice. Three week old mice had subdermal implants of DHT controlled release pellet or placebo for 90 days. The mouse model was validated by performing glucose tolerance test, HbA1c levels, body weight and estrous cycle analyses. Oocytes were subsequently isolated and were used to investigate mitochondrial membrane potential, oxidative stress, lipid peroxidation, ATP production, mtDNA copy number, transcript abundance, histology and electron microscopy. Results showed glucose intolerance and hyperinsulinemia along with dysregulated estrus cycle. Analysis of the oocytes demonstrated impaired inner mitochondrial membrane function, increased ATP production and mtDNA copy number, altered RNA transcript abundance and aberrant ovarian histology. Electron microscopy of the oocytes showed severely impaired mitochondrial ultrastructure. The obese PCOS mouse model shows a decreased oocyte quality related to impaired mitochondrial function.

1720-P: The Modulation in Glucose Metabolism by B1 Kinin Receptor Does Not Depend in Hepatic Insulin Signaling

Background: The kinin B1 receptor (B1R), an inducible effector of Kallikrein-Kinin System during inflammation, has been blamed also to influence glucose metabolism and leptin sensitivity. Aim: To investigate the effects of cafeteria diet (CAF) on hepatic glucose metabolism in B1R knockout mice (B1RKO). Methods: Two months old male C57Bl/6 wild type and B1RKO mice were fed with standard chow (SC) or CAF ad libitumfor 14 weeks (WT-SC n=7; B1RKO-SC n=8; WT-CAF n=7; B1RKO-CAF n =10). We performed glucose tolerance test (GTT) and insulin tolerance test (ITT) at the last week before organs collection. HOMA IR index was calculated. Quantitative PCR was used to determine hepatic expression of glucose-6-phospatase (G6Pase), glucokinase (GK), phosphoenolpyruvate carboxykinase (PEPCK), fructose 1,6-bisphosphatase (FBPase1) and hepatocyte nuclear factor 4 alpha (HNF4A). We also performed western blot to analyze AKT phosphorylation in liver. Two-way ANOVA was used to analyze differences between groups. Values were expressed as mean ± SEM and p ≤0.05 was considered statistically significant. Results: Although the increment of glucose area under the curve during GTT was lower in B1RKO-CAF than WT-CAF (WT-SC 46.246 ± 4.302 vs. B1RKO-SC 35.699 ± 3.383; p=0.03; and B1RKO-CAF 28.521 ± 5.338 vs. WT-CAF 56.564 ± 3.477; AUC p=0.0001), B1RKO mice presented a similar decay in glucose levels during ITT as well as HOMA-IR values . While there was a decrease in liver mRNA expression of G6Pase and PEPCK, GK expression increased in mice fed with CAF diet, without differences between genotypes. FBPase1 and HNF4A mRNA expression were not different between groups. Liver AKT phosphorylation increased with CAF in both C57Bl/6 wild type and B1RKO mice. Conclusion: The increased glucose uptake of B1RKO mice during GTT might not be related to insulin signaling in the liver, since no changes were observed in insulin resistance or in the hepatic expression of gluconeogenesis regulatory enzymes. Disclosure P. Espíndola Correia: None. C.B. Gomes: None. P.N. Merello: None. G.R. Natividade: None. C.C. Barros: None. F. Gerchman: None. Funding Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (16-0397)

The Metabolic Effects of Vitamin D and Fish Oil on Obesity

Abstract Objectives Obesity is a widespread epidemic affecting approximately 93.3 million people in the United States. Common underlying causes of obesity include adipose tissue inflammation and insulin resistance. Vitamin D and fish oil both offer potential health benefits that include lowering inflammation and triglycerides. However, their combined effects have not been carefully evaluated in the context of obesity. Hence, we hypothesized that vitamin D and fish oil supplementation exert synergistic and/or additive effects to reduce obesity. Methods To test this hypothesis, male B6 mice were fed a high fat (HF) diet supplemented with a low dose (200 IU) or high dose (1000 IU) of vitamin D (HF + D), with or without fish oil (36 g/kg of diet) for 12 weeks. We measured body weight and food intake weekly and performed glucose tolerance test. At termination, liver and epididymal fat were harvested for gene and protein analyses. Results There were no differences in body weight or food intake across the 4 groups. Glucose clearance was higher in the fish oil supplemented groups with or without Vitamin D compared to mice fed HF. Only the group supplemented with fish oil along with Vitamin D had lower fatty acid synthesis and higher fatty acid oxidation in epididymal adipose tissue. However, in the liver, fatty acid synthesis was not altered, while fatty acid oxidation was increased by fish oil and Vitamin D combination compared to other groups (P < 0.05). Furthermore, in liver, the mRNA levels for the gluconeogenic marker, Pdk4, was higher in groups supplemented with fish oil with or without Vitamin D compared to HF (P < 0.05). Conclusions Additional molecular analyses are currently ongoing to determine the mechanistic basis for beneficial combined effects of vitamin D and fish oil in diet-induced obesity. Funding Sources Funded by a Come N Go grant from the College of Human Sciences, TTU.

The effects of heart rate, adherence to antihypertensive pharmacotherapy and physical exercise on clinical course of first grade hypertension

Objective . To analyze the prognostic effects of metabolic and hemodynamic characteristics and adherence to treatment in patients with first grade arterial hypertension (HTN). Design and methods . We have examined twice (with interval 71,3 ± 10,5 months) 67 patients with first grade HTN. Baseline and final investigations included office blood pressure (BP) measurements, heart rate and body mass index calculation, ambulatory BP monitoring. In addition, at baseline we assessed the levels of total cholesterol, low and high density lipoproteins, triglycerides. vascular endothelial growth factor, glucose and insulin. We also performed glucose tolerance test. At follow-up, life style changes and adherence to treatment were assessed via structured questionnaires. Eleven patients with adverse outcomes composed a separate subgroup including 5 with HTN worsening, 2 with angina pectoris worsening, 3 with myocardial infarction, 1 case of sudden death. Results . Insulin levels at glucose tolerance test was higher in patients with adverse outcomes. At baseline, fasting and postprandial heart rate was greater than 80 bpm in 91 % of patients with first grade HTN who developed adverse outcomes and in 21 % in the rest of the group (p < 0,001). Disease progression and complication development were registered only in patients with both high/very high cardiovascular risk and heart rate greater than 80 bpm. Only in patients with very high cardiovascular risk major cardiovascular events were detected. Low adherence to treatment significantly worsened prognosis: the majority (80 %) of patients with adverse outcomes took antihypertensive drugs irregularly; 60 % patients with adverse outcomes reduced level of physical activity. Increment in regular physical activity was found more frequently in patients with serum vascular endothelial growth factor > 200 pg/ml. Conclusions . Heart rate greater than 80 bpm is associated with unfavorable prognostic effect in patients with first grade HTN and high/very high total cardiovascular risk. Disease progression and complication development are more frequent in patients with irregular therapy and/or those who reduced physical activity level.

Prenatal androgen induced lean PCOS impairs mitochondria and mRNA profiles in oocytes.

Polycystic ovary syndrome (PCOS) is the most common ovulatory defect in women. Although most PCOS patients are obese, a subset of PCOS women are lean but show similar risks for adverse fertility outcomes. A lean PCOS mouse model was created using prenatal androgen administration. This developmentally programmed mouse model was used for this study. Our objective was to investigate if mitochondrial structure and functions were compromised in oocytes obtained from lean PCOS mouse. The lean PCOS mouse model was validated by performing glucose tolerance test, HbA1c levels, body weight and estrous cycle analyses. Oocytes were isolated and were used to investigate inner mitochondrial membrane potential, oxidative stress, lipid peroxidation, ATP production, mtDNA copy number, transcript abundance and electron microscopy. Our results demonstrate that lean PCOS mice have similar weight to that of the controls but exhibit glucose intolerance and hyperinsulinemia along with dysregulated estrus cycle. Analysis of their oocytes show impaired inner mitochondrial membrane function, elevated reactive oxygen species (ROS) and increased RNA transcript abundance. Electron microscopy of the oocytes showed impaired mitochondrial ultrastructure. In conclusion, the lean PCOS mouse model shows a decreased oocyte quality related to impaired mitochondrial ultrastructure and function.

Overexpression of apelin in Wharton\u2019 jelly mesenchymal stem cell reverses insulin resistance and promotes pancreatic \u03b2 cell proliferation in type 2 diabetic rats

BackgroundApelin plays a key beneficial role in energy metabolism by increasing glucose uptake and insulin sensitivity; however, apelin has a short half-life because it is rapidly cleared from the circulation limiting its therapeutic benefit. The aim of this study is to create a new approach to treat type 2 diabetes by inducing prolonged expression of apelin in Wharton’s jelly-derived mesenchymal stem cells (WJ-MSCs).MethodsA type 2 diabetic rat model was given a high-fat diet combined with low-dose streptozotocin (STZ) injection. The human WJ-MSCs were isolated and subsequently transduced with apelin-expressing lentiviral particles (WJMSCs-apelin), and expression was verified by flow cytometry, Western blot, ELISA, and RT-PCR analysis. Type 2 diabetic rats were infused with either WJMSCs-apelin (2 × 106 cells) or an equivalent dose of saline through the tail vein injection 7 days after STZ injection. The therapeutic effects of each infusion group were evaluated by monitoring plasma glucose levels and performing glucose tolerance tests (OGTTs), insulin tolerance tests (IPITTs), confocal microscopy, and immunocytochemical analysis for quantitating islet beta cells. Plasma inflammatory cytokines IL-6 and TNF-α and anti-inflammatory factors adiponectin were measured as well.ResultsType 2 diabetic rats infused with WJ-MSCs-apelin significantly decreased levels of blood glucose (from 26.03 ± 2.83 to 15.85 ± 2.13 mmol/L on 7 days P < 0.001, and to 9.41 ± 2.05 on 14 days, P < 0.001). Infusion of WJMSCs-apelin not only improved significantly insulin sensitivity and glucose disposal, but also promoted endogenous pancreatic ß cell proliferation (9.6-fold increase compared to the control group). Furthermore, infusion of the WJMSCs-apelin consistently increased insulin and C-peptide levels in the plasma, and the above effects persisted up to 42 days. The inflammatory cytokines IL-6 and TNF-α were significantly decreased, whereas anti-inflammatory factor adiponectin was significantly increased after WJ-MSC-apelin infusion.ConclusionIn this study, we report a novel approach to treat type 2 diabetic rats that combines apelin gene therapy with WJ-MSC cell therapy, which could provide a promising therapeutic option for management of type 2 diabetes clinically.

Diabetes Screening in Patients with Macrovascular Coronary Disease: Are the New European Guidelines a Step Backwards?

The new European guidelines on diabetes mellitus and cardiovascular diseases propose that the FINnish Diabetes RIsk SCore should be used to evaluate the risk of diabetes mellitus and that diabetes mellitus screening in coronary artery disease patients should be based on fasting glucose and HbA1c. The 2 hour oral glucose tolerance test, recommended for all pts in the previous guidelines, is now only recommended for 'inconclusive' cases. We aimed to evaluate this new strategy. Fasting glucose, HbA1c and glucose tolerance test (75 g, 2h) were prospectively evaluated in a consecutive group of pts with coronary artery disease. ADA criteria (both glucose tolerance test and HbA1c) were used to define diabetes mellitus and pre-diabetes mellitus. Diabetes mellitus risk was evaluated according to the FINnish Diabetes RIsk SCore. A total of 135 patients were included (mean age 62.3 +/- 13.1 years, 99 males). Glucose tolerance test and HbA1c together diagnosed 18 (13.3%) new cases of diabetes mellitus and 77 (57.0%) patients with pre-diabetes mellitus. Fasting glucose + HbA1c (guidelines strategy) identified 12/18 patients with diabetes mellitus (Sens 66.7%; negative predictive value 95.1%; Kappa 0.78; p < 0.0001) and 83/95 patients with glucose anomalies (pre- diabetes mellitus + diabetes mellitus) (Sens 87.4%; negative predictive value 76.9%). Performing glucose tolerance test in the 29 patients with an elevated FINnish Diabetes RIsk SCore would allow identifying 15/18 patients with diabetes mellitus (Sens 83.3%; negative predictive value 97.5%; Kappa 0.85; p < 0.0001) and 86/95 patients with glucose anomalies (Sens 90.5%; negative predictive value 81.6%). Although this strategy improved the screening accuracy, one in each six patients with diabetes mellitus would still remain undiagnosed, as compared to measuring HbA1c and performing an glucose tolerance test in all patients. Using the FINnish Diabetes RIsk SCore to select candidates to additional glucose tolerance test improves the accuracy for identifying diabetic patients, as compared with fasting glucose + HbA1c alone. However, 1/6 patients diabetes mellitus is still left undiagnosed with this strategy proposed by the current guidelines.

Anti-hyperglycaemic activity of Moringa oleifera is partly mediated by carbohydrase inhibition and glucose-fibre binding.

Moringa oleifera has potential anti-hyperglycaemic effects that have been reported earlier by different scientific groups using animal models of diabetes. We aimed to explore the possible mechanisms of action of M. oleifera extract through different methods. Primarily, we measured fasting blood glucose and performed glucose tolerance test, in Type 2 diabetic rats. Further, we studied the effects of extracts on pancreatic insulin concentration. Extracts’ effect on carbohydrate breakdown was assayed using α-amylase inhibition assays and assay of six different segments of gastrointestinal (GI) tracts. An in situ intestinal perfusion model and a glucose fibre assay were performed to see the potentiality of M. oleifera on glucose absorption. M. oleifera showed no significant change in insulin secretion in vivo. Additionally, substantial effect of the extract was seen on retarded glucose absorption and in the in situ perfusion study of rat intestinal model. α-amylase action was inhibited by the extract, yet again, these findings were further confirmed via the Six Segment assay, where sucrose digestion was found to be inhibited throughout the length of the GI tract. A combined in vitro, in vivo and in situ tests justified the potential of anti-hyperglycaemic activity of M. oleifera and its tissue level mechanism is also justified.

CD68GFP/APOE-/- mouse: A novel model to study macrophage biology in atherosclerosis

CD68GFP/APOE-/- mouse: A novel model to study macrophage biology in atherosclerosis

Ablation of Perilipin 1 Alters Whole Body Glucose Homeostasis

Lipid droplets are cellular organelles that enclose neutral lipid depots and play dynamic roles in lipid metabolism by lipid droplet proteins. Perilipin 1 is one of the major lipid droplet binding proteins in adipocytes. Perilipin1 protein is phosphorylated by protein kinase A and its phosphorylation is necessary for translocation of hormone-sensitive lipase to the lipid droplets to facilitate lipolysis. As well known, depletion of perilipin 1 gene in mice is resistance to diet-induced obesity as well as increases basal lipolysis and reduces stimulated lipolysis. However, it is largely unknown whether insulin signaling is changed in perilipin 1 knockout (Plin1 KO) mice compared with wild type (WT) mice. To investigate potential roles for perilipin 1 in glucose homeostasis, we performed glucose tolerance test in Plin1 KO mice and WT mice. We discovered that the glucose responsiveness was more sensitive in Plin1 KO mice compared with WT mice under normal chow diet condition. Moreover, insulin downstream signalings were altered in metabolic tissues of Plin1 KO mice. Together, these data suggest that perilipin 1 would be involved in systemic glucose metabolism, at least in part, through insulin signaling. This work was supported by National Creative Research Initiative Program (2011-0018312) funded by the ministry of Education, Science, and Technology (MEST). J. H. Sohn and J. S. Han were supported by the BK21 program, Korea.

Effects of a high-energy diet on oocyte quality and in vitro embryo production in Bos indicus and Bos taurus cows

The effects of different dietary energy levels [100 and 170% for maintenance (M) and high energy (1.7M), respectively] on metabolic, endocrine, and reproductive parameters were evaluated in nonlactating Bos indicus (Gir; n=14) and Bos taurus (Holstein; n=14) cows submitted to ultrasound-guided ovum pick-up followed by in vitro embryo production. The oocyte donor cows were housed in a tiestall system and fed twice daily (0800 and 1600 h). Twenty-one days before the beginning of the experiment, the animals were fed with a maintenance diet for adaptation followed by the experimental diets (M and 1.7M), and each cow underwent 9 ovum pick-up procedures 14 d apart. The recovered oocytes were cultured in vitro for 7 d. We measured glucose and insulin concentrations and performed glucose tolerance tests and the relative quantification of transcripts (PRDX1, HSP70.1, GLUT1, GLUT5, IGF1R, and IGF2R) from the oocytes recovered at the end of the experimental period. No interactions were observed between the effects of genetic groups and dietary energy level on the qualitative (viable oocytes, quality grade, and oocyte quality index) and quantitative (oocytes recovered) oocyte variables. There were no effects of dietary energy level on the qualitative and quantitative oocyte variables. However, Bos indicus cows had greater numbers of recovered structures, viable oocytes, and A and B oocyte grades as well as better oocyte quality index scores and lower DNA fragmentation rates compared with Bos taurus donors. In vitro embryo production (cleavage and blastocyst rates and number of embryos) was similar between diets, but the 1.7M diet reduced in vitro embryo production in Bos indicus cows after 60 d of treatment. Moreover, Bos indicus cows on the 1.7M diet showed lower transcript abundance for the HSP70.1, GLUT1, IGF1R, and IGF2R genes. All cows fed 1.7M diets had greater glucose and insulin concentrations and greater insulin resistance according to the glucose tolerance test. In conclusion, increasing dietary energy did not interfere with oocyte numbers and quality, but the 1.7M diet reduced in vitro embryo production in Bos indicus cows after 60 d of treatment. Finally, Bos indicus cows had greater oocyte quality, greater numbers of viable oocytes and greater in vitro embryo yield than Bos taurus.

Anti-hyperglycemic activity of Centella asiatica is partly mediated by carbohydrase inhibition and glucose-fiber binding

BackgroundCentella asiatica (C. asiatica) was previously reported to have anti-hyperglycemic effects in animal diabetic model rats. However, its activity on organ and tissue level remains unstudied. Our study aims at exploring the possible effects, C. asiatica extract and insoluble fiber has on carbohydrate absorption, insulin secretion, insulin sensitivity and glucose utilization.MethodsFor primary evaluation of anti-hyperglycemic activity, we measured Fasting Blood Glucose and performed Glucose Tolerance Test, in type 2 diabetic rats. To further study the pancreatic effect and glucose utilization, plasma insulin concentration, insulin secreted from isolated rat islets and liver glycogen were assayed. Effect on carbohydrate break down was assayed using intestinal disaccharidase enzyme, α-amylase inhibition assays and Six-Segment study of the GI tract. Effect of C. asiatica on glucose absorption was studied by an in-situ, perfused, intestinal model in rats and by glucose-fiber binding assay. Gastrointestinal motility was seen by a BaSO4 milk traverse test. Additionally, a complete lipid profile assay, after a chronic study, was conducted.ResultsC. asiatica showed no significant change in insulin secretion in-vivo and in isolated rat islets. Additionally, no effect of the extract was seen on liver glycogen deposition. Retarded glucose absorption was seen in the in-situ perfused rat intestinal model at a dose. The extract was also found to inhibit action of both intestinal disaccharidase and α-amylase. This was confirmed, yet again, via the Six Segment study, where sucrose digestion was found to be inhibited throughout the length of the GI Tract. Significant glucose-fiber binding was demonstrated in the in-vitro models. During the chronic study, body mass of C. asiatica treated Type 2 diabetic rats returned to normal and their polydipsic and polyphagic conditions were also improved. Chronic treatment of C. asiatica also improved subject’s lipid profile.ConclusionA combination of in-vitro, in-vivo and in-situ tests confirmed the anti-hyperglycemic activity of C. asiatica and its tissue level mechanism. Further study is required to fully elucidate the effect this extract or the active compounds have on the individual glucose transporters and the precise mechanism of glucose-fiber binding.

LRH-1 heterozygous knockout mice are prone to mild obesity

Obesity is a global health problem that increases the risk of several common diseases. Liver receptor homologue-1 (LRH-1) has an important role in steroid hormone metabolism, which influences body weight. Whether LRH-1 gene deletion causes obesity is yet to be clarified. In this study using LRH-1 heterozygous knockout (LRH-1(+/-)) mice, we investigated the role of LRH-1 on body weight gain and glucose and lipid metabolism. LRH-1(+/-) mice showed mild but significant body weight gains compared with wild-type littermate mice after being fed a high-fat diet. We performed glucose tolerance tests and insulin tolerance tests and did not find any significant differences between wild-type and LRH-1(+/-) mice. To clarify how LRH-1 gene deletion affects body weight gain, we measured food intake, oxygen consumption, respiratory quotient, spontaneous activity and rectal temperature, and found no significant differences between wild-type and LRH-1(+/-) mice fed a normal diet and a high-fat diet. The results suggest that heterozygous gene deletion of LRH-1 causes body weight gains without any apparent worsening of glucose and lipid metabolism. Identifying the effects of LRH-1 on body weight will aid in understanding the pathogenesis of obesity.

Cafeteria diet inhibits insulin clearance by reduced insulin-degrading enzyme expression and mRNA splicing

Insulin clearance plays a major role in glucose homeostasis and insulin sensitivity in physiological and/or pathological conditions, such as obesity-induced type 2 diabetes as well as diet-induced obesity. The aim of the present work was to evaluate cafeteria diet-induced obesity-induced changes in insulin clearance and to explain the mechanisms underlying these possible changes. Female Swiss mice were fed either a standard chow diet (CTL) or a cafeteria diet (CAF) for 8 weeks, after which we performed glucose tolerance tests, insulin tolerance tests, insulin dynamics, and insulin clearance tests. We then isolated pancreatic islets for ex vivo glucose-stimulated insulin secretion as well as liver, gastrocnemius, visceral adipose tissue, and hypothalamus for subsequent protein analysis by western blot and determination of mRNA levels by real-time RT-PCR. The cafeteria diet induced insulin resistance, glucose intolerance, and increased insulin secretion and total insulin content. More importantly, mice that were fed a cafeteria diet demonstrated reduced insulin clearance and decay rate as well as reduced insulin-degrading enzyme (IDE) protein and mRNA levels in liver and skeletal muscle compared with the control animals. Furthermore, the cafeteria diet reduced IDE expression and alternative splicing in the liver and skeletal muscle of mice. In conclusion, a cafeteria diet impairs glucose homeostasis by reducing insulin sensitivity, but it also reduces insulin clearance by reducing IDE expression and alternative splicing in mouse liver; however, whether this mechanism contributes to the glucose intolerance or helps to ameliorate it remains unclear.

Recombinant production of mGLP-1 by coupling of refolding and intein-mediated self-cleavage (CRIS)

Glucagon-like peptide-1 as an endogenous glucose-lowering peptide is a promising candidate for anti-diabetic drug development. Here, we developed a convenient method by coupling of refolding and intein-mediated self-cleavage (CRIS) to improve the recombinant production of a mutated glucagon-like peptide-1 (mGLP-1). Bacterial cell culture employing auto-induction was performed at 37°C to avoid the intracellular self-cleavage of the intein fusion protein. The impacts of urea, pH, and temperature on the efficiency of CRIS were tested, and then, the optimized CRIS was established. Using the optimized method, we obtained the purified mGLP-1 with a yield of 3.41mg peptide/g bacterial cells which was 5.6-fold higher than before. After that, using chromatography, peptide electrophoresis, and mass spectrometry, we determined the purity and molecular weight of the purified peptide and then confirmed its glucose-lowering activity by performing glucose tolerance test in mice. These results suggest that CRIS is a relatively simple and efficacious method for the recombinant production of mGLP-1, and as a general method, it can also be used for the recombinant preparation of some other proteins and peptides.