Reduced Plasma Glucose Levels Research Articles

SGLT inhibitors attenuate NO-dependent vascular relaxation in the pulmonary artery but not in the coronary artery.

Inhibitors of sodium-glucose cotransporter (SGLT)2 are a new class of oral drugs for type 2 diabetic patients that reduce plasma glucose levels by inhibiting renal glucose reabsorption. There is increasing evidence showing the beneficial effect of SGLT2 inhibitors on glucose control; however, less information is available regarding the impact of SGLT2 inhibitors on cardiovascular outcomes. The present study was designed to determine whether SGLT inhibitors regulate vascular relaxation in mouse pulmonary and coronary arteries. Phlorizin (a nonspecific SGLT inhibitor) and canagliflozin (a SGLT2-specific inhibitor) relaxed pulmonary arteries in a dose-dependent manner, but they had little or no effect on coronary arteries. Pretreatment with phlorizin or canagliflozin significantly inhibited sodium nitroprusside (SNP; a nitric oxide donor)-induced vascular relaxation in pulmonary arteries but not in coronary arteries. Phlorizin had no effect on cGMP-dependent relaxation in pulmonary arteries. SNP induced membrane hyperpolarization in human pulmonary artery smooth muscle cells, and pretreatment of cells with phlorizin and canagliflozin attenuated SNP-induced membrane hyperpolarization by decreasing K(+) activities induced by SNP. Contrary to the result observed in ex vivo experiments with SGLT inhibitors, SNP-dependent relaxation in pulmonary arteries was not altered by chronic administration of canagliflozin. On the other hand, canagliflozin administration significantly enhanced SNP-dependent relaxation in coronary arteries in diabetic mice. These data suggest that SGLT inhibitors differentially regulate vascular relaxation depending on the type of arteries, duration of the treatment, and health condition, such as diabetes.

Transdermal nanoemulsions of Foeniculum vulgare Mill. essential oil: Preparation, characterization and evaluation of antidiabetic potential

Foeniculum vulgare Mill., family Umbelliferae, is well known for its essential oil. One of the major components of F. vulgare seed's essential oil is trans-anethole. F. vulgare (fennel) possesses antioxidant and antidiabeic activities. Transdermal nanoemulsions (NEs) were employed to encapsulate fennel essential oil (FEO) with the aim of attaining effective prolonged antidiabetic action. A large NE existence area was obtained on phase diagrams employing oleic acid; oil phase and Tween20/propylene glycol; Smix in the ratios 1:1, 2:1 and 3:1 and water. Encapsulation efficiency was evaluated for trans-anethole (TA) by HPLC analysis and reached 64% in the prepared NEs. NEs were characterized for thermodynamic stability, conductivity, pH, particle size and zeta potential. Values obtained were promising. Permeation profiles for 24 h showed the superiority of FEO NE, F1, which showed also a high potential of reducing plasma glucose levels in rats which continued for 7-days after a single topical application of a dose of 120 mg/kg of FEO. These results highlight the high efficiency of F1, formed of 2% FEO, 5.6% oleic acid, 68% Smix (1:1) and distilled water, in bringing glucose levels to normal in diabetic rats.

Oral magnesium supplementation improves glycaemic status in subjects with prediabetes and hypomagnesaemia: A double-blind placebo-controlled randomized trial

AimThis study evaluated the efficacy of oral magnesium supplementation in the reduction of plasma glucose levels in adults with prediabetes and hypomagnesaemia. MethodsA total of 116 men and non-pregnant women, aged 30 to 65years with hypomagnesaemia and newly diagnosed with prediabetes, were enrolled into a randomized double-blind placebo-controlled trial to receive either 30mL of MgCl2 5% solution (equivalent to 382mg of magnesium) or an inert placebo solution once daily for four months. The primary trial endpoint was the efficacy of magnesium supplementation in reducing plasma glucose levels. ResultsAt baseline, there were no significant statistical differences in terms of anthropometric and biochemical variables between individuals in the supplement and placebo groups. At the end of follow-up, fasting (86.9±7.9 and 98.3±4.6mg/dL, respectively; P=0.004) and post-load glucose (124.7±33.4 and 136.7±23.9mg/dL, respectively; P=0.03) levels, HOMA-IR indices (2.85±1.0 and 4.1±2.7, respectively; P=0.04) and triglycerides (166.4±90.6 and 227.0±89.7, respectively; P=0.009) were significantly decreased, whereas HDL cholesterol (45.6±10.9 and 46.8±9.2mg/dL, respectively; P=0.04) and serum magnesium (1.96±0.27 and 1.60±0.26mg/dL, respectively; P=0.005) levels were significantly increased in those taking MgCl2 compared with the controls. A total of 34 (29.4%) people improved their glucose status (50.8% and 7.0% in the magnesium and placebo groups, respectively; P<0.0005). ConclusionOur results show that magnesium supplementation reduces plasma glucose levels, and improves the glycaemic status of adults with prediabetes and hypomagnesaemia.

Acute Hepatic Insulin Resistance Contributes to Hyperglycemia in Rats Following Myocardial Infarction.

Although hyperglycemia is common in patients with acute myocardial infarction (MI), the underlying mechanisms are largely unknown. Insulin signaling plays a key role in the regulation of glucose homeostasis. In this study, we test the hypothesis that rapid alteration of insulin signaling pathways could be a potential contributor to acute hyperglycemia after MI. Male rats were used to produce MI by ligation of the left anterior descending coronary artery. Plasma glucose and insulin levels were significantly higher in MI rats than those in controls. Insulin-stimulated tyrosine phosphorylation of insulin receptor substrate 1 (IRS1) was reduced significantly in the liver tissue of MI rats compared with controls, followed by decreased attachment of phosphatidylinositol 3-kinase (PI3K) p85 subunit with IRS1 and Akt phosphorylation. However, insulin-stimulated signaling was not altered significantly in skeletal muscle after MI. The relative mRNA levels of phosphoenolpyruvate carboxykinase (PEPCK) and G6Pase were slightly higher in the liver tissue of MI rats than those in controls. Rosiglitazone (ROSI) markedly restored hepatic insulin signaling, inhibited gluconeogenesis and reduced plasma glucose levels in MI rats. Insulin resistance develops rapidly in liver but not skeletal muscle after MI, which contributes to acute hyperglycemia. Therapy aimed at potentiating hepatic insulin signaling may be beneficial for MI-induced hyperglycemia.

A Case of Diabetic Ketoacidosis Induced by Sodium-Glucose Cotransporter 2 Inhibitor

Sodium-glucose cotransporter 2 (SGLT2) inhibitors are a new class of oral antihyperglycemic drugs; inhibition of the cotransporter allows for increased renal glucose excretion that consequently leads to reduced plasma glucose level. We report a rare case of a 73-year-old woman with type 2 diabetes mellitus who developed severe ketoacidosis caused by an SGLT2 inhibitor. At admission, severe ketoacidosis with arterial PH 6.99 was observed, though her serum glucose level of 232 mg/dL was not excessively high. It is necessary to pay attention to patients with type 2 diabetes being treated with an SGLT2 inhibitor, as anorexia, diarrhea, dehydration, and weight loss can develop in conjunction with a high fat/protein diet.

Inhibitory effect of black tea and its combination with acarbose on small intestinal α-glucosidase activity

Ethnopharmacological relevanceIt is said that black tea is effective against type 2 diabetes mellitus because it can help modulate postprandial hyperglycemia. However, the mechanism underlying its therapeutic and preventive effects on type 2 diabetes mellitus is unclear. In this study, we focused on the effect of black tea on the carbohydrate digestion and absorption process in the gastrointestinal tract. We examined whether black tea can modulate postprandial hyperglycemia. Materials and methodsThe freeze-dried powder of the aqueous extract of black tea leaves (JAT) was used for in vitro studies of α-amylase activity, α-glucosidase activity, and glucose uptake by glucose transporters in Caco-2 cells; ex vivo studies of small intestinal α-glucosidase activity; and in vivo studies of oral sugar tolerance in GK rats, an animal model of nonobese type 2 diabetes mellitus. ResultsHalf maximal inhibitory concentration values indicated that JAT significantly reduced α-glucosidase activity, but weakly reduced α-amylase activity. Kinetic studies of rat small intestinal α-glucosidase activity revealed that the combination of JAT and the α-glucosidase inhibitor, acarbose, showed a mixed-type inhibition. JAT had no effect on the uptake of 2′-deoxy-d-glucose by glucose transporter 2 (GLUT2) and the uptake of α-methyl-d-glucose by sodium-dependent glucose transporter 1 (SGLT1). In the oral sucrose tolerance test in GK rats, JAT reduced plasma glucose levels in a dose-dependent manner compared with the control group. The hypoglycemic action of JAT was also confirmed: JAT, in combination with acarbose, produced a synergistic inhibitory effect on plasma glucose levels in vivo. In contrast to the oral sucrose tolerance test, JAT showed no effect in the oral glucose tolerance test. ConclusionsJAT was demonstrated to inhibit the degradation of disaccharides into monosaccharides by α-glucosidase in the small intestine. Thereby indirectly preventing the absorption of the dietary source of glucose mediated by SGLT1 and GLUT2 transporters localized at the apical side of enterocytes in the small intestine. The results indicate that black tea could be useful as a functional food in the dietary therapy for borderline type 2 diabetes mellitus that could modulate postprandial hyperglycemia.

Dapagliflozin efficacy and safety: a perspective review.

Type 2 diabetes mellitus is a prevalent, progressive disease with a need for innovative therapeutic agents to continue to advance disease management. Dapagliflozin is the second agent in a new class of oral antihyperglycemic drugs: sodium-glucose cotransporter 2 (SGLT2) inhibitors. SGLT2 is responsible for the majority of renal glucose reuptake; inhibition of the cotransporter allows for increased renal glucose excretion that consequently leads to reduced plasma glucose levels. Because this mechanism does not require the action of insulin, dapagliflozin rarely causes hypoglycemia and is effective in patients both early and late in the course of their disease. Studies of dapagliflozin have demonstrated efficacy both as monotherapy and in combination with oral antihyperglycemic agents and insulin. Dapagliflozin has been shown to decrease hemoglobin A1c (HbA1c) values 6 mmol/mol (0.5%) to 8 mmol/mol (0.7%). The most common adverse reactions observed with dapagliflozin in clinical trials were female genital mycotic infections, urinary tract infections, and nasopharyngitis. Dapagliflozin is a new oral agent for type 2 diabetes with short-term efficacy similar to dipeptidyl peptidase 4 inhibitors; its long-term safety and efficacy are unknown.

Fisiología del GLP-1 y su papel en la fisiopatología de la diabetes mellitus tipo 2

The hormone glucagon-like peptide-1 (GLP-1) is synthesized and secreted by L cells in the small intestine in response to food ingestion. After reaching the general circulation it has a half-life of 2-3 minutes due to degradation by the enzyme dipeptidyl peptidase-4.Its physiological role is directed to control plasma glucose concentration, though GLP-1 also plays other different metabolic functions following nutrient absorption. Biological activities of GLP-1 include stimulation of insulin biosynthesis and glucose-dependent insulin secretion by pancreatic beta cell, inhibition of glucagon secretion, delay of gastric emptying and inhibition of food intake.GLP-1 is able to reduce plasma glucose levels in patients with type 2 diabetes and also can restore beta cell sensitivity to exogenous secretagogues, suggesting that the increasing GLP-1 concentration may be an useful therapeutic strategy for the treatment of patients with type 2 diabetes.

Pharmacokinetic and pharmacodynamic study of ipragliflozin in Japanese patients with type 2 diabetes mellitus: A randomized, double-blind, placebo-controlled study

AimsIpragliflozin is a novel and highly selective sodium–glucose transporter 2 (SGLT2) inhibitor that reduces plasma glucose levels by enhancing urinary glucose excretion in patients with type 2 diabetes mellitus (T2DM). We examined the pharmacokinetic and pharmacodynamic characteristics of two oral doses of ipragliflozin in Japanese patients with T2DM. MethodsIn this randomized, placebo-controlled, double-blind study, patients were treated with placebo, 50mg or 100mg ipragliflozin once daily for 14 days. Plasma and urine pharmacodynamic parameters were measured on Days −1 and 14, and pharmacokinetic parameters on Day 14. Pharmacodynamic characteristics included area under the curve (AUC) for plasma glucose and insulin for 0–3h (AUC0–3h) and 0–24h (AUC0–24h). Pharmacokinetic characteristics included AUC0–24h, maximum ipragliflozin concentration (Cmax), and time to maximum plasma ipragliflozin concentration (tmax). ResultsThirty patients were enrolled; 28 were included in pharmacokinetic/pharmacodynamic analyses and 30 in safety analyses. Administration of 50 and 100mg ipragliflozin significantly reduced fasting plasma glucose, as well as the AUC0–3h and AUC0–24h for plasma glucose relative to placebo. Both doses of ipragliflozin also reduced AUC0–24h for insulin, body weight, and glycoalbumin, while urinary glucose excretion increased remarkably. Cmax and AUC0–24h were 1.7- and 1.9-fold higher, respectively, in the 100-mg group than in the 50-mg group. ConclusionsIpragliflozin increased urinary glucose excretion and improved fasting and postprandial glucose, confirming its pharmacokinetic/pharmacodynamic properties in Japanese patients with T2DM.

Seguridad cardiovascular de los antidiabéticos no insulínicos. Posicionamiento científico SEMERGEN

Diabetes increases the risk of both microvascular and macrovascular complications. Although reducing plasma glucose levels to recommended targets decreases the risk of microvascular outcomes, the effects of anti-diabetic drugs on macrovascular complications and cardiovascular death are of concern. In fact, it has been suggested that some anti-diabetic agents could even be harmful for cardiovascular outcomes.In this context, several health care regulatory agencies have established the need for performing clinical trials specifically designed to assess the cardiovascular safety of anti-diabetic drugs. The results of 2 clinical trials have recently been published that provide important information on the cardiovascular safety of dipeptidyl peptidase 4 (DPP-4) inhibitors.The aim of this document was to review the available evidence on the cardiovascular safety of non-insulin anti-diabetic drugs and provide practical recommendations on their use in this context.

Abstract 438: Peripheral but Not Central Glucagon-Like Peptide-1 Receptor Agonism Regulates Fasting Dyslipidemia by Reducing VLDL Production

Glucagon-like peptide-1 (GLP-1) is an incretin hormone that reduces plasma glucose levels and thus acts as an important drug target in the treatment of type 2 diabetes (T2D). Our laboratory has further shown that GLP-1 regulates intestinal lipoprotein metabolism and may also play a similar role in the liver. Hepatic lipids are packaged with apolipoprotein B-100 (apoB100) into very low density lipoproteins (VLDL) and secreted into the plasma. Dysregulation of VLDL production results in the fasting dyslipidemia that is observed in T2D. We postulate that GLP-1 receptor (GLP-1R) agonism regulates fasting dyslipidemia by decreasing VLDL production in insulin resistance through a peripheral or central pathway. To test this, experiments were conducted in fructose-fed insulin resistant Syrian golden hamsters. Hamsters were given twice daily intraperitoneal(i.p) injections of the GLP-1R agonist exendin-4 (ex4; 5nM/kg) for 7 days and placed into metabolic cages. Plasma was collected for lipid analysis following i.p poloxamer to prevent lipoprotein uptake and livers were excised. Peripheral ex4 prevented fructose-induced fasting dyslipidemia and decreased fasting plasma- and VLDL-triglyceride (TG), -cholesterol and -apoB100 accumulation. Ex4 also reduced food intake and body weight and thus pair-fed controls were added. Pair-feeding did not account for the full ex4 lipid-lowering effect. In comparison to both controls, ex4 treated hamsters had reduced respiratory exchange ratio and CO 2 production indicating a switch from glucose to fat metabolism as the main source of energy, and also decreased hepatic mRNA markers for de novo lipogenesis. To determine involvement of a central pathway, hamsters received a 4 day intracerebroventricular administration of ex4 (250ng) into the third ventricle. Central ex4 reduced body weight and food intake but did not modulate fasting plasma and VLDL-lipid or apoB100 accumulation, further suggesting that decreases in food intake cannot solely explain the changes in VLDL production. Our studies suggest that GLP-1R agonism reduces fasting dyslipidemia in insulin resistance by decreasing VLDL production through a peripheral pathway. GLP-1R agonism may be a potential therapy in the treatment of fasting dyslipidemia.

Anti‐diabetic efficacy of Fenfuroœ, a novel, patented Trigonella foenum‐graecum seed extract (1019.14)

Anti‐diabetic efficacy of a novel Trigonella foenum‐graecum seed extract (FenfuroTM) enriched in furostanolic saponins was investigated. Sprague‐Dawley rats were given high‐fat diet for 2 weeks followed by streptozotocin (STZ, 35 mg/kg ip). Animals were checked for plasma glucose level (PGL) 2 days post+STZ injection to confirm diabetes. Rats showed &gt;300 mg/dl of PGL were included. FenfuroTM (150‐ and 450 mg/kg po) and glipizide (5 mg/kg po) were administered once daily for 20 days and then twice daily for 10 days over 30 days. Blood was collected on 0, 10, 20 and 30 days and estimated for fasting plasma triglyceride (PTG), TC and Insulin levels. On day 30, FenfuroTM and glipizide‐treated diabetic animals were treated with/without metformin (100 mg/kg) twice daily for the next 10 days. FenfuroTM didn’t affect the body weight, feed and water intake. FenfuroTM (150 mg/kg po) reduced the PTG levels by 22%, 24.6% and 29% on 10‐, 20‐ and 30‐days of treatment, respectively, while glipizide (5 mg/kg po) reduced the PTG levels by 57.4%, 46.2% and 39.4%. FenfuroTM (450 mg/kg) treatment exhibited significant hypoglycemic activity (31.5%) as compared to insulin (48.2% with 1 U/kg i.p.). Fenugreek (150 mg/kg po) and Metformin (100 mg/kg po) combination produced significant reduction in PGL (20.7%). These studies demonstrated the efficacy of this FenfuroTM extract in type 2 diabetes.Grant Funding Source: Supported by Cepham Inc, NJ

Efek hipoglikemik tepung komposit (ubi jalar ungu, jagung kuning, dan kacang tunggak) pada tikus diabetes induksi streptozotocin

Background: The composite flour (50% sweet potato, 30% corn, and 20% cowpea) had proven that it could substitute 100% wheat flour for biscuit making. Intake of antioxidants, dietary fiber, and protein, had been known to reduce plasma glucose level. Objective: To evaluate the effect of composite flour diet on plasma glucose levels, body weight and food consumption of streptozotocin (STZ)-diabetic rats.Method: Thirty male Sprague-Dawley rats aged ± 2 months (± 200 grams), were divided into three groups of ten rats. They were (1) non-diabetic standard diet (ND-STD), (2) diabetic (65 mg/kg of body weight by STZ induction) standard diet (D-STD), and (3) diabetic composite flour diet (1,5 g/100 g of body weight/day) (D-CFD), for 4 weeks, 3 days after STZ induction. The plasma glucose obtained from GOD-PAP method were determined before induction, after induction and every week during diet intervention.Results: Plasma glucose levels was significantly lower in D-CFD when compared with D-STD (p&lt;0,05). The weight of D-STD was found to be significantly decreased as compared to ND-STD (p&lt;0,05). There were no changes in food consumption of ND-STD, D-STD and D-CFD (p&lt;0,05).Conclusion: The composite flour could reduce plasma glucose level in diabetic rats and did not give negative effects on body weight and food consumption.

MAPK pathway mediates the induction of visfatin in neonatal SD rat cardiomyocytes pretreated with glucose

The protein visfatin is an insulin mimetic that has been shown to reduce plasma glucose levels, increase cytokine production and induce angiogenesis. However, few studies have focused on visfatin expression in cardiomyocytes at the cellular level. Therefore, the aim of the present study was to investigate visfatin expression and its potential mechanisms in cultured neonatal rat cardiomyocytes exposed to high-glucose concentrations. Primary cultures of 2-to 3-day-old Sprague Dawley (SD) rat cardiomyocytes were pretreated with increasing concentrations of glucose. P38 mitogen-activated protein kinase (MAPK) pathway inhibitor SB203580, extra cellular signal-regulated kinase (ERK1/2) pathway inhibitor PD098059 and c-Jun NH 2-terminal kinase (JNK) pathway inhibitor SP600125 were used to block the effect of glucose on visfatin expression. Cell viability following each glucose treatment was determined using the MTT assay. Expression of visfatin was detected using RT-PCR and western blot analysis. Increased glucose concentration directly correlated with an increased expression of visfatin mRNA and protein in neonatal rat cardiomyocytes. Following high doses of glucose, visfatin mRNA and protein expression peaked after 24 h with no significant change thereafter. Increased visfatin expression was blocked by the P38 MAPK inhibitor SB203580, suggesting a potential mechanism not yet identified. Expression of visfatin in cardiomyocytes was increased through the P38 MAPK pathway in the presence of high-glucose concentrations.

Novel treatment approaches in hypertensive type 2 diabetic patients.

Type 2 diabetes mellitus (T2DM) and hypertension represent two common conditions worldwide. Their frequent association with cardiovascular diseases makes management of hypertensive patients with T2DM an important clinical priority. Carvedilol and renal denervation are two promising choices to reduce plasma glucose levels and blood pressure in hypertensive patients with T2DM to reduce future complications and improve clinical outcomes and prognosis. Pathophysiological mechanisms of both options are under investigation, but one of the most accepted is an attenuation in sympathetic nervous system activity which lowers blood pressure and improves insulin sensitivity. Choice of these therapeutic approaches should be individualized based on specific characteristics of each patient. Further investigations are needed to determine when to consider their use in clinical practice.

Alteration of De Novo Glucose Production Contributes to Fasting Hypoglycaemia in Fyn Deficient Mice

Previous studies have demonstrated that glucose disposal is increased in the Fyn knockout (FynKO) mice due to increased insulin sensitivity. FynKO mice also display fasting hypoglycaemia despite decreased insulin levels, which suggested that hepatic glucose production was unable to compensate for the increased basal glucose utilization. The present study investigates the basis for the reduction in plasma glucose levels and the reduced ability for the liver to produce glucose in response to gluconeogenic substrates. FynKO mice had a 5-fold reduction in phosphoenolpyruvate carboxykinase (PEPCK) gene and protein expression and a marked reduction in pyruvate, pyruvate/lactate-stimulated glucose output. Remarkably, de novo glucose production was also blunted using gluconeogenic substrates that bypass the PEPCK step. Impaired conversion of glycerol to glucose was observed in both glycerol tolerance test and determination of the conversion of 13C-glycerol to glucose in the fasted state. α-glycerol phosphate levels were reduced but glycerol kinase protein expression levels were not changed. Fructose-driven glucose production was also diminished without alteration of fructokinase expression levels. The normal levels of dihydroxyacetone phosphate and glyceraldehyde-3-phosphate observed in the FynKO liver extracts suggested normal triose kinase function. Fructose-bisphosphate aldolase (aldolase) mRNA or protein levels were normal in the Fyn-deficient livers, however, there was a large reduction in liver fructose-6-phosphate (30-fold) and fructose-1,6-bisphosphate (7-fold) levels as well as a reduction in glucose-6-phosphate (2-fold) levels. These data suggest a mechanistic defect in the allosteric regulation of aldolase activity.

Beneficial effect of melatonin treatment on age-related insulin resistance and on the development of type 2 diabetes.

Abstract This paper will review the effect of aging on glucose metabolism and insulin resistance in pancreas and in peripheral tissues and how melatonin administration could affect these parameters. In SAMP8 mice insulin levels in plasma were found to be increased together with enhanced HOMA-IR values, whereas insulin content in pancreas showed a decrease with aging. Aging in SAMP8 mice was also associated with a significant increase in the relative expression of both protein and mRNA of different pro-inflammatory mediators. Furthermore, aging was associated with a decrease in the expression of Pdx-1, FoxO 1 and FoxO 3A and Sirt 1 in pancreas SAMP8 samples. Melatonin administration was able to reduce these age-related alterations, decreasing plasma insulin levels and increasing its pancreatic content in SAMP8 mice. HOMA-IR was decreased with melatonin treatment in all animals. Conversely, in SAMP8 mice, melatonin treatment decreased the expression of glucagon, GLUT2, somatostatin and insulin. Furthermore it was also able to increase the expression of Sirt 1, Pdx-1 and FoxO 3A. The present study has shown that aging is associated with significant alterations in the relative expression of pancreatic genes involved in both insulin secretion and glucose metabolism and that these are associated with an increase in inflammation and oxidative stress. Melatonin administration was able to reduce oxidative stress and inflammation and thus to improve pancreatic function in old mice. By doing so, insulin resistance is diminished and plasma insulin is reduced, enhancing insulin pancreatic content and reducing plasma glucose levels and HOMA index.

Effects of small interfering RNA-mediated hepatic glucagon receptor inhibition on lipid metabolism in db/db mice

Hepatic glucose overproduction is a major characteristic of type 2 diabetes. Because glucagon is a key regulator for glucose homeostasis, antagonizing the glucagon receptor (GCGR) is a possible therapeutic strategy for the treatment of diabetes mellitus. To study the effect of hepatic GCGR inhibition on the regulation of lipid metabolism, we generated siRNA-mediated GCGR knockdown (si-GCGR) in the db/db mouse. The hepatic knockdown of GCGR markedly reduced plasma glucose levels; however, total plasma cholesterol was increased. The detailed lipid analysis showed an increase in the LDL fraction, and no change in VLDL HDL fractions. Further studies showed that the increase in LDL was the result of over-expression of hepatic lipogenic genes and elevated de novo lipid synthesis. Inhibition of hepatic glucagon signaling via siRNA-mediated GCGR knockdown had an effect on both glucose and lipid metabolism in db/db mice.

In vitro and in vivo evaluation of quinine in gilthead sea bream, Sparus aurata naturally infected with the ciliate Cryptocaryon irritans

The use of quinine as a potential antiparasitic compound was evaluated at cellular level and in naturally infected gilthead sea bream, Sparus aurata with the ciliate Cryptocaryon irritans. Quinine concentrations up to 10μg/ml (30μΜ) did not exhibit any in vitro hemolytic or pro-apoptotic effects on red blood cells or head kidney macrophages, respectively. Dietary administration of quinine in gilthead sea bream at a concentration of 100mg/kg fish for 10days was incomplete due to palatability problems after the fifth day post treatment. A decreasing distribution profile of quinine was evident in the analyzed tissues even during the period where quinine consumption was supposedly ensured. The highest concentrations were measured on day 1 reaching 8.98±3.85μg/ml (27μΜ), 1.33±0.45μg/g and 0.75±0.48μg/g in plasma, skin and gills respectively. Quinine was rapidly removed from the tissue compartment while it remained at low concentration in fish circulation after therapy. A 100% C. irritans prevalence was accompanied with no mortalities during the experiment. Parasitic intensity, measured as trophont number, was significantly reduced in quinine-treated fish at the first sampling point (3rd day: 8±0.8 vs 11±2.6), while no statistical differences were observed thereafter. A significant reduction in plasma glucose level was also observed at the same time point. Organoleptic evaluation in fillets, showed no difference in the flesh bitterness between quinine-treated and control fish.In conclusion, quinine has no cytotoxic effect on the assessed fish cells and is adequately absorbed in circulation, affecting the glycemic level but its distribution to the targeted tissues by the ciliate tissues is relatively small. Quinine significantly reduced C. irritans' intensity in lightly-infected gilthead sea bream. The sensory attributes of quinine-treated fish are not affected by the treatment.

Abstract 373: Mineralocorticoid Receptor and Rhoa/rho Kinase Contribute to Vascular Dysfunction in Obese Db/db Mice

Increasing evidence indicates that adipose tissue modulates vascular function. Our previous studies demonstrated that adipocytes secrete aldosterone. We hypothesized that adipocyte-releasing factors induce vascular dysfunction through mineralocorticoid receptor (MR)-dependent mechanisms. This study explored the small G protein RhoA/Rho kinase as a pathway linking aldosterone/MR and the paracrine effects of adipose tissue in the vasculature, since the activation of this pathway regulates vascular contraction. Diabetic obese mice (db/db) and their control counterparts (db/+) were treated with MR antagonist (MRA) (K canrenoate, 30mg/Kg/day, S.C., 4 weeks) or RhoA/Rho kinase inhibitor, fasudil (30 mg/Kg/day, S.C., 3 weeks). Blood pressure levels were similar between groups. Fasudil, but not MRA, reduced plasma glucose levels in db/db mice (db/+:12.3±6; db/db: 30.1±3; MRA-treated db/db: 32.5±2; fasudil treated db/db: 17.1±2; mmoL/mL). Arteries from db/db mice displayed reduced relaxation to 10 - 5 M acetycholine (Ach; db/+:79.4±3.9% vs db/db: 14.3±3.1%). Arteries from MRA-treated db/db mice exposed to fat conditioned medium (FCM) had improved responses to Ach (MRA-treated db/db: 28.3±1.9% vs MRA-treated db/db +FCM: 42.8±4.3%). Increased norepinephrine (NE)-induced contraction was observed in db/db mice in endothelium-denuded arteries (10 -5 M NE; db/+: 1.5 ± 0.1 vs db/db: 2.2 ± 0.1; mN/mm). NE responses were reduced in MRA-treated db/db mice (1.7±0.1 mN/mm) or fasudil (1.6±0.2 mN/mm). Vascular calcium sensitivity was similar between depolarized arteries from db/+ and db/db. Fasudil treatment reduced calcium-induced contraction in both groups with greater effect in db/db mice (5 mmol/L CaCl 2 ; db/+: 73 % vs db/db: 57 %). MR blockade did not affect vascular RhoA/Rho kinase activity (RhoA membrane to cytosol translocation) in db/db mice. Our data suggest that in db/db mice: MR and RhoA/Rho kinase signaling contribute to adipose modulation of vascular/contraction. While MR plays a role in vascular relaxation, RhoA/Rho kinase signalling is important in contractile dysfunction, adipocyte secretion, and glucose metabolism - processes that may contribute to cardiovascular injury in obesity-associated diabetes.