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)

Receptors for opiates, opiate-like substances, and their antagonists, such as naloxone (a close chemical and conformational congener of morphine), on brain cell homogenates and neuroblastoma X glioma hybrid cells in tissue culture have been reported. The present study on the binding of [3H]naloxone to lymphocytes and platelets freshly isolated from the peripheral blood of 39 healthy adult human volunteers showed that (1) [3H]naloxone bound to lymphocytes and platelets at 4 degrees C, reaching equilibrium in 30 min, and was not removed by washing (three times) with the suspending medium; (2) the binding of [3H]naloxone to cells decreased in the presence of increasing amounts of unlabeled naloxone, approaching a plateau; (3) significant amounts of the radioligand remained bound in the presence of micromolar quantities of the unlabeled ligand; and (4) in the absence of Na+ ions, 1 to 10 nmol of morphine hydrochloride for 10(6) lymphocytes, and 1 to 25 nmol of morphine hydrochloride for 10(8) platelets, decreased the binding of [3H]naloxone by 43 to 57%. It is concluded that at least some of the [3H]naloxone binding sites on human lymphocytes and platelets are specific opioid receptor sites of the mu type (Enkephalins define the delta sites.) The observations on the binding of naloxone to cells do not appear to be artifacts. Opioid receptor sites on lymphocyte and platelet membranes may have properties similar to those on nerve cell membranes.
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PMID:Opiate receptors on lymphocytes and platelets in man. 630 70

BALB/c mice were immunized with an opioid receptor complex over the period of 1 year. Spleen cells from the mouse, whose serum inhibited opiate binding to rat neural membranes to the greatest extent, were fused with P3-X63-Ag8. 653.3 myeloma cells. By radioimmunoassay (RIA), 32 cell lines have been detected that secrete an antibody to a component of the isolated receptor complex. Antibodies from 2 of the cell lines have an effect on opiate binding to rat neural membranes. One antibody, OR-689.2.4 is an IgM cryoglobulin. This antibody partially inhibited the binding of 3H-dihydromorphine (3H-DHM), 3H-naloxone, 3H-ethylketocyclazocine (3H-EKC), and 3H-D-Ala2, D-Leu5 enkephalin (3H-DADLE) to rat neural membranes. The other antibody, OR-465.3, inhibited the binding of 3H-DHM and 3H-naloxone to rat neural membranes by a maximum of 70%. This antibody also inhibited the binding of 3H-DADLE to neural membranes but, did not affect the binding of this peptide to membranes from the neuroblastoma-glioma hybrid cell line, NG108-15. Work is ongoing to generate monoclonal antibodies specific for each subclass of opioid receptor.
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PMID:Generating monoclonal antibodies to the opioid receptor. 631 52

A new cDNA clone, NGD5, has been identified from a subtraction cDNA library constructed with mRNA isolated from control neuroblastoma x glioma NG108-15 cells and cells treated for 48 h with the delta-opioid agonist, D-Ala2, D-Leu5 enkephalin (DADLE). NGD5 mRNA is decreased, in a naloxone-reversible manner, upon long-term treatment of NG108-15 cells with DADLE, indicating that this clone may be related to opioid receptor function. Northern analysis indicates that NGD5 mRNA is expressed in rat brain. Two similar nearly full-length NGD5 clones, NGD5A and NGD5B, were isolated from a lambda gt10 NG108-15 cDNA library and sequenced. The predicted 40-kDa peptide encoded for by the NGD5 cDNA has no significant homology to the recently cloned mu, delta or kappa opioid receptors nor to any other known proteins.
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PMID:Molecular cloning of a novel protein regulated by opioid treatment of NG108-15 cells. 749 58

Phosphodiester antisense oligodeoxynucleotides (ODNs) directed against various domains of the cloned mouse delta receptor DOR-1 reduce delta-opioid receptor binding in vivo and in vitro. The present study examines the stability of an antisense ODN (275 nM) directed against the delta-opioid receptor and its effect on DOR-1 mRNA in cultured neuroblastoma cells and in vivo. When added to NG108-15 cells, much of the antisense ODN is degraded. However, > 1% is intact, associated with cells, and stable for at least 72 h. Northern blot analysis demonstrates that treatment of NG108-15 cells with the antisense ODN reduces the levels of a species of DOR-1 mRNA by approximately 25%. Similarly, intrathecal administration of the antisense ODN results in the accumulation of intact ODN within the spinal cord, which is stable for at least 72 h, although the levels of accumulation in vivo are lower than in vitro after either 4 or 72 h. Antisense ODN treatment lowers DOR-1 mRNA levels by approximately 25%. The loss of mRNA both in vivo and in vitro corresponds quite well to the decreases in receptor binding previously observed by our laboratory and is consistent with reduction of delta-opioid receptor protein in vitro as determined by western blot with a monoclonal antibody selective for the delta-opioid receptor. In conclusion, these studies indicate that a small, but significant, proportion of ODN is taken up by cells and remains intact for up to 72 h. This appears to be sufficient to down-regulate mRNA levels of delta-opioid receptors and their expression.
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PMID:Antisense oligodeoxynucleotides to the cloned delta receptor DOR-1: uptake, stability, and regulation of gene expression. 759 81

Several cellular systems display desensitization and downregulation of opioid receptors upon chronic treatment, suggesting that they could be used as a model system to understand opioid tolerance/dependence. However, a model system containing a homogeneous population of mu-opioid receptors, the receptors at which morphine and related opioids act, has been lacking. To approach this problem, the mu-opioid receptor (MOR-1) was stably expressed in murine neuroblastoma Neuro2A cells after transfection. The expressed receptor was negatively coupled to adenylyl cyclase through Gi/Go proteins, displayed high affinity ligand binding, and was expressed in high number (2.06 pmol/mg of [3H]diprenorphine binding sites). In addition, loss of ability of mu-opioids to acutely inhibit forskolin-stimulated cAMP formation was observed after 4-24 h of chronic exposure to these agonists with concentrations as low as 300-500 nM. The effects of chronic morphine or [D-Ala2,N-MePhe4,Gly-ol]enkephalin (DAMGO) administration were found to be time- and concentration-dependent. Cross 'tolerance' was also observed. Thus the IC50 value of DAMGO to inhibit adenylyl cyclase was increased by 27-fold from 4.3 nM in control cells to 117 nM in cells pretreated with 300 nM morphine; there was no effect on the inhibition of adenylyl cyclase mediated by muscarinic receptors. Further, receptor downregulation accompanied the desensitization process. However, different time-dependence for these two processes suggests, in line with other studies, that these are entirely different cellular adaptation processes. In addition, the opioid antagonist naloxone induced an acute increase in intracellular cAMP level (2-3 times above the control level) following chronic agonist exposure. This process was also concentration-dependent. Overall, these results suggest that the cell line utilized in this study has a homogeneous population of mu-opioid receptors, providing an ideal cellular model to study the molecular mechanisms underlying chronic morphine treatment.
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PMID:Neuroblastoma Neuro2A cells stably expressing a cloned mu-opioid receptor: a specific cellular model to study acute and chronic effects of morphine. 763 78

Voltage-dependent Ca2+ currents were measured in NG108-15 neuroblastoma x glioma hybrid cells transformed to express the rat mu-opioid receptor by the whole-cell configuration of the patch-clamp technique with Ba2+ as charge carrier. A mu-opioid receptor-selective agonist, [D-Ala2,N-Me-Phe4,Gly5-ol]-enkephalin caused significant inhibition of voltage-dependent Ca2+ currents in mu-receptor-transformed NG108-15 cells but not in nontransfected or vector-transformed control cells. On the other hand, a delta-opioid receptor-selective agonist, [D-penicillamine2,D-penicillamine5]enkephalin, induced inhibition of voltage-dependent Ca2+ currents in both control and mu-receptor-transformed cells, which is mediated by the delta-opioid receptor expressed endogenously in NG108-15 cells. The inhibition of voltage-dependent Ca2+ currents induced by [D-Ala2,N-Me-Phe4,Gly5-ol]enkephalin [D-penicillamine2,D-penicillamine5]enkephalin was reduced by pretreatment of the cells with pertussis toxin or omega-contoxin GVIA. These results indicate that the mu-opioid receptor expressed from cDNA functionally couples with omega-contoxin-sensitive N-type Ca2+ channels through the action of pertussis toxin-sensitive G proteins in NG108-15 cells.
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PMID:Coupling of the cloned mu-opioid receptor with the omega-conotoxin-sensitive Ca2+ current in NG108-15 cells. 764 19

Opioid peptides, Met5- and Leu5-enkephalin, are known endogenous ligands for the delta-opioid receptor (DOR) associated with opioid analgesia at the spinal level. To determine the cellular sites for DOR-mediated actions, we examined the ultrastructural localization of DOR and Met5-enkephalin (ME) in the spinal cord by combining immunoperoxidase and immunogold-silver labeling for antibodies against DOR and ME, respectively. Antibodies for DOR localization were raised in guinea pig against peptide 34-47 (p34), an amino acid sequence within the extracellular N-terminus of the DOR recently cloned from mouse neuroblastoma glioma (NG-108) cells. Selective immunoperoxidase labeling for DOR was detected by light microscopy in NG-108 cells and in the lamina I and II of the dorsal horn of the spinal cord (C2-C4). Electron microscopy of these spinal laminae revealed that the majority of the punctate varicosities seen by light microscopy were axon terminals. delta-opioid receptor-like immunoreactivity (DOR-LI) in axon terminals was most prominently associated with large dense core vesicles, and sometimes seen along the membranes of small clear vesicles and segments of the plasmalemma. A semiquantitative analysis of dually labeled sections revealed that of the terminals showing DOR-LI, 23/102 (23%) also contained Met5-enkephalin-like immunoreactivity (ME-LI). Conversely, 23/35 (66%) of the terminals showing ME-LI also showed DOR-LI. In addition to the presynaptic localization, selective postsynaptic densities within dendrites were also occasionally (9%) immunolabeled for the opioid receptor. These results provide the first ultrastructural evidence that DOR may serve autoreceptor functions on ME terminals as well as presynaptic modulation of other transmitters in the dorsal horn of the rat spinal cord. Additionally, the vesicular localization of DOR-LI in axon terminals suggests the involvement of these organelles in the transport of the receptors to the plasma membrane.
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PMID:Ultrastructural immunolabeling shows prominent presynaptic vesicular localization of delta-opioid receptor within both enkephalin- and nonenkephalin-containing axon terminals in the superficial layers of the rat cervical spinal cord. 766 82

Continuous elevation of intracellular cyclic AMP (cAMP) by culturing neuroblastoma x glioma NG108-15 hybrid cells in the presence of forskolin and isobutylmethylxanthine (IBMX) in a chemically defined medium resulted in differentiation of the hybrid cells, as indicated by extension of neurite-like structures and induction of a subclass of G-protein, Go, as monitored by Western analysis. This cellular differentiation also resulted in an initial 25 to 30% increase in [3H]diprenorphine binding 3 hr after forskolin and IBMX treatment, followed by a decrease in opioid receptor density to the maximal level of 35% of control 4 days later. However, the potencies and maximal inhibitory levels of various opioid agonists to inhibit adenylate cyclase activity was not altered during differentiation. When the differentiated hybrid cells were treated with DADLE chronically, an apparent decrease in the ability of the agonist to desensitize and to down-regulate the delta-opioid receptor was observed. It is unlikely that this observed attenuation was due to activation of cAMP-dependent protein kinase A, because (1) attenuation of DADLE desensitization was time-dependent, reaching maximal effects 48 hr after the initiation of treatment; and (2) pretreatment of NG108-15 cells with forskolin and IBMX resulted in attenuation of forskolin's ability to stimulate adenylate cyclase activity and parallel decrease in the ability of forskolin to activate the cAMP-dependent protein kinases in these cells was also observed. Thus, it is unlikely that the activation of protein kinase A by forskolin and IBMX is the cause for the attenuation of DADLE-induced delta-opioid receptor desensitization in differentiated NG108-15 cells.
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PMID:Effect of forskolin and isobutylmethylxanthine on delta-opioid receptor activity in neuroblastoma x glioma NG108-15 cells. 768 Jul 18

The ability of mu-opioid agonists to activate G proteins has been demonstrated by studying the binding of the GTP analogue guanosine-5'-O-(3-[35S]thio)triphosphate ([35S]GTP gamma S) to membranes from the human neuroblastoma SH-SY5Y cell line. The potent opioid agonist fentanyl caused an approximate doubling of basal [35S]GTP gamma S binding in a naloxone-sensitive manner, confirming this to be an opioid receptor-mediated process. The presence of GDP was necessary to observe this effect. Pretreatment of the cells with pertussis toxin (100 ng/ml, for 24 hr) completely prevented the fentanyl-stimulated increase in [35S]GTP gamma S binding and lowered the basal binding of [35S]GTP gamma S. These latter data suggest an involvement of Gi and/or Go proteins and their activation by added membrane-bound receptors even in the absence of agonist. The order of potency of a series of opioid agonists in stimulating the binding of [35S]GTP gamma S was buprenorphine > cyclazocine = levallorphan > nalorphine > [D-Ala2,MePhe4,Gly-ol5]enkephalin (DAMGO) > fentanyl > morphine > pentazocine. DAMGO, fentanyl, and morphine were full agonists but the remaining compounds showed decreasing levels of intrinsic activity in the order buprenorphine > pentazocine > cyclazocine = nalorphine > levallorphan. The opioid antagonist naloxone was without effect. Under the conditions of the [35S]GTP gamma S assay, binding of agonists was to a high affinity site, indicating that a high agonist affinity state of the mu-opioid receptor is responsible for the observed stimulation of [35S]GTP gamma S binding. The level of [35S]GTP gamma S binding (597 fmol/mg of protein) stimulated by DAMGO was 2-fold greater than the maximal number of mu-opioid agonist binding sites (Bmax) determined using [3H]DAMGO (254 fmol/mg of protein). The opioid agonist-mediated stimulation of [35S]GTP gamma S binding in SH-SY5Y cell membranes thus provides a "functional" measure of agonist occupation of mu-opioid receptors and offers a simple method for the determination of efficacy and intrinsic activity of mu-opioid agonists.
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PMID:Modulation by mu-opioid agonists of guanosine-5'-O-(3-[35S]thio)triphosphate binding to membranes from human neuroblastoma SH-SY5Y cells. 772 47

The present article investigates chronic opioid regulation of the stimulatory adenylate cyclase-coupled prostaglandin E1 (PGE1) receptor system in neuroblastoma x glioma (NG108-15) hybrid cells. Persistent activation of delta-opioid receptors by morphine (10 mumol/L; 3 days) substantially down-regulates the number of PGE1 binding sites by approximately 30%, without affecting their affinity. Radioligand binding studies performed in the presence of GTP gamma S (100 mumol/L) further revealed that the remaining PGE1 binding sites are still capable of interacting functionally with their associated stimulatory G proteins, Gs. On the postreceptor level, neither changes in the abundance nor in the intrinsic activity of the alpha subunit of Gs (Gs alpha) were found during the state of opioid dependence, as has been verified by western blot and S49 cyc- reconstitution experiments, respectively. Evaluation of the functional interaction between PGE1 receptors and Gs by means of receptor-stimulated, cholera toxin-catalyzed ADP-ribosylation of Gs alpha revealed a significant increase in the ability of PGE1 receptors to activate Gs alpha (3.3-fold increase in EC50; p < 0.05) in cells chronically exposed to morphine. This effect was completely blocked by coincubation of the cells together with the opiate antagonist naloxone (100 mumol/L; 3 days), whereas precipitation of morphine withdrawal by naloxone (100 mumol/L) had no further effect on sensitization in PGE1 receptor/Gs coupling. These findings provide evidence that the stimulatory adenylate cyclase-coupled PGE1 receptor system represents a potential target of chronic delta-opioid receptor activation in NG108-15 hybrid cells. They further suggest that sensitization in stimulatory signal transduction plays a critical role in the generation of opioid dependence.
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PMID:Chronic activation of inhibitory delta-opioid receptors cross-regulates the stimulatory adenylate cyclase-coupled prostaglandin E1 receptor system in neuroblastoma x glioma (NG108-15) hybrid cells. 776 24

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