Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The MIN6 pancreatic beta-cell line responds to glutamate, alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and kainate, but not N-methyl-D-aspartate (NMDA) or 1S,3R-trans-ACPD, with increases in [Ca2+]i. This correlates with MIN6 expression of AMPA receptor subunits (GluR1-4) but only weak expression of NMDA NR2 receptor subunits, as determined by reverse transcriptase polymerase chain reaction (RT-PCR). Pharmacological characterization of the MIN6 AMPA receptors showed that AMPA-triggered [Ca2+]i responses were blocked by GYKI 52466, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and pentobarbital. AMPA-triggered [Ca2+]i responses were also blocked in Na(+)-free medium and by the voltage-sensitive Ca2+ channel antagonist La3+. Unlike cortical neuronal cultures, which show a loss of membrane-associated protein kinase C (PKC) activity and die in response to excitatory amino acid exposure, glutamate was not toxic to MIN6 cells and it did not decrease PKC activity. These studies indicate that MIN6 cells possess Ca(2+)-impermeable AMPA receptors that secondarily allow Ca2+ influx following AMPA-induced depolarization and that, despite elevating [Ca2+]i, AMPA is not toxic to these cells. The effects of glutamate and glutamate receptor antagonists on pancreatic cells needs to be better understood if these compounds are to be used as therapeutic agents to treat stroke.
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PMID:Pharmacological and molecular characterization of glutamate receptors in the MIN6 pancreatic beta-cell line. 1087 87

Stroke occurs due to haemorrhage or occlusive injury and results in ischaemia and reperfusion injury. A variety of destructive mechanisms are involved including oxygen radical generation, calcium overload, cytotoxicity and apoptosis as well as the generation of inflammatory mediators. Ebselen, 2-phenyl-1, 2-benzisoselenazol-3(2H)-one (PZ 51, DR3305), is a mimic of GSH peroxidase which also reacts with peroxynitrite and can inhibit enzymes such as lipoxygenases, NO synthases, NADPH oxidase, protein kinase C and H(+)/K(+)-ATPase. Ebselen is in a late stage of development for the treatment of stroke. The molecular actions of ebselen contribute to its anti-inflammatory and anti-oxidant properties, which have been demonstrated in a variety of in vivo models. Numerous in vitro experiments using isolated LDL, liposomes, microsomes, isolated cells and organs have established that ebselen protects against oxidative challenge. Unlike many inorganic and aliphatic selenium compounds, ebselen has low toxicity as metabolism of the compound does not liberate the selenium moiety, which remains within the ring structure. Subsequent metabolism involves methylation, glucuronidation and hydroxylation. Experimental studies in rats and dogs have revealed that ebselen is able to inhibit both vasospasm and tissue damage in stroke models, which correlates with its inhibitory effects on oxidative processes. Results from randomised, placebo-controlled, double-blind clinical studies on the neurological consequences of acute ischaemic stroke, subarachnoid haemorrhage and acute middle cerebral artery occlusion, have revealed that ebselen significantly enhances outcome in patients who have experienced occlusive cerebral ischaemia of limited duration. The benefit achieved with ebselen is closely related to the rapidity with which the treatment is initiated, following the onset of the stroke attack. Safety and tolerability are good and no adverse effects have become apparent. Ebselen is currently at the pre-registration stage for subarachnoid haemorrhage and stroke in Japan.
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PMID:Ebselen: prospective therapy for cerebral ischaemia. 1106 Jun 99

Nefiracetam is a new pyrrolidone nootropic drug that is being developed for clinical use in the treatment of post-stroke vascular-type and Alzheimer's-type dementia. Among a few neuroreceptors that have been identified as potential targets of nootropics, neuronal nicotinic acetylcholine receptors (nnAChRs) are deemed the most important since they are related to learning, memory, and Alzheimer's disease dementia. We have recently found potent stimulating action of nefiracetam on nnAChRs. Rat cortical neurons in long-term primary culture expressed nnAChRs. Whole-cell patch clamp experiments revealed two types of currents induced by ACh, alpha-bungarotoxin (alpha-BuTX)-sensitive, rapidly desensitizing, alpha 7-type currents and alpha-BuTX-insensitive, slowly desensitizing, alpha 4 beta 2-type currents. Although alpha 7-type currents were only weakly inhibited by nefiracetam, alpha 4 beta 2-type currents were potently and efficaciously potentiated by nefiracetam. Nefiracetam at 0.1 nM reversibly potentiated ACh-induced currents to 200-300% of control. Very high concentrations (about 10 microM) also potentiated these currents, but to a lesser extent, indicative of the bell-shaped dose-response relationship known to occur for nefiracetam, even in animal behavior experiments. Three specific inhibitors of each of PKA and PKC did not prevent nefiracetam from potentiating ACh-induced currents, indicating that these protein kinases are not involved in nefiracetam action. Pretreatment with pertussis toxin did not alter nefiracetam potentiation, indicating Gi/Go proteins are not involved. Pretreatment with cholera toxin did abolish nefiracetam potentiation. Thus, nefiracetam potentiation is mediated via Gs proteins. In conclusion, nefiracetam stimulates alpha 4 beta 2-type nnAChRs via Gs proteins at nanomolar concentrations. The potentiation of alpha 4 beta 2-type nnAChRs is thought to be at least partially responsible for cognitive enhancing action.
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PMID:Post-stroke dementia. Nootropic drug modulation of neuronal nicotinic acetylcholine receptors. 1146 69

The heme oxygenase (HO) and nitric oxide (NO) synthase (NOS) systems display notable similarities as well as differences. HO and NOS are both oxidative enzymes using NADPH as an electron donor. The constitutive forms of the enzyme are differentially activated, with calcium entry stimulating NOS by binding to calmodulin, whereas calcium entry activates protein kinase C to phosphorylate and activate HO2. Although both NO and carbon monoxide (CO) stimulate soluble guanylyl cyclase to form cGMP, NO also S-nitrosylates selected protein targets. Both involve constitutive and inducible biosynthetic enzymes. However, functions of the inducible forms are virtual opposites. Macrophage-inducible NOS generates NO to kill other cells, whereas HO1 generates bilirubin to exert antioxidant cytoprotective effects and also provides cytoprotection by facilitating iron extrusion from cells. The neuronal form of HO, HO2, is also cytoprotective. Normally, neural NO in the brain seems to exert some sort of behavioral inhibition. However, excess release of NO in response to glutamate's N-methyl-d-aspartate receptor activation leads to stroke damage. On the other hand, massive neuronal firing during a stroke presumably activates HO2, leading to neuroprotective actions of bilirubin. Loss of this neuroprotection after HO inhibition by mutant forms of amyloid precursor protein may mediate neurotoxicity in Familial Alzheimer's Disease. NO and CO both appear to be neurotransmitters in the brain and peripheral autonomic nervous system. They also are physiologic endothelial-derived relaxing factors for blood vessels. In the gastrointestinal pathway, NO and CO appear to function as coneurotransmitters, both stimulating soluble guanylyl cyclase to cause smooth muscle relaxation.
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PMID:Neural roles for heme oxygenase: contrasts to nitric oxide synthase. 1157 59

The expression of cyclooxygenase-2 (COX-2) and the synthesis of prostaglandin E2 (PGE2) as well as of cytokines such as interleukin-6 (IL-6) have all been suggested to propagate neuropathology in different brain disorders such as HIV-dementia, prion diseases, stroke and Alzheimer's disease. In this report, we show that PGE2-stimulated IL-6 release in U373 MG human astroglioma cells and primary rat astrocytes. PGE2-induced intracellular cAMP formation was mediated via prostaglandin E receptor 2 (EP2), but inhibition of cAMP formation and protein kinase A or blockade of EP1/EP2 receptors did not affect PGE2-induced IL-6 synthesis. This indicates that the cAMP pathway is not part of PGE2-induced signal transduction cascade leading to IL-6 release. The EP3/EP1-receptor agonist sulprostone failed to induce IL-6 release, suggesting an involvement of EP4-like receptors. PGE2-activated p38 mitogen-activated kinase (p38 MAPK) and protein kinase C (PKC). PGE2-induced IL-6 synthesis was inhibited by specific inhibitors of p38 MAPK (SB202190) and PKC (GF203190X). Although, up to now, EP receptors have only rarely been linked to p38 MAPK or PKC activation, these results suggest that PGE2 induces IL-6 via an EP4-like receptor by the activation of PKC and p38 MAPK via an EP4-like receptor independently of cAMP.
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PMID:Mechanisms of prostaglandin E2-induced interleukin-6 release in astrocytes: possible involvement of EP4-like receptors, p38 mitogen-activated protein kinase and protein kinase C. 1173 6

Essential hypertension is characterized by significant and persistent elevations in arterial pressure. Hypertension is a multifactorial disorder that may involve abnormalities in the functions of the heart pump, the blood vessels, and the kidneys. Short-term and long-term regulation of arterial pressure is influenced by changes in cardiac function, the peripheral vascular resistance, and the renal control mechanisms of plasma electrolytes and volume. Increases in the heart rate and stroke volume lead to increases in the cardiac output and could contribute to increases in arterial pressure particularly in relatively young individuals. Vascular endothelial cell dysfunction could lead to reduction in endothelium-derived relaxing factors such as nitric oxide, prostacyclin, and endothelium-derived hyperpolarizing factor, or increased production of contracting factors such as endothelin-1 and thromboxane A2. Also, increased activity of signaling pathways of vascular smooth muscle contraction such as [Ca(2+)]i, protein kinase C, mitogen-activated protein kinase, and Rho kinase could enhance vasoconstriction. The decreased vascular relaxation and excessive vasoconstriction lead to significant increases in the peripheral vascular resistance and arterial pressure over time, particularly with aging. Alterations in body fluid regulation by the kidneys could lead to salt and water retention, increased plasma volume, and cardiac output. Also, activation of the renin-angiotensin system increases the levels of angiotensin II in the plasma, leading to generalized vasoconstriction, or locally in the kidneys, leading to salt and water retention. Individual changes in cardiac, vascular, or renal function seldom occur separately, and, if so, they may lead to mild or moderate increases in arterial pressure. Combined alterations in cardiac, vascular, and renal functions are more common and are often associated with pathologic increases in arterial pressure and established hypertension.
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PMID:Pathophysiology of essential hypertension: role of the pump, the vessel, and the kidney. 1178 64

Fas, (APO-1/CD95), a transmembrane glycoprotein belonging to the tumor necrosis (TNF) receptor superfamily, transduces apoptotic death upon crosslinking by its cognate ligand (FasL). As upregulation of Fas/FasL expression occurs in neuropathological conditions (e.g., stroke, central nervous system [CNS] trauma and seizures) associated with oxidative damage, we questioned whether reactive oxygen species (ROS) can directly affect Fas and FasL expression in neuronal cells. Utilizing rat PC12 cells neuronally differentiated with nerve growth factor (NGF), we observed that concentrations of H(2)O(2) inducing apoptotic cell death rapidly trigger the expression of Fas mRNA and protein as well as FasL mRNA. Although NGF-addition to naive PC12 downregulated constitutive Fas and FasL transcription, the H(2)O(2)-induced Fas and FasL mRNA upregulation invariably occurred either in the presence or in the absence of NGF. Similarly, phorbol 1,2-myristate 1, 3-acetate (PMA), a potent protein kinase C (PKC) activator, did not modify Fas and FasL mRNA upregulation subsequent to H(2)O(2) exposure. On the contrary, forskolin and dibutyryl cAMP, which elevate intracellular cAMP by independent mechanisms, both counteracted H(2)O(2)-induced Fas, but not FasL, mRNA upregulation and increased constitutive expression of FasL mRNA. Altogether, our data show that oxidative stress is a major stimulus in eliciting Fas and FasL expression in NGF-differentiated PC12 cells. Moreover, we describe here for the first time the existence of cAMP-dependent mechanism(s) modulating Fas and FasL expression.
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PMID:H(2)O(2) induces upregulation of Fas and Fas ligand expression in NGF-differentiated PC12 cells: modulation by cAMP. 1211 99

Both type I and type II diabetes are powerful and independent risk factors for coronary artery disease (CAD), stroke, and peripheral arterial disease. Atherosclerosis accounts for virtually 80% of all deaths among diabetic patients. Prolonged exposure to hyperglycemia is now recognized a major factor in the pathogenesis of atherosclerosis in diabetes. Hyperglycemia induces a large number of alterations at the cellular level of vascular tissue that potentially accelerate the atherosclerotic process. Animal and human studies have elucidated three major mechanisms that encompass most of the pathological alterations observed in the diabetic vasculature: 1) Nonenzymatic glycosylation of proteins and lipids which can interfere with their normal function by disrupting molecular conformation, alter enzymatic activity, reduce degradative capacity, and interfere with receptor recognition. In addition, glycosylated proteins interact with a specific receptor present on all cells relevant to the atherosclerotic process, including monocyte-derived macrophages, endothelial cells, and smooth muscle cells. The interaction of glycosylated proteins with their receptor results in the induction of oxidative stress and proinflammatory responses 2) oxidative stress 3) protein kinase C (PKC) activation with subsequent alteration in growth factor expression. Importantly, these mechanisms may be interrelated. For example, hyperglycemia-induced oxidative stress promotes both the formation of advanced glycosylation end products and PKC activation.
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PMID:How hyperglycemia promotes atherosclerosis: molecular mechanisms. 1211 59

Two mechanisms are proposed to account for the inhibition of myosin phosphatase (MP) involved in Ca2+ sensitization of vascular muscle, ie, phosphorylation of either MYPT1, a target subunit of MP or CPI-17, an inhibitory phosphoprotein. In cultured vascular aorta smooth muscle cells (VSMCs), stimulation with angiotensin II activated RhoA, and this was blocked by pretreatment with 8-bromo-cGMP. VSMCs stimulated by angiotensin II, endothelin-1, or U-46619 significantly increased the phosphorylation levels of both MYPT1 (at Thr696) and CPI-17 (at Thr38). The angiotensin II-induced phosphorylation of MYPT1 was completely blocked by 8-bromo-cGMP or Y-27632 (a Rho-kinase inhibitor), but not by GF109203X (a PKC inhibitor). In contrast, phosphorylation of CPI-17 was inhibited only by GF109203X. Y-27632 dramatically corrected the hypertension in N(omega)-nitro-L-arginine methyl ester (L-NAME)-treated rats, and this hypertension also was sensitive to isosorbide mononitrate. The level of the active form of RhoA was significantly higher in aortas from L-NAME-treated rats. Expression of RhoA, Rho-kinase, MYPT1, CPI-17, and myosin light chain kinase were not significantly different in aortas from L-NAME-treated and control rats. Activation of RhoA without changes in levels of other signaling molecules were observed in three other rat models of hypertension, ie, stroke-prone spontaneously hypertensive rats, renal hypertensive rats, and DOCA-salt rats. These results suggest that independent of the cause of hypertension, a common point in downstream signaling and a critical component of hypertension is activation of RhoA and subsequent activation of Rho-kinase.
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PMID:Activation of RhoA and inhibition of myosin phosphatase as important components in hypertension in vascular smooth muscle. 1260 Aug 88

The sequelae of chronic hyperglycemia in diabetes of all phenotypes are divided into microvascular and macrovascular complications. Microvascular disease causes blindness, renal failure, and neuropathy, and diabetes-accelerated macrovascular disease causes excessive risk for myocardial infarction, stroke, and lower limb amputation. The link between chronic hyperglycemia and vascular damage has been established by four independent biochemical abnormalities: increased polyol pathway flux, increased formation of advanced glycation end-products (AGEs), activation of protein kinase C (PKC), and increased hexosamine pathway flux. These seemingly unrelated pathways have an underlying common denominator: overproduction of superoxide by the mitochondrial electron transport chain. Mitochondrial reactive oxygen species (ROS) partially inhibit the glycolytic enzymes glyceraldehyde-3-phosphate dehydrogenase, which diverts increased substrate flux from glycolysis to pathways of glucose overutilization. Preliminary experimental evidence in vivo suggests that this new paradigm provides a novel basis for research and drug development.
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PMID:Pathophysiological mechanisms of diabetic angiopathy. 1262 64


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