• The Korean Journal of Physiology and Pharmacology
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• v.2 no.4
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• pp.479-491
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• 1998

In order to know the pathogenesis of adult respiratory distress syndrome (ARDS) in association with the oxidative stress by neutrophils, the role of platelet activating factor (1-0-alkyl-2-acetyl-snglycero-3-phosphocholine, PAF) was investigated during acute lung injury induced by interleukin- $1{\alpha}$ (IL-1) in rats. An insufflation of IL-1 into the rat's trachea increased the acetyltransferase activity in the lung and the increase of PAF content was followed. As evidences of acute lung injury by neutrophilic respiratory burst, lung leak index, myeloperoxidase activity, numbers of neutrophils in the bronchoalveolar lavage fluid, neutrophilic adhesions to endothelial cells and NBT positive neutrophils were increased after IL-1 treatment. In addition, a direct instillation of PAF into the trachea caused acute lung leak and the experimental results showed a similar pattern in comparison with IL-1 induced acute lung injury. For the confirmation of oxidative stress during acute lung leak by IL-1 and PAF, a histochemical electron microscopy was performed. In IL-1 and PAF treated lungs of rats, the deposits of cerrous perhydroxide were found. To elucidate the role of PAF, an intravenous injection of PAF receptor antagonist, WEB 2086 was given immediately after IL-1 or PAF treatment. WEB 2086 decreased the production of hydrogen peroxide and the acute lung leak. In ultrastructural study, WEB 2086 mitigated the pathological changes induced by IL-1 or PAF. The nuclear factor kappa B (NFkB) was activated by PAF and this activation was inhibited by WEB 2086 almost completely. Based on these experimental results, it is suggested that the PAF produced in response to IL-1 through the remodeling pathway has the major role for acute lung injury by neutrophilic respiratory burst. In an additional experiment, we can also come to conclude that the activation of the NFkB by PAF is thought to be the fundamental mechanism to initiate the oxidative stress by neutrophils causing release of proinflammatory cytokines and activation of phospholipase $A_2$.

• The Korean Journal of Physiology and Pharmacology
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• v.25 no.2
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• pp.159-166
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• 2021

Nicotinamide adenine dinucleotide phosphate oxidases (NOXs) are the major enzymatic source of reactive oxygen species (ROS). NOX2 and NOX4 are expressed in the heart but its role in hypoxia-induced atrial natriuretic peptide (ANP) secretion is unclear. This study investigated the effect of NOX on ANP secretion induced by hypoxia in isolated beating rat atria. The results showed that hypoxia significantly upregulated NOX4 but not NOX2 expression, which was completely abolished by endothelin-1 (ET-1) type A and B receptor antagonists BQ123 (0.3 μM) and BQ788 (0.3 μM). ET-1-upregulated NOX4 expression was also blocked by antagonists of secreted phospholipase A2 (sPLA2; varespladib, 5.0 μM) and cytosolic PLA2 (cPLA2; CAY10650, 120.0 nM), and ET-1-induced cPLA2 expression was inhibited by varespladib under normoxia. Moreover, hypoxia-increased ANP secretion was evidently attenuated by the NOX4 antagonist GLX351322 (35.0 μM) and inhibitor of ROS N-Acetyl-D-cysteine (NAC, 15.0 mM), and hypoxia-increased production of ROS was blocked by GLX351322. In addition, hypoxia markedly upregulated Src expression, which was blocked by ET receptors, NOX4, and ROS antagonists. ET-1-increased Src expression was also inhibited by NAC under normoxia. Furthermore, hypoxia-activated extracellular signal-regulated kinase 1/2 (ERK1/2) and protein kinase B (Akt) were completely abolished by Src inhibitor 1 (1.0 μM), and hypoxia-increased GATA4 was inhibited by the ERK1/2 and Akt antagonists PD98059 (10.0 μM) and LY294002 (10.0 μM), respectively. However, hypoxia-induced ANP secretion was substantially inhibited by Src inhibitor. These results indicate that NOX4/Src modulated by ET-1 regulates ANP secretion by activating ERK1/2 and Akt/GATA4 signaling in isolated beating rat hypoxic atria.

• Journal of Ginseng Research
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• v.46 no.1
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• pp.23-32
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• 2022

Panax polysaccharides are biopolymers that are isolated and purified from the roots, stems, leaves, flowers, and fruits of Panax L. plants, which have attracted considerable attention because of their immunomodulatory activities. In this paper, the composition and structural characteristics of purified polysaccharides are reviewed. Moreover, the immunomodulatory activities of polysaccharides are described both in vivo and in vitro. In vitro, Panax polysaccharides exert immunomodulatory functions mainly by activating macrophages, dendritic cells, and the complement system. In vivo, Panax polysaccharides can increase the immune organ indices and stimulate lymphocytes. In addition, this paper also discusses the membrane receptors and various signalling pathways of immune cells. Panax polysaccharides have many beneficial therapeutic effects, including enhancing or activating the immune response, and may be helpful in treating cancer, sepsis, osteoporosis, and other conditions. Panax polysaccharides have the potential for use in the development of novel therapeutic agents or adjuvants with beneficial immunomodulatory properties.

• Molecules and Cells
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• v.39 no.7
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• pp.557-565
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• 2016

The paired immunoglobulin-like type 2 receptor (PILR) family consists of two functionally opposite members, inhibitory $PILR{\alpha}$ and activating $PILR{\beta}$ receptors. PILRs are widely expressed in various immune cells and interact with their ligands, especially CD99 expressed on activated T cells, to participate in immune responses. Here we investigated whether PILR-derived agonists inhibit ${\beta}1$ integrin activity as ligands for CD99. PILR-derived peptides as well as PILR-Fc fusion proteins prevented cell adhesion to fibronectin through the regulation of ${\beta}1$ integrin activity. Especially, PILRpep3, a representative 3-mer peptide covering the conserved motifs of the PILR extracellular domain, prevented the clustering and activation of ${\beta}1$ integrin by dephosphorylating FAK and vinculin, which are major components of focal adhesion. In addition, PILRpep3 inhibited transendothelial migration of monocytes as well as endothelial cell tube formation. Furthermore, upon intraperitoneal injection of PILRpep3 into mice with collagen-induced arthritis, the inflammatory response of rheumatoid arthritis was strongly suppressed. Taken together, these results suggest that PILR-derived agonist ligands may prevent the inflammatory reactions of rheumatoid arthritis by activating CD99.

• Molecules and Cells
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• v.47 no.3
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• pp.100007.1-100007.11
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• 2024

Recent evidence establishes a pivotal role for obesity-induced inflammation in precipitating insulin resistance and type-2 diabetes. Central to this process is the proinflammatory M1 adipose-tissue macrophages (ATMs) in epididymal white adipose tissue (eWAT). Notably, natural killer (NK) cells are a crucial regulator of ATMs since their cytokines induce ATM recruitment and M1 polarization. The importance of NK cells is shown by the strong increase in NK-cell numbers in eWAT, and by studies showing that removing and expanding NK cells respectively improve and worsen obesity-induced insulin resistance. It has been suggested that NK cells are activated by unknown ligands on obesity-stressed adipocytes that bind to NKp46 (encoded by Ncr1), which is an activating NK-cell receptor. This was supported by a study showing that NKp46-knockout mice have improved obesity-induced inflammation/insulin resistance. We therefore planned to use the NKp46-knockout mice to further elucidate the molecular mechanism by which NKp46 mediates eWAT NK-cell activation in obesity. We confirmed that obesity increased eWAT NKp46⁺ NK-cell numbers and NKp46 expression in wild-type mice and that NKp46-knockout ablated these responses. Unexpectedly, however, NKp46-knockout mice demonstrated insulin resistance similar to wild-type mice, as shown by fasting blood glucose/insulin levels and glucose/insulin tolerance tests. Obesityinduced increases in eWAT ATM numbers and proinflammatory gene expression were also similar. Thus, contrary to previously published results, NKp46 does not regulate obesity-induced insulin resistance. It is therefore unclear whether NKp46 participates in the development of obesity-induced inflammation and insulin resistance. This should be considered when elucidating the obesity-mediated molecular mechanisms that activate NK cells.

• Journal of Embryo Transfer
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• v.17 no.3
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• pp.171-177
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• 2002

Glucocorticoid is activating mammary gland cells for lactating animals, resulting in increasing abilities of the milk synthesis. Expression of the prolactin receptor(PRL-R) in mammary gland cells was closely associated with milk production. To increase lactation ability for the Korean Native Goats at mid-lactation period. 0.05, 0.1. and 0.2 g of hydrocortisone was administrated with 5 $m\ell$ of saline. and injected into vein. For the control, 5 $m\ell$ of saline was administrated in to vein. After 24 H, the mammary gland tissue was collected, and mRNA expression rates were investigated for the alpha-casein and PRL-R using competitive PCR(polymerase chain reaction). There was no significant differences between treatment and control groups for the mRNA expression rate of PRL-R in mammary gland cells after 24 h of administration of hydrocortisone. The rate of mRNA expression for the alpha-casein was increased 37%, 630%, and 380% at 0.05, 0.1, and 0.2 g of hydrocortisone administration groups, respectively, comparing with control group. The results suggested that PR L-R mRNA expression of mammary gland cell by administration of hydrocortison was not significant, but increase of the alpha-casein mRNA expression my be differences of expression of functional proteins in the cell and expression patterns of protein secretion time to out of the cell. This study showed increase of alpha-casein mRNA expression by administration of hydrocortisone at mid-lactation period of Korean native goat.

• The Korean Journal of Physiology and Pharmacology
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• v.21 no.3
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• pp.293-300
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• 2017

Prostaglandin $D_2$ ($PGD_2$) may act against myocardial ischemia-reperfusion (I/R) injury and play an anti-inflammatory role in the heart. Although the effect of $PGD_2$ in regulation of ANP secretion of the atrium was reported, the mechanisms involved are not clearly identified. The aim of the present study was to investigate whether $PGD_2$ can regulate ANP secretion in the isolated perfused beating rat atrium, and its underlying mechanisms. $PGD_2$ (0.1 to $10{\mu}M$) significantly increased atrial ANP secretion concomitantly with positive inotropy in a dose-dependent manner. Effects of $PGD_2$ on atrial ANP secretion and mechanical dynamics were abolished by AH-6809 ($1.0{\mu}M$) and AL-8810 ($1.0{\mu}M$), $PGD_2$ and prostaglandin $F2{\alpha}$ ($PGF2{\alpha}$) receptor antagonists, respectively. Moreover, $PGD_2$ clearly upregulated atrial peroxisome proliferator-activated receptor gamma ($PPAR{\gamma}$) and the $PGD_2$ metabolite 15-deoxy-${\Delta}12$, 14-$PGJ_2$ (15d-$PGJ_2$, $0.1{\mu}M$) dramatically increased atrial ANP secretion. Increased ANP secretions induced by $PGD_2$ and 15d-$PGJ_2$ were completely blocked by the $PPAR{\gamma}$ antagonist GW9662 ($0.1{\mu}M$). PD98059 ($10.0{\mu}M$) and LY294002 ($1.0{\mu}M$), antagonists of mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) and phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt) signaling, respectively, significantly attenuated the increase of atrial ANP secretion by $PGD_2$. These results indicated that $PGD_2$ stimulated atrial ANP secretion and promoted positive inotropy by activating $PPAR{\gamma}$ in beating rat atria. MAPK/ERK and PI3K/Akt signaling pathways were each partially involved in regulating $PGD_2$-induced atrial ANP secretion.

• Molecules and Cells
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• v.37 no.9
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• pp.656-663
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• 2014

Gintonin, a novel, ginseng-derived G protein-coupled lysophosphatidic acid (LPA) receptor ligand, elicits $[Ca^{2+}]_i$ transients in neuronal and non-neuronal cells via pertussis toxin-sensitive and pertussis toxin-insensitive G proteins. The slowly activating delayed rectifier $K^+$ ($I_{Ks}$) channel is a cardiac $K^+$ channel composed of KCNQ1 and KCNE1 subunits. The C terminus of the KCNQ1 channel protein has two calmodulin-binding sites that are involved in regulating $I_{Ks}$ channels. In this study, we investigated the molecular mechanisms of gintonin-mediated activation of human $I_{Ks}$ channel activity by expressing human $I_{Ks}$ channels in Xenopus oocytes. We found that gintonin enhances $I_{Ks}$ channel currents in concentration- and voltage-dependent manners. The $EC_{50}$ for the $I_{Ks}$ channel was $0.05{\pm}0.01{\mu}g/ml$. Gintonin-mediated activation 1 of the $I_{Ks}$ channels was blocked by an LPA1/3 receptor antagonist, an active phospholipase C inhibitor, an $IP_3$ receptor antagonist, and the calcium chelator BAPTA. Gintonin-mediated activation of both the $I_{Ks}$ channel was also blocked by the calmodulin (CaM) blocker calmidazolium. Mutations in the KCNQ1 $[Ca^{2+}]_i$/CaM-binding IQ motif sites (S373P, W392R, or R539W)blocked the action of gintonin on $I_{Ks}$ channel. However, gintonin had no effect on hERG $K^+$ channel activity. These results show that gintonin-mediated enhancement of $I_{Ks}$ channel currents is achieved through binding of the $[Ca^{2+}]_i$/CaM complex to the C terminus of KCNQ1 subunit.

• Animal Bioscience
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• v.34 no.10
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• pp.1590-1599
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• 2021

Objective: This study investigates the expression patterns of toll-like receptors (TLRs) and intracellular mediators in horse muscle cells after exercise, and the relationship between TLRS expression in stressed horse muscle cells and immune cell migration toward them. Methods: The expression patterns of the TLRs (TLR2, TLR4, and TLR8) and downstream signaling pathway-related genes (myeloid differentiation primary response 88 [MYD88]; activating transcription factor 3 [ATF3]) are examined in horse tissues, and horse peripheral blood mononuclear cells (PBMCs), polymorphonuclear cells (PMNs) and muscles in response to exercise, using the quantitative reverse transcription-polymerase chain reaction (qPCR). Expressions of chemokine receptor genes, i.e., C-X-C motif chemokine receptor 2 (CXCR2) and C-C motif chemokine receptor 5 (CCR5), are studied in PBMCs and PMNs. A horse muscle cell line is developed by transfecting SV-T antigen into fetal muscle cells, followed by examination of muscle-specific genes. Horse muscle cells are treated with stressors, i.e., cortisol, hydrogen peroxide (H₂O₂), and heat, to mimic stress conditions in vitro, and the expression of TLR4 and TLR8 are examined in stressed muscle cells, in addition to migration activity of PBMCs toward stressed muscle cells. Results: The qPCR revealed that TLR4 message was expressed in cerebrum, cerebellum, thymus, lung, liver, kidney, and muscle, whereas TLR8 expressed in thymus, lung, and kidney, while TLR2 expressed in thymus, lung, and kidney. Expressions of TLRs, i.e., TLR4 and TLR8, and mediators, i.e., MYD88 and ATF3, were upregulated in muscle, PBMCs and PMNs in response to exercise. Expressions of CXCR2 and CCR5 were also upregulated in PBMCs and PMNs after exercise. In the muscle cell line, TLR4 and TLR8 expressions were upregulated when cells were treated with stressors such as cortisol, H₂O₂, and heat. Migration of PBMCs toward stressed muscle cells was increased by exercise and oxidative stresses, and combinations of these. Treatment with methylsulfonylmethane (MSM), an antioxidant on stressed muscle cells, reduced migration of PBMCs toward stressed muscle cells. Conclusion: In this study, we have successfully cultured horse skeletal muscle cells, isolated horse PBMCs, and established an in vitro system for studying stress-related gene expressions and function. Expression of TLR4, TLR8, CXCR2, and CCR5 in horse muscle cells was higher in response to stressors such as cortisol, H₂O₂, and heat, or combinations of these. In addition, migration of PBMCs toward muscle cells was increased when muscle cells were under stress, but inhibition of reactive oxygen species by MSM modulated migratory activity of PBMCs to stressed muscle cells. Further study is necessary to investigate the biological function(s) of the TLR gene family in horse muscle cells.

• Korean Journal of Veterinary Research
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• v.41 no.4
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• pp.497-503
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• 2001

Evidence from the last 10 years have been suggested that melatonin mainly produce a depressant effect on the cardiac system, but we found an activating effect of melatonin on heart rate in this research. To determine the hypothesis that melatonin has dual effects on physiological behaviour of cardiac system, we investigated the effects of melatonin on heart rate in isolated rat atria and anesthetized rats. Regardless of concentration, melatonin produced bradycardia in the 84 cases of 148 experiments (57 %) and tachycardia in the 64 cases of 148 experiments (43 %). And in atrium, melatonin produced a decrease automaticity in 52 cases of 86 experiments (60 %) and increase automaticity in 40 % (34/86 cases). Also, these effects are not significnat relationship with concetration of melatonin. The melatonin-induced bradycardia in vivo was inhibited by pretreatment of atropine or bilateral cervical vagotomy. Also, in isolated atrium the melatonin-induced decrease in automaticity was inhibited by pretreatment of atropine. These melatonin-induced responses were potenitated by pretreatment of propranolol. The melatonin-induced tachycardia in vivo was inhibited by pretreatment of propranolol, nifedipine or bilateral cervical vagotomy, but not by pretreatment of atropine. The melatonin-induced incease in automaticity in isolated atrium was converted to decrease in automaticity by pretreatment of propranolol. In addition, the change in heart rate caused by adrenoceptor agonists was inhibited by pretreatment of melatonin. These results indicate that melatonin-induced bradycardia may be related to a muscarinic receptor activation and melatonin-induced tachycardia may be related to a $\beta$-adrenoceptor stimulation.