Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011860 (type 2 diabetes)
 57,723 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Endothelial dysfunction is associated with hypertension, hypercholesterolemia, and heart failure. We tested the hypothesis that spontaneously diabetic Goto-Kakizaki (GK) rats, a model for type 2 diabetes, exhibit endothelial dysfunction. Rats also received a high-sodium diet (6% NaCl [wt/wt]) and chronic angiotensin type 1 (AT(1)) receptor blockade (10 mg/kg PO valsartan for 8 weeks). Compared with age-matched nondiabetic Wistar control rats, GK rats had higher blood glucose levels (9.3+/-0.5 versus 6.9+/-0.2 mmol/L for control rats), 2.7-fold higher serum insulin levels, and impaired glucose tolerance (all P<0.05). Telemetry-measured mean blood pressure was 15 mm Hg higher in GK rats (P<0.01) compared with control rats, whereas heart rates were not different. Heart weight- and kidney weight-to-body weight ratios were higher in GK rats (P<0.05), and 24-hour albuminuria was increased 50%. Endothelium-mediated relaxation of noradrenaline-precontracted mesenteric arterial rings by acetylcholine was impaired compared with the control condition (P<0.05), whereas the sodium nitroprusside-induced relaxation was similar. Preincubation of the arterial rings with the NO synthase inhibitor N(G)-nitro-L-arginine methyl ester and the cyclooxygenase inhibitor diclofenac inhibited relaxations to acetylcholine almost completely in GK rats but not in Wistar rats, suggesting that endothelial dysfunction can be in part attributed to reduced relaxation via arterial K(+) channels. Perivascular monocyte/macrophage infiltration and intercellular adhesion molecule-1 overexpression were observed in GK rat kidneys. A high-sodium diet increased blood pressure by 24 mm Hg and 24-hour albuminuria by 350%, induced cardiac hypertrophy, impaired endothelium-dependent relaxation further, and aggravated inflammation (all P<0.05). The serum level of 8-isoprostaglandin F(2alpha), a vasoconstrictor and antinatriuretic arachidonic acid metabolite produced by oxidative stress, was increased 400% in GK rats on a high-sodium diet. Valsartan decreased blood pressure in rats fed a low-sodium diet and prevented the inflammatory response. In rats fed a high-sodium diet, valsartan did not decrease blood pressure or improve endothelial dysfunction but protected against albuminuria, inflammation, and oxidative stress. As measured by quantitative autoradiography, AT(1) receptor expression in the medulla was decreased in GK compared with Wistar rats, whereas cortical AT(1) receptor expression, medullary and cortical angiotensin type 2 (AT(2)) receptor expressions, and adrenal ACE and neutral endopeptidase expressions were unchanged. A high-sodium diet did not influence renal AT(1), AT(2), ACE, or neutral endopeptidase expressions. In valsartan-treated GK rats, the cortical and medullary AT(1) receptor expressions were decreased in the presence and absence of a high-sodium diet. A high-sodium diet increased plasma brain natriuretic peptide concentrations in presence and absence of valsartan treatment. We conclude that hypertension in GK rats is salt sensitive and associated with endothelial dysfunction and perivascular inflammation. AT(1) receptor blockade ameliorates inflammation during a low-sodium diet and partially protects against salt-induced vascular damage by blood pressure-independent mechanisms.
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PMID:Endothelial dysfunction and salt-sensitive hypertension in spontaneously diabetic Goto-Kakizaki rats. 1123 Mar 14

Although nonsteroidal anti-inflammatory drugs (NSAIDs) are used as cancer chemopreventative agents, their mechanism is unclear because NSAIDs have cyclooxygenase-independent actions. We investigated an alternative target for NSAIDs, peroxisome proliferator-activated receptor-gamma (PPARgamma), activation of which decreases cancer cell proliferation. NSAIDs have been shown to activate this receptor, but only at high concentrations. Here, we have examined binding of diclofenac to PPARgamma using a cis-parinaric acid displacement assay and studied the effect of diclofenac effect on PPARgamma trans-activation in a COS-1 cell reporter assay. Unexpectedly, diclofenac bound PPARgamma at therapeutic concentrations (K(i) = 700 nM) but induced only 2-fold activation of PPARgamma at a concentration of 25 microM and antagonized PPARgamma trans-activation by rosiglitazone. This antagonism was overcome with increasing rosiglitazone concentrations, indicating that diclofenac is a partial agonist. No effect of diclofenac was seen without exogenous receptor, confirming that it was working through a PPARgamma-specific mechanism. This is the first description of an NSAID that can antagonize PPARgamma. In addition, this is the first time that an NSAID has been shown to bind this receptor at clinically meaningful concentrations. The physiological relevance of these findings was tested using adipocyte differentiation and cancer cell proliferation assays. Diclofenac decreased PPARgamma-mediated adipose cell differentiation by 60% and inhibited the action of rosiglitazone on the prostate cancer cell line, DU-145, allowing a 3-fold increase in proliferation. This work shows that standard doses of diclofenac may have pharmacodynamic interactions with rosiglitazone and this has therapeutic implications, both in the management of type 2 diabetes and during cancer treatment.
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PMID:Diclofenac antagonizes peroxisome proliferator-activated receptor-gamma signaling. 1175

This study was aimed to characterize the vascular production of superoxide in Otsuka Long-Evans Tokushima Fatty (OLETF) rat, a model of type 2 diabetes. The nitroblue tetrazolium staining in the aorta from old (30 weeks) OLETF rat was more prominent than that of age-matched control (LETO) rat, which was significantly inhibited by diphenyleneiodonium (10 micromol/l), but not by inhibitors for other oxidases such as xanthine oxidase, mitochondrial oxidase, nitric oxide synthase, and cyclooxygenase. In the aorta from old OLETF rat with hyperglycemia, the enhanced NADH oxidase activity in association with upregulated expression of p22phox and gp91phox was observed, but not in both LETO and young (10 weeks) OLETF rats without hyperglycemia. Furthermore, there was a positive correlation (P<0.01) between elevation of blood glucose level and increase in vascular NADH oxidase activity. Based on these results, it was suggested that the enhanced NADH oxidase activity in the aorta from OLETF rat occurred after the onset of hyperglycemia, thereby resulting in the increased vascular production of superoxide.
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PMID:Enhanced vascular production of superoxide in OLETF rat after the onset of hyperglycemia. 1263 60

The glucose disposal effect of insulin after a meal is accounted for in approximately equal measure by the direct action of insulin and the action of HISS (hepatic insulin sensitizing substance) released from the liver and acting on skeletal muscle to stimulate glucose storage as glycogen. The ability of insulin to cause HISS release is determined by hepatic parasympathetic nerves. Eliminating the parasympathetic signal by surgical denervation of the liver or by blockade of hepatic muscarinic receptors, hepatic nitric oxide synthase, or hepatic cyclooxygenase results in insulin resistance that can be accounted for by the absence of HISS action and is referred to as HISS-dependent insulin resistance (HDIR). Animal models in which the insulin resistance has been shown to be HDIR includes the spontaneously hypertensive rat, sucrose fed rats, animals with liver disease, adult offspring of fetal alcohol exposure, acute stress, and ageing. We suggest that HDIR accounts for the major metabolic disturbances in type 2 diabetes, including the postprandial hyperglycemia that results in the majority of pathologies related to diabetes. The observation of meal-induced insulin sensitization (MIS) and the role of HISS allows for consideration of a new paradigm relating meal processing, diabetes, obesity, and insulin resistance. New diagnostic approaches and therapeutic targets are described.
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PMID:A new paradigm for diabetes and obesity: the hepatic insulin sensitizing substance (HISS) hypothesis. 1515 45

1. A fructose (Fru)-enriched diet induces a mild increase in blood pressure associated with hyperglycaemia, hypertriglyceridaemia, and insulin resistance, resembling the human 'syndrome X', being an useful model to study hypertension and type 2 diabetes. 2. A sustained elevation of blood pressure is associated with cardiovascular structural modifications such as left ventricular hypertrophy and increased wall thickness:lumen diameter ratio in blood vessels. 3. Prostanoids (PR), metabolites of arachidonic acid through the cyclooxygenase pathway, include vasoactive substances synthesized and released by the vessel walls. 4. The aim of the present study was to analyse, in Fru-treated rats: (i) the morphology of mesenteric vessels and; (ii) the PR production in aorta and mesenteric vessels, in order to assess whether these parameters are related with the haemodynamic alterations observed in this experimental model. 5. Blood pressure, glycaemia and triglyceridaemia, were significantly elevated in both (4 and 22 weeks) Fru-treated groups. Meanwhile body and heart weight as well as insulinaemia were similar between experimental animals and controls. 6. The mesenteric vessels of Fru-treated rats (22 weeks) showed an increased thickness and area of the media when compared with the controls; meanwhile, the lumen diameter was similar in both groups. 7. The Fru treatment for 4 weeks did not modify PR production in aorta, whereas in the mesenteric bed it diminished prostaglandin (PG) E(2) release significantly compared with the controls. However, in the group treated for 22 weeks, Fru reduced PGI(2) production in the aorta, as assessed by 6-keto-PGF(1)alpha measurements. Meanwhile, in the mesenteric bed, the chronic Fru treatment decreased PGE(2) release but, rather surprisingly, increased the output of PGI(2) when compared with its corresponding controls. 8. In conclusion, the present study shows the existence of an alteration in the morphology of mesenteric vessels in Fru-treated rats, which could be related to an increase in peripheral resistance and the consequent mild hypertension observed in this model. However, a diminished release of vasodilator PRs, such as PGE(2) in mesenteric vessels at 4 and 22 weeks and PGI(2) in aorta at 22 weeks could further impair the vessel response. The increase in PGI(2) observed in the chronic group in mesenteric vessels could be attributed to a compensatory mechanism.
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PMID:Fructose overload modifies vascular morphology and prostaglandin production in rats. 1545 41

We have recently reported that ingestion of Ginkgo biloba extract (EGb 761) (a) significantly reduced collagen-induced platelet aggregation and thromboxane B2 (TXB2) production in both non-diabetic individuals as well as those with type 2 diabetes mellitus (T2DM), (b) significantly reduced platelet malondialdehyde (MDA), an index of lipid peroxidation, in non-diabetic subjects. In the present study we report that ingestion of EGb 761 (120 mg daily for 3 months), significantly decreased platelet MDA-thiobarbituric acid reacting substances (TBARS) (41 +/- 9 pmol/10(7) platelets versus 30 +/- 11 pmol/10(7) platelets) (p < 0.005) in T2DM subjects with normal cholesterol levels (total cholesterol, 164 +/- 22 mg/dl; age, 54 +/- 9 years; BMI, 35.0 +/- 8.8 kg/m2, n = 12). In T2DM subjects with high cholesterol (total cholesterol, 218 +/- 15 mg/dl; age, 52 +/- 5 years; BMI, 36.2 +/- 6.6 kg/m2, n = 7), EGb 761 ingestion reduced the platelet TBARS from 29 +/- 9 to 22 +/- 9 pmol/10(7) platelets (p < 0.04). Because ingestion of EGb 761 did not alter platelet counts it is concluded that EGb 761, probably due to the flavonoid fraction, reduced the TBARS by inhibiting cyclooxygenase (COX)-1-mediated arachidonic acid oxygenation or by reducing the arachidonic acid pool. This is likely to lead to a reduction of platelet hyperactivity, a significant contributor to the development of cardiovascular disease in T2DM patients. Because of other reported beneficial properties of EGb 761, such as stimulation of pancreatic beta-cell function in T2DM subjects with pancreatic exhaustion, it appears that T2DM subjects might benefit from ingesting EGb 761 as a dietary supplement.
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PMID:Short-term oral ingestion of Ginkgo biloba extract (EGb 761) reduces malondialdehyde levels in washed platelets of type 2 diabetic subjects. 1581 63

There is a growing body of evidence for the role of inflammation in type 2 diabetes. In addition to the evidence presented elsewhere, evidence is emerging that many drugs that have apparent "anti-inflammatory" properties may reduce the incidence and/or delay the onset of type 2 diabetes. Statins have been found to lower inflammatory markers, and a post hoc analysis of the West of Scotland Coronary Prevention Study (WOSCOPS) suggested that pravastatin may reduce the risk of developing diabetes, although the Lipid Lowering Arm of the Anglo-Scandinavian Cardiac Outcomes Trial (ASCOT) found no statistically significant effect of atorvastatin on risk of developing diabetes. Fibrates have been found to lower some markers of inflammation, and a prospective trial found that bezafibrate reduces risk of developing diabetes. Angiotensin converting enzyme (ACE) inhibitors and angiotensin receptor blockers appear to reduce some markers of inflammation, and a meta-analysis concluded that ACE inhibitors and angiotensin receptor blockers reduce risk of developing type 2 diabetes. Metformin is known to reduce the risk of developing diabetes, and more recent evidence suggests it also lowers C-reactive protein, in part because of its modest weight-reducing effect. Thiazolidinediones reduce risk of developing diabetes, and consistently lower inflammatory markers independent of adiposity effects. High-dose aspirin inhibits cyclooxygenase and IkappaB kinase-beta and reduces fasting plasma glucose concentration, although there has not, as yet, been a large-scale trial to examine the effect of aspirin on the risk of developing diabetes. We conclude that although many drugs with potential anti-inflammatory properties reduce the risk of developing diabetes, it is difficult to prove that such anti-inflammatory properties contribute to their diabetes prevention since nearly all drugs have other, often more pronounced, actions. Studies with more specific inhibitors of inflammatory pathways (e.g., interleukin- 6 blockers) and mendelian randomization (genetic studies) will help determine whether targeting the inflammation axis is a fertile mechanism to treat or prevent type 2 diabetes.
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PMID:"Anti-inflammatory" drugs and their effects on type 2 diabetes. 1647 47

The perspective presented here is a working hypothesis suggesting a new paradigm for insulin resistance where, analogous to the cause of type 1 diabetes being attributed to lack of insulin, type 2 diabetes is due to lack of action of a hepatic insulin sensitizing substance (HISS). In both cases, the major metabolic dysfunction is with post-meal nutrient processing. In the immediate postprandial state, insulin causes the release of the putative hormone, HISS, from the liver. HISS stimulates glucose uptake in skeletal muscle. The hepatic parasympathetic nerves determine, in a permissive manner, the ability of insulin to cause HISS release maximally in the postprandial state. HISS release in response to insulin is progressively reduced with fasting. The glucose disposal effect of insulin in the fed state is decreased by approximately 55% by blocking HISS release. HISS release is blocked by fasting, surgical parasympathetic denervation of the liver, blockade of hepatic cholinergic muscarinic receptors, blockade of hepatic nitric oxide production, or blockade of hepatic cyclooxygenase, and results in a condition referred to as HISS-dependent insulin resistance (HDIR). HDIR is physiologically and appropriately produced in the fasted state and, pathologically, in chronic liver disease, sucrose fed, fetal alcohol exposed, spontaneously hypertensive, and aging rats. Therapeutic approaches to correct the metabolic imbalance in processing the meal nutrients that occur in type 2 diabetes can be approached through this paradigm.
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PMID:A proposed new paradigm for insulin resistance. 1837 Jun 50

We previously reported that in mesenteric arteries from aged Otsuka Long-Evans Tokushima fatty (OLETF) rats (a type 2 diabetes model) endothelium-derived hyperpolarizing factor (EDHF)-type relaxation is impaired while endothelium-derived contracting factor (EDCF)-mediated contraction is enhanced (Matsumoto T, Kakami M, Noguchi E, Kobayashi T, Kamata K. Am J Physiol Heart Circ Physiol 293: H1480-H1490, 2007). Here we investigated whether acute and/or chronic treatment with metformin might improve this imbalance between the effects of the above endothelium-derived factors in mesenteric arteries isolated from OLETF rats. In acute studies on OLETF mesenteric arteries, ACh-induced relaxation was impaired and the relaxation became weaker at high ACh concentrations. Both metformin and 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside [AICAR, an AMP-activated protein kinase (AMPK) activator that is also activated by metformin] 1) diminished the tendency for the relaxation to reverse at high ACh concentrations and 2) suppressed both ACh-induced EDCF-mediated contraction and ACh-stimulated production of prostanoids (thromboxane A2 and PGE2). In studies on OLETF arteries from chronically treated animals, metformin treatment (300 mg.kg(-1).day(-1) for 4 wk) 1) improved ACh-induced nitric oxide- or EDHF-mediated relaxation and cyclooxygenase (COX)-mediated contraction, 2) reduced EDCF-mediated contraction, 3) suppressed production of prostanoids, and 4) reduced superoxide generation. Metformin did not alter the protein expressions of endothelial nitric oxide synthase (eNOS), phospho-eNOS (Ser1177), or COX-1, but it increased COX-2 protein. These results suggest that metformin improves endothelial functions in OLETF mesenteric arteries by suppressing vasoconstrictor prostanoids and by reducing oxidative stress. Our data suggest that within the timescale studied here, metformin improves endothelial function through this direct mechanism, rather than by improving metabolic abnormalities.
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PMID:Metformin normalizes endothelial function by suppressing vasoconstrictor prostanoids in mesenteric arteries from OLETF rats, a model of type 2 diabetes. 1864 Dec 73

The purpose of this study was to determine whether cyclooxygenase expression in arteries is affected by diabetes. Streptozotocin-injected rats and Goto-Kakizaki rats were used as animal models for type 1 and type 2 diabetes, respectively. Cyclooxygenase-2 expression was induced by lipopolysaccharide. Lipopolysaccharide-induced cyclooxygenase-2 expression was significantly lower in aortas isolated from streptozotocin-injected rats and Goto-Kakizaki rats than in aortas of control rats, while expression level of cyclooxygenase-1 was not affected by lipopolysaccharide and was not different in aortas of the three groups of rats. The level of 6-keto-prostaglandin F(1alpha) that accumulated in the presence of lipopolysaccharide as well as the basal accumulation level in the absence of lipopolysaccharide was significantly lower in aortas of streptozotocin-injected rats and Goto-Kakizaki rats than in aortas of control rats. The net increase in 6-keto-prostaglandin F(1alpha) level in response to stimulation with lipopolysaccharide, which was calculated by subtracting the basal accumulation level from the total accumulation level, was also significantly lower in aortas of streptozotocin-injected rats and Goto-Kakizaki rats than in aortas of control rats. There were no significant differences in the accumulated 6-keto-prostaglandin F(1alpha) levels in the absence or presence of lipopolysaccharide and the levels of basal and lipopolysaccharide-induced cyclooxygenase-2 expression in control or Goto-Kakizaki rat aortas under the conditions of different glucose concentrations in the medium. These results suggest that lipopolysaccharide-induced cyclooxygenase-2 expression and subsequent prostacyclin production are decreased in aortas isolated from both type 1 and type 2 diabetes rats.
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PMID:Depression of cyclooxygenase-2 induction in aortas of rats with type 1 and type 2 diabetes mellitus. 1870 4


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