• Biomolecules & Therapeutics
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• v.15 no.3
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• pp.150-155
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• 2007

In the present study, we have tested the effect of dioleoyl phosphatidic acid (PA) on intracellular $Ca_{2+}$ concentration ($[Ca^{2+}]_{i}$) in two human colon cancer cell lines (HCT116 and HT29). PA and lysophosphatidic acid (LPA), a bioactive lysolipid, increased $[Ca^{2+}]_{i}$ in both HCT116 and HT29 cell lines. Increases of $[Ca^{2+}]_{i}$ by PA and LPA were more robust in HCT116 cells than in HT29 cells. A specific inhibitor of phospholipase C (U73122), however, was not inhibitory to the cell responses. Pertussis toxin, a specific inhibitor of $G_{i/o}$ type G proteins, however, had an inhibitory effect on the responses except for an LPA-induced one in HT29 cells. Ruthenium red, an inhibitor of the ryanodine receptor, was not inhibitory on the responses, however, 2-APB, a specific inhibitor of inositol 1,4,5-trisphosphate receptor, completely inhibited both lipid-induced $Ca^{2+}$ increases in both cell types. Furthermore, by using Ki16425 and VPC32183, two structurally dissimilar specific antagonists for $LPA_{1}/LPA_{3}$ receptors, an involvement of endogenous LPA receptors in the $Ca^{2+}$ responses was observed. Ki16425 completely inhibited the responses but the susceptibility to VPC32183 was different to PA and LPA in the two cell types. Expression levels of five LPA receptors in the HCT116 and HT29 cells were also assessed. Our data support the notion that PA could increase $[Ca^{2+}]_{i}$ in human colon cancer cells, probably via endogenous LPA receptors, G proteins and $IP_{3}$ receptors, thereby suggesting a role of PA as an intercellular lipid mediator.

• Biomedical Science Letters
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• v.23 no.3
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• pp.251-260
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• 2017

Platelet activation is essential at the sites of vascular injury, which leads to hemostasis through adhesion, aggregation, and secretion process. However, potent and continuous platelet activation may be an important reason of circulatory disorders. Therefore, proper regulation of platelet activation may be an effective treatment for vascular diseases. In this research, inhibitory effects of cordycepin (3'-deoxyadenosine) on platelet activation were determined. As the results, cordycepin increased cAMP and cGMP, which are intracellular $Ca^{2+}$-antagonists. In addition, cordycepin reduced collagen-elevated $[Ca^{2+}]_i$ mobilization, which was increased by a cAMP-dependent protein kinase (PKA) inhibitor (Rp-8-Br-cAMPS), but not a cGMP-protein kinase (PKG) inhibitor (Rp-8-Br-cGMPS). Furthermore, cordycepin increased $IP_3RI$ ($Ser^{1756}$) phosphorylation, indicating inhibition of $IP_3$-mediated $Ca^{2+}$ release from internal store via the $IP_3RI$, which was strongly inhibited by Rp-8-Br-cAMPS, but was not so much inhibited by Rp-8-Br-cGMPS. These results suggest that the reduction of $[Ca^{2+}]_i$ mobilization is caused by the cAMP/A-kinase-dependent $IP_3RI$ ($Ser^{1756}$) phosphorylation. In addition, cordycepin increased the phosphorylation of VASP ($Ser^{157}$) known as PKA substrate, but not VASP ($Ser^{239}$) known as PKG substrate. Cordycepin-induced VASP ($Ser^{157}$) phosphorylation was inhibited by Rp-8-Br-cAMPS, but was not inhibited by Rp-8-Br-cGMPS, and cordycepin inhibited collagen-induced fibrinogen binding to ${\alpha}IIb/{\beta}_3$, which was increased by Rp-8-Br-cAMPS, but was not inhibited by Rp-8-Br-cGMPS. These results suggest that the inhibition of ${\alpha}IIb/{\beta}_3$ activation is caused by the cAMP/A-kinase-dependent VASP ($Ser^{157}$) phosphorylation. In conclusion, these results demonstrate that inhibitory effects of cordycepin on platelet activation were due to inhibition of $[Ca^{2+}]_i$ mobilization through cAMP-dependent $IP_3RI$ ($Ser^{1756}$) phosphorylation and suppression of ${\alpha}IIb/{\beta}_3$ activation through cAMP-dependent VASP ($Ser^{157}$) phosphorylation. These results strongly indicated that cordycepin might have therapeutic or preventive potential for platelet activation-mediated disorders including thrombosis, atherosclerosis, myocardial infarction, or cardiovascular disease.

• The Korean Journal of Physiology and Pharmacology
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• v.2 no.3
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• pp.279-286
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• 1998

It has been well documented that transient forebrain global ischemia causes selective neuronal degeneration in hippocampal CA1 pyramidal neurons with a delay of a few days. The mechanism of this delayed hippocampal CA1 pyramidal neuronal death (DND) is still controversial. To delineate the mechanisms of the DND, the effects of treatment with MK-801, an NMDA receptor antagonist, kynurenic acid, a NMDA/non-NMDA receptor antagonist, and/or cycloheximide, a protein synthesis inhibitor, on the DND were investigated in male Wistar rats. To examine the participation of apoptotic neuronal death in the DND, TUNEL staining was performed in ischemic brain section. Global ischemia was induced by 4-vessel occlusion for 20 min. All animals in this study showed the DND 3 and 7 days after the ischemic insult. The DND that occured 3 days and 7 days after the ischemia were not affected by pretreatment with MK-801 (1 mg/kg), but markedly attenuated by the pretreatment with kynurenic acid (500 mg/kg). Treatment with cycloheximide (1 mg/kg) also markedly inhibited the DND. The magnitudes of attenuation by the two drugs were similar. The magnitude of attenuation by co-treatments with kynurenic acid and cycloheximide was not greater than that with any single treatment. TUNEL staining was negative in the sections obtained 1 or 2 days after the ischemic insults, but it was positive at hippocampal CA1 pyramidal cells in sections collected 3 days after the ischemia. These results suggested that the DND should be mediated by the activation of non-NMDA receptor, not by the activation of NMDA receptor and that the activation of AMPA receptor should induce the apoptotic process in the DND.

• Journal of Plant Biotechnology
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• v.49 no.4
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• pp.316-324
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• 2022

Hair loss causes psychological stress due to its effect on appearance. Therefore, the global market for hair loss treatment products is rapidly growing. The present study demonstrated that ginseng berry-derived and sequence-modified peptides promoted the proliferation rate of dermal papilla (DP) cells and keratinocytes, in addition to having antioxidant properties. Moreover, the potential role of these ginseng berry peptides as TGF-β2 antagonists was confirmed through in silico computer docking. In addition to promoting the growth of ,the ginseng berry-derived peptides also promoted the proliferation of keratinocytes experimental Particularly, an unmodified ginseng berry-derived peptide (GB-1) and two peptides with sequence modifications (GB-2 and GB-3) decreased ROS generation and exhibited a protective effect on damaged HaCaT keratinocytes. Computer-aided peptide discovery was conducted to identify the potential interactions of important proteins with transforming growth factor-beta 2 (TGF-β2), a key protein that plays a crucial role in the human hair growth cycle. Our results demonstrated that MAGH, an amino acid sequence present in herbal supplements and plant-based natural compounds, can inhibit TGF-β2.

• International Journal of Oral Biology
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• v.31 no.4
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• pp.141-148
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• 2006

The effects of adenosine triphosphate(ATP) on salivary glands have been recognized since 1982. The presence of purinergic recepetors(P2Rs) that mediate the effects of ATP in various tissues, including parotid and submandibular salivary gland, has been supported by the cloning of receptor cDNAs and the expression of the receptor proteins. P2Rs have many subtypes, and the activation of these receptor subtypes increase intracellular $Ca^{2+}$, a key ion in the regulation of the secretion in the salivary gland. The apical pores of taste buds in circumvallate and foliate papillae are surrounded by the saliva from von Ebner salivary gland(vEG). Thus, it is important how the secretion of vEG is controlled. This study was designed to elucidate the roles of P2Rs on salivary secretion of vEG. Male Sprague-Dawley rats (about 200 g) were used for this experiment. vEG-rich tissues were obtained from dissecting $500-1,000\;{\mu}m$ thick posterior tongue slices under stereomicroscope view. P2Rs mRNA in vEG acinar cells were identified with RT-PCR. To observe the change in intracellular $Ca^{2+}$ activity, we employed $Ca^{2+}-ion$ specific fluorescence analysis with fura-2. Single acinar cells and cell clusters were isolated by a sequential trypsin/collagenase treatment and were loaded with $10\;{\mu}M$ fura -2 AM for 60 minutes at room temperature. Several agonists and antagonists were used to test a receptor specificity. RT-PCR revealed that the mRNAs of $P2X_4$, $P2Y_1$, $P2Y_2$ and $P2Y_3$ are expressed in vEG acinar cells. The intracellular calcium activity was increased in response to $10\;{\mu}M$ ATP, a P2Rs agonist, and 2-MeSATP, a $P2Y_1$ and $P2Y_2R$ agonist. However, $300\;{\mu}M\;{\alpha}{\beta}-MeATP$, a $P2X_1$ and $P2X_3R$ agonist, did not elicit the response. The responses elicited by $10\;{\mu}M$ ATP and UTP, a $P2Y_2R$ agonists, were maintained when extracellular calcium was removed. $10\;{\mu}M$ suramin, a P2XR antagonist, and reactive blue 2, a P2YR antagonist, partially blocked ATP-induced response. However, when extracellular calciums were removed, suramin did not abolish the responses elicited by ATP. These results suggest that P2Rs play an important role in salivary secretion of vEG acinar cells and the effects of ATP on vEG salivary secretion may be mediated by $P2X_4$, $P2Y_1$, $P2Y_2$, and/or $P2Y_3$.

• The Korean Journal of Physiology and Pharmacology
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• v.7 no.5
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• pp.251-254
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• 2003

The present study was designed to examine whether the co-application of morphine with $Ca^{2+}$ channel antagonist $(Mn^{2+},\;verapamil)$, N-methyl-D-aspartate (NMDA) receptor antagonist (2-amino-5-phosphonopentanoic acid$[AP_5]$, $Mg^{2+}$) or protein kinase C inhibitor (H-7) causes the potentiation of morphine-induced antinociceptive action by using an in vivo electrophysiological technique. A single iontophoretic application of morphine or an antagonist alone induced weak inhibition of wide dynamic range (WDR) cell responses to iontophoretically applied NMDA and C-fiber stimulation. Although there was a little difference in the potentiating effects, the antinociceptive action of morphine was potentiated when morphine was iontophoretically applied together with $Mn^{2+}$, verapamil, $AP_5$, $Mg^{2+}$ or H-7. However, the potentiating action between morphine and each antagonist was not apparent, when the antinociceptive action evoked by morphine or the antagonist alone was too strong. These results suggest that the potentiating effect can be caused by the interaction between morphine and each antagonist in the spinal dorsal horn.

• The Korean Journal of Physiology and Pharmacology
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• v.22 no.2
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• pp.155-162
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• 2018

3-(2-Carboxypiperazin-4-yl)propyl-1-phosphonic acid (CPP), a competitive N-methyl-D-aspartate (NMDA) receptor antagonist, produces rapid antidepressant-like effects in animal models of depression. However, the molecular mechanisms underlying these behavioral actions remain unknown. Here, we demonstrate that CPP rapidly stimulates histone deacetylase (HDAC) 5 phosphorylation and nuclear export in rat hippocampal neurons. These effects are accompanied by calcium/calmodulin kinase II (CaMKII) and protein kinase D (PKD) phosphorylation. Behavioral experiments revealed that viral-mediated hippocampal knockdown of HDAC5 blocked the antidepressant effects of CPP in stressed animals. Taken together, our results imply that CPP acts via HDAC5 and suggest that HDAC5 is a common regulator contributing to the antidepressant actions of NMDA receptor antagonists such as CPP.

• International Journal of Oral Biology
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• v.34 no.4
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• pp.215-222
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• 2009

Medial vestibular nucleus (MVN) neurons are involved in the reflex control of the head and eyes, and in the recovery of vestibular function after the formation of peripheral vestibular lesions. In our present study, whole cell patch clamp recordings were carried out on MVN neurons in brainstem slices from neonatal rats to investigate the actions of a group I metabotropic glutamate receptor (mGluR) agonist upon synaptic transmission and ionic currents. Application of the mGluR I agonist (S)-3,5- dihydroxyphenylglycine (DHPG) increased the frequency of miniature inhibitory postsynaptic currents (mIPSCs) but had no effect upon amplitude distributions. To then identify which of mGluR subtypes is responsible for the actions of DHPG in the MVN, we employed two novel subtype selective antagonists. (S)-(+)-$\alpha$-amino-a-methylbenzeneacetic acid (LY367385) is a potent competitive antagonist that is selective for mGluR1, whereas 2-methyl-6-(phenylethynyl)-pyridine (MPEP) is a potent noncompetitive antagonist of mGluR5. Both LY367385 and MPEP antagonized the DHPG-induced increase of mIPSCs, with the former being more potent. DHPG was also found to induce an inward current, which can be enhanced under depolarized conditions. This DHPG-induced current was reduced by both LY367385 and MPEP. The DHPG-induced inward current was also suppressed by the PLC blocker U-73122, the $IP_3$ receptor antagonist 2-APB, and following the depletion of the intracellular $Ca^{2+}$ pool by thapsigargin. These data suggest that the DHPG-induced inward current may be mainly regulated by the intracellular $Ca^{2+}$ store via the PLC-$IP_3$ pathway. In conclusion, mGluR I, via pre- and postsynaptic actions, may modulate the excitability of the MVN neurons.

• The Korean Journal of Pharmacology
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• v.17 no.2
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• pp.7-16
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• 1981

Higenamine ($Ca_{26}H_{17}No_3$. HCI, d1-1- (4-hydroxybenzyl) -6,7-dihydroxy-1,2,3,4-tetrahydroiso-quinoline hydrochloride), which has recently teen isolated from the Aconite root, was known to the cardiotonic component of the Aconite root. The positive inotropic effect of Higenamine was observed in the isolated electrically driven left atrium from rabbits with respect to the influences of extracellular calcium and of calcium antagonists, e.g. $La^{+++}$ and verapamil. A synergistic relation in the positive inotropic effect could be demonstrated between Higenamine and extra cellular calcium. The inotropic potency of $10^{-7}\;g/ml$ Higenamine was equivalant to that of 0.058 mM of calcium in the medium. In the preparation, of which contractility had been reduced by the treatment of $La^{+++}(10^{-5}-10^{-4}M)$ and verapamil$(2{\times}10^{-7}-10^{-6}M)$, Higenamine was able to restore the contractility. These results indicated that one of the possible mechanism of positive inotropism of Higenamine was to accelerate the influx of calcium from the extracellular space through the sarcolemma.

• The Korean Journal of Physiology
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• v.18 no.2
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• pp.139-150
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• 1984

Vanadate is a potent inhibitor of Na-K-ATPase. Ouabain, the another specific inhibitor of Na-K-ATPase, induces the contraction in cardiac muscle and smooth muscle. But, some investigators observed the discrepancies between vanadate and ouabain-induced contraction in cardiac muscle. The difference of vanadate and ouabain-induced contraction was investigated in the cat ileal smooth muscle. The following results were obtained. 1) Ouabain-induced contraction was biphasic, but vanadate-induced contraction had one peak. 2) Atropine inhibited ouabain·induced contraction, but did not inhibit vanadate-induced contraction. 3) Changes in external $Ca^{++}$concentration or $Ca^{++}$ antagonists had a greater influence on the contraction induced hy vanadate than by ouabain. 4) Removal of $Na^+$ from incubation medium and high $K^+$ abolished ouabain-induced contraction, but had no effect on vanadate-induced contraction. 5) Vanadate-induced contraction was potentiated in the presence of ouabain. 6) After 3 hrs incubation with vanadate, there was no change in intracellular $Na^+$ concentrations in contrast with ouabain. These results suggest that vanadate contracts ileal smooth muscle through the mechanism different from ouabain, and this is independent of the inhibition of Na-K-ATPase activity.