Glucose Tolerance Test In Mice Research Articles

Anti-diabetic mechanism and potential bioactive peptides of casein hydrolysates in STZ/HFD-induced diabetic rats.

Casein hydrolysates have attracted much interest as anti-diabetic food, but their hypoglycemic mechanism and biopeptides are not well understood. This study aimed to explore the anti-diabetic mechanism and potential biopeptides of casein hydrolysates in streptozotocin/high-fat-diet-induced diabetic rats and HepG2 cells. Oral administration of casein hydrolysate prepared with papain-Flavourzyme combination (P-FCH) decreased fasting blood glucose, improved oral glucose tolerance, and reduced HbA1c values in diabetic rats. P-FCH was ineffective in alleviating insulin resistance (homeostasis model assessment and insulin sensitivity index) and enhancing hepatic insulin signaling transduction (phosphorylated Akt, hexokinase activity, and pyruvate kinase activity) in diabetic rats. However, P-FCH significantly upregulated adenosine monophosphate-activated protein kinase phosphorylation and glucose transporter-2 expression, inhibited phosphoenolpyruvate carboxylase kinase activity, and elevated glycogen content in liver tissue of diabetic rats. Furthermore, P-FCH increased glucose consumption independently in normal and insulin-resistant HepG2 cells without the presence of insulin. The peptide composition of P-FCH was characterized. The potential biopeptides in P-FCH showed the sequence characteristic of a Val at the N-terminal or a Pro at the P2 position, and the hypoglycemic activity of Val-Pro-Leu-Gly (the most potential biopeptide in P-FCH) was verified by oral glucose tolerance test in mice. These results suggested that activation of the non-insulin-mediated AMPK pathway might be the determinant mechanism of P-FCH on the hypoglycemic effect. The novel peptide Val-Pro-Leu-Gly in P-FCH was effective in reducing blood glucose levels when orally administered to mice. © 2023 Society of Chemical Industry.

Phytochemical and pharmacological activities of Schefflera bojeri (Seem.) R. Vig. (Araliaceae)

Schefflera bojeri possesses several therapeutic virtues: the leaves are used to alleviate hypertension and the bark for the treatment of diabetes. This work aims to verify its potential medicinal virtues. Quantitative analyses of phytochemicals from the leaves and bark were performed using spectrophotometric methods. The antioxidant capacity was determined with DPPH and FRAP assays. The analgesic and anti-inflammatory activities of the two methanol extracts were respectively assessed on the in vivo experimental pain and oedema models. Their antidiabetic property was determined using the oral glucose tolerance test in mice. The acute toxicity of the methanolextracts was evaluated in mice. The total bioactive compound content (TBCC) in the leaves was two-fold more than in the bark as well as the total phenolic compounds (TPC). Oxalic acid (22.39%) was the main compound quantified in the bark, while ferulic acid (18.42%) was of the main molecule in the leaves. The leaves exerted a stronger antioxidant activity than the bark against DPPH but exerted a similar activity on ferric ions. Both the methanol extracts showed a similar dose-dependent analgesic activity ( p < 0.05). Yet, the anti-inflammatory activity of the methanol extracts at each phase of observation (1h, 2h, 3h and 4h, p < 0.05, respectively) was in a dose-dependent manner however the leaves exerted more potent activity than the bark at the dose of 200 mg/kg at each time of observation. Both of the extracts demonstrated a dose-dependent hypoglycaemic activity at 60- and 120 min post glucose administration ( p < 0.01). Both of the methanol extracts did not show any sign of preliminary toxicity. The secondary metabolites in the extracts could be at the origin of preliminary pharmacological properties justifying the therapeutic virtues of this species. Further phytochemical, pharmacological and toxicological studies should be undertaken to better clarify these biological activities. • Schefflera bojeri leaves are used to alleviate hypertension and its bark is used to treat diabetes. • Oxalic acid (22.39%) was the major compound quantified in the bark and ferulic acid (18.42%) was those of the leaves. • The methanol extracts exerted antalgic and anti-inflammatory activities in a dose-dependent manner. • The methanol extracts decreased the glycaemia dose-dependently. • The methanol extracts did not reveal any toxicity signs using an acute toxicity assay.

Abstract 13767: A Novel Pharmacological Inhibitor of Type 5 Adenylyl Cyclase Inhibitor Enhances Exercise Capacity and Protects Against Glucose Intolerance and Myocardial Ischemia

Disruption of adenylyl cyclase 5 (AC5 KO) is a healthful longevity model; not only do the AC5 KO mice live a third longer than wild type (WT) mice, but are also protected against heart failure, obesity and diabetes and exercise intolerance. To translate to the clinics, we developed a new drug, C90, which inhibits AC5, and examined its effects on cardioprotection in pigs, exercise capacity and glucose tolerance in mice. C90 (30 mg/kg/day) or vehicle were chronically administered to age-matched C57/BL6 male mice via osmotic pump. After baseline exercise, the WT mice, all performing similarly, were divided into two groups; one that received C90 for 14 days and the other receiving vehicle for 14 days. After 14 days of C90 treatment, WT mice exhibited greater exercise capacity reflected by longer running distance (384 ± 27 m vs. 253 ± 16 m, p&lt;0.05) and greater work to exhaustion (18.1 ± 1.5 J vs. 12.4 ± 0.7 J, p&lt;0.05) than mice receiving vehicle. Sensitivity to glucose was measured using a glucose tolerance test in mice. Following 14-days treatment with C90 (30 mg/kg/day), the mice exhibited an overall improvement in glucose tolerance, measured as area under the curve (A.U.) for glucose levels following insulin injection, when compared to vehicle (6414 ± 890 A.U. vs. 9658 ± 1039 A.U., p&lt;0.04). Furthermore, C90-treated mice had a lower fasting glucose level on a regular diet, when compared to vehicle (113 ± 6.5 mg/dl vs. 129 ± 4.2 mg/dl, p&lt;0.05). The cardioprotective effects of C90 were previously demonstrated in mice. In the current study, we investigated the cardioprotective effects of C90 in a porcine model of ischemia/reperfusion (I/R). Ischemia was induced for 60 min coronary artery occlusion, followed by 3-hours reperfusion. C90 (1.2 mg/kg), infused 5 min following the start of the reperfusion led to a decreased infarct size/area at risk (INF/AAR) (21.6 ± 4.3% vs. 36.8 ± 2.9%, p&lt;0.05) when compared to vehicle, with no difference between AAR/left ventricle between the C90 and vehicle groups. In view of its lower level of toxicity than other AC5 inhibitors, C90 is an excellent candidate for clinical development for pharmacological treatment of myocardial ischemia, glucose intolerance and exercise intolerance.

The glucose tolerance test in mice: Sex, drugs and protocol.

To establish the impact of sex, dosing route, fasting duration and acute habituation stress on glucose tolerance test (GTT) measurements used in the preclinical evaluation of potential glucose-modulating therapeutics. Adult male and female C57Bl/6J mice, implanted with HD-XG glucose telemetry devices, were fasted for 16 hours or 6hours following acute habituation stress due to whole cage change, cage change with retention of used bedding or no cage change prior to intraperitoneal (IP) GTTs. To evaluate protocol refinement and sex on the ability of the GTT to detect drug effects, we administered 250 mg/kg oral metformin or 10nmol/kg IP exendin-4 using optimized protocols. Female mice were less sensitive to human intervention when initiating fasting. Following a 6-hour fast, retention of bedding whilst changing the cage base promotes quicker stabilization of basal blood glucose in both sexes. Prolonged fasting for 16 hours resulted in an exaggerated GTT response but induced pronounced basal hypoglycaemia. Following GTT protocol optimization the effect of exendin-4 and metformin was equivalent in both sexes, with females showing a more modest but more reproducible GTT response. Variations in GTT protocol have profound effects on glucose homeostasis. Protocol refinement and/or the use of females still allows for detection of drug effects, providing evidence that more severe phenotypes are not an essential prerequisite when characterizing/validating new drugs.

Design of Potent and Proteolytically Stable Biaryl-Stapled GLP-1R/GIPR Peptide Dual Agonists.

Recent clinical trials have revealed that the chimeric peptide hormones simultaneously activating glucagon-like peptide-1 receptor (GLP-1R) and glucose-dependent insulinotropic polypeptide receptor (GIPR) demonstrate superior efficacy in glycemic control and body weight reduction, better than those activating the GLP-1R alone. However, the linear peptide-based GLP-1R/GIPR dual agonists are susceptible to proteolytic cleavage by common digestive enzymes present in the gastrointestinal tract and thus not suitable for oral administration. Here, we report the design and synthesis of biaryl-stapled peptides, with and without fatty diacid attachment, that showed potent GLP-1R/GIPR dual agonist activities. Compared to a linear peptide dual agonist and semaglutide, the biaryl-stapled peptides displayed drastically improved proteolytic stability against the common digestive enzymes. Furthermore, two stapled peptides showed excellent efficacy in an oral glucose tolerance test in mice, owing to their potent receptor activity in vitro and good pharmacokinetics exposure upon subcutaneous injection. By exploring a more comprehensive set of biaryl staplers, we expect that this stapling method could facilitate the design of the stapled peptide-based dual agonists suitable for oral administration.

Comparative analysis of oral and intraperitoneal glucose tolerance tests in mice

ObjectiveThe glucose tolerance test (GTT) is widely used in preclinical research to investigate glucose metabolism, but there is no standardised way to administer glucose. The aim of this study was to directly compare the effect of the route of glucose administration on glucose and insulin kinetics during a GTT in mice. MethodsA GTT was performed in lean male and female mice and obese male mice and glucose was administered via the oral or intraperitoneal (I.P.) route. Samples were collected frequently during the GTT to provide a full time-course of the insulin and glucose excursions. In another cohort of lean male mice, plasma concentrations of insulin, c-peptide, and incretin hormones were measured at early time points after glucose administration. A stable-isotope labelled GTT (SiGTT) was then performed to delineate the contribution of exogenous and endogenous glucose to glycemia during the GTT, comparing both methods of glucose administration. Finally, we present a method to easily measure insulin from small volumes of blood during a GTT by directly assaying whole-blood insulin using ELISA and show a good concordance between whole-blood and plasma insulin measurements. ResultsWe report that I.P. glucose administration results in an elevated blood glucose excursion and a largely absent elevation in blood insulin and plasma incretin hormones when compared to oral administration. Utilising stable-isotope labelled glucose, we demonstrate that the difference in glucose excursion between the two routes of administration is mainly due to the lack of suppression of glucose production in I.P. injected mice. Additionally, rates of exogenous glucose appearance into circulation were different between lean and obese mice after I.P., but not after oral glucose administration. ConclusionReflecting on these data, we suggest that careful consideration be given to the route of glucose administration when planning a GTT procedure in mice and that in most circumstances the oral route of glucose administration should be preferred over the I.P. route to avoid possible artifacts originating from a non-physiological route.

Inhibitory Effect of Tangeretin and Cardamonin on Human Intestinal SGLT1 Activity In Vitro and Blood Glucose Levels in Mice In Vivo.

Rapid postprandial blood glucose elevation can cause lifestyle-related diseases, such as type II diabetes. The absorption of food-derived glucose is primarily mediated by sodium/glucose cotransporter 1 (SGLT1). Moderate SGLT1 inhibition can help attenuate postprandial blood glucose elevation and prevent lifestyle-related diseases. In this study, we established a CHO cell line stably expressing human SGLT1 and examined the effects of phytochemicals on SGLT1 activity. Among the 50 phytochemicals assessed, tangeretin and cardamonin inhibited SGLT1 activity. Tangeretin and cardamonin did not affect the uptake of L-leucine, L-glutamate, and glycyl-sarcosine. Tangeretin, but not cardamonin, inhibited fructose uptake, suggesting that the inhibitory effect of tangeretin was specific to the monosaccharide transporter, whereas that of cardamonin was specific to SGLT1. Kinetic analysis suggested that the suppression of SGLT1 activity by tangeretin was associated with a reduction in Vmax and an increase in Km, whereas suppression by cardamonin was associated with a reduction in Vmax and no change in Km. Oral glucose tolerance tests in mice showed that tangeretin and cardamonin significantly suppressed the rapid increase in blood glucose levels. In conclusion, tangeretin and cardamonin were shown to inhibit SGLT1 activity in vitro and lower blood glucose level in vivo.

Novel Broccoli-Derived Peptides Hydrolyzed by Trypsin with Dual-Angiotensin I-Converting Enzymes and Dipeptidyl Peptidase-IV-Inhibitory Activities.

Broccoli-derived peptides show beneficial metabolic effects, and it is necessary to examine their exact functional sequences. First, peptides from the trypsin hydrolysate of broccoli proteins were isolated and identified using column chromatography and quadrupole time-of-flight mass spectrometry. After that, their functions were verified by oral administration. The results identified two novel peptides as Leu-Pro-Gly-Val-Leu-Pro-Val-Ala (LPGVLPVA) and Tyr-Leu-Tyr-Ser-Pro-Ala-Tyr (YLYSPAY). LPGVLPVA exhibited an ACE IC50 value of 0.776 ± 0.03 μM and a DPP-IV IC50 value of 392 ± 24 μM; YLYSPAY showed an ACE IC50 value of 8.52 ± 0.63 μM and a DPP-IV IC50 value of 181 ± 4 μM. Administration of the peptides reduced the blood pressure of spontaneously hypertensive rats and reduced blood glucose levels in the oral glucose tolerance test in mice. The results indicated that LPGVLPVA and YLYSPAY could be potential nutritional candidates for hypertensive and diabetic people, especially for those with diabetes associated with hypertension.

Translating glucose tolerance data from mice to humans: Insights from stable isotope labelled glucose tolerance tests

ObjectiveThe glucose tolerance test (GTT) is widely used in human and animal biomedical and pharmaceutical research. Despite its prevalent use, particularly in mouse metabolic phenotyping, to the best of our knowledge we are not aware of any studies that have attempted to qualitatively compare the metabolic events during a GTT in mice with those performed in humans. MethodsStable isotope labelled oral glucose tolerance tests (siOGTTs; [6,6-2H2]glucose) were performed in both human and mouse cohorts to provide greater resolution into postprandial glucose kinetics. The siOGTT allows for the partitioning of circulating glucose into that derived from exogenous and endogenous sources. Young adults spanning the spectrum of normal glucose tolerance (n = 221), impaired fasting (n = 14), and impaired glucose tolerance (n = 19) underwent a 75g siOGTT, whereas a 50 mg siOGTT was performed on chow (n = 43) and high-fat high-sucrose fed C57Bl6 male mice (n = 46). ResultsDuring the siOGTT in humans, there is a long period (>3hr) of glucose absorption and, accordingly, a large, sustained insulin response and robust suppression of lipolysis and endogenous glucose production (EGP), even in the presence of glucose intolerance. In contrast, mice appear to be highly reliant on glucose effectiveness to clear exogenous glucose and experience only modest, transient insulin responses with little, if any, suppression of EGP. In addition to the impaired stimulation of glucose uptake, mice with the worst glucose tolerance appear to have a paradoxical and persistent rise in EGP during the OGTT, likely related to handling stress. ConclusionsThe metabolic response to the OGTT in mice and humans is highly divergent. The potential reasons for these differences and their impact on the interpretation of mouse glucose tolerance data and their translation to humans are discussed.

Bornyl Derivatives of p-(Benzyloxy)Phenylpropionic Acid: In Vivo Evaluation of Antidiabetic Activity.

A series of bornyl derivatives of p-(benzyloxy)phenylpropionic acid were prepared, and their hypoglycemic activities were examined by an oral glucose tolerance test in mice. The results of this test revealed two compounds, 1 and 3, that can reduce the blood level of glucose similarly to reference compound vildagliptin. Both compounds were tested in an experiment on mice with metabolic disorders: the C57BL/6Ay strain. Along with hypoglycemic properties, the two compounds showed different abilities to correct lipid metabolism disorders. In silico prediction revealed that the studied substances are most likely bifunctional multitarget hypoglycemic compounds whose mechanism of action is based on a pronounced reduction in insulin resistance and a strong incretin-mimetic effect. The difference in the size of effects of these compounds on biochemical parameters of blood in the experiment on C57BL/6Ay mice was in good agreement with the computational prediction of the priority ranking of biological targets for these compounds. These results indicate that bornyl derivatives of p-(benzyloxy)phenylpropionic acid have a good potential as new agents for diabetes mellitus treatment due to their hypoglycemic and lipid-normalizing properties.

Exploring bulky natural and natural-like periphery in the design of p-(benzyloxy)phenylpropionic acid agonists of free fatty acid receptor 1 (GPR40).

Six derivatives of 3-phenylpropionic acid bearing various natural and natural-like, spatially defined peripheral motifs have been synthesized and evaluated in vitro for free fatty acid receptor 1 (FFA1) activation. Two frontrunner compounds (bearing a bornyl and cytosine groups) were evaluated in an oral glucose tolerance test in mice where both demonstrated the ability to sustain blood glucose levels following a glucose challenge. The bornyl compound displayed a somewhat superior, dose-dependent efficacy and, therefore, can be regarded as a lead compounds for further development as a therapeutic agent for type 2 diabetes mellitus. Its high affinity to FFA1 was rationalized by docking experiments.

The first assessment on antioxidant and antidiabetic activities of leaves and stems of Vaccinium secundiflorum Hook. (Ericaceae), an endemic plant of Madagascar

Vaccinium secundiflorum Hook. (Ericaceae family) is an endemic shrub of the Tapia forests of Madagascar widely used by local Malagasy population to treat diabetes mellitus. This study aims to preliminarily determine the antioxidant activity and anti-diabetic properties of this plant. Plant leaf and stem powders were macerated in methanol 95%. The methanol extract (MVS) was used for (i) phytochemical fingerprint by High Performance Liquid Chromatography (HPLC), (ii) total phenolic content (TPC) evaluation by the Folin–Ciocalteu colourimetric method, (iii) 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenger spectrophotometric assay, (iv) antioxidant capacity by Ferric Reducing Antioxidant Power (FRAP) assay, and (v) antidiabetic activity evaluation by oral glucose tolerance test and acute toxicity in mice. Leaves and stems of V. secundiflorum presented a high rate of TPC (4151.02 ± 745.21mgGAE/100 g of dry weight). The HPLC fingerprint analysis showed the presence of several secondary metabolite classes including organic acids (55.31%), phenolic compounds (29.66%), carotenoids (10.90%), vitamin C (3.96%), and monoterpenes (0.10%). The DPPH free radical scavenger spectrometric assay showed a MVS high potential scavenging activity (IC50 = 76.06 ± 1.08 µg/mL). This potential antioxidant capacity was confirmed by the FRAP assay results (69.31 ± 3.31 mmol Fe2+/Kg of dry weight). The oral glucose tolerance test in mice showed a highly significant blood glucose-lowering effect. The acute toxicity in mice revealed that the MVS did not show toxicity at the dose of 2000 mg/kg. Leaves and stems of V. secundiflorum showed significant antioxidant and antidiabetic properties supporting the plant traditional use, even if further studies on bioactive compounds and their action mechanisms should be carried out to confirm these preliminary results.

Synthesis and Hypoglycemic Activity of Aryl(Hetaryl)Propenoic Cyanopyrrolidine Amides

A series of amides based on (2S)-cyanopyrrolidine and α, β-unsaturated aryl- and hetarylcarboxylic acids have been synthesized. The dependence of the hypoglycemic activity of compounds on the structure of the aromatic fragment has been studied in the oral glucose tolerance test in mice. Amides based on (E)-3-phenylprop-2-enoic and (E)-3-(4-methoxyphenyl)prop-2-enoic acids and (2S)-cyanopyrrolidine have been shown to significantly reduce blood glucose levels in mice. The observed hypoglycemic effect at a dose of 10 mg/kg is comparable to the effect of hypoglycemic drug vildagliptin.

Triterpenoids from Hibiscus sabdariffa L.with PPARδ/γ Dual Agonist Action: In Vivo, In Vitro and In Silico Studies.

Hibiscus sabdariffa is a medicinal plant consumed as a diuretic and anti-obesity remedy. Several pharmacological studies have shown its beneficial effects in metabolism. Peroxisome proliferator-activated receptors δ and γ may play a role in the actions of H. sabdariffa. These nuclear receptors regulate lipid and glucose metabolism and are therapeutic targets for type 2 diabetes. This research aimed to perform a phytochemical study guided by a bioassay from H. sabdariffa to identify compounds with peroxisome proliferator-activated receptor δ and peroxisome proliferator-activated receptor γ agonist activity, supported by messenger ribonucleic acid expression, molecular docking, lipid accumulation, and an antihyperglycemic effect. An oral glucose tolerance test in mice with the aqueous extract of H. sabdariffa and the dichloromethane extract of H.sabdariffa was performed. The dichloromethane extract of H. sabdariffa exhibited an antihyperglycemic effect. The dichloromethane extract of H. sabdariffa was fractioned, and four fractions were evaluated in 3T3-L1 adipocytes on peroxisome proliferator-activated receptor δ, peroxisome proliferator-activated receptor γ, fatty acid transporter protein, and glucose transporter type 4 messenger ribonucleic acid expression. Fraction F3 exhibited peroxisome proliferator-activated receptor δ/γ dual agonist activity, and a further fractionation yielded two subfractions, F3-1 and F3-2, which also increased peroxisome proliferator-activated receptor δ and peroxisome proliferator-activated receptor γ expression. Subfractions were analyzed by GC/MS. The main compounds identified in F3-1 were linoleic acid, oleic acid, and palmitic acid, while in F3-2, the main compounds identified were α-amyrin and lupeol. These molecules were subjected to molecular docking analysis. α-Amyrin and lupeol showed the highest affinity. Moreover, both produced an increase in peroxisome proliferator-activated receptor δ, peroxisome proliferator-activated receptor γ, fatty acid transporter protein, and glucose transporter type 4 expression. Additionally, α-amyrin and lupeol decreased lipid accumulation in 3T3-L1 adipocytes and blood glucose in mice. Until now, α-amyrin and lupeol have not been reported with activity on peroxisome proliferator-activated receptors. This study provides evidence that α-amyrin and lupeol possess antidiabetic effects through a peroxisome proliferator-activated receptor δ/γ dual agonist action.

Nitric oxide donor-based FFA1 agonists: Design, synthesis and biological evaluation as potential anti-diabetic and anti-thrombotic agents

The cardiovascular complications were highly prevalent in type 2 diabetes mellitus (T2DM), even at the early stage of T2DM or the state of intensive glycemic control. Thus, there is an urgent need for the intervention of cardiovascular complications in T2DM. Herein, the new hybrids of FFA1 agonist and NO donor were design to obtain dual effects of anti-hyperglycemic and anti-thrombosis. As expected, the induced-fit docking study suggested that it is feasible for our design strategy to hybrid NO donor with compound 1. These hybrids exhibited moderate FFA1 agonistic activities and anti-platelet aggregation activities, and their anti-platelet effects mediated by NO were also confirmed in the presence of NO scavenger. Moreover, compound 3 revealed significantly hypoglycemic effect and even stronger than that of TAK-875 during an oral glucose tolerance test in mice. Potent and multifunctional hybrid, such as compound 3, is expected as a potential candidate with additional cardiovascular benefits for the treatment of T2DM.

Design, synthesis and biological evaluation of nitric oxide releasing derivatives of dapagliflozin as potential anti-diabetic and anti-thrombotic agents

The cardiovascular complications were highly prevalent in type 2 diabetes mellitus (T2DM), even at the early stage of T2DM or the state of intensive glycemic control. Therefore, there is an urgent need for the intervention of cardiovascular complications in T2DM. Herein, the new hybrids of NO donor and SGLT2 inhibitor were design to achieve dual effects of anti-hyperglycemic and anti-thrombosis. As expected, the preferred hybrid 2 exhibited moderate SGLT2 inhibitory effects and anti-platelet aggregation activities, and its anti-platelet effect mediated by NO was also confirmed in the presence of NO scavenger. Moreover, compound 2 revealed significantly hypoglycemic effects and excretion of urinary glucose during an oral glucose tolerance test in mice. Potent and multifunctional hybrid, such as compound 2, is expected as a potential candidate for the intervention of cardiovascular complications in T2DM.

Angptl8 antisense oligonucleotide improves adipose lipid metabolism and prevents diet-induced NAFLD and hepatic insulin resistance in rodents.

Targeting regulators of adipose tissue lipoprotein lipase could enhance adipose lipid clearance, prevent ectopic lipid accumulation and consequently ameliorate insulin resistance and type 2 diabetes. Angiopoietin-like 8 (ANGPTL8) is an insulin-regulated lipoprotein lipase inhibitor strongly expressed in murine adipose tissue. However, Angptl8 knockout mice do not have improved insulin resistance. We hypothesised that pharmacological inhibition, using a second-generation antisense oligonucleotide (ASO) against Angptl8 in adult high-fat-fed rodents, would prevent ectopic lipid accumulation and insulin resistance by promoting adipose lipid uptake. ANGPTL8 expression was assessed by quantitative PCR in omental adipose tissue of bariatric surgery patients. High-fat-fed Sprague Dawley rats and C57BL/6 mice were treated with ASO against Angptl8 and insulin sensitivity was assessed by hyperinsulinaemic-euglycaemic clamps in rats and glucose tolerance tests in mice. Factors mediating lipid-induced hepatic insulin resistance were assessed, including lipid content, protein kinase Cε (PKCε) activation and insulin-stimulated Akt phosphorylation. Rat adipose lipid uptake was assessed by mixed meal tolerance tests. Murine energy balance was assessed by indirect calorimetry. Omental fat ANGPTL8 mRNA expression is higher in obese individuals with fatty liver and insulin resistance compared with BMI-matched insulin-sensitive individuals. Angptl8 ASO prevented hepatic steatosis, PKCε activation and hepatic insulin resistance in high-fat-fed rats. Postprandial triacylglycerol uptake in white adipose tissue was increased in Angptl8 ASO-treated rats. Angptl8 ASO protected high-fat-fed mice from glucose intolerance. Although there was no change in net energy balance, Angptl8 ASO increased fat mass in high-fat-fed mice. Disinhibition of adipose tissue lipoprotein lipase is a novel therapeutic modality to enhance adipose lipid uptake and treat non-alcoholic fatty liver disease and insulin resistance. In line with this, adipose ANGPTL8 is a candidate therapeutic target for these conditions.

A gut–brain axis regulating glucose metabolism mediated by bile acids and competitive fibroblast growth factor actions at the hypothalamus

ObjectiveBile acids have been implicated as important regulators of glucose metabolism via activation of FXR and GPBAR1. We have previously shown that FGF19 can modulate glucose handling by suppressing the activity of hypothalamic AGRP/NPY neurons. As bile acids stimulate the release of FGF19/FGF15 into the circulation, we pursued the potential of bile acids to improve glucose tolerance via a gut–brain axis involving FXR and FGF15/FGF19 within enterocytes and FGF receptors on hypothalamic AGRP/NPY neurons. MethodsA 5-day gavage of taurocholic acid, mirroring our previous protocol of a 5-day FGF19 treatment, was performed. Oral glucose tolerance tests in mice with genetic manipulations of FGF signaling and melanocortin signaling were used to define a gut–brain axis responsive to bile acids. ResultsThe taurocholic acid gavage led to increased serum concentrations of taurocholic acid as well as increases of FGF15 mRNA in the ileum and improved oral glucose tolerance in obese (ob/ob) mice. In contrast, lithocholic acid, an FXR antagonist but a potent agonist for GPBAR1, did not improve glucose tolerance. The positive response to taurocholic acid is dependent upon an intact melanocortinergic system as obese MC4R-null mice or ob/ob mice without AGRP did not show improvements in glucose tolerance after taurocholate gavage. We also tested the FGF receptor isoform necessary for the bile acid response, using AGRP:Fgfr1−/− and AGRP:Fgfr2−/− mice. While the absence of FGFR1 in AGRP/NPY neurons did not alter glucose tolerance after taurocholate gavage, manipulations of Fgfr2 caused bidirectional changes depending upon the experimental model. We hypothesized the existence of an endogenous hypothalamic FGF, most likely FGF17, that acted as a chronic activator of AGRP/NPY neurons. We developed two short peptides based on FGF8 and FGF17 that should antagonize FGF17 action. Both of these peptides improved glucose homeostasis after a 4-day course of central and peripheral injections. Significantly, daily average blood glucose from continuous glucose monitoring was reduced in all tested animals but glucose concentrations remained in the euglycemia range. ConclusionsWe have defined a gut–brain axis that regulates glucose metabolism mediated by antagonistic fibroblast growth factors. From the intestine, bile acids stimulate FGF15 secretion, leading to activation of the FGF receptors in hypothalamic AGRP/NPY neurons. FGF receptor intracellular signaling subsequently silences AGRP/NPY neurons, leading to improvements of glucose tolerance that are likely mediated by the autonomic nervous system. Finally, short peptides that antagonize homodimeric FGF receptor signaling within the hypothalamus have beneficial effects on glucose homeostasis without inducing hypoglycemia. These peptides could provide a new mode of regulating glucose metabolism.

Chemical composition and pharmacological activities of Pisum sativum

BackgroundConsumption of vegetables has been proven to be effective in the prevention of different diseases. Traditionally edible aerial part of Pisum sativum L. subsp. sativum (Fabaceae) is used to treat diabetes, heart diseases and as blood purifier. Present study was aimed to explore the traditional use of aerial parts of P. sativum as a source of antidiabetic agent. In addition, antioxidant activity and chemical composition was carried out.MethodsTotal polyphenol content was spectrophotometrically determined using Folin Chiocalteu’s reagent while the flavonoids by aluminum chloride colorimetric assay. Identification of compounds of the extract was made through HPLC and LCMS. Antihyperglycemic activity was assessed by oral glucose tolerance test in mice. Antioxidant activity was determined by DPPH free radical scavenging and reducing power assay.ResultsTotal polyphenol and total flavonoids content were found to be 51.23 mg gallic acid equivalent and 30.88 mg quercetin equivalent per gram of dried plant extract respectively. Ellagic acid and p-coumeric acid were detected through HPLC. A total of eight compounds including naringenin, β-sitosterol were indentified through LCMS. In OGTT, extract (200 mg/kg bw) showed a 30.24% decrease (P< 0.05) in blood glucose levels at 30 min compared to the normal control. The extract showed IC50 value of 158.52 μg/mL in DPPH scavenging assay and also showed comparable reducing power.ConclusionAlong with other compounds ellagic acid and β-sitosterol present in the extract may be responsible for its antioxidant as well as antihyperglycemic activities. Altogether these results rationalize the use of this vegetable in traditional medicine.

Phytochemical screening and study of antioxidant, antimicrobial, antidiabetic, anti-inflammatory and analgesic activities of extracts from stem wood of Pterocarpus marsupium Roxburgh.

The main aims of the study were to evaluate the phytochemical constituents and to study the antioxidant, antimicrobial, antidiabetic, anti-inflammatory, and analgesic activities of extracts from stem wood of Pterocarpus marsupium. Ethanol, acetone and isopropyl alcohol (IPA) (1:1) extracts of stem wood of P. marsupium were subjected to phytochemical screening and analysis of biological activities from August 2015 to January 2016. The antioxidant assay was carried out using 2, 2-diphenyl-1-picrylhydrazyl scavenging method, antimicrobial activity testing by cup diffusion method, antidiabetic test evaluation by oral glucose tolerance test in mice, anti-inflammatory effect was evaluated by hind paw edema method in mice and analgesic test evaluation by a chemical writhing method in mice. The results of the study revealed that P. marsupium is a source of various phytoconstituents such as alkaloids, glycosides, saponins, tannins, proteins, carbohydrates, cardiac glycosides, flavonoids, and terpenoids. Both the acetone and IPA extract as well as the ethanol extract of stem wood of P. marsupium exhibited a dose-dependent antioxidant activity. Acetone and IPA extract showed antibacterial activity against Gram-positive bacteria, while the ethanolic extract was found to possess antidiabetic activity. The antidiabetic activity of the extract was found to be time and dose-dependent. Similarly, the acetone and IPA extract was found to have anti-inflammatory activity, which was also time and dose-dependent. Furthermore, the ethanolic extract showed analgesic activity, which was dose-dependent. The ethanolic extract was found to be nontoxic. Thus, this study laid sufficient background for the further research on extracts from stem wood of P. marsupium for identification, subsequent purification and isolation of compounds having antibacterial, antidiabetic, anti-inflammatory, and analgesic activities.