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)

In membranes from SH-SY5Y human neuroblastoma cells differentiated with retinoic acid, the mu-selective agonist Tyr-D-Ala-Gly-N-Me-Phe-Gly-ol (DAMGO) inhibited cAMP formation with an IC50 of 26 nM. Two separate antibodies raised against distinct regions of the Go alpha sequence attenuated the effect of DAMGO by 50-60%, whereas antibodies to Gi alpha 1,2 or Gi alpha 3 reduced the mu-opioid signal insignificantly or to a lesser extent. In contrast, inhibition of adenylyl cyclase by the delta-opioid agonist Tyr-D-Pen-Gly-Phe-D-Pen-OH (DPDPE; Pen = penicillamine) was very sensitive to the Gi alpha 1,2 antibody. In membranes from rat brain striatum, coupling of the mu opioid receptor to adenylyl cyclase was also maximally blocked by antibodies to Go alpha. After long-term treatment of the cells with DAMGO, the content of Go alpha was reduced by 26%, whereas the levels of Gi alpha 1,2, Gi alpha 3, and Gs alpha were unaltered. Addition of Go, purified from bovine brain, to membranes from pertussis toxin-treated SH-SY5Y cells restored the inhibition of adenylyl cyclase by DAMGO to 70% of that in toxin-untreated cells. To comparably restore the effect of DPDPE, much higher concentrations of Go were required. By demonstrating mediation of cAMP-dependent signal transduction by Go, these results describe (i) an additional role for this G protein present at a high concentration in brain, (ii) preferential, although not exclusive, interaction of mu and delta opioid receptors with different G protein subtypes in coupling to adenylyl cyclase, and (iii) reduced levels of Go following chronic opioid treatment of SH-SY5Y cells with mu opioids.
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PMID:Go mediates the coupling of the mu opioid receptor to adenylyl cyclase in cloned neural cells and brain. 809 84

In an effort to gain insight into the bioactive conformation of neuropeptide Y upon interaction with its receptors, all single-point D-amino acid substituted NPY analogues were prepared, and their Y1 and Y2 receptor binding affinities were evaluated using the human neuroblastoma cell lines, SK-N-MC and SK-N-BE2, respectively. Solid-phase synthesis (Boc strategy) followed by preparative HPLC purification produced analogues of high purity that were characterized by RP-HPLC, AAA, LSIMS, CZE, and optical rotation. Of the 37 isomers (a naturally occurring glycine at position 9 was replaced by Ala and D-Ala), Y1 receptor binding was most perturbed by chiral inversion of residues at the C-terminus (residues 20, 27, 29-35, Ki > or = 300 nM). Substitutions at residues 2-5, 28, and 36 had Ki values ranging from 40 to 260 nM. Substitutions at all other positions yielded analogues with affinities ranging from 1.5 to 20 nM. Binding affinities to the Y2 class of receptors all measured in the low or sub-nanomolar concentrations, with the exception of C-terminally modified isomers (residues 30-35). Only [D-Arg33]- and [D-Gln34]NPY displayed no measurable binding affinity to Y2 receptors at the highest concentration tested (1000 nM). Representative analogues were selected on the basis of their binding affinities and position in the sequence for structural analysis using circular dichroism (CD) spectroscopy. Of the nine peptide evaluated ([D-Pro5]-, [Ala9]-, [D-Glu10]-, [D-Asp11]-, [D-Ala18]-, [D-Tyr20]-, [D-Tyr27]-, and [D-Arg33]NPY), only [D-Tyr27]NPY expressed a definitive correlation between loss of binding affinity and disruption of secondary structure by having the propensity to form beta-sheets at the expense of alpha-helical content. It was concluded that although the incorporation of a single D-amino acid within the sequence of NPY may confer a conformational perturbation, the receptor interaction was only affected when certain critical residues were modified, findings that provide a basis for the identification of the binding pharmacophore of NPY.
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PMID:Neuropeptide Y: Y1 and Y2 affinities of the complete series of analogues with single D-residue substitutions. 825 9

In differentiated SH-SY5Y human neuroblastoma cells, various opioids exhibited a wide range of potencies (Ki) in acutely inhibiting adenylate cyclase to different extents (Imax). After exposure of the cells to opioids for 24 hr, the initially reduced cAMP content of the cells recovered toward pre-exposure levels. Withdrawal of agonist from, or addition of antagonist to, the tolerant cells rapidly increased the cAMP content to 1.5 times the basal value. Long term treatment of the cells with agonists of high acute potency, such as Tyr-D-Ala-Gly-(Me)Phe-Gly-ol and levorphanol, decreased the Bmax of the antagonist [3H]naltrexone by 80-95%, increased the Ks for GTPase stimulation 10-14-fold, and increased the Ki for adenylate cyclase inhibition 2-3-fold. On the other hand, these parameters were only marginally affected by agonists of lower acute potency, such as profadol and morphiceptin, regardless of their Imax in inhibiting adenylate cyclase. The reduction in the level of receptor binding was experimentally not dissociable from effector desensitization. Tyr-D-Ala-Gly-(Me)Phe-Gly-ol retained the characteristics of a potent agonist in inducing tolerance even under conditions of submaximal signal, produced by lower concentrations of the peptide or by pretreatment with pertussis toxin. Alkylation of receptors by beta-chlornaltrexamine, although it reduced [3H]naltrexone binding by 50%, did not significantly alter the rank order of opioid agonists based on their ability to acutely inhibit adenylate cyclase. These results show that in opioid-tolerant SH-SY5Y cells the concurrently occurring down-regulation of receptor and shifts in the concentration dependence of effector response correlate with the potency of a given opioid in producing its acute effect but not with the maximum extent of that effect.
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PMID:Receptor mechanisms of opioid tolerance in SH-SY5Y human neural cells. 838 4

The effects of the mu opioid receptor agonists, morphine and Tyr-D-Ala-Gly-N-methyl-Phe-Gly-ol (DAGO), the delta opioid receptor agonist, Tyr-D-Pen-Gly-Phe-D-penicillamine (DPDPE) and the kappa-opioid receptor agonist, dynorphin A-(1-13) on the whole-cell K+ currents (IK) of cultured mouse DRG neurons and neuroblastoma X DRG neuron hybrid F11 cells were studied. These opioid ligands all elicited dual effects. Low concentrations (< nM) usually elicited a transient increase in IK (within 1 min), followed by a sustained decrease in IK. In contrast, microM concentrations rapidly elicited a sustained increase in IK. After brief treatment with cholera toxin subunit B (CTX-B), the usual sustained decrease in IK evoked by < nM opioid agonists no longer occurred. Low concentrations then elicited only a sustained increase in IK. On the other hand, after chronic treatment with pertussis toxin (PTX), the usual microM opioid-induced increases in IK no longer occurred and more than half of the cells responded with a sustained decrease of IK to microM as well as nM opioids. The results suggest that mu, delta and kappa opioid receptors are each coupled to K+ channels through CTX-B- and PTX-sensitive transduction systems. Both systems have similar threshold concentrations to opioids. Activation of the CTX-B-sensitive opioid receptor/transduction system resulted in a decrease in K+ conductance of the cell which is generally associated with an increase in neuronal excitability. Activation of the other system resulted in an increase in K+ conductance which will, in general, decrease neuronal excitability. The net change in the IK depends upon which effect predominates. The dominance at different opioid concentrations may depend on the relative efficacies of the coupling of these two systems to K+ channels.
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PMID:Dual regulation by mu, delta and kappa opioid receptor agonists of K+ conductance of DRG neurons and neuroblastoma X DRG neuron hybrid F11 cells. 857 91

1. In this study we have investigated delta and mu opioid receptor-mediated elevation of intracellular Ca2+ concentration ([Ca2+]i) in the human neuroblastoma cell line, SH-SY5Y. 2. The Ca(2+)-sensitive dye, fura-2, was used to measure [Ca2+]i in confluent monolayers of SH-SY5Y cells. Neither the delta-opioid agonist, DPDPE ([D-Pen2,5]-enkephalin) nor the mu-opioid agonist, DAMGO (Tyr-D-Ala-Gly-N-Me-Phe-Gly-ol enkephalin) elevated [Ca2+]i when applied alone. However, when either DPDPE or DAMGO was applied in the presence of the cholinoceptor agonist, carbachol (100 nM-1 mM) they evoked an elevation of [Ca2+]i above that caused by carbachol alone. 3. In the presence of 1 microM or 100 microM carbachol, DPDPE elevated [Ca2+]i with an EC50 of 10 nM. The elevation of [Ca2+]i was independent of the concentration of carbachol. The EC50 for DAMGO elevating [Ca2+]i in the presence of 1 microM and 100 microM carbachol was 270 nM and 145 nM respectively. 4. The delta-receptor antagonist, naltrindole (30 nM), blocked the elevations of [Ca2+]i by DPDPE (100 nM) without affecting those caused by DAMGO while the mu-receptor antagonist, CTAP (D-Phe-Cys-Tyr-D-Trp-Arg-Pen-Thr-NH2) (100 nM-1 microM) blocked the elevations of [Ca2+]i caused by DAMGO (1 microM) without affecting those caused by DPDPE. 5. Block of carbachol activation of muscarinic receptors with atropine (10 microM) abolished the elevation of [Ca2+]i by the opioids. The nicotinic receptor antagonist, mecamylamine (10 microM), did not affect the elevations of [Ca2+]i caused by opioids in the presence of carbachol. 6. Muscarinic receptor activation, not a rise in [Ca2+]i, was required to reveal the opioid response. The Ca2+ channel activator, maitotoxin (3 ng ml-1), also elevated [Ca2+]i but subsequent application of opioid in the presence of maitotoxin caused no further changes in [Ca2+]i. 7. The elevations of [Ca2+]i by DPDPE and DAMGO were abolished by pretreatment of the cells with pertussis toxin (200 ng ml-1, 16 h). This treatment did not significantly affect the response of the cells to carbachol. 8. The opioids appeared to elevate [Ca2+]i by mobilizing Ca2+ from intracellular stores. Both DPDPE and DAMGO continued to elevate [Ca2+]i when applied in nominally Ca(2+)-free external buffer or when applied in a buffer containing a cocktail of Ca2+ entry inhibitors. Thapsigargin (100 nM), an agent which discharges intracellular Ca2+ stores, also blocked the opioid elevations of [Ca2+]i. 9. delta and mu Opioids did not appear to mobilize intracellular Ca2+ by modulating the activity of protein kinases. The application of H-89 (10 microM), an inhibitor of protein kinase A, H-7 (100 microM), an inhibitor of protein kinase C, protein kinase A and cyclic GMP-dependent protein kinase, or Bis I, an inhibitor of protein kinase C, did not alter the opioid mobilization of [Ca2+]i. 10. Thus, in SH-SY5Y cells, opioids can mobilize Ca2+ from intracellular stores but they require ongoing muscarinic receptor activation. Opioids do not elevate [Ca2+]i when applied alone.
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PMID:delta- and mu-opioid receptor mobilization of intracellular calcium in SH-SY5Y human neuroblastoma cells. 878 87

Whole-cell patch-clamp recordings were used to study Ba2+ currents through voltage-dependent Ca2+ channels in dorsal root ganglion x mouse neuroblastoma hybrid (F-11) cells. Opioid agonists selective for either mu (Tyr-D-Ala-Gly-Mephe-Gly-ol; DAMGO) or delta (Tyr-D-Pen-Gly-Phe-D-Pen-OH; DPDPE) receptors inhibited high-threshold Ba2+ currents. The inhibition was reversible, naloxone-sensitive, and dose-dependent. The inhibitory effects of both DAMGO and DPDPE were blocked by pretreatment of the cells with pertussis toxin (PTX) as well as by brief exposure to the sulfhydryl alkylating agent, N-ethylmaleimide (NEM). The N-type Ca2+ channel antagonist omega-conotoxin GVIA (omega-CTX GVIA) irreversibly inhibited high threshold Ba2+ currents by 66% and blocked the inhibitory effect of DAMGO or DPDPE. In contrast, the L-type Ca2+ channel blocker nifedipine inhibited high threshold Ba2+ currents by 15% and failed to block the inhibitory effect of DAMGO or DPDPE. These results demonstrate that mu and delta opioid receptors are negatively coupled to N-type Ca2+ channels via PTX- and NEM-sensitive GTP-binding proteins in F-11 cells.
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PMID:Mu and delta opioids but not kappa opioid inhibit voltage-activated Ba2+ currents in neuronal F-11 cell. 935 88

The efficacy of different opioid agonists to induce acute desensitization of the human delta-opioid receptor-mediated inhibition of cAMP accumulation was investigated in the neuroblastoma cell line SK-N-BE, which endogenously expresses these receptors. While etorphine, a non-selective alkaloid agonist, caused 50% desensitization after a 30-min incubation, the same treatment in the presence of the selective peptide agonists, DPDPE ([D-Pen2,D-Pen5]enkephalin) and deltorphin I (Tyr-D-Ala-Phe-Asp-Val-Val-Gly), almost totally desensitized the delta-opioid receptor-mediated inhibition of adenylyl cyclase. When SK-N-BE cells were prechallenged either with alkaloid or peptide agonist, we observed a cross-desensitization that was less marked when cells were pretreated with peptide agonists and then challenged with etorphine. Taken together, these results demonstrate that human delta-opioid receptors are differentially desensitized by alkaloid and peptide agonists.
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PMID:Differential desensitization of human delta-opioid receptors by peptide and alkaloid agonists. 1035 61

The two pharmacological delta-opioid receptor subtypes, delta1 and delta2, have been defined on the basis of pharmacological tools but remain to be characterized at the molecular level, since only a single cDNA has been cloned. The present study aimed to investigate the pharmacological properties of delta1- and delta2-opioid subtypes expressed in the human neuroblastoma cell line SK-N-BE and to characterize their putative corresponding mRNAs. Binding experiments using "selective" delta1- and delta2-opioid agonists and antagonists revealed the presence of two binding sites, demonstrating the presence of these delta1-opioid subtypes as they were previously described. The activation of these pharmacological subtypes by the selective agonists induced the incorporation of [alpha-(32)P]azidoanilide-GTP into Galpha(i2)/Galpha(0) subunits with the same efficiency and potency and inhibited adenosine 3', 5'-cyclic monophosphate (cAMP) accumulation with similar efficiency, while their sustained activation for 15 min induced a cross-desensitization. The "selective" delta1 and delta2 antagonists, 7-benzylidenenaltrexone and naltrindole benzofuran, respectively, were found to be as potent in blocking the inhibition of cAMP accumulation induced by both [D-Pen(2,5)]enkephalin and Tyr-D-Ala-Phe-Asp-Val-Val-Gly-NH(2). The possibility that delta-opioid subtypes could arise from alternative splicing was ruled out by reverse transcription-polymerase chain reaction (RT-PCR) experiments and the sequencing of PCR products, which revealed the presence of a single transcript encoding for the delta-opioid receptor. Different possibilities which could account for the delta-opioid receptor heterogeneity observed in the SN-N-BE cell line are discussed.
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PMID:Pharmacological delta1- and delta2-opioid receptor subtypes in the human neuroblastoma cell line SK-N-BE: no evidence for distinct molecular entities. 1069 56

Previously, we reported that the time course for the rapid phosphorylation rate of mu-opioid receptor expressed in human embryonic kidney (HEK)293 cells did not correlate with the slow receptor desensitization rate induced by [D-Ala(2),N-MePhe(4), Gly-ol(5)]-enkephalin (DAMGO). However, others have suggested that receptor phosphorylation is the trigger for mu-opioid receptor desensitization. In this study, we demonstrated the relatively slow rate of receptor desensitization could be attributed partially to the recycling of internalized receptor as determined by fluorescence-activated cell-sorting analysis. However, the blockade of the endocytic and Golgi transport events in HEK293 cells with monensin and brefeldin A did not increase the initial rate of receptor desensitization. But the desensitization rate was increased by reduction of the mu-opioid receptor level with beta-furnaltrexamine (betaFNA). The reduction of the receptor level with 1 microM betaFNA significantly increased the rate of etorphine-induced receptor desensitization. By blocking the ability of receptor to internalize with 0.4 M sucrose, a significant degree of receptor being rapidly desensitized was observed in HEK293 cells pretreated with betaFNA. Hence, mu-opioid receptor is being resensitized during chronic agonist treatment. The significance of resensitization of the internalized receptor in affecting receptor desensitization was demonstrated further with human neuroblastoma SHSY5Y cells that expressed a low level of mu-opioid receptor. Although DAMGO could not induce a rapid desensitization in these cells, in the presence of monensin and brefeldin A, DAMGO desensitized the mu-opioid receptor's ability to regulate adenylyl cyclase with a t(1/2) = 9.9 +/- 2.1 min and a maximal desensitized level at 70 +/- 4.7%. Furthermore, blockade of receptor internalization with 0.4 M sucrose enhanced the DAMGO-induced receptor desensitization, and the inclusion of monensin prevented the resensitization of the mu-opioid receptor after chronic agonist treatment in SHSY5Y cells. Thus, the ability of the mu-opioid receptor to resensitize and to recycle, and the relative efficiency of the receptor to regulate adenylyl cyclase activity, contributed to the observed slow rate of mu-opioid receptor desensitization in HEK293 cells.
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PMID:Receptor density and recycling affect the rate of agonist-induced desensitization of mu-opioid receptor. 1090 7

The steroid SC17599 (17alpha-acetoxy-6-dimethylaminomethyl-21-fluoro-3-ethoxypregna -3, 5-dien-20-one) has mu-opioid actions in vivo. The ability of SC17599 to interact with opioid receptors has been studied using radioligand and [(35)S]guanosine-5'-O-(3-thio)triphosphate (GTPgammaS) binding assays. SC17599 bound to mu-opioid receptors in SH-SY5Y neuroblastoma cells and to recombinant receptors expressed in rat C6 glioma cells and Chinese hamster ovary cells with good affinity and with greater than 100-fold selectivity for mu- over both delta- and kappa-opioid receptors. Binding was much reduced when aspartate 147 in the wild-type mu-opioid receptor was replaced with asparagine. The affinity of SC17599 for the mu-opioid receptor was decreased in the presence of sodium ions, indicating agonist activity. SC17599 stimulated the binding of [(35)S]GTPgammaS in a naloxone-reversible manner with good potency and maximal effect equivalent to that of the mu-opioid agonists fentanyl and [D-Ala(2),N-Me-Phe(4),Gly(5)-ol]-enkephalin. In rat brain membranes, SC17599-mediated stimulation of [(35)S]GTPgammaS binding was reversed by the antagonist naltrexone. SC17599 lacks an aromatic ring and para-hydroxyl substituent considered critical in the pharmacophore for mu-opioids. The structural relationship between SC17599 and more traditional opioid ligands was investigated through genetic algorithm-based modeling techniques for pharmacophore generation (GASP) and ligand-receptor docking (GOLD). The relatively planar and electron-rich A ring of the steroid compensated for the lack of aromaticity. Modeling of ligand-receptor docking showed that both morphine and SC17599 occupy the same binding pocket within the transmembrane helix bundle of the mu-opioid receptor and that the relationship between their binding modes largely mimicked the pharmacophore alignment.
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PMID:The steroid 17alpha-acetoxy-6-dimethylaminomethyl-21-fluoro-3-ethoxy-pregna-3, 5-dien-20-one (SC17599) is a selective mu-opioid agonist: implications for the mu-opioid pharmacophore. 1099 35

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