Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027819 (neuroblastoma)
 27,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In the presence of substance P (SP; 10 microM), serotonin (5-HT; 1 microM) triggered a cation permeability in cells of the hybridoma (mouse neuroblastoma x rat glioma) clone NG 108-15 that could be assessed by measuring the cell capacity to accumulate [14C]guanidinium for 10-15 min at 37 degrees C. In addition to 5-HT (EC50 0.33 microM), the potent 5-HT3 receptor agonists 2-methyl-serotonin, phenylbiguanide, and m-chlorophenylbiguanide, and quipazine, markedly increased [14C]guanidinium uptake in NG 108-15 cells exposed to 10 microM SP. In contrast, 5-HT3 receptor antagonists prevented the effect of 5-HT. The correlation (r = 0.97) between the potencies of 16 different ligands to mimic or prevent the effects of 5-HT on [14C]guanidinium uptake, on the one hand, and to displace [3H]zacopride specifically bound to 5-HT3 receptors on NG 108-15 cells, on the other hand, clearly demonstrated that [14C]guanidinium uptake was directly controlled by 5-HT3 receptors. Various compounds such as inorganic cations (La3+, Mn2+, Ba2+, Ni2+, and Zn2+), D-tubocurarine, and memantine inhibited [14C]guanidinium uptake in NG 108-15 cells exposed to 5-HT and SP, as expected from their noncompetitive antagonistic properties at 5-HT3 receptors. However, ethanol (100 nM), which has been reported to potentiate the electrophysiological response to 5-HT3 receptor stimulation, prevented the effects of 5-HT plus SP on [14C]guanidinium uptake. The cooperative effect of SP on this 5-HT3-evoked response resulted neither from an interaction of the peptide with the 5-HT3 receptor binding site nor from a possible direct activation of G proteins in NG 108-15 cells. Among SP derivatives, [D-Pro9]SP, a compound inactive at the various neurokinin receptor classes, was the most potent to mimic the stimulatory effect of SP on [14C]guanidinium uptake in NG 108-15 cells exposed to 5-HT. Although the cellular mechanisms involved deserve further investigations, the 5-HT-evoked [14C]guanidinium uptake appears to be a rapid and reliable response for assessing the functional state of 5-HT3 receptors in NG 108-15 cells.
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PMID:Characteristics of [14C]guanidinium accumulation in NG 108-15 cells exposed to serotonin 5-HT3 receptor ligands and substance P. 768 66

1. The aim of this study was to provide evidence that anpirtoline, which is an agonist at 5-HT1B and 5-HT1D receptors and also displays submicromolar affinity for 5-HT1A recognition sites, in addition, acts as an antagonist at 5-HT3 receptors. 2. In radioligand binding studies on rat brain cortical membranes, anpirtoline inhibited specific binding of [3H]-(S)-zacopride to 5-HT3 receptor recognition sites (pKi: 7.53). 3. In N1E-115 neuroblastoma cells in which [14C]-guanidinium was used as a tool to measure cation influx through the 5-HT3 receptor channel, the 5-HT-induced influx was concentration-dependently inhibited by anpirtoline. In this respect, anpirtoline mimicked other 5-HT3 receptor antagonists; the rank order of potency was ondansetron > anpirtoline > metoclopramide. 4. The concentration-response curve for 5-HT as a stimulator of [14C]-guanidinium influx was shifted to the right by anpirtoline (apparent pA2: 7.78). 5. In urethane-anaesthetized rats, anpirtoline inhibited (at lower potency than zacopride and tropisetron) the 5-HT- or phenylbiguanide-induced bradycardia (Bezold-Jarisch reflex), but did not induce this reflex by itself. 6. Intravenous infusion of cisplatin in the domestic pig caused a consistent emetic response which was antagonized by anpirtoline. 7. It is concluded that anpirtoline, which was previously characterized as a 5-HT1 receptor agonist also proved to be a 5-HT3 receptor antagonist in several experimental models and, hence, exhibits a unique pattern of properties at different 5-HT receptors.
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PMID:5-HT3 receptor antagonism by anpirtoline, a mixed 5-HT1 receptor agonist/5-HT3 receptor antagonist. 788 26

Modes of Ca2+ activation by bradykinin, serotonin, and ATP and the possible receptor cross-talk were investigated in mouse neuroblastoma x rat glioma hybrid cells (108CC15) by monitoring fura-2 fluorescence in single cells. A transient rise of cytosolic Ca2+ activity was induced by short pulses of the hormones. Brief exposure of cells to ionomycin, which depletes intracellular Ca2+ stores, reduced the size of subsequent responses to bradykinin or ATP, but not to serotonin. Superfusion of the cells with Ca(2+)-free medium abolished the Ca2+ response to serotonin, whereas the responses to bradykinin and to ATP were only slightly reduced. This indicates that ATP, like bradykinin, induces the release of Ca2+ from intracellular stores. Serotonin, in contrast, activates Ca2+ entry from the extracellular space. To investigate whether ATP releases Ca2+ from the same stores as bradykinin, we examined the interaction of the hormones by applying them consecutively. When ATP was applied after bradykinin, the nucleotide did not evoke any response, irrespective of the presence or absence of extracellular Ca2+. The application of ATP before that of bradykinin reduced the size of a following bradykinin-induced Ca2+ response in Ca(2+)-free medium, but not in Ca(2+)-containing medium. This suggests that bradykinin may interact with the ATP-activated mechanism by cross-desensitization. Possibly, bradykinin receptors are coupled to additional Ca2+ stores not accessible to ATP that are refilled by extracellular Ca2+. Cyclic AMP and cyclic GMP apparently do not affect the Ca2+ responses to bradykinin and serotonin, as shown by the lack of influence of preincubation of the cells with forskolin or sodium nitroprusside.
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PMID:Cross-talk of the receptors for bradykinin, serotonin, and ATP shown by single cell Ca2+ responses indicating different modes of Ca2+ activation in a neuroblastoma x glioma hybrid cell line. 790 21

In order to resolve single channel events underlying the 5-HT3 receptor-gated ion current in N1E-115 neuroblastoma cells patch clamp experiments have been performed on excised outside-out membrane patches under optimized experimental conditions. When the driving force for Na+ through the 5-HT3 receptor-gated ion channel is enhanced by raising the external Na+ concentration to 180 mM and by substituting internal K+ with the relatively impermeable cation N-methyl-D-glucamine, a single conductance level is observed in the presence of 5-HT. Single channel activity is observed only in the presence of the agonist and is blocked by 50 nM of the selective 5-HT3 receptor antagonist MDL 72222 in a reversible manner. At membrane potentials more negative than -60 mV discrete single channel events can be resolved with a conductance of 5.6 +/- 1.2 pS.
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PMID:Single 5-HT3 receptor-gated ion channel events resolved in N1E-115 mouse neuroblastoma cells. 812 17

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

The effect of a novel 5-HT3 receptor antagonist, BRL 46470, has been studied on two electrophysiological models for 5-HT3 receptors: grease-gap recordings from rat isolated vagus nerve and whole-cell patch-clamp recordings from mouse neuroblastoma-rat glioma NG108-15 cells. Its action on the rat vagus nerve was compared to that of four other 5-HT3 receptor antagonists. On the rat vagus, BRL 46470 reduced the maximum depolarizing response to 5-HT in a concentration-dependent manner with an IC50 of 0.3-1.0 nM, but the EC50 for 5-HT was not appreciably affected. This action was similar to that of granisetron and ICS 205-930, but differed from that of GR38032F and (+)-tubocurarine which produced clear rightward shifts of the concentration-response curve to 5-HT. The 5-HT-induced fast inward current of voltage-clamped NG108-15 cells was also antagonized by 1 nM BRL 46470 in an insurmountable manner. In contrast to (+)-tubocurarine, the action of BRL 46470 on the rat vagus nerve and NG108-15 cells did not readily reverse on washing with antagonist-free medium. It is concluded that BRL 46470 is a potent, insurmountable 5-HT3 receptor antagonist on the rat vagus and NG108-15 cells.
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PMID:BRL 46470 potently antagonizes neural responses activated by 5-HT3 receptors. 841 36

Characterization of the serotonin-induced increase in guanosine 3',5'-cyclic monophosphate (cyclic GMP) was investigated and compared with that induced by atrial natriuretic peptide (ANP) in NG108-15 cells. The cyclic GMP formed by serotonin or ANP was transported in a similar manner to the extracellular medium, although the cyclic GMP formed by bradykinin was not. Serotonin and ANP raised cyclic GMP additively. Serotonin-induced cyclic GMP formation was completely inhibited by pretreatment with 100 nM 12-o-tetradecanoylphorbol 13-acetate (TPA), although that induced by ANP was only partially inhibited and the effects were blocked by pretreatment with staurosporin. In membrane preparations, ANP stimulated cyclic GMP formation in the presence of ATP, but serotonin did not. Serotonin-stimulated cyclic GMP formation was found to occur in neuroblastoma N18TG-2, but not in glioma C6Bu-1. These results suggest that a novel subtype of serotonin receptors (5-HTGC) which stimulates membrane-bound guanylyl cyclase, different from that stimulated by natriuretic peptide, may exist especially in neurons.
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PMID:Studies on the activation mechanisms of guanylyl cyclase by serotonin, probably through a novel subtype of serotonin receptor (5-HTGC). 853 98

The 5-HT3-receptor antagonist, ondansetron, has been shown to have positive effects in selected in-vivo models of memory impairment and anxiety. The exact mechanisms underlying such bioactivities are unknown. In the present work, an 86Rb efflux bioassay was used to show that ondansetron has a unique ability to block voltage-gated potassium channels in TE671 human neuroblastoma cells. This intrinsic potassium-channel-blocking (KCB) property is relatively weak (IC50 20 microM), but is not shared by other 5-HT3-receptor ligands including zatosetron, MDL 72222, LY 278, 584, zacopride, 1-phenylbiguanide, and ICS 205-930 (tropisetron). Pre-incubation of the target neuroblastoma cells with several 5-HT-receptor ligands including 5-hydroxytryptamine, 8-OH-DPAT, ketanserin, 2-methyl-5-HT, as well as a number of potent 5-HT3 agonists and antagonists and two selective neurotoxins, failed to abolish the KCB action of ondansetron. A preliminary structure-activity relationship analysis indicates that the KCB activity of ondansetron is almost entirely attributable to its structural nucleus, 2,3-dihyro-9-methyl-4(1H)-carbazolone. It is hypothesized that the KCB action of ondansetron is mediated through receptors other than 5-HT3 receptors. The KCB activity of ondansetron may be a significant factor in the in-vivo cognition-enhancing activities of this compound, conceivably due to depolarization of the hippocampal synaptic membranes and a consequent augmentation of neurotransmission.
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PMID:5-HT3 receptor-independent inhibition of the depolarization-induced 86Rb efflux from human neuroblastoma cells, TE671, by ondansetron. 856 32

Two splice variants of the ligand-gated 5-hydroxytryptamine or serotonin 5-HT3 receptor that differ in a six-amino-acid deletion were cloned by polymerase chain reaction from the hippocampus x neuroblastoma cell line HN9.10e. When expressed in Xenopus oocytes, both variants individually formed 5-HT3 receptors that revealed no significant differences in current responses to the agonists 5-HT and 1-phenylbiguanide and block by the specific antagonist LY-278, 584-maleate. For both receptors, the monovalent cations Na+, K+, Rb+ and Li+ showed the same relative permeability; NH4(+)permeated approximately 2.7 times better than Na+, and Tris+ was only poorly permeable. In contrast to other reports, the receptors were completely and reversibly blocked by extracellular Cs+ in both oocytes and native HN9.10 cells. Moreover, Ca2+ was not permeant and exhibited a concentration-dependent decrease (0.9-18 mM) of the 5-HT-induced currents without affecting the inward rectification of the current/voltage relation. The two receptors were reversibly inhibited by nanomolar concentrations of the specific inhibitor of protein kinase C (PKC) bisindolylmaleimide, but not by the equipotent and less specific inhibitor staurosporine. A regulatory effect on both 5-HT3 receptor subunits by PKC-mediated protein phosphorylation might be possible, however, a functional role of the two splice variants present in one cell remains to be determined.
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PMID:Functional characterization of two 5-HT3 receptor splice variants isolated from a mouse hippocampal cell line. 866 78

We have isolated and characterized the 5'-flanking region and the proximal polyadenylation site of the human 5-HT transporter gene. The major gene transcript is 2,793 bp in length and it contains 208 bp of 5'-untranslated region (5'-UTR) and 694 bases of 3'-UTR. While only a single mRNA species occurs in rats and mice, the most proximal signal for polyadenylation in the human gene appears to be highly degenerate in comparison to the rat and murine motif. This polyadenylation signal-like motif may lead to alternate usage of additional polyadenylation sites resulting in multiple mRNA species in humans. A TATA-like motif and several potential binding sites for transcription factors including AP1, AP2, SP1, and a cAMP response element (CRE)-like motif are present in the 5'-flanking region. A approximately 1.7 kb fragment beginning 217 bp downstream from the transcription start site, which had been ligated into a luciferase reporter vector and transiently expressed in JAR human placental choriocarcinoma cells, displayed both constitutive and forskolin/cholera toxin-induced promoter activity. Functional promoter mapping revealed that there are negative attenuating elements between bp -1,428 and -1,185 and positive elements between bp -1,184 and -78 from the transcription initiation site. Studies with deletional mutants also indicated that core promoter sequences are contained within 78 bp of the transcription start site and that regulation of cAMP-inducible promoter activity depends on multiple cis-acting elements including two AP1 binding sites and a single CRE-like element located at bp -99. Our findings suggest that (1) the 5-HT transporter gene promoter is active in human JAR cells, but inactive in 5-HT transporter-deficient human SK-N-SH neuroblastoma and HeLa cells, (2) the information contained within 1.4 kb of 5'-flanking sequence is sufficient to confer its cell-specific expression, (3) the promoter responds to cAMP induction, and (4) the expression of the 5-HT transporter gene is regulated by a combination of positive and negative cis-acting elements operating through a basal promoter unit defined by a TATA-like motif.
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PMID:Functional promoter and polyadenylation site mapping of the human serotonin (5-HT) transporter gene. 878 73


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