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Choi MR, Oh DH, Kim SH, Yang BH, Lee JS, Choi J, Jeon HS, Chai YG, Park YC. Fluoxetine Up-Regulates Bcl-xL Expression in Rat C6 Glioma Cells. Psychiatry Investig 2011; 8:161-8. [PMID: 21852994 PMCID: PMC3149112 DOI: 10.4306/pi.2011.8.2.161] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Revised: 12/03/2010] [Accepted: 12/27/2010] [Indexed: 12/29/2022] Open
Abstract
OBJECTIVE To analyze both differentially expressed genes and the Bcl-xL protein expression after acute and chronic treatment with fluoxetine in rat C6 glioma cells. METHODS C6 glioma cells were cultured for 24 h or 72 h after treatment with 10 µM fluoxetine, and gene expression patterns were observed using microarray and qRT-PCR. Then, cells were cultured for 6 h, 24 h, 72 h or 96 h after treatment with 10 µM fluoxetine, and the expression of Bcl-xL protein was measured using western blot. RESULTS As determined by microarray, treatment with fluoxetine for 24 h up-regulated 33 genes (including Bcl-xL and NCAM140) and down-regulated 7 genes (including cyclin G-associated kinase). Treatment with fluoxetine for 72 h up-regulated 53 genes (including Gsα and Bcl-xL) and down-regulated 77 genes (including Gαi2 and annexin V). Based on the qRT-PCR results, there was an increase in Gsα mRNA and a decrease in Gαi2 mRNA at 72 h in fluoxetine-treated cells as compared to control, a result that was consistent with microarray. We also observed an increase in Bcl-xL mRNA (both at 24 h and at 72 h) in fluoxetine-treated cells as compared to control, demonstrating a tendency to increase gradually. Bcl-xL protein expression increased as the duration of fluoxetine treatment increased. CONCLUSION These results suggest that chronic treatment with fluoxetine not only initiates the cAMP pathway through inducing Gsα expression but also induces Bcl-xL expression, thus inhibiting apoptosis.
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Affiliation(s)
- Mi Ran Choi
- Division of Molecular and Life Sciences, Hanyang University, Ansan, Korea
| | - Dong Hoon Oh
- Department of Neuropsychiatry, College of Medicine and Institute of Mental Health, Hanyang University, Seoul, Korea
| | - Seok Hyeon Kim
- Department of Neuropsychiatry, College of Medicine and Institute of Mental Health, Hanyang University, Seoul, Korea
| | - Byung-Hwan Yang
- Department of Neuropsychiatry, College of Medicine and Institute of Mental Health, Hanyang University, Seoul, Korea
| | | | - Joonho Choi
- Department of Neuropsychiatry, College of Medicine and Institute of Mental Health, Hanyang University, Seoul, Korea
| | - Hyun-Soo Jeon
- Department of Neuropsychiatry, College of Medicine and Institute of Mental Health, Hanyang University, Seoul, Korea
| | - Young Gyu Chai
- Division of Molecular and Life Sciences, Hanyang University, Ansan, Korea
| | - Yong-Chon Park
- Department of Neuropsychiatry, College of Medicine and Institute of Mental Health, Hanyang University, Seoul, Korea
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2
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Roh K, Roh S, Yang BH, Lee JS, Chai YG, Choi MR, Park YC, Kim DJ, Kim D, Choi J, Kim SH. Effects of haloperidol and risperidone on the expression of heat shock protein 70 in MK-801-treated rat C6 glioma cells. Prog Neuropsychopharmacol Biol Psychiatry 2008; 32:1793-7. [PMID: 18721842 DOI: 10.1016/j.pnpbp.2008.07.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2008] [Revised: 07/24/2008] [Accepted: 07/28/2008] [Indexed: 10/21/2022]
Abstract
Non-competitive N-methyl-D-aspartate (NMDA) receptor antagonists such as dizocilpine (MK-801) produce schizophrenia-like psychosis in humans and induce the expression of heat shock protein 70 (HSP70) in rats. The present study examines the effects of antipsychotic drugs, haloperidol and risperidone, on the expression of HSP70 produced by MK-801 in rat C6 glioma cells. After pretreating with haloperidol and risperidone for 1 h, 6 h, 24 h and 72 h, respectively, C6 glioma cells were cultivated again in MK-801 for 6 h, and then, the extent of HSP70 expression was measured by immunoblotting using anti-HSP70 monoclonal antibody. The expression of HSP70 induced by MK-801 significantly decreased as the duration of haloperidol pretreatment was extended (p=0.002). Risperidone also increasingly attenuated the expression of HSP70 produced by MK-801 as the duration of pretreatment grew longer (p=0.003). The present findings show that haloperidol and risperidone decrease the HSP70 expression in MK-801-treated rat C6 glioma cells. These results suggest that HSP70 and NMDA receptors may play a significant role in the pathophysiology of schizophrenia.
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Affiliation(s)
- Kyungsoo Roh
- Department of Neuropsychiatry, Hanyang University College of Medicine, Seoul, Republic of Korea
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3
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Tsuchioka M, Takebayashi M, Hisaoka K, Maeda N, Nakata Y. Serotonin (5-HT) induces glial cell line-derived neurotrophic factor (GDNF) mRNA expression via the transactivation of fibroblast growth factor receptor 2 (FGFR2) in rat C6 glioma cells. J Neurochem 2008; 106:244-57. [DOI: 10.1111/j.1471-4159.2008.05357.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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4
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Clark MJ, Traynor JR. Mediation of adenylyl cyclase sensitization by PTX-insensitive GalphaoA, Galphai1, Galphai2 or Galphai3. J Neurochem 2007; 99:1494-504. [PMID: 17230639 DOI: 10.1111/j.1471-4159.2006.04176.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Chronic activation of mu-opioid receptors, which couple to pertussis toxin-sensitive Galphai/o proteins to inhibit adenylyl cyclase (AC), leads to a compensatory sensitization of AC. Pertussis toxin-insensitive mutations of Galphai/o subtypes, in which the pertussis toxin-sensitive cysteine is mutated to isoleucine (Galpha ), were used to determine whether each of the Galphai/o subtypes is able to mediate sensitization of AC. Galpha , G , G or G were individually transiently transfected into C6 glioma cells stably expressing the mu-opioid receptor, or transiently co-expressed with the mu-opioid receptor into human embryonic kidney (HEK)293T cells. Cells were treated with pertussis toxin to uncouple endogenous Galphai/o proteins, followed by acute or chronic treatment with the mu-opioid agonist, [D-Ala2,N-Me-Phe4,Gly5-ol]enkephalin (DAMGO). Each Galphai/o subtype mediated acute DAMGO inhibition of AC and DAMGO-induced sensitization of AC. The potency for DAMGO to stimulate sensitization was independent of the Galphai/o subtype, but the level of sensitization was increased in clones expressing higher levels of Galphai/o subunits. Sensitization of AC mediated by a component of fetal bovine serum, which was also dependent on the level of functional Galphai/o subunits in the cell, was observed. This serum-mediated sensitization partially masked mu-opioid-mediated sensitization when expressed as percentage overshoot due to an apparent increase in AC activity.
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Affiliation(s)
- Mary J Clark
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan USA
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5
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Myers RL, Airey DC, Manier DH, Shelton RC, Sanders-Bush E. Polymorphisms in the regulatory region of the human serotonin 5-HT2A receptor gene (HTR2A) influence gene expression. Biol Psychiatry 2007; 61:167-73. [PMID: 16697352 DOI: 10.1016/j.biopsych.2005.12.018] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2005] [Revised: 11/03/2005] [Accepted: 12/30/2005] [Indexed: 11/26/2022]
Abstract
BACKGROUND Genomic variation in the regulatory region of the serotonin (5-HT) 2A receptor gene (HTR2A) may contribute to altered levels of 5-HT2A receptor and to psychiatric disease. METHODS Frequency and linkage disequilibrium (LD) were determined for promoter single nucleotide polymorphisms (SNPs) -1438A/G, -1420C/T, and -783A/G in 156 subjects. Functional relevance of -1438A/G and -783A/G was assayed in vitro using a luciferase reporter assay and ex vivo using quantitative real time polymerase chain reaction in a set of human fibroblast cell lines. RESULTS Significant LD was observed between SNPs -1438A/G and -783A/G. In vitro assays showed no significant differences in promoter activity between the A- and G-allele of -1438 locus when expressed with the major alleles at -1420C/T and -783A/G; however, when the minor allele G at -783 was expressed with G-allele at -1438, promoter activity was significantly decreased. 5-HT2A receptor mRNA expression in human fibroblast cell lines confirmed that -783A/G polymorphism significantly modified the effects of -1438A/G SNP. CONCLUSIONS Our results demonstrate that SNP -783A/G modifies the effects of the major SNP -1438A/G. Future studies examining the association of -1438A/G polymorphism with diseases and 5-HT2A receptor expression analyses should account for this epistasis.
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Affiliation(s)
- Regina L Myers
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232-8548, USA
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6
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Hisaoka K, Takebayashi M, Tsuchioka M, Maeda N, Nakata Y, Yamawaki S. Antidepressants Increase Glial Cell Line-Derived Neurotrophic Factor Production through Monoamine-Independent Activation of Protein Tyrosine Kinase and Extracellular Signal-Regulated Kinase in Glial Cells. J Pharmacol Exp Ther 2007; 321:148-57. [PMID: 17210798 DOI: 10.1124/jpet.106.116558] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Recent studies show that neuronal and glial plasticity are important for therapeutic action of antidepressants. We previously reported that antidepressants increase glial cell line-derived neurotrophic factor (GDNF) production in rat C6 glioma cells (C6 cells). Here, we found that amitriptyline, a tricyclic antidepressant, increased both GDNF mRNA expression and release, which were selectively and completely inhibited by mitogen-activated protein kinase kinase inhibitors. Indeed, treatment of amitriptyline rapidly increased extracellular signal-regulated kinase (ERK) activity, as well as p38 mitogen-activated protein kinase and c-Jun NH2-terminal kinase activities. Furthermore, different classes of antidepressants also rapidly increased ERK activity. The extent of acute ERK activation and GDNF release were significantly correlated to each other in individual antidepressants, suggesting an important role of acute ERK activation in GDNF production. Furthermore, antidepressants increased the acute ERK activation and GDNF mRNA expression in normal human astrocytes as well as C6 cells. Although 5-hydroxytryptamine (serotonin) (5-HT), but not noradrenaline or dopamine, increased ERK activation and GDNF release via 5-HT2A receptors, ketanserin, a 5-HT2A receptor antagonist, did not have any effect on the amitriptyline-induced ERK activation. Thus, GDNF production by amitriptyline was independent of monoamine. Both of the amitriptyline-induced ERK activation and GDNF mRNA expression were blocked by genistein, a general protein tyrosine kinase (PTK) inhibitor. Actually, we found that amitriptyline acutely increased phosphorylation levels of several phosphotyrosine-containing proteins. Taken together, these findings indicate that ERK activation through PTK regulates antidepressant-induced GDNF production and that the GDNF production in glial cells may be a novel action of the antidepressant, which is independent of monoamine.
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Affiliation(s)
- Kazue Hisaoka
- Institute of Clinical Research, Kure Medical Center, 3-1 Aoyama, Kure 737-0023, Japan
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7
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8
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Mahé C, Bernhard M, Bobirnac I, Keser C, Loetscher E, Feuerbach D, Dev KK, Schoeffter P. Functional expression of the serotonin 5-HT7 receptor in human glioblastoma cell lines. Br J Pharmacol 2004; 143:404-10. [PMID: 15339860 PMCID: PMC1575348 DOI: 10.1038/sj.bjp.0705936] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Serotonin 5-HT(7) receptors are present in astrocytes. Understanding their role in this type of cell would greatly benefit from the identification of astroglial cell lines expressing this receptor type. The aim of the present study was to assess the expression of native 5-HT(7) receptors and 5-HT(7) receptor mRNA in a number of human glioblastoma cell lines, by means of cAMP measurements, Western blot analysis and reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. 5-Hydroxytryptamine (5-HT), 5-carboxamidotryptamine (5-CT), 5-methoxytryptamine (5-MeOT) and 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) induced concentration-dependent stimulations of cAMP accumulation in the human glioblastoma cell lines, U-373 MG, U-138 MG, U-87 MG, DBTRG-05MG, T98G, H4, CCF-STTG1 and Hs 683. The rank order of potency was 5-CT>5-HT=5-MeOT>>8-OH-DPAT. The effect of 5-CT was inhibited in a concentration-dependent manner by the selective 5-HT(7) receptor antagonist SB-269970 in all human glioblastoma cells. Schild analyses yielded slope factors close to unity (0.89-1.13) and pA(2) values of 8.69-9.05. Western blot analysis revealed the presence of immunoreactive bands corresponding to the human 5-HT(7) receptor in extracts of all human glioblastoma cell lines. The presence of the three splice variants of the 5-HT(7) receptor (5-HT(7(a/b/d))) was visualized by RT-PCR analysis with specific primers in all human glioblastoma cell lines. In conclusion, human glioblastoma cell lines express functional 5-HT(7) receptors and the three splice variants of the corresponding mRNA. These cell lines could serve as model systems of native 5-HT(7) receptors in glial cells to investigate their putative role in processes like release of neurotrophic factors or inflammatory cytokines.
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Affiliation(s)
- Cécile Mahé
- Neuroscience Research, Novartis Institutes for BioMedical Research, Novartis Pharma AG, WSJ-386.7.44, CH-4002 Basel, Switzerland
| | - Michel Bernhard
- Neuroscience Research, Novartis Institutes for BioMedical Research, Novartis Pharma AG, WSJ-386.7.44, CH-4002 Basel, Switzerland
| | - Ionel Bobirnac
- Neuroscience Research, Novartis Institutes for BioMedical Research, Novartis Pharma AG, WSJ-386.7.44, CH-4002 Basel, Switzerland
| | - Corinna Keser
- Neuroscience Research, Novartis Institutes for BioMedical Research, Novartis Pharma AG, WSJ-386.7.44, CH-4002 Basel, Switzerland
| | - Erika Loetscher
- Neuroscience Research, Novartis Institutes for BioMedical Research, Novartis Pharma AG, WSJ-386.7.44, CH-4002 Basel, Switzerland
| | - Dominik Feuerbach
- Neuroscience Research, Novartis Institutes for BioMedical Research, Novartis Pharma AG, WSJ-386.7.44, CH-4002 Basel, Switzerland
| | - Kumlesh K Dev
- Neuroscience Research, Novartis Institutes for BioMedical Research, Novartis Pharma AG, WSJ-386.7.44, CH-4002 Basel, Switzerland
| | - Philippe Schoeffter
- Neuroscience Research, Novartis Institutes for BioMedical Research, Novartis Pharma AG, WSJ-386.7.44, CH-4002 Basel, Switzerland
- Author for correspondence:
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9
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Hisaoka K, Nishida A, Takebayashi M, Koda T, Yamawaki S, Nakata Y. Serotonin increases glial cell line-derived neurotrophic factor release in rat C6 glioblastoma cells. Brain Res 2004; 1002:167-70. [PMID: 14988048 DOI: 10.1016/j.brainres.2004.01.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/02/2004] [Indexed: 10/26/2022]
Abstract
Antidepressants, which increase monoamine levels, induce glial cell line-derived neurotrophic factor (GDNF) release in C6 cells. Thus, we examined whether monoamines affect on GDNF release in C6 cells. We found that serotonin (5-HT) specifically increased GDNF mRNA expression and GDNF release in a dose- and time-dependent manner. The 5-HT-induced GDNF release was mediated through the MEK/mitogen-activated protein kinase (MAPK) pathway and, at least, 5-HT(2A) receptors. The action of 5-HT on GDNF release may provide important insights into the mechanism of antidepressants.
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Affiliation(s)
- Kazue Hisaoka
- Department of Psychiatry and Neuroscience, Institute of Clinical Research, National Kure Medical Center, 3-1 Aoyama, Kure 737-0023, Japan.
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10
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Noda M, Yasuda S, Okada M, Higashida H, Shimada A, Iwata N, Ozaki N, Nishikawa K, Shirasawa S, Uchida M, Aoki S, Wada K. Recombinant human serotonin 5A receptors stably expressed in C6 glioma cells couple to multiple signal transduction pathways. J Neurochem 2003; 84:222-32. [PMID: 12558985 DOI: 10.1046/j.1471-4159.2003.01518.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Human serotonin 5A (5-HT5A) receptors were stably expressed in undifferentiated C6 glioma. In 5-HT5A receptors-expressing cells, accumulation of cAMP by forskolin was inhibited by 5-HT as reported previously. Pertussis toxin-sensitive inhibition of ADP-ribosyl cyclase was also observed, indicating a decrease of cyclic ADP ribose, a potential intracellular second messenger mediating ryanodine-sensitive Ca2+ mobilization. On the other hand, 5-HT-induced outward currents were observed using the patch-clamp technique in whole-cell configuration. The 5-HT-induced outward current was observed in 84% of the patched 5-HT5A receptor-expressing cells and was concentration-dependent. The 5-HT-induced current was inhibited when intracellular K+ was replaced with Cs+ but was not significantly inhibited by typical K+ channel blockers. The 5-HT-induced current was significantly attenuated by 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) in the patch pipette. Depleting intracellular Ca2+ stores by application of caffeine or thapsigargin also blocked the 5-HT-induced current. Blocking G protein, the inositol triphosphate (IP3) receptor, or pretreatment with pertussis toxin, all inhibited the 5-HT-induced current. IP3 showed a transient increase after application of 5-HT in 5-HT5A receptor-expressing cells. It was concluded that in addition to the inhibition of cAMP accumulation and ADP-ribosyl cyclase activity, 5-HT5A receptors regulate intracellular Ca2+ mobilization which is probably a result of the IP3-sensitive Ca2+ store. These multiple signal transduction systems may induce complex changes in the serotonergic system in brain function.
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Affiliation(s)
- Mami Noda
- Laboratory of Pathophysiology, Kyushu University Graduate School of Pharmaceutical Sciences, Fukuoka, Japan.
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11
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Meller R, Harrison PJ, Sharp T. Studies on the role of calcium in the 5-HT-stimulated release of glutamate from C6 glioma cells. Eur J Pharmacol 2002; 445:13-9. [PMID: 12065189 DOI: 10.1016/s0014-2999(02)01718-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We recently reported that 5-hydroxytryptamine(2A) (5-HT(2A)) receptor activation on cultured glial cells induces glutamate release [J. Neurosci. Res. 67 (2002) 399]. Here we use C6 glioma cells to examine the role of calcium in this response. 5-Hydroxytryptamine (5-HT) increases glutamate release from C6 glioma cells, an effect blocked by low calcium conditions. The calcium ionophores ionomycin and calcimycin also released glutamate from C6 glioma cells in a Ca(2+)-dependent manner. The effect of 5-HT was reduced by the phospholipase C inhibitor U73122 (1-[6[[(17 beta)-3-methoxyestra-1,3,5(10)-trien-17-yl]amino]hexyl]-1H-pyrrole-2,5-dione), but not its inactive enantomer U73343(1-[6[[(17 beta)-3-methoxyestra-1,3,5(10)-trien-17-yl]amino]hexyl]-2,5-pyrrolidinedione). The protein kinase C inhibitors staurosporine and calphostin C had no effect on the response to 5-HT, whereas the response was blocked by thapsigargin and caffeine. Neither the L-type calcium channel blockers, nifedipine and verapamil, nor the N-type calcium channel blocker omega-conotoxin GVIA inhibited the effect of 5-HT, whereas NiCl(2) and KCl blocked the response to 5-HT. We conclude that the 5-HT-induced efflux of glutamate from C6 glioma cells is Ca(2+)-dependent and involves, at least in part, the mobilisation of Ca(2+) from inositol (1,4,5) tris phosphate (IP(3)) sensitive intracellular stores.
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Affiliation(s)
- Robert Meller
- University Department of Clinical Pharmacology, Radcliffe Infirmary, Oxford OX2 6HE, UK.
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12
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Meller R, Harrison PJ, Elliott JM, Sharp T. In vitro evidence that 5-hydroxytryptamine increases efflux of glial glutamate via 5-HT(2A) receptor activation. J Neurosci Res 2002; 67:399-405. [PMID: 11813245 DOI: 10.1002/jnr.10126] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Recent studies have established the presence of 5-hydroxytryptamine (5-HT)(2A) receptors on glial cells in culture and in the brain in situ. Here we used cultured C6 glioma cells to investigate the possibility that 5-HT(2A) receptors on glia regulate glutamate release from the cell. The efflux of endogenous glutamate from cultured C6 glioma cells was increased by addition of 5-HT in a concentration-dependent manner (maximal effect +200%). The efflux of serine and aspartate was not altered. The effect of 5-HT was mimicked by both the nonselective 5-HT receptor agonist quipazine and the selective 5-HT(2) receptor agonist 4-iodo-2,5-dimethoxyamphetamine (DOI; both 0.01-100 microM). The 5-HT(2A) receptor antagonists ketanserin (1 microM) and spiperone (1 microM) inhibited the glutamate response to 5-HT, quipazine, and DOI, whereas the effect of 5-HT was not inhibited by the 5-HT(2B/C) receptor antagonist SB200646 (1 microM). The effect of 5-HT on glutamate was specific in that it was reduced in low-calcium medium but was not prevented by furosemide (5 mM), which prevents cell swelling-induced glutamate release. Finally, the glutamate uptake inhibitor 2,4,trans-pyrollidine dicarboxylic acid (50 microM) did not block the 5-HT-induced efflux of glutamate, making involvement of glutamate transport unlikely. In conclusion, 5-HT stimulates the efflux of glutamate from C6 glioma cells following 5-HT(2A) receptor activation and involves a calcium-dependent mechanism.
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Affiliation(s)
- R Meller
- University Department of Clinical Pharmacology, Radcliffe Infirmary, Oxford, United Kingdom.
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13
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Gray JA, Sheffler DJ, Bhatnagar A, Woods JA, Hufeisen SJ, Benovic JL, Roth BL. Cell-type specific effects of endocytosis inhibitors on 5-hydroxytryptamine(2A) receptor desensitization and resensitization reveal an arrestin-, GRK2-, and GRK5-independent mode of regulation in human embryonic kidney 293 cells. Mol Pharmacol 2001; 60:1020-30. [PMID: 11641430 DOI: 10.1124/mol.60.5.1020] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The effect of endocytosis inhibitors on 5-hydroxytryptamine(2A) (5-HT(2A)) receptor desensitization and resensitization was examined in transiently transfected human embryonic kidney (HEK) 293 cells and in C6 glioma cells that endogenously express 5-HT(2A) receptors. In HEK-293 cells, 5-HT(2A) receptor desensitization was unaffected by cotransfection with a dominant-negative mutant of dynamin (DynK44A), a truncation mutant of arrestin-2 [Arr2(319-418)], or by two well-characterized chemical inhibitors of endocytosis: concanavalin A (conA) and phenylarsine oxide (PAO). In contrast, beta 2-adrenergic receptor desensitization was significantly potentiated by each of these treatments in HEK-293 cells. In C6 glioma cells, however, DynK44A, Arr2(319-418), conA, and PAO each resulted in the potentiation of 5-HT(2A) and beta-adrenergic receptor desensitization. The cell-type-specific effect of Arr2(319-418) on 5-HT(2A) receptor desensitization was not related to the level of GRK2 or GRK5 expression. Interestingly, although beta 2-adrenergic receptor resensitization was potently blocked by cotransfection with DynK44A, 5-HT(2A) receptor resensitization was enhanced, suggesting the existence of a novel cell-surface mechanism for 5-HT(2A) receptor resensitization in HEK-293 cells. In addition, Arr2(319-418) had no effect on 5-HT(2A) receptor resensitization in HEK-293 cells, although it attenuated the resensitization of the beta 2-adrenergic receptor. However, in C6 glioma cells, both DynK44A and Arr2(319-418) significantly reduced 5-HT(2A) receptor resensitization. Taken together, these results provide the first convincing evidence of cell-type-specific roles for endocytosis inhibitors in regulating GPCR activity. Additionally, these results imply that novel GRK and arrestin-independent mechanisms of 5-HT(2A) receptor desensitization and resensitization exist in HEK-293 cells.
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MESH Headings
- Animals
- Arrestin/metabolism
- Arrestins/pharmacology
- Cells, Cultured
- Cyclic AMP-Dependent Protein Kinases/metabolism
- Dynamins
- Endocytosis/drug effects
- G-Protein-Coupled Receptor Kinase 5
- GTP Phosphohydrolases/pharmacology
- Glioma/metabolism
- Humans
- Kidney/cytology
- Kidney/embryology
- Phosphoproteins/pharmacology
- Protein Serine-Threonine Kinases/metabolism
- Rats
- Receptor, Serotonin, 5-HT2A
- Receptors, Adrenergic, beta-2/drug effects
- Receptors, Adrenergic, beta-2/metabolism
- Receptors, Serotonin/drug effects
- Receptors, Serotonin/metabolism
- Tumor Cells, Cultured
- beta-Adrenergic Receptor Kinases
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Affiliation(s)
- J A Gray
- Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106-4935, USA
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14
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Whittle IR, Kelly PA. Mechanisms of peritumoural brain dysfunction: metabolic and neuroreceptor findings in striatal C6 glioma. J Clin Neurosci 2001; 8:430-4. [PMID: 11535011 DOI: 10.1054/jocn.2000.0936] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The aetiology of the peritumoural brain dysfunction that is rectified by steroids is unknown. To determine potential aspects of its pathophysiological basis we performed metabolic, histochemical and neuroreceptor studies in rodents with striatal C6 glioma. This model is known to cause focal neurobehavioural and electrophysiological dysfunction. The fully quantitative [(14)C]-2-deoxyglucose autoradiographic technique of measuring local cerebral metabolism of glucose (LCMRglu) showed raised LCMRglu (22-29%) in the pallidum, substantia nigra and endopeduncular nucleus. Acetylcholinesterase (AChE) histochemistry and a range of ligand binding studies for dopamine type 1 and 2, and serotonergic 5-HT(2)receptors were negative in the tumour and normal in peritumoural brain. 5-HT uptake sites and strong peripheral benzodiazepine receptor expression were present in the tumour. There was extensive up-regulation of peripheral benzodiazepine receptor expression in the peritumoural brain. These studies show there is metabolic dysregulation in brain regions functionally connected to, but anatomically distant from the striatum. There is also a peritumoural region of up-regulated receptors that have many, predominantly inhibitory, functions. The relationship of these findings to peritumoural brain dysfunction is discussed.
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Affiliation(s)
- I R Whittle
- Department of Clinical Neurosciences, University of Edinburgh, Western General Hospital, Edinburgh, UK.
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Thomas EA, Matli JR, Hu JL, Carson MJ, Sutcliffe JG. Pertussis toxin treatment prevents 5-HT(5a) receptor-mediated inhibition of cyclic AMP accumulation in rat C6 glioma cells. J Neurosci Res 2000; 61:75-81. [PMID: 10861802 DOI: 10.1002/1097-4547(20000701)61:1<75::aid-jnr9>3.0.co;2-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
We have investigated the functional coupling of the rat 5HT(5a) receptor subtype to adenylate cyclase in a rat C6 glioma cell line. In 5HT(5a) receptor-transfected cells, 5HT caused a concentration-dependent inhibition of forskolin-stimulated cAMP accumulation, with an EC(50) value of 41 nM and a maximal effect of 57% inhibition. This effect was dependent on the concentration of forskolin used to elevate cAMP levels. Methiothepin (1 mcM), which has high affinity for the 5HT(5a) receptor, antagonized the 5HT(5a) receptor-mediated inhibition, and unmasked a stimulation of cAMP formation similar to that observed in untransfected cells, whereas ketanserin (0.1 mcM) enhanced the inhibitory effect of 5HT. Pertussis toxin treatment (0.5 mcg/ml) completely blocked the inhibitory effect of 5HT on cAMP formation, also revealing increase in cAMP accumulation. Pretreatment of the transfected membranes with pertussis toxin abolished subsequent ADP-ribosylation of a 41 kDa protein, correlating the cAMP effect with a functional uncoupling of an inhibitory G protein from its receptor. These results demonstrate an efficient functional coupling of the rat 5HT(5a) receptor to the inhibition of adenylate cyclase via a pertussis toxin-sensitive G[alpha(i)], inhibitory G-protein.
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Affiliation(s)
- E A Thomas
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, California 92037, USA
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Le Grand B, Panissié A, Perez M, Pauwels PJ, John GW. Zolmitriptan stimulates a Ca(2+)-dependent K(+) current in C6 glioma cells stably expressing recombinant human 5-HT(1B) receptors. Eur J Pharmacol 2000; 397:297-302. [PMID: 10844127 DOI: 10.1016/s0014-2999(00)00284-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Stimulation of a Ca(2+)-dependent K(+) current by zolmitriptan, a 5-HT(1B/1D) receptor partial agonist, was investigated in C6 glioma cells stably expressing recombinant human 5-HT(1B) receptors. Outward K(+) currents (I(K)) were examined in non-transfected C6 glioma cells and in cells expressing cloned human 5-HT(1B) receptors using the patch-clamp technique in the whole-cell configuration. In C6 glioma cells expressing recombinant human 5-HT(1B) receptor, zolmitriptan increased I(K) in a concentration-dependent manner (maximum increase 16.3+/-7.8%, n=5, p<0.001) with a pD(2) value (geometric mean with 95% confidence intervals) of 7.03 (7.90-6.10). Zolmitriptan failed to elicit increases in I(K) in non-transfected C6 cells. In the presence of the mixed 5-HT(1B/1D) receptor antagonist, N-[4-methoxy-3-(4-methyl-1-piperazinyl)phenyl]-2(-methyl-4(5-methyl-1 ,2,4)-oxadiazol-3-yl)[1,1-biphenyl]-4-carboxamide 2HCl (GR 127935, 0. 1 mcM), zolmitriptan (1 mcM) failed to significantly increase I(K) in C6 cells expressing human 5-HT(1B) receptors confirming that zolmitriptan-evoked responses were indeed mediated by human 5-HT(1B) receptors. In C6 cells expressing cloned human 5-HT(1B) receptors, zolmitriptan-induced increases in I(K) were prevented by the calcium chelator, EGTA (5 mM) when included in the patch pipette (maximum increase -3.3+/-4.2%, n=4, P=NS). The Ca(2+)-dependent K(+) channel blockers, iberiotoxin (0.1 mcM) and tetraethylammonium (TEA, 1 mM), abolished zolmitriptan-induced increases in I(K) (4.5+/-7.3%, n=4 and -0.8+/-1.7%, n=4, respectively, P=NS in each case) in C6 cells expressing human 5-HT(1B) receptors, confirming the involvement of Ca(2+)-dependent K(+) channels. In conclusion, the 5-HT(1B/1D) receptor partial agonist, zolmitriptan, stimulates I(K/Ca) in C6 glioma cells stably transfected with human 5-HT(1B) receptors suggesting an increase of hyperpolarizing current.
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Affiliation(s)
- B Le Grand
- Division of Cardiovascular Diseases, Centre de Recherche Pierre Fabre, 17 Av. Jean Moulin, 81106 Cedex, Castres, France
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Storm SM, Khawaja XZ. Probing for drug-induced multiplex signal transduction pathways using high resolution two-dimensional gel electrophoresis: application to beta-adrenoceptor stimulation in the rat C6 glioma cell. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 1999; 71:50-60. [PMID: 10407186 DOI: 10.1016/s0169-328x(99)00167-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Whole-cell [(32)P]-protein phosphorylation assays and two-dimensional gel electrophoresis (2-DGE) were applied to the analysis of the beta-adrenoceptor (betaAR)-linked signal transduction pathway. Rat C6 glioma cells were stimulated with isoproterenol and the protein lysates were resolved by 2-DGE. Two dimensional [(32)P]-phosphoprotein 'maps' were generated depicting the modulation of intracellular proteins after isoproterenol stimulation versus unstimulated cells. A total of 274 distinct phosphoprotein spots were detected, of which 200 were up-regulated, 69 were down-regulated, and 5 remained unchanged. An evaluation of isoproterenol's activity across several kinase pathways was performed using a computer-generated 2-DGE template incorporating the location and identification of individual signaling phosphoprotein intermediaries. The template served as a 'reference map' for drug treatment comparisons. We observed a significant increase in the phosphorylation states of several nuclear transcription factors, notably CREB-1, ATF-1, NFkappaB/IkappaBalpha and ELK-1, but not c-Jun. A parallel series of radioimmunoprecipitation studies confirmed our 2-DGE findings. Moreover, isoproterenol increased the phosphorylation state of PKC and of several MAPK-dependent pathway kinases which correlated with a significant increase in their endogenous kinase activity. Isoproterenol's effects on PKA, PKC and ERK-dependent activities were blocked by propranolol, a betaAR antagonist. In conclusion, an acute isoproterenol stimulus induced multiplex pathway modulation via the betaAR in the C6 glioma cell indicating that signaling pathway cross-talk is an essential feature for the regulation of cellular function. Moreover, the immediate advantages of the 2-DGE analytical approach were apparent, and further development of the protein database will provide a valuable tool to screen for broad-based drug-mediated signaling activities.
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Affiliation(s)
- S M Storm
- CNS Disorders, Wyeth-Ayerst Research, CN 8000, Princeton, NJ 08543-8000, USA
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Sevcík J, Masek K. The interaction of immunomodulatory muramyl dipeptide with peripheral 5-HT receptors: overview of the current state. INTERNATIONAL JOURNAL OF IMMUNOPHARMACOLOGY 1999; 21:227-32. [PMID: 10348372 DOI: 10.1016/s0192-0561(98)00079-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Immunomodulator muramyl dipeptide (MDP) exerts also pronounced neuropharmacological activities which are probably mediated by an interaction with 5-HT receptors. Some of these effects are considered as undesirable by its clinical use. More precise information concerning MDP effects on 5-HT receptors with respect to their many subtypes could result from studies using isolated organs in vitro. Earlier conducted studies of this type provided data that are concisely overviewed and reinterpreted here from the view of current 5-HT receptor classification. Since new 5-HT receptor types have emerged recently, new studies are under way. The results might contribute to the development of novel immunomodulatory drugs devoid of adverse effects.
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Affiliation(s)
- J Sevcík
- Institute of Pharmacology, Academy of Sciences of the Czech Republic, Prague.
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Miller KJ, Gonzalez HA. Serotonin 5-HT2A receptor activation inhibits cytokine-stimulated inducible nitric oxide synthase in C6 glioma cells. Ann N Y Acad Sci 1998; 861:169-73. [PMID: 9928254 DOI: 10.1111/j.1749-6632.1998.tb10188.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
C6-glioma cells endogenously express both 5-HT2A receptors and inducible nitric oxide synthase (iNOS). iNOS can be induced by transcriptional activation to produce nitric oxide (NO) in response to a challenge with the pro-inflammatory cytokines TNF-alpha and IFN-gamma. Experiments were conducted to determine whether 5-HT2A receptor activation could modify the production of NO in response to the inducing agents. 1 muM DOI produced a dose-dependent inhibition of the cytokine-inducted nitrite levels of 40% which was inhibited by spiperone and ritanserin. In addition, the DOI-mediated decrease was prevented by the PKC inhibitor chelerythrine (100 nM). The effectiveness of DOI was lost when added more than two hours after the addition of inducing agent, suggesting that DOI was regulating iNOS at the level of transcription rather than post-translationally. We suggest that there is a link between the serotonergic system and NO-mediated immune responses in the brain.
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Affiliation(s)
- K J Miller
- Department of Pharmaceutical Sciences, College of Pharmacy, Nova Southeastern University, Ft. Lauderdale, Florida 33328, USA.
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Briddon SJ, Leslie RA, Elliott JM. Comparative desensitization of the human 5-HT2A and 5-HT2C receptors expressed in the human neuroblastoma cell line SH-SY5Y. Br J Pharmacol 1998; 125:727-34. [PMID: 9831908 PMCID: PMC1571005 DOI: 10.1038/sj.bjp.0702145] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
1. We have used previously characterized clones of the human neuroblastoma cell line, SH-SY5Y. constitutively expressing either the human 5-HT2A or 5-HT2C receptor to compare their desensitization profiles after exposure to 5-HT. 2. 5-HT stimulated [3H]-inositol phosphate ([3H]-IPx) production at both the 5-HT2C (pEC50=8.03+/-0.15) and 5-HT2A receptors (pEC50=7.15+/-0.08), with maximal responses occurring after exposure to 1 microM and 10 microM 5-HT, respectively. 3. Exposure of cells to maximally effective concentrations of 5-HT caused time- and concentration-dependent desensitization of [3H]-IPx formation. The 5-HT2A response desensitized slower (t1/2 = 110 min) and with lower sensitivity than that of the 5-HT2C receptor (t1/2 = 12.5 min). In each case, desensitization was blocked by co-administration of a specific receptor antagonist. Following exposure to 10 microM 5-HT for 2 h, both receptors exhibited extensive desensitization, with subsequent responses to 5-HT reduced by more than 80%. 4. 5-HT stimulated Ins(1,4,5)P3 production with a potency similar to that for [3H]-IPx production at each receptor. In both cases Ins(1,4,5)P3 levels peaked rapidly then returned to basal level within a short time. This peak consistently occurred earlier for the 5-HT2C receptor (5 s) than for the 5-HT2A receptor (20 s). 5. Prior exposure of SH-SY5Y/5-HT2C cells to 5-HT (1 microM/15 min) caused a significant decrease in the 5-HT-stimulated peak in Ins(1,4,5)P3 levels whereas no such change occurred in SH-SY5Y/5-HT2A cells following exposure to 10 microM 5-HT for 15 min. 6 These results indicate that the human 5-HT2A and 5-HT2C receptors both exhibit desensitization at the level of inositol phosphate formation when expressed in the same cellular environment, with the 5-HT2C receptor being more sensitive to 5-HT-mediated desensitization than the 5-HT2A receptor.
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Affiliation(s)
- S J Briddon
- Oxford-University Smith Kline Beecham Centre for Applied Neuropsychobiology, Radcliffe Infirmary
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Miller KJ, Mariano CL, Cruz WR. Serotonin 5HT2A receptor activation inhibits inducible nitric oxide synthase activity in C6 glioma cells. Life Sci 1997; 61:1819-27. [PMID: 9365229 DOI: 10.1016/s0024-3205(97)00806-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
C6-glioma cells endogenously express both 5HT2A receptors and inducible nitric oxide synthase (iNOS). iNOS can be induced by transcriptional activation to produce nitric oxide (NO) in response to a challenge with lipopolysaccharide (LPS). Experiments were conducted to determine whether 5HT2A receptor activation could modify the production of NO in response to LPS. Incubation of 10 microg/ml LPS with C6-glioma cells for a period of 24 hours resulted in a 2.6 fold increase in nitrite levels, as a measure of NO levels, over vehicle treated controls. Co-incubation with the selective 5HT2A receptor partial agonist (+/-)-2,5-dimethoxy-4-iodoamphetamine (DOI) produced a dose-dependent inhibition of the LPS-induced nitrite levels of 22% with an IC50 of 16 nM. The full agonists serotonin (5HT) and alpha-methyl-5HT produced an inhibition of approximately 30% at a concentration of 1 microM. The inhibitory effect of 1 microM DOI was blocked by the 5HT2A receptor antagonists spiperone and ritanserin (10 nM). Inhibition of protein kinase C (PKC) using 100 nM chelerythrine prevented the DOI-mediated decrease in LPS-induced nitrite levels. Addition of DOI to the cells after 1 hr following the LPS addition did not produce a decrease in nitrite levels indicating iNOS was not modified post-translationally. The data demonstrate that iNOS activity can be modulated by serotonin 5HT2A receptor activation, most likely at the initiation of the induction process, via PKC. We therefore suggest that there may be a link between the serotonergic system and NO-mediated immune responses in the brain.
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Affiliation(s)
- K J Miller
- Department of Pharmaceutical Sciences, College of Pharmacy, Nova Southeastern University, Davie, FL 33325, USA.
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Garcia MC, Kim KY, Hough C, Kim HY. Effects of Chronic Ethanol on the Mobilization of Arachidonate and Docosahexaenoate Stimulated by the Type 2A Serotonin Receptor Agonist (+-)-2,5-Dimethoxy-4-iodoamphetamine Hydrochloride in C6 Glioma Cells. Alcohol Clin Exp Res 1997. [DOI: 10.1111/j.1530-0277.1997.tb04477.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Garcia MC, Kim HY. Mobilization of arachidonate and docosahexaenoate by stimulation of the 5-HT2A receptor in rat C6 glioma cells. Brain Res 1997; 768:43-8. [PMID: 9369299 DOI: 10.1016/s0006-8993(97)00583-0] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
In this study, we demonstrate that astroglial 5-HT2A receptors are linked to the mobilization of polyunsaturated fatty acids (PUFA). Stimulation of C6 glioma cells, prelabeled with [3H]arachidonate (AA, 20:4n6) and [14C]docosahexaenoate (DHA, 22:6n3), with serotonin and the 5-HT(2A/2C) receptor agonist (+/-)-2,5-dimethoxy-4-iodoamphetamine hydrochloride (DOI) resulted in the mobilization of both [3H] and [14C] into the supernatant of the cell monolayers. The increased radioactivity in the supernatant was mainly associated with free fatty acids. Experiments using inhibitors of phosphoinositide-specific phospholipase C and PLA2, inhibited the DOI-stimulated mobilization of AA and DHA, suggesting the involvement of both phospholipases. Ketanserin (1 microM), a 5-HT(2A/2C) receptor antagonist, and MDL 100,907 (R(+)-alpha-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenylethyl)]-4-pi peridine-methanol) (1 microM), a highly selective antagonist for 5-HT2A receptors, significantly decreased the DOI-stimulated release of AA and DHA. These results indicate that the 5-HT2A receptor is coupled to the mobilization of PUFA. The release of AA and DHA in response to serotonin may represent a mechanism through which astroglia provide these polyunsaturated fatty acids to neurons.
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Affiliation(s)
- M C Garcia
- Laboratory of Membrane Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Rockville, MD 20852, USA
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Abstract
We have investigated the modulation of the intracellular calcium concentration ([Ca2+]i) in rat C6 glioma cells following their activation by the agonists 5-hydroxytryptamine.HCl (5-HT) and bradykinin, using single cell imaging of [Ca2+]i with the calcium-sensitive dye Fura-2. The majority of the signals observed involved release of calcium from intracellular stores, and after prolonged application of 5-HT, but not bradykinin, the cells exhibited oscillations in [Ca2+]i levels. These calcium oscillations were dependent on the presence of extracellular calcium, and were unaffected by the calcium channel antagonists nifedipine and verapamil. Caffeine, which in other cell types is able to release calcium from inositol trisphosphate-insensitive stores, had very little effect on [Ca2+]i levels in C6 cells. On the other hand, bradykinin, although able to elevate [Ca2+]i probably by acting via the B2-receptor subtype, was unable to induce any calcium oscillations in these cells.
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Affiliation(s)
- A J Cholewinski
- Oxford University-Smith Kline Beecham Centre for Applied Neuropsychobiology, Radcliffe Infirmary, U.K
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