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)

The effect of the novel agonist, 1-(m-chlorophenyl)-biguanide (mCPBG) was examined on 5-HT3 receptors in NG108-15 mouse neuroblastoma x rat glioma hybrid cells, using whole-cell voltage-clamp and radioligand binding on intact cells. Electrophysiological studies showed that mCPBG is a partial agonist, with an EC50 of 3.1 microM. Displacement of the selective 5-HT3 receptor antagonist [3H]GR65630 by mCPBG revealed a Ki of 14.2 nM. The study suggests that mCPBG may have a high affinity for desensitized 5-HT3 receptors and also revealed some differences between 5-HT3 receptors in NG108-15 and N1E-115 cells.
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PMID:5-HT3 receptors in NG108-15 neuroblastoma x glioma cells: effect of the novel agonist 1-(m-chlorophenyl)-biguanide. 140 96

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

Homopentameric complexes of either the A or As subunit of the 5-hydroxytryptamine3 receptor form Ca(2+)-permeable channels that can be activated by the selective agonist 1-(m-chlorophenyl)-biguanide (mCPBG). In both N1E-115 neuroblastoma cells and human embryonic kidney 293 cells stably expressing the 5-HT3 receptor As subunit, (+)-verapamil, (-)-verapamil, diltiazem, and nimodipine caused reversible and concentration-dependent (IC50 = 2.5-6.5 microM) inhibition of the increases in cytosolic [Ca2+] evoked by mCPBG. In voltage-clamped human embryonic kidney 293 cells stably expressing the 5-HT3 receptor As subunit, similar concentrations of the Ca2+ channel antagonists (IC50 = 3.0-6.8 microM) accelerated the rate at which 5-HT-evoked currents decayed without affecting the amplitude of the peak current. In equilibrium competition binding assays to membranes from Sf9 cells infected with the 5-HT3 receptor As subunit, [3H]mCPBG and [3H]granisetron were displaced by (+)-verapamil, (-)-verapamil, and diltiazem; (+)-verapamil was approximately 10-fold more potent than (-)-verapamil and approximately-30-fold more potent than diltiazem. Nimodipine neither displaced [3H]granisetron binding nor affected its displacement by diltiazem and (+)-verapamil. The stereoselectivity of verapamil binding, which contrasts with the similar potency of each isomer in functional assays, was maintained when the incubations were performed at 20 degrees or when an antagonist of the 5-HT3 receptor, [3H]granisetron, was used as the radioligand. The interaction between verapamil and either [3H]mCPBG or [3H]granisetron binding was not competitive. We conclude that the inhibition of [3H]mCPBG binding by diltiazem and verapamil is mediated by a site that is distinct from both the agonist-binding site and from the site through which nimodipine inhibits 5-HT3 receptor function. Our results provide evidence for allosteric regulation of agonist binding to 5-HT3 receptors and the first example of a ligandgated ion channel whose function is directly inhibited by members of all three major classes of L-type Ca2+ channel antagonists.
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PMID:Direct inhibition of 5-hydroxytryptamine3 receptors by antagonists of L-type Ca2+ channels. 891 60

A complete understanding of how excitatory ligand-gated ion channels regulate intracellular Ca2+ in nerve cells remains to be elucidated. Laser-scanning confocal microscopy was used here to measure Ca2+ changes in the neuroblastoma x glioma hybrid cell line NG108-15, employed as a model nerve cell line, upon activation by the 5-HT3 receptor, a serotonin-activated ligand-gated ion channel. Addition of the 5-HT3 agonist 1-m-(chlorophenyl)-biguanide (mCPBG) induced increases in [Ca2+]i in both the cytoplasm and the nuclei of the NG108-15 cells. Using high-time resolution line scanning, no delay was evident between the mCPBG-induced rise in cytosolic [Ca2+]i and the rise in nuclear [Ca2+]i. The agonist-induced responses were completely blocked by addition of EGTA to chelate external Ca2+ and by addition of the 5-HT3 receptor antagonist tropisetron or the L-type Ca2+ channel blocker nitrendipine. Caffeine, but not thapsigargin, treatment significantly reduced the mCPBG-induced responses in the nucleus and the cytoplasm, both to the same extent. We conclude that, upon 5-HT3 receptor activation, Ca2+ enters the cells through voltage-gated Ca2+ channels and then triggers the release of Ca2+ from ryanodine-sensitive intracellular stores, greatly amplifying the increases in Ca2+ in the cytoplasm and the nucleus.
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PMID:5-HT3 receptors induce rises in cytosolic and nuclear calcium in NG108-15 cells via calcium-induced calcium release. 944 42

The identification of a second 5-HT(3) (5-HT(3B)) subunit provides an explanation for 5-HT(3) receptor heterogeneity. We investigated whether introduction of recombinant 5-HT(3B) subunits would alter the functional properties of mouse neuroblastoma 5-HT(3) receptors. RT-PCR analysis revealed that NB41A3 cells contain mRNAs encoding 5-HT(3A) and 5-HT(3B) subunits. 5-HT increased intracellular Ca(2+) concentration ([Ca(2+)](i)) and caused the concentration-dependent activation of inward currents recorded at -60 mV. Both actions of 5-HT were antagonized by ondansetron. The 5-HT concentration-response relationship of NB41A3 cells was indistinguishable from that of the related NG108-15 cell line. The selective 5-HT(3)-receptor agonist mCPBG also elevated [Ca(2+)](i) and activated inward currents. 2-M-5HT was less efficacious than 5-HT as an activator of 5-HT(3) receptors in NB41A3 cells and did not significantly increase [Ca(2+)](i). The 5-HT induced increase in [Ca(2+)](i) did not involve caffeine- or thapsigargin-sensitive intracellular Ca(2+) stores. The introduction of the 5-HT(3B) subunit by transient transfection of NB41A3 cells caused 5-HT to become less potent as an activator of 5-HT(3) receptors and altered the kinetics of 5-HT activated currents so that they resembled currents mediated by 5-HT(3AB) receptors. The 5-HT(3B) subunit also abolished the 5-HT induced [Ca(2+)](i) increase seen in untransfected NB41A3 cells. These data are consistent with the hypothesis that NB41A3 cells predominantly express homomeric 5-HT(3A) receptors that become heteromeric 5-HT(3AB) receptors upon introduction of the recombinant 5-HT(3B) subunit.
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PMID:Introduction of the 5-HT3B subunit alters the functional properties of 5-HT3 receptors native to neuroblastoma cells. 1262 20

The multimodal antidepressant vortioxetine is thought to mediate its pharmacological effects via 5-HT1A receptor agonism, 5-HT1B receptor partial agonism, 5-HT1D, 5-HT3, 5-HT7 receptor antagonism and 5-HT transporter inhibition. Here we studied vortioxetine's functional effects across species (canine, mouse, rat, guinea pig and human) in cellular assays with heterologous expression of 5-HT3A receptors (in Xenopus oocytes and HEK-293 cells) and in mouse neuroblastoma N1E-115 cells with endogenous expression of 5-HT3A receptors. Furthermore, we studied the effects of vortioxetine on activity of CA1 Stratum Radiatum interneurons in rat hippocampus slices using current- and voltage-clamping methods. The patched neurons were subsequently filled with biocytin for confirmation of 5-HT3 receptor mRNA expression by in situ hybridization. Whereas, both vortioxetine and the 5-HT3 receptor antagonist ondansetron potently antagonized 5-HT-induced currents in the cellular assays, vortioxetine had a slower off-rate than ondansetron in oocytes expressing 5-HT3A receptors. Furthermore, vortioxetine's but not ondansetron's 5-HT3 receptor antagonistic potency varied considerably across species. Vortioxetine had the highest potency at rat and the lowest potency at guinea pig 5-HT3A receptors. Finally, in 5-HT3 receptor-expressing GABAergic interneurons from the CA1 stratum radiatum, vortioxetine and ondansetron blocked depolarizations induced by superfusion of either 5-HT or the 5-HT3 receptor agonist mCPBG. Taken together, these data add to a growing literature supporting the idea that vortioxetine may inhibit GABAergic neurotransmission in some brain regions via a 5-HT3 receptor antagonism-dependent mechanism and thereby disinhibit pyramidal neurons and enhance glutamatergic signaling.
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PMID:The multimodal antidepressant vortioxetine may facilitate pyramidal cell firing by inhibition of 5-HT3 receptor expressing interneurons: An in vitro study in rat hippocampus slices. 2927 75