UMLS:C0027819 - FACTA Search

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Query: UMLS:C0027819 (neuroblastoma)
27,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The 5-hydroxytryptamine3 receptor 5-HT3R has been implicated in gut and cardiac motility and in behavioral disorders. Characteristics of 5-HT3Rs appear to be heterogeneous among species, but human 5-HT3R cDNA has not been identified. We isolated a cDNA encoding 5-HT3R from human hippocampus. The mouse 5-HT3R gene has been reported to generate two alternative splicing isoforms that differ by six amino acids. All of our isolated human clones corresponded to the shorter isoform. Amino acid identities with mouse neuroblastoma N1E-115 and rat brain 5-HT3Rs were 84% for each. Southern blot analysis of human genomic DNA suggested that our cloned transcript encoded a human counterpart for the rodent 5-HT3Rs. This gene was assigned to chromosome 11 using polymerase chain reaction analysis of a human/rodent somatic cell hybrid panel. With the use of Northern blot analysis, 5-HT3R transcripts were identified in human small intestine, colon, and brain regions including hippocampus, amygdala, and striatum. In human heart, 5-HT3R expression was not detectable even with reverse transcriptase-polymerase chain reaction analysis, although it was detectable in mouse heart. Transfection of COS-1 with human 5-HT3R cDNA induced specific binding of the 5-HT3R-selective radioligand [3H]YM060. Human 5-HT3R showed typical characteristics of the 5-HT3R, but its affinity for the 5-HT3R agonist m-chlorophenylbiguanide was much lower than that of rat 5-HT3R. When injected with human 5-HT3R cRNA, the oocytes responded to 5-HT3R agonists with a rapidly developing inward current. The potency of the agonists to induce inward current paralleled that to compete with the radioligand binding, and 2-methyl-5-hydroxytryptamine, a partial agonist for mouse 5-HT3R, was a full agonist for human 5-HT3R. Our data revealed that the 5-HT3R molecule has interspecies differences in both tissue distribution and functional profile.
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PMID:Molecular cloning of human 5-hydroxytryptamine3 receptor: heterogeneity in distribution and function among species. 756 20

1. The effects of chronic in vitro administration of amitriptyline, a tricyclic antidepressant, on 5-hydroxytryptamine (5-HT) receptor-mediated adenylyl cyclase activity was studied in the neuroblastoma x glioma hybrid cell line, NG 108-15. 2. Treatment of NG 108-15 cells with 8 microM amitriptyline for 3 days increased forskolin-stimulated (0.1 microM) adenosine 3':5'-cyclic monophosphate (cyclic AMP) accumulation. Addition of 5-HT (0.1-100 microM) increased forskolin-stimulated cyclic AMP accumulation in amitriptyline-treated cells in a concentration-dependent manner. However, 5-HT did not affect forskolin-stimulated cyclic AMP accumulation in untreated cells. 3. The 5-HT4 receptor agonist, 5-methoxytryptamine, significantly enhanced forskolin-stimulated cyclic AMP accumulation in amitriptyline-treated cells. In contrast, amitriptyline treatment failed to modify 8-hydroxy-2-(di-n-propylamine) tetralin-induced inhibition of forskolin-stimulated cyclic AMP accumulation. 4. Pretreatment of cells with pertussis toxin did not affect the 5-HT-induced enhancement of cyclic AMP accumulation. 5. The 5-HT-induced enhancement of cyclic AMP accumulation in amitriptyline-treated cells was attenuated by the 5-HT4 receptor antagonists, GR 113808 and ICS 205-930, with relatively low potency. However, spiperone, SCH 23390, and pindolol were completely ineffective against this 5-HT-induced enhancement. 6. Chronic treatment with amitriptyline did not modify the cyclic AMP production stimulated by prostaglandin E1 or cholera toxin. This treatment also had no effect on GTP gamma S-, NaF-, and Mn(2+)-stimulated cyclic AMP accumulation in isolated cell membranes. 7. Chronic treatment with the 5-HT receptor antagonists, pindolol or ICS 205-930, did not inhibit the 5-HT-induced enhancement of cyclic AMP accumulation.8. Chronic treatment with other antidepressant drugs, imipramine, mianserin or paroxetine, elicited the 5-HT-induced enhancement of cyclic AMP accumulation.9. Taken together, these results suggest that chronic amitriptyline treatment of NG 108-15 cells causes 5-HT to enhance forskolin-stimulated cyclic AMP accumulation by enhancing 5-HT receptor-mediated stimulation of adenylyl cyclase and not by reducing 5-HT-mediated inhibition of adenylyl cyclase. The 5-HT-induced enhancement of cyclic AMP accumulation in amitriptyline-treated cells may result from changes at the level of the 5-HT receptor rather than at the level of G, proteins or adenylyl cyclase. It is unlikely that this enhancement of cyclic AMP accumulation is caused by long-term antagonism of the 5-HT receptor by amitriptyline.
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PMID:Enhancement of cyclic AMP accumulation mediated by 5-HT after chronic amitriptyline treatment in NG 108-15 cells. 762 Jul 19

Effects of 5-hydroxyindole (5-OHi) on 5-HT3 receptor-operated ion current were investigated in voltage-clamped N1E-115 neuroblastoma cells. In the presence of 1 mM 5-OHi, the amplitudes of inward currents induced by the agonists 5-hydroxytryptamine (5-HT), 2-methyl-5-HT and dopamine were enhanced and desensitization of the responses was markedly slowed down. The results indicate that 5-OHi selectively modifies the desensitization of the 5-HT3 receptor-mediated ion current.
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PMID:5-Hydroxyindole slows desensitization of the 5-HT3 receptor-mediated ion current in N1E-115 neuroblastoma cells. 768 May 89

We have used single-cell imaging of fura-2-loaded cells to examine the Ca2+ signals evoked by activation of 5-hydroxytryptamine type 3 (5-HT3) receptors in undifferentiated N1E-115 neuroblastoma cells and in human embryonic kidney (HEK) 293 cells transfected with either of the two cloned 5-HT3 receptor subunits. The selective 5-HT3 receptor agonist 1-(m-chlorophenyl)-biguanide (mCPBG) caused a concentration-dependent increase in the cytoplasmic Ca2+ concentration ([Ca2+]i) in N1E-115 cells and in HEK 293 cells transfected with either the 5-HT3 A subunit or the 5-HT3 As subunit. In each case, the [Ca2+]i rise was steeply dependent on the mCPBG concentration (nH = 2-4) and abolished by removal of extracellular Ca2+ or addition of ondansetron. Pretreatment of N1E-115 cells with thapsigargin, caffeine, and ryanodine to deplete intracellular Ca2+ stores had no effect on the mCPBG-evoked Ca2+ signals, indicating that they result entirely from stimulated Ca2+ entry. The steep concentration-effect curves therefore are not a consequence of amplification of Ca2+ influx by Ca(2+)-induced Ca2+ release from intracellular stores and probably reflect cooperative activation of 5-HT3 receptors by mCPBG. Depolarization of transfected HEK 293 cells with medium containing increased K+ concentrations invariably failed to evoke an increase in [Ca2+]i, confirming the absence of voltage-gated Ca2+ channels and indicating that the mCPBG-evoked rise in [Ca2+]i results from Ca2+ permeation of 5-HT3 receptors. However, in N1E-115 cells and transfected HEK 293 cells, both extracellular Na+ and K+ substantially inhibited the Ca2+ influx evoked by activation of 5-HT3 receptors, possibly by inhibition of agonist binding or by competition with Ca2+ for permeation of the channel. We conclude that 5-HT3 receptors are Ca2+ permeant, that the Ca2+ influx is sufficient to generate a significant rise in [Ca2+]i, and that, because the A and As subunits behave similarly, conflicting electrophysiological analyses of Ca2+ currents cannot be explained by differences between these two subunits.
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PMID:Ca2+ permeability of cloned and native 5-hydroxytryptamine type 3 receptors. 780 32

The effects of 24 biguanide and four guanidine derivatives on 5-hydroxytryptamine (5-HT)3 receptors in N1E-115 neuroblastoma cells were examined using radioligand binding and whole-cell voltage-clamp techniques. Displacement of the selective 5-HT3 receptor antagonist [3H]BRL 43694 by phenylbiguanide (PBG) derivatives revealed Ki values ranging from 3.4 x 10(-4) to 4.4 x 10(-10) M. The rank order of potency of agonists was 2,3,5-trichloro-PBG > 2,3-dichloro-PBG = 2,5-dichloro-PBG = 3,5-dichloro-PBG > 3,4-dichloro-PBG = 3-chloro-PBG > 2-chloro-PBG = 4-chloro-PBG = 2-methyl-PBG = 2,4-difluoro-PBG > PBG = 2-trifluoro-5-chloro-PBG > 4-fluoro-PBG = 3-trifluoromethyl-PBG > 4-nitro-PBG = 1,5-bis-4-chloro-PBG = 3,5-ditrifluoromethyl-PBG > 4-ethoxy-PBG >> 4-sulfonic acid-PBG. All of the benzylbiguanides and indanylbiguanide were inactive on [3H]BRL 43694 binding or displaced it only weakly. The four guanidine derivatives were quite inactive. In the PBG series, all antagonist competition curves were steep (pseudo-Hill coefficients ranging from 1.05 to 1.58), monophasic, and best fit with a one-site model. Among PBG derivatives, the chlorinated compounds exhibited a good degree of selectivity for 5-HT3 receptors versus other 5-HT receptor subtypes and other neurotransmitter binding sites. Electrophysiological studies showed that the PBG derivatives tested produced rapid inward currents, at a holding potential of -65 mV, that showed rapid desensitization. The current induced by the 2,3,5-trichloro-PBG derivative was inhibited by the specific 5-HT3 receptor antagonist ICS 205-930 but was unaffected by the 5-HT2 receptor antagonist ketanserin. Analysis of concentration-response curves for the PBG derivatives gave EC50 values ranging from 2.2 x 10(-5) to 2.7 x 10(-8) M and Hill slopes ranging from 1.02 to 2.10. The rank order of potency was similar to that obtained from the binding data, and a good correlation was found between Ki and EC50 values. It is concluded that the triple-chloro substitution yielded a compound that is 30-fold more potent than 3-chloro-PBG and approximately 10-fold more potent than dichloro-PBG derivatives, making 2,3,5-trichloro-PBG the most potent 5-HT3 agonist described thus far.
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PMID:Biguanide derivatives: agonist pharmacology at 5-hydroxytryptamine type 3 receptors in vitro. 796 53

Stereoselective effects of mianserin and ORG3770 on serotonin 5-HT3 receptors in mouse neuroblastoma N1E-115 cells have been investigated in radioligand binding and in whole-cell voltage clamp experiments. The specific binding of [3H]GR65630 to 5-HT3 recognition sites in N1E-115 cell homogenates is reduced by mianserin and ORG3770 and their enantiomers. The pKi values of the more potent (R)enantiomers of mianserin and ORG3770 are 8.44 and 8.62, respectively. The (R)enantiomers of mianserin and ORG3770 are 15 and 37 times more potent than their respective (S)enantiomers. The racemates are only 1.9 and 3.3 times less potent than the corresponding (R)enantiomers. In voltage clamp experiments the (R)enantiomers block the 5-hydroxytryptamine(5-HT)-induced ion current with pIC50 values of 8.52 for (R)mianserin and 8.26 for the (R)enantiomer of ORG3770. The (R)enantiomers of mianserin and ORG3770 are 24 and 145 times more potent in blocking the 5-HT-induced ion current than their respective (S)enantiomers. The racemates are 6 and 13 times less potent than the corresponding (R)enantiomers. In addition, the block of 5-HT-induced ion current by the (R)enantiomer of ORG3770 is partially reversed by a low concentration of its (S)enantiomer. The results indicate that the two enantiomers block the 5-HT3 receptor-mediated ion current in a mutually dependent manner.
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PMID:Interaction between enantiomers of mianserin and ORG3770 at 5-HT3 receptors in cultured mouse neuroblastoma cells. 798 89

1. Effects of 5-hydroxyindole (5-OH-indole) (the aromatic moiety of 5-hydroxytryptamine (5-HT)) on 5-HT-evoked ion current and the nature of these effects on 5-HT3 receptors have been investigated in whole-cell voltage clamp and radioligand binding experiments on cultured N1E-115 mouse neuroblastoma cells. 2. The amplitude of 10 microM 5-HT-evoked ion currents was enhanced up to 150% of the control value by increasing concentrations up to 10 mM 5-OH-indole with half maximum effect of 0.8 mM. At concentrations between 10 mM and 50 mM, 5-OH-indole blocked the 5-HT-evoked ion current. Both the enhancement and the block by 5-OH-indole were accompanied by a marked slowing of the kinetics of decay of the 5-HT-evoked inward currents. 3. The blocking effect was surmounted when the 5-HT concentration was raised from 10 microM to 100 microM. Conversely, the increase in amplitude and the slowing of the decay of the 5-HT-evoked ion current induced by 1 mM 5-OH-indole were not reversed by the same increase of 5-HT concentration. 4. The binding of the selective antagonist [3H]-GR65630 to 5-HT3 receptors was displaced by 5-OH-indole in a concentration-dependent manner with a pKi of 1.96. In saturation binding experiments 10 mM 5-OH-indole reduced the affinity of [3H]-GR65630, whereas the total number of binding sites remained unaffected. 5. It is concluded that the blocking effect of high concentrations of 5-OH-indole is due to a competitive interaction with the antagonist recognition sites of 5-HT3 receptors, whereas the potentiating effect of lower concentrations of 5-OH-indole appears to be mediated by a distinct non-competitive interaction.
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PMID:Competitive and non-competitive effects of 5-hydroxyindole on 5-HT3 receptors in N1E-115 neuroblastoma cells. 807 73

Cyclic AMP formation was found to increase in mouse neuroblastoma N18TG2 cells exposed to 5-hydroxytryptamine (5-HT). This response was concentration-dependent with an EC50 value of 0.22 microM. Tryptamine and other tryptamine-related compounds were also agonists in this assay with a rank order of potency of 5-methoxytryptamine > 5-HT > tryptamine > 2-methyl-5-HT > 5-carboxamidotryptamine >> alpha-methyl-5-HT. (D)-Lysergic acid diethylamide and 2-bromo-lysergic acid diethylamide were partial agonists in this system with maximal responses of 44 and 34%, respectively, compared to 5-HT. 5-HT-stimulated cyclic AMP formation was inhibited by clozapine, mianserin and methiothepin with pA2 values of 6.6, 6.5 and 6.4, respectively. Radioligand binding studies using [125I]iodolysergic acid diethylamide revealed a binding site present at a density of 10.4 fmol/mg of protein, with an affinity for the ligand of 1.18 nM. In competition studies this binding site displayed a pharmacology similar to that defined in studies of cyclic AMP formation. The pharmacological profile of this receptor, characterized by both radioligand binding and functional coupling to adenylyl cyclase, does not correspond to that of any of the currently classified subtypes of 5-HT receptor, but is similar to the 5-HT receptor cloned recently from rat striatum and referred to as the 5-HT6 receptor. The N18TG2 cell line represents a useful model system in which this novel 5-HT receptor may be characterized fully.
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PMID:Characterization of a 5-hydroxytryptamine receptor in mouse neuroblastoma N18TG2 cells. 816 32

The binding characteristics of a radiolabelled 5-HT3 receptor agonist, [3H]meta-chlorophenylbiguanide (mCPBG), were examined in membranes from N1E-115 neuroblastoma cells. Scatchard plots of saturation binding data showed the presence of two populations of binding sites, with Kd = 0.03 +/- 0.01 nM and 4.4 +/- 1.2 nM and Bmax = 11.9 +/- 4.2 and 897.9 +/- 184.7 fmol/mg protein respectively. Competition studies with a selection of agonists and antagonists revealed the pharmacological profile expected for a 5-HT3 receptor. The rank order of potency for antagonists was granisetron > quipazine > GR65630 > ondansetron > MDL72222, and for agonists was mCPBG > 5-HT (5-hydroxytryptamine, serotonin) > 2-methyl-5-HT. IC50 values for 5-HT and 2-methyl-5-HT were lower than those observed using radiolabelled antagonists, and combined with functional experiments, the data suggest that [3H]mCPBG may label high affinity desensitized states of the receptor. We conclude that [3H]mCPBG labels 5-HT3 receptors in N1E-115 neuroblastoma cell membranes and may be a useful compound with which to explore 5-HT3 receptors in other systems.
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PMID:Characterization of [3H]meta-chlorophenylbiguanide binding to 5-HT3 receptors in N1E-115 neuroblastoma cells. 825 26

Mouse neuroblastoma x rat glioma hybrid cells (N x G, NG108-15) were used to study the mechanism of Ca(2+)-current (ICa) inhibition by 5-hydroxytryptamine (5-HT). 5-HT caused a dose-dependent decrease of ICa which was abolished by ICS 205-930 (10)(-8) M) while 2-methyl-5-HT was an agonist. Intracellular infusion of GDP beta S (50 microM) prevented the 5-HT-induced inhibition of ICa whereas pertussis toxin (PTX) pretreatment did not alter the 5-HT response. The 5-HT-induced inhibition depended on the free Ca(2+)-concentration in the pipette solution. Pretreating N x G cells with low molecular weight (LMW) heparin (160 micrograms/ml), 200 microM ryanodine or 2-10 mM caffeine attenuated the 5-HT-induced inhibition of ICa. From these results we suggest that the 5-HT-induced ICa inhibition requires release of Ca2+ from intracellular stores.
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PMID:Role of intracellular Ca(2+)-stores in the 5-hydroxytryptamine-induced Ca(2+)-current inhibition in NG108-15 hybrid cells. 839 30

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