scholarly journals Melatonin and Microglia

2021 ◽  
Vol 22 (15) ◽  
pp. 8296
Author(s):  
Rüdiger Hardeland
Keyword(s):  
Oxidative Stress ◽  
Nitric Oxide ◽  
Signal Transduction ◽  
Endothelial Cells ◽  
Bacterial Infections ◽  
Melatonin Receptors ◽  
Sterile Inflammation ◽  
High Complexity ◽  
Anti Inflammatory ◽  
Multiple Signaling

Melatonin interacts in multiple ways with microglia, both directly and, via routes of crosstalk with astrocytes and neurons, indirectly. These effects of melatonin are of relevance in terms of antioxidative protection, not only concerning free-radical detoxification, but also in prevention of processes that cause, promote, or propagate oxidative stress and neurodegeneration, such as overexcitation, toxicological insults, viral and bacterial infections, and sterile inflammation of different grades. The immunological interplay in the CNS, with microglia playing a central role, is of high complexity and includes signaling toward endothelial cells and other leukocytes by cytokines, chemokines, nitric oxide, and eikosanoids. Melatonin interferes with these processes in multiple signaling routes and steps. In addition to canonical signal transduction by MT1 and MT2 melatonin receptors, secondary and tertiary signaling is of relevance and has to be considered, e.g., via the upregulation of sirtuins and the modulation of pro- and anti-inflammatory microRNAs. Many details concerning the modulation of macrophage functionality by melatonin are obviously also applicable to microglial cells. Of particular interest is the polarization toward M2 subtypes instead of M1, i.e., in favor of being anti-inflammatory at the expense of proinflammatory activities, which is well-documented in macrophages but also applies to microglia.

scholarly journals Dissection of a Hypoxia-induced, Nitric Oxide–mediated Signaling Cascade

2009 ◽  
Vol 20 (18) ◽  
pp. 4083-4090 ◽  
Author(s):  
Pascale F. Dijkers ◽  
Patrick H. O'Farrell
Keyword(s):  
Nitric Oxide ◽  
Signal Transduction ◽  
Signaling Cascade ◽  
S2 Cells ◽  
Signal Transduction System ◽  
Signaling Systems ◽  
Calcium Dependent ◽  
Drosophila S2 Cells ◽  
Oxide Synthase ◽  
Multiple Signaling

Befitting oxygen's key role in life's processes, hypoxia engages multiple signaling systems that evoke pervasive adaptations. Using surrogate genetics in a powerful biological model, we dissect a poorly understood hypoxia-sensing and signal transduction system. Hypoxia triggers NO-dependent accumulation of cyclic GMP and translocation of cytoplasmic GFP-Relish (an NFκB/Rel transcription factor) to the nucleus in Drosophila S2 cells. An enzyme capable of eliminating NO interrupted signaling specifically when it was targeted to the mitochondria, arguing for a mitochondrial NO signal. Long pretreatment with an inhibitor of nitric oxide synthase (NOS), L-NAME, blocked signaling. However, addition shortly before hypoxia was without effect, suggesting that signaling is supported by the prior action of NOS and is independent of NOS action during hypoxia. We implicated the glutathione adduct, GSNO, as a signaling mediator by showing that overexpression of the cytoplasmic enzyme catalyzing its destruction, GSNOR, blocks signaling, whereas knockdown of this activity caused reporter translocation in the absence of hypoxia. In downstream steps, cGMP accumulated, and calcium-dependent signaling was subsequently activated via cGMP-dependent channels. These findings reveal the use of unconventional steps in an NO pathway involved in sensing hypoxia and initiating signaling.

Oxidative stress and diabetic cardiovascular disorders: roles of mitochondria and NADPH oxidaseThis review is one of a selection of papers published in a Special Issue on Oxidative Stress in Health and Disease.

2010 ◽  
Vol 88 (3) ◽  
pp. 241-248 ◽  
Author(s):  
Garry X. Shen
Keyword(s):  
Oxidative Stress ◽  
Nitric Oxide ◽  
Endothelial Cells ◽  
Cardiovascular Diseases ◽  
Mitochondrial Dysfunction ◽  
Cardiovascular Complications ◽  
Hypoglycemic Agents ◽  
Diabetic Patients ◽  
Plasminogen Activator Inhibitor 1 ◽  
In Cells

Cardiovascular diseases are the predominant cause of death in patients with diabetes mellitus. Underlying mechanism for the susceptibility of diabetic patients to cardiovascular diseases remains unclear. Elevated oxidative stress was detected in diabetic patients and in animal models of diabetes. Hyperglycemia, oxidatively modified atherogenic lipoproteins, and advanced glycation end products are linked to oxidative stress in diabetes. Mitochondria are one of major sources of reactive oxygen species (ROS) in cells. Mitochondrial dysfunction increases electron leak and the generation of ROS from the mitochondrial respiratory chain (MRC). High levels of glucose and lipids impair the activities of MRC complex enzymes. NADPH oxidase (NOX) generates superoxide from NADPH in cells. Increased NOX activity was detected in diabetic patients. Hyperglycemia and hyperlipidemia increased the expression of NOX in vascular endothelial cells. Accumulated lines of evidence indicate that oxidative stress induced by excessive ROS production is linked to many processes associated with diabetic cardiovascular complications. Overproduction of ROS resulting from mitochondrial dysfunction or NOX activation is associated with uncoupling of endothelial nitric oxide synthase, which leads to reduced production of nitric oxide and endothelial-dependent vasodilation. Gene silence or inhibitor of NOX reduced oxidized or glycated LDL-induced expression of plasminogen activator inhibitor-1 in endothelial cells. Statins, hypoglycemic agents, and exercise may reduce oxidative stress in diabetic patients through the reduction of NOX activity or the improvement of mitochondrial function, which may prevent or postpone the development of cardiovascular complications.

Abstract 153: Bile Acid Receptor TGR5 Agonism Represents Anti-inflammatory Effects via Stimulating Nitric Oxide Production in Vascular Endothelial Cells

2012 ◽  
Vol 32 (suppl_1) ◽  
Author(s):  
Taiki Kida ◽  
Yoshiki Tsubosaka ◽  
Masatoshi Hori ◽  
Hiroshi Ozaki ◽  
Takahisa Murata
Keyword(s):  
Nitric Oxide ◽  
Endothelial Cells ◽  
Bile Acids ◽  
Inflammatory Responses ◽  
Vascular Endothelial Cells ◽  
Lithocholic Acid ◽  
Signal Pathways ◽  
No Production ◽  
Vascular Endothelial ◽  
Anti Inflammatory

Objective TGR5, a membrane-bound, G-protein-coupled receptor for bile acids, is known to be involved in regulation of energy homeostasis and inflammation. However, little is known about the function of TGR5 in vascular endothelial cells. In the present study, we examined whether TGR5 agonism represents anti-inflammatory effects in vascular endothelial cells focusing on nitric oxide (NO) production. Methods and Results In human umbilical vein endothelial cells (HUVECs), treatment with taurolithocholic acid (TLCA), which has the highest affinity to TGR5 among various bile acids, significantly reduced tumor necrosis factor (TNF)-α-induced vascular cell adhesion molecule (VCAM)-1 protein expression and adhesion of human monocytes, U937. These effects were abrogated by a NO synthase (NOS) inhibitor, N G -Monomethyl-L-arginine (L-NMMA). In bovine aortic endothelial cells (BAECs), treatment with TLCA as well as lithocholic acid, which also has high affinity to TGR5, significantly increased the NO production. In contrast, deoxycholic acid and chenodeoxycholic acid, which possess low affinity to TGR5, did not affect the NO production. Gene depletion of TGR5 by siRNA transfection abolished TLCA-induced NO production in BAECs. TLCA-induced NO production was also observed in HUVECs measured as intracellular cGMP accumulation. We next investigated the signal pathways responsible for the TLCA-induced NO production in endothelial cells. Treatment with TLCA increased endothelial NOS (eNOS) ser1177 phosphorylation in HUVECs. This response was accompanied by increased Akt ser473 phosphorylation and intracellular Ca 2+ ([Ca 2+ ] i ). Treatment with phosphoinositide 3-kinase (PI3K) inhibitor, LY294002, or blockade of calcium channel with La 3+ , significantly decreased TLCA-induced eNOS ser1177 phosphorylation and subsequent NO production. Conclusion These results indicate that TGR5 agonism can mediate anti-inflammatory responses by suppressing VCAM-1 expression and monocytes adhesion to endothelial cells. This function is dependent on NO production via Akt activation and [Ca 2+ ] i increase.

scholarly journals Lipoic acid antagonizes paraquat-induced vascular endothelial dysfunction by suppressing mitochondrial reactive oxidative stress

2019 ◽  
Vol 8 (6) ◽  
pp. 918-927 ◽  
Author(s):  
Li Pang ◽  
Ping Deng ◽  
Yi-dan Liang ◽  
Jing-yu Qian ◽  
Li-Chuan Wu ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Nitric Oxide ◽  
Endothelial Cells ◽  
Endothelial Dysfunction ◽  
Lipoic Acid ◽  
Microvascular Endothelial Cells ◽  
Ros Generation ◽  
Protective Effects ◽  
Migration Ability ◽  
Microvascular Endothelial

Abstract Paraquat (PQ) is a widely used herbicide in the agricultural field. The lack of an effective antidote is the significant cause of high mortality in PQ poisoning. Here, we investigate the antagonistic effects of alpha lipoic acid (α-LA), a naturally existing antioxidant, on PQ toxicity in human microvascular endothelial cells (HMEC-1). All the doses of 250, 500 and 1000 μM α-LA significantly inhibited 1000 μM PQ-induced cytotoxicity in HMEC-1 cells. α-LA pretreatment remarkably diminished the damage to cell migration ability, recovered the declined levels of the vasodilator factor nitric oxide (NO), elevated the expression level of endothelial nitric oxide synthases (eNOS), and inhibited the upregulated expression of vasoconstrictor factor endothelin-1 (ET-1). Moreover, α-LA pretreatment inhibited reactive oxygen species (ROS) generation, suppressed the damage to the mitochondrial membrane potential (ΔΨm) and mitigated the inhibition of adenosine triphosphate (ATP) production in HMEC-1 cells. These results suggested that α-LA could alleviate PQ-induced endothelial dysfunction by suppressing oxidative stress. In summary, our present study provides novel insight into the protective effects and pharmacological potential of α-LA against PQ toxicity in microvascular endothelial cells.

scholarly journals Differential Signal Transduction of Progesterone and Medroxyprogesterone Acetate in Human Endothelial Cells

Endocrinology ◽  
2004 ◽  
Vol 145 (12) ◽  
pp. 5745-5756 ◽  
Author(s):  
Tommaso Simoncini ◽  
Paolo Mannella ◽  
Letizia Fornari ◽  
Antonella Caruso ◽  
Monica Y. Willis ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Signal Transduction ◽  
Endothelial Cells ◽  
Glucocorticoid Receptor ◽  
Adhesion Molecules ◽  
Adhesion Molecule ◽  
Medroxyprogesterone Acetate ◽  
Intercellular Adhesion Molecule ◽  
Human Endothelial Cells ◽  
Intercellular Adhesion Molecule 1

Abstract The conjugated equine estrogens-only arm of the Women’s Health Initiative trial, showing a trend toward protection from heart disease as opposed to women receiving also medroxyprogesterone acetate (MPA), strengthens the debate on the cardiovascular effects of progestins. We compared the effects of progesterone (P) or MPA on the synthesis of nitric oxide and on the expression of leukocyte adhesion molecules, characterizing the signaling events recruited by these compounds. Although P significantly increases nitric oxide synthesis via transcriptional and nontranscriptional mechanisms, MPA is devoid of such effects. Moreover, when used together with physiological estradiol (E2) concentrations, P potentiates E2 effects, whereas MPA impairs E2 signaling. These findings are observed both in isolated human endothelial cells as well as in vivo, in ovariectomized rat aortas. A marked difference in the recruitment of MAPK and phosphatidylinositol-3 kinase explains the divergent effects of the two gestagens. In addition, both P and MPA decrease the adhesiveness of endothelial cells for leukocytes when given alone or with estrogen. MPA is more potent than P in inhibiting the expression of vascular cell adhesion molecule-1 and intercellular adhesion molecule-1. However, when administered together with physiological amounts of glucocorticoids, MPA (which also binds glucocorticoid receptor) markedly interferes with the hydrocortisone-dependent stabilization of the transcription factor nuclear factor κB and with the expression of adhesion molecules, acting as a partial glucocorticoid receptor antagonist. Our findings show significant differences in the signal transduction pathways recruited by P and MPA in endothelial cells, which may have relevant clinical implications.

scholarly journals Bacterial Infections Affect Male Fertility: A Focus on the Oxidative Stress-Autophagy Axis

2021 ◽  
Vol 9 ◽  
Author(s):  
Sutian Wang ◽  
Kunli Zhang ◽  
Yuchang Yao ◽  
Jianhao Li ◽  
Shoulong Deng
Keyword(s):  
Oxidative Stress ◽  
Reproductive System ◽  
Bacterial Infections ◽  
Reproductive Organs ◽  
Innate Immune ◽  
Male Reproductive System ◽  
Pathogenic Microorganisms ◽  
Immune Functions ◽  
Molecular Patterns ◽  
Multiple Signaling

Numerous factors trigger male infertility, including lifestyle, the environment, health, medical resources and pathogenic microorganism infections. Bacterial infections of the male reproductive system can cause various reproductive diseases. Several male reproductive organs, such as the testicles, have unique immune functions that protect the germ cells from damage. In the reproductive system, immune cells can recognize the pathogen-associated molecular patterns carried by pathogenic microorganisms and activate the host’s innate immune response. Furthermore, bacterial infections can lead to oxidative stress through multiple signaling pathways. Many studies have revealed that oxidative stress serves dual functions: moderate oxidative stress can help clear the invaders and maintain sperm motility, but excessive oxidative stress will induce host damage. Additionally, oxidative stress is always accompanied by autophagy which can also help maintain host homeostasis. Male reproductive system homeostasis disequilibrium can cause inflammation of the genitourinary system, influence spermatogenesis, and even lead to infertility. Here, we focus on the effect of oxidative stress and autophagy on bacterial infection in the male reproductive system, and we also explore the crosslink between oxidative stress and autophagy during this process.

scholarly journals β‐arrestin‐mediated signal transduction participates in laminar shear stress‐induced production of nitric oxide in endothelial cells

2013 ◽  
Vol 27 (S1) ◽  
Author(s):  
Ana Paula Carneiro Santos ◽  
Valério Garrone Barauna ◽  
Miriam Helena Fonseca Alaniz ◽  
Adriana Castello Costa Girardi ◽  
José Eduardo Krieger
Keyword(s):  
Nitric Oxide ◽  
Signal Transduction ◽  
Endothelial Cells ◽  
Shear Stress ◽  
Laminar Shear Stress ◽  
Laminar Shear

scholarly journals Remarkable rutin-rich Hypericum capitatum extract exhibits anti-inflammatory effects on turpentine oil-induced inflammation in rats

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Anca D. Farcas ◽  
Augustin C. Mot ◽  
Cezara Zagrean-Tuza ◽  
Madalina Ticolea ◽  
Bogdan Sevastre ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Nitric Oxide ◽  
Good Alternative ◽  
Oxidative Status ◽  
Paramagnetic Resonance ◽  
Chromatographic Techniques ◽  
Total Oxidative Status ◽  
Anti Inflammatory ◽  
Electron Paramagnetic

Abstract Background Natural extracts with beneficial biological activities are nowadays of high interest, in various treatment or prophylaxis. Hypericum capitatum has been known for its curative effects for centuries and its extracts have become of interest due to their distinct activity among other Hypericaceae members. In this study, further light is aimed to be shed on the secondary-metabolites composition of H. capitatum extracts, using chromatographic techniques and Electron paramagnetic resonance profiles in alkaline medium. Considering that no previous works explored the anti-inflammatory activity of H. capitatum, here, an in vivo study is also designed in order to evaluate this property by assessing the impact of one of H. capitatum extracts in ameliorating turpentine oil-induced inflammation on rats and to quantify their blood antioxidants level. Methods Chromatographic techniques and Electron paramagnetic resonance spectroscopy were used in order to describe the chemical profile in different parts of the plant. The in vivo study on turpentine-oil induced inflammation in rats included three doses of H. capitatum extract expressed in rutin concentration. Oxidative stress was measured using total oxidative status, total antioxidant capacity, oxidative stress index, 3-nitrotyrosine, nitric oxide, malondialdehyde, superoxide dismutase, catalase and the inflammatory response was evaluated by performing a complete blood cells count and C reactive protein. Results The extract was remarkably rich in rutin; however, other polyphenolic-like minor components appeared important in explaining the observed biological properties. The tested extract prevents the increase of inflammation-induced white blood cell count, number of neutrophils, and serum nitric oxide, and did so in a dose-dependent manner, similarly to the positive control—diclofenac. In addition, the same extract appeared to be a good alternative to diclofenac to restore total oxidative status, thiobarbituric active reactive species, total proteins and C reactive proteins. Moreover, antioxidant enzymes such as catalase, superoxide dismutase and total serum thiol concentration were significantly increased by the tested extract. Conclusions Due to its powerful reservoir rich in rutin, H. capitatum extract depicted its in vivo antioxidant and anti-inflammatory effects indicating it to be a good alternative to conventional drugs for oxidative stress protection.

Sign in / Sign up

Export Citation Format

Share Document