Adenosine inhibition of neutrophil damage during reperfusion does not involve KATP-channel activation

1997 ◽  
Vol 273 (4) ◽  
pp. H1677-H1687 ◽  
Author(s):  
Zhi-Qing Zhao ◽  
James C. Todd ◽  
Hiroki Sato ◽  
Xin-Liang Ma ◽  
J. Vinten-Johansen
Keyword(s):  
Infarct Size ◽  
Superoxide Radical ◽  
Receptor Activation ◽  
Polymorphonuclear Neutrophils ◽  
Vehicle Group ◽  
Myeloperoxidase Activity ◽  
Dependent Manner ◽  
Glucose Levels ◽  
Radical Generation ◽  
Dose Dependent

This study tests the hypothesis that cardioprotection exerted by adenosine A2-receptor activation and neutrophil-related events involves stimulation of ATP-sensitive potassium (KATP) channels on neutrophils during reperfusion. The adenosine A2 agonist CGS-21680 (CGS) inhibited superoxide radical generation from isolated rabbit polymorphonuclear neutrophils (PMNs) in a dose-dependent manner from 17.7 ± 2.1 to 7.4 ± 1.3 nmol/5 × 106 PMNs ( P < 0.05). Pinacidil, a KATP-channel opener, partially inhibited superoxide radical production, which was completely reversed by glibenclamide (Glib). Incremental doses of Glib in combination with CGS (1 μM) did not alter CGS-induced inhibition of superoxide radical generation. CGS significantly reduced PMN adherence to the endothelial surface of aortic segments in a dose-dependent manner from 189 ± 8 to 50 ± 6 PMNs/mm2( P < 0.05), which was also not altered by incremental doses of Glib. Infusion of CGS (0.025 mg/kg) before reperfusion reduced infarct size from 29 ± 2% in the Vehicle group to 15 ± 1% in rabbits undergoing 30 min of ischemia and 120 min of reperfusion ( P< 0.05). Glib (0.3 mg/kg) did not change the infarct size (28 ± 2%) vs. the Vehicle group and did not attenuate infarct size reduction by CGS (16 ± 1%). Glib did not change blood glucose levels. Cardiac myeloperoxidase activity was decreased in the ischemic tissue of the CGS group (0.15 ± 0.03 U/100 mg tissue) compared with the Vehicle group (0.37 ± 0.05 U/100 mg tissue; P < 0.05). We conclude that adenosine A2 activation before reperfusion partially reduces infarct size by inhibiting neutrophil activity and that this effect does not involve KATP-channel stimulation.

Presynaptic Modulation of Synaptic Transmission by Pregnenolone Sulfate as Studied by Optical Recordings

2005 ◽  
Vol 94 (6) ◽  
pp. 4131-4144 ◽  
Author(s):  
Ling Chen ◽  
Masahiro Sokabe
Keyword(s):  
Synaptic Transmission ◽  
Glutamate Release ◽  
Hippocampal Slices ◽  
Receptor Activation ◽  
Optical Recording ◽  
Perforant Path ◽  
Dependent Manner ◽  
Pregnenolone Sulfate ◽  
Voltage Sensitive Dyes ◽  
Dose Dependent

The effects of pregnenolone sulfate (PREGS), a putative neurosteroid, on the transmission of perforant path–granule cell synapses were investigated with an optical recording technique in rat hippocampal slices stained with voltage-sensitive dyes. Application of PREGS to the bath solution resulted in an acute augmentation of EPSP in a dose-dependent manner. The PREGS effect was dependent on the extracellular Ca2+ concentration ([Ca2+]o), but independent of NMDA receptor activation. PREGS caused a decrease in paired-pulse facilitation, which implies that PREGS positively modulates presynaptic neurotransmitter releases. Firmer support for this mechanism was that PREGS augmented the synaptically induced glial depolarization (SIGD) that reflects the activity of electrogenic glutamate transporters in glial cells during the uptake of released glutamate. The selective α7nAChR antagonist α-BGT or MLA prevented the SIGD increase by PREGS. Furthermore DMXB, a selective α7nAChR agonist, mimicked the PREGS effect on SIGD and antagonized the effect of PREGS. The presynaptic effect of PREGS was partially attenuated by the L-type Ca2+ channel (VGCC) blocker nifedipine. Based on these findings, we proposed a novel mechanism underlying the facilitated synaptic transmission by PREGS: this neurosteroid sensitizes presynaptic α7nAChR that is followed by an activation of L-type VGCC to increase the presynaptic glutamate release.

scholarly journals Mechanisms of L-Triiodothyronine-Induced Inhibition of Synaptosomal Na+-K+-ATPase Activity in Young Adult Rat Brain Cerebral Cortex

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Pradip K. Sarkar ◽  
Avijit Biswas ◽  
Arun K. Ray ◽  
Joseph V. Martin
Keyword(s):  
Cerebral Cortex ◽  
Atpase Activity ◽  
Adrenergic Receptor ◽  
Receptor Activation ◽  
Mammalian Brain ◽  
Neuronal Membrane ◽  
Dependent Manner ◽  
Adrenergic Agonist ◽  
Adult Rat ◽  
Dose Dependent

The role of thyroid hormones (TH) in the normal functioning of adult mammalian brain is unclear. Our studies have identified synaptosomal Na+-K+-ATPase as a TH-responsive physiological parameter in adult rat cerebral cortex. L-triiodothyronine (T3) and L-thyroxine (T4) both inhibited Na+-K+-ATPase activity (but not Mg2+-ATPase activity) in similar dose-dependent fashions, while other metabolites of TH were less effective. Although both T3and theβ-adrenergic agonist isoproterenol inhibited Na+-K+-ATPase activity in cerebrocortical synaptosomes in similar ways, theβ-adrenergic receptor blocker propranolol did not counteract the effect of T3. Instead, propranolol further inhibited Na+-K+-ATPase activity in a dose-dependent manner, suggesting that the effect of T3on synaptosomal Na+-K+-ATPase activity was independent ofβ-adrenergic receptor activation. The effect of T3on synaptosomal Na+-K+-ATPase activity was inhibited by theα2-adrenergic agonist clonidine and by glutamate. Notably, both clonidine and glutamate activateGi-proteins of the membrane second messenger system, suggesting a potential mechanism for the inhibition of the effects of TH. In this paper, we provide support for a nongenomic mechanism of action of TH in a neuronal membrane-related energy-linked process for signal transduction in the adult condition.

scholarly journals A Pilot Study on Antimalarial Effects of Moringa oleifera Leaf Extract in Plasmodium berghei Infection in Mice

2017 ◽  
Vol 15 (2) ◽  
pp. 151-156
Author(s):  
Somrudee NAKINCHAT ◽  
Voravuth SOMSAK
Keyword(s):  
Plasma Glucose ◽  
Crude Extract ◽  
Plasmodium Berghei ◽  
Leaf Extract ◽  
Moringa Oleifera ◽  
Dependent Manner ◽  
Glucose Levels ◽  
New Compounds ◽  
Dose Dependent

The emergence and spread of antimalarial drug resistance of Plasmodium parasites, as well as hypoglycemia, during malaria infection, and subsequent death, are critical problems in malaria-endemic areas. Hence, finding new compounds, especially plant extracts having antimalarial and anti-hypoglycemic activities, are urgently needed. The present study aimed to investigate the antimalarial and anti-hypoglycemic effects of Moringa oleifera leaf extract in Plasmodium berghei infection in mice. Aqueous crude extract of M. oleifera leaves was freshly prepared and used for an efficacy test in vivo. Groups of ICR mice (5 mice in each) were infected with 1´107 infected red blood cells of P. berghei ANKA by intraperitoneal injection and given the extract orally with doses of 100, 500, and 1000 mg/kg for 4 consecutive days. Parasitemia and plasma glucose levels were subsequently measured. The results showed that M. oleifera leaf extract presented significant (p < 0.001) inhibition of parasitemia in a dose-dependent manner. Moreover, this extract exerted anti-hypoglycemia effects in infected mice in a dose-dependent manner. The highest degrees of activity were found at a dose of 1000 mg/kg of the extract. Additionally, no effect on plasma glucose was found in normal mice treated with this extract. It can be concluded that aqueous crude extract of M. oleifera leaves exerted antimalarial and anti-hypoglycemic effects in P. berghei infection in mice.

scholarly journals AGEs and Glucose Levels Modulate Type I and III Procollagen mRNA Synthesis in Dermal Fibroblasts Cells Culture

2008 ◽  
Vol 2008 ◽  
pp. 1-7 ◽  
Author(s):  
Serban Iren Andreea ◽  
Costache Marieta ◽  
Dinischiotu Anca
Keyword(s):  
Extracellular Matrix ◽  
High Glucose ◽  
Dermal Fibroblasts ◽  
Type I ◽  
Dependent Manner ◽  
Human Dermal Fibroblasts ◽  
Mrna Synthesis ◽  
Quantitative Real Time Pcr ◽  
Glucose Levels ◽  
Dose Dependent

In the dermis, fibroblasts play an important role in the turnover of the dermal extracellular matrix. Collagen I and III, the most important dermal proteins of the extracellular matrix, are progressively altered during ageing and diabetes. For mimicking diabetic conditions, the cultured human dermal fibroblasts were incubated with increasing amounts of AGE-modified BSA andD-glucose for 24 hours. The expression of procollagenα2(I) and procollagenα1(III) mRNA was analyzed by quantitative real-time PCR. Our data revealed that the treatment of fibroblasts with AGE-modified BSA upregulated the expression of procollagenα2(I) and procollagenα1(III) mRNA in a dose-dependent manner. High glucose levels mildly induced a profibrogenic pattern, increasing the procollagenα2(I) mRNA expression whereas there was a downregulation tendency of procollagenα1(III) mRNA.

Alleviation of Simvastatin-Induced Myopathy in Rats by the Standardized Extract of Ginkgo Biloba (EGb761): Insights into the Mechanisms of Action

2019 ◽  
Vol 208 (3-4) ◽  
pp. 158-176
Author(s):  
Amany R. Mahmoud ◽  
Esam Omar Kamel ◽  
Marwa A. Ahmed ◽  
Esraa A. Ahmed ◽  
Tarek Hamdy Abd-Elhamid
Keyword(s):  
Ginkgo Biloba ◽  
Muscle Performance ◽  
Vehicle Group ◽  
Control Group ◽  
Dependent Manner ◽  
Histopathological Changes ◽  
Leaf Extracts ◽  
Muscle Changes ◽  
Dose Dependent ◽  
Antioxidant Effects

Statins are the most widely prescribed cholesterol-lowering drugs to reduce the risk of cardiovascular diseases. Statin-induced myopathy is the major side effect of this class of drugs. Here, we studied whether standardized leaf extracts of ginkgo biloba (EGb761) would improve simvastatin (SIM)-induced muscle changes. Sixty Wistar rats were allotted into six groups: control group, vehicle group receiving 0.5% carboxymethyl cellulose (CMC) for 30 days, SIM group receiving 80 mg/kg/day SIM in 0.5% CMC orally for 30 days, SIM withdrawal group treated with SIM for 16 days and sacrificed 14 days later, and EGb761-100 and EGb761-200 groups posttreated with either 100 or 200 mg/kg/day EGb761 orally. Muscle performance on the rotarod, serum creatine kinase (CK), coenzyme Q10 (CoQ10), serum and muscle nitrite, muscle malondialdehyde (MDA), superoxide dismutase (SOD), and catalase (CAT) activities were estimated. Additionally, muscle samples were processed for histopathological evaluation. We found that SIM decreased muscle performance on the rotarod, serum CoQ10, as well as muscle SOD and CAT activities while it increased serum CK, serum and muscle nitrite, as well as muscle MDA levels. SIM also induced sarcoplasmic vacuolation, splitting of myofibers, disorganization of sarcomeres, and disintegration of myofilaments. In contrast, posttreatment with EGb761 increased muscle performance, serum CoQ10, as well as muscle SOD and CAT activities while it reduced serum CK as well as serum and muscle nitrite levels in a dose-dependent manner. Additionally, EGb761 reversed SIM-induced histopathological changes with better results obtained by its higher dose. Interestingly, SIM withdrawal increased muscle performance on the rotarod, reduce serum CK and CoQ10, and reduced serum and muscle nitrite while it reversed SIM-induced histopathological changes. However, SIM withdrawal was not effective enough to restore their normal values. Additionally, SIM withdrawal did not improve SIM-induce muscle MDA, SOD, or CAT activities during the period studied. Our results suggest that EGb761 posttreatment reversed SIM-induces muscle changes possibly through its antioxidant effects, elevation of CoQ10 levels, and antagonizing mitochondrial damage.

scholarly journals Beneficial Effect of Shikonin on Experimental Colitis Induced by Dextran Sulfate Sodium in Balb/C Mice

2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
Isabel Andújar ◽  
José Luis Ríos ◽  
Rosa María Giner ◽  
José Miguel Cerdá ◽  
María del Carmen Recio
Keyword(s):  
Disease Activity ◽  
Activity Index ◽  
Disease Activity Index ◽  
Experimental Colitis ◽  
Myeloperoxidase Activity ◽  
Dependent Manner ◽  
Inflammatory Bowel ◽  
Activity Index Score ◽  
Bloody Stools ◽  
Dose Dependent

The naphthoquinone shikonin, a major component of the root ofLithospermum erythrorhizon, now is studied as an anti-inflammatory agent in the treatment of ulcerative colitis (UC). Acute UC was induced in Balb/C mice by oral administration of 5% dextran sodium sulfate (DSS). The disease activity index was evaluated, and a histologic study was carried out. Orally administered shikonin reduces induced UC in a dose-dependent manner, preventing the shortening of the colorectum and decreasing weight loss by 5% while improving the appearance of feces and preventing bloody stools. The disease activity index score was much lower in shikonin-treated mice than in the colitic group, as well as the myeloperoxidase activity. The expression of cyclooxygenase-2 was reduced by 75%, activation of NF-κB was reduced by 44%, and that of pSTAT-3 by 47%, as well as TNF-α, IL-1β, and IL-6 production. Similar results were obtained in primary macrophages culture. This is the first report of shikonin’s ability to attenuate acute UC induced by DSS. Shikonin acts by blocking the activation of two major targets: NF-κB and STAT-3, and thus constitutes a promising potential therapeutic agent for the management of the inflammatory bowel disease.

scholarly journals Neuroprotection in Rats Following Ischaemia-Reperfusion Injury by GLP-1 Analogues—Liraglutide and Semaglutide

2019 ◽  
Vol 33 (6) ◽  
pp. 661-667 ◽  
Author(s):  
Maryna V. Basalay ◽  
Sean M. Davidson ◽  
Derek M. Yellon
Keyword(s):  
Infarct Size ◽  
Ischaemic Stroke ◽  
Experimental Studies ◽  
Treatment Strategies ◽  
Reperfusion Therapy ◽  
Diabetic Rat ◽  
Dependent Manner ◽  
Ischaemia Reperfusion Injury ◽  
Neuroprotective Effects ◽  
Dose Dependent

Abstract Purpose A substantial number of ischaemic stroke patients who receive reperfusion therapy in the acute phase do not ever fully recover. This reveals the urgent need to develop new adjunctive neuroprotective treatment strategies alongside reperfusion therapy. Previous experimental studies demonstrated the potential of glucagon-like peptide-1 (GLP-1) to reduce acute ischaemic damage in the brain. Here, we examined the neuroprotective effects of two GLP-1 analogues, liraglutide and semaglutide. Methods A non-diabetic rat model of acute ischaemic stroke involved 90, 120 or 180 min of middle cerebral artery occlusion (MCAO). Liraglutide or semaglutide was administered either i.v. at the onset of reperfusion or s.c. 5 min before the onset of reperfusion. Infarct size and functional status were evaluated after 24 h or 72 h of reperfusion. Results Liraglutide, administered as a bolus at the onset of reperfusion, reduced infarct size by up to 90% and improved neuroscore at 24 h in a dose-dependent manner, following 90-min, but not 120-min or 180-min ischaemia. Semaglutide and liraglutide administered s.c. reduced infarct size by 63% and 48%, respectively, and improved neuroscore at 72 h following 90-min MCAO. Neuroprotection by semaglutide was abolished by GLP1-R antagonist exendin(9-39). Conclusion Infarct-limiting and functional neuroprotective effects of liraglutide are dose-dependent. Neuroprotection by semaglutide is at least as strong as by liraglutide and is mediated by GLP-1Rs.

Potential Natural Dual Agonist PPARα/γ-induced Antidiabetic and Antidyslipidemic Properties of Safrole-Free Nutmeg Seed (Myristica fragrans Houtt) Extract

2019 ◽  
Vol 9 (3) ◽  
pp. 248-253
Author(s):  
Keri Lestari ◽  
Ajeng Diantini ◽  
Melisa I. Barliana ◽  
Tri H. Achmad ◽  
Anas Subarnas ◽  
...  
Keyword(s):  
Blood Glucose ◽  
Luciferase Assay ◽  
Dependent Manner ◽  
Control Blood Glucose ◽  
Glucose Levels ◽  
Myristica Fragrans ◽  
Myristica Fragrans Houtt ◽  
Dose Dependent ◽  
Dual Agonist

Background: Nutmeg (Myristica fragrans Houtt) has the potential to control blood glucose and lipid levels. However, it contains safrole compounds, which are dangerous when humans consume them. Objective: In this study, we eliminated safrole from nutmeg and investigated its antidiabetic and antidyslipidemic properties. Methods: Nutmeg seeds were powdered, extracted with 90% ethanol, and chromatographed to remove the safrole. Safrole-free nutmeg extract was concentrated, and its antidiabetic and antidyslipidemic agents were tested in a type 2 diabetes mellitus rat model. Results: The results showed that the blood glucose level decreased by 20% after 2 days of treatment, 30% after 4 days of treatment and 40% after 6 days of treatment with nutmeg extracts. The blood triglyceride level did not change in the first 2 days of treatment, and it decreased by 25% after 4 days of treatment and by another 25% after 6 days of treatment. Luciferase assay showed that safrole- free nutmeg increased the activities of PPAR α and γ in a dose-dependent manner, which marked the potential mechanism of lowering the triglyceride and glucose levels. Conclusion: Results thus obtained are suggestive of the potential dual effect of safrole-free nutmeg extract on antidiabetic and antidyslipidemic management.

scholarly journals Curcumin Ameliorates Benzo[a]pyrene-Induced DNA Damages in Stomach Tissues of Sprague-Dawley Rats

2019 ◽  
Vol 20 (22) ◽  
pp. 5533 ◽  
Author(s):  
Kyeong Seok Kim ◽  
Na Yoon Kim ◽  
Ji Yeon Son ◽  
Jae Hyeon Park ◽  
Su Hyun Lee ◽  
...  
Keyword(s):  
High Dose ◽  
Dependent Manner ◽  
Protective Effects ◽  
Sprague Dawley ◽  
Dna Damages ◽  
Glucose Levels ◽  
Cooking Process ◽  
Sprague Dawley Rats ◽  
Cyp1a1 Expression ◽  
Dose Dependent

Benzo[a]pyrene (BaP) is a well-known carcinogen formed during the cooking process. Although BaP exposure has been implicated as one of the risk factors for lung cancer in animals and humans, there are only limited data on BaP-induced gastrointestinal cancer. Therefore, this study investigated the protective effects of curcumin on BaP-induced DNA damage in rat stomach tissues. BaP (20 mg/kg/day) and curcumin (50, 100, or 200 mg/kg) were administered daily to Sprague-Dawley rats by oral gavage over 30 days. Curcumin was pre-administered before BaP exposure. All rats were euthanized, and liver, kidney, and stomach tissues were removed at 24 h after the last treatment. We observed that aspartate aminotransferase (AST), alanine aminotransferase (ALT), and glucose levels were significantly reduced in rats treated with high dose co-administration of curcumin (200 mg/kg) compared to BaP alone. The expression levels of cytochrome P450 (CYP) 1A1 and CYP1B1 were significantly increased in the liver of rats treated with BaP. However, co-administration of curcumin (200 mg/kg) with BaP markedly reduced CYP1A1 expression in a dose-dependent manner. Furthermore, plasma levels of BaP-diolepoxide (BPDE) and BaP metabolites were significantly reduced by co-administration of curcumin (200 mg/kg). Additionally, co-administration of curcumin (200 mg/kg) with BaP significantly reduced the formation of BPDE-I-DNA and 8-hydroxydeoxy guanosine (8-OHdG) adducts in the liver, kidney, and stomach tissues. The inhibition of these adduct formations were more prominent in the stomach tissues than in the liver. Overall, our observations suggest that curcumin might inhibit BaP-induced gastrointestinal tumorigenesis and shows promise as a chemopreventive agent.

Ventilatory output and acetylcholine: perturbations in release and muscarinic receptor activation

1994 ◽  
Vol 77 (5) ◽  
pp. 2275-2284 ◽  
Author(s):  
M. D. Burton ◽  
K. Nouri ◽  
S. Baichoo ◽  
N. Samuels-Toyloy ◽  
H. Kazemi
Keyword(s):  
Muscarinic Receptors ◽  
Receptor Activation ◽  
Neonatal Rat ◽  
Dependent Manner ◽  
Cholinergic Transmission ◽  
Ach Release ◽  
Tetraethylammonium Chloride ◽  
Spinal Axis ◽  
Dose Dependent ◽  
Stimulation Of

Cholinergic transmission may be part of the normal neurochemical processes that support spontaneous ventilation. If this is true, perturbations in acetylcholine (ACh) turnover should alter ventilatory output in a predictable manner. With the use of the isolated perfused brain stem-spinal axis from the neonatal rat, the effects of modifiers of ACh release and blockers of muscarinic receptors on spontaneous C4 (phrenic) output were determined. Vesamicol and cetiedil, inhibitors of ACh release, caused depression and cessation of the C4 output in a dose-dependent manner when added to the perfusate. Muscarinic blockers, particularly M1 and M3 blockers, caused a similar depression. 4-Aminopyridine and tetraethylammonium chloride, facilitators of ACh release, caused stimulation of C4 (phrenic) output. The depressive effects of the blockers and inhibitors were reversible with facilitation of ACh release except in the case of cetiedil. These findings are consistent with the view that the synaptic turnover of endogenous ACh is an important part of the normal neurochemical process that supports and modulates ventilation.

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