oxalates and Neuroblastoma

Methamphetamine (METH) and many other abused substances interact with sigma receptors. sigma receptors are found on dopaminergic neurons and can modulate dopaminergic neurotransmission. Antisense knock down of sigma receptors also mitigates METH-induced stimulant effects, suggesting that these proteins are viable medication development targets for treating psychostimulant abuse. In the present study, AC927, a sigma receptor antagonist, was evaluated for its ability to attenuate METH-induced effects in vivo and in vitro. Radioligand binding studies showed that AC927 had preferential affinity for sigma receptors compared to 29 other receptors, transporters and ion channels. Pretreatment of male, Swiss Webster mice with AC927 significantly attenuated METH-induced locomotor stimulation, striatal dopamine depletions, striatal dopamine transporter reductions, and hyperthermia. When the neurotoxicity of METH was further examined in vitro under temperature-controlled conditions, co-incubation with AC927 mitigated METH-induced cytotoxicity. Together, the results demonstrate that AC927 protects against METH-induced effects, and suggests a new strategy for treating psychostimulant abuse.

Topics: Animals; Behavior, Animal; Body Temperature; Brain; Cell Line, Tumor; Cell Shape; Cytokines; Dopamine; Dopamine Plasma Membrane Transport Proteins; Dopamine Uptake Inhibitors; Dose-Response Relationship, Drug; Male; Methamphetamine; Mice; Motor Activity; Neuroblastoma; Oxalates; Piperidines; Protein Binding; Radioligand Assay; Random Allocation; Rats; Rats, Sprague-Dawley; Receptors, sigma; Time Factors

The immunophilin FKBP12 associates with intracellular Ca2+ channels and this interaction can be disrupted by the immunosuppressant FK506. We have investigated the effect of FK506 on Ca2+ release and Ca2+ uptake in permeabilized cell types. Changes in medium free [Ca2+] were detected by the fluorescent Ca2+ indicator fluo-3 in digitonin-permeabilized SH-SY5Y human neuroblastoma cells, DT40 and R23-11 (i.e. triple inositol 1,4,5-trisphosphate (IP3) receptor knockout cells) chicken B lymphocytes and differentiated and undifferentiated BC3H1 skeletal muscle cells. 45Ca2+ fluxes were studied in saponin-permeabilized A7r5 rat smooth muscle cells. Addition of FK506 to permeabilized SH-SY5Y cells led to a sustained elevation of the medium [Ca2+] corresponding to approximately 30 % of the Ca2+ ionophore A23187-induced [Ca2+] rise. This rise in [Ca2+] was not dependent on mitochondrial activity. This FK506-induced [Ca2+] rise was related to the inhibition of the sarcoplasmic/endoplasmic reticulum Ca2+-Mg2+-ATPase (SERCA) Ca2+ pump. Oxalate-facilitated 45Ca2+ uptake in SH-SY5Y microsomes was inhibited by FK506 with an IC50 of 19 microM. The inhibition of the SERCA Ca2+ pump was not specific since several macrocyclic lactone compounds (ivermectin > FK506, ascomycin and rapamycin) were able to inhibit Ca2+ uptake activity. FK506 (10 microM) did not affect IP3-induced Ca2+ release in permeabilized SH-SY5Y and A7r5 cells, but enhanced caffeine-induced Ca2+ release via the ryanodine receptor (RyR) in differentiated BC3H1 cells. In conclusion, FK506 inhibited active Ca2+ uptake by the SERCA Ca2+ pump; in addition, FK506 enhanced intracellular Ca2+ release through the RyR, but it had no direct effect on IP3-induced Ca2+ release.

Topics: Animals; Antiprotozoal Agents; Aorta; B-Lymphocytes; Biological Transport; Caffeine; Calcimycin; Calcium; Calcium Channels; Calcium Signaling; Calcium-Transporting ATPases; Chickens; Enzyme Inhibitors; Humans; Immunosuppressive Agents; Inositol 1,4,5-Trisphosphate Receptors; Ionophores; Ivermectin; Mice; Microsomes; Muscle, Smooth, Vascular; Neuroblastoma; Oxalates; Phosphodiesterase Inhibitors; Rats; Receptors, Cytoplasmic and Nuclear; Sirolimus; Spermine; Tacrolimus; Thapsigargin; Tumor Cells, Cultured

The effect of GTP on Ca2+ uptake and release was studied in a microsomal fraction isolated from neuroblastoma x glioma hybrid NG108-15 cells. GTP did not alter the ATP-dependent initial uptake of Ca2+ but markedly enhanced the efflux of Ca2+ from microsomes. GTP-dependent Ca2+ release requires the presence of millimolar concentration of Mg2+. The effect of GTP was not mimicked by other nucleotides and was competitively blocked by the thiophosphate analogue of GTP, GTP gamma S but not by the non-hydrolyzable nucleotide GMP-PNP. Addition of an inhibiting concentration of GTP gamma S after completion of GTP-induced calcium release did not result in a re-uptake of Ca2+, showing the irreversibility of the releasing effect of GTP. Our data are consistent with the hypothesis of Ca2+-dependent GTP-induced opening of a channel responsible for vectorial transport of Ca2+ ions from one intracellular compartment to another. A model is proposed suggesting that the GTP-binding protein is a GTP-specific diacylglycerol kinase.

Topics: Animals; Calcimycin; Calcium; Cell Line; Glioma; Guanosine Triphosphate; Hybrid Cells; Intracellular Membranes; Kinetics; Magnesium; Mice; Microsomes; Neuroblastoma; Oxalates; Rats

The GTP-activated Ca2+ release process we recently described (Gill, D. L., Ueda, T., Chueh, S. H., and Noel, M. W. (1986) Nature 320, 461-464) was revealed in the preceding report to operate via a mechanism likely to be induced by close membrane association but which appears not to involve membrane fusion (Chueh, S. H., Mullaney, J. M., Ghosh, T. K., Zachary, A. L., and Gill, D. L. (1987) J. Biol. Chem. 262, 13857-13864). To determine more about the GTP-activated Ca2+ translocation process, effects of GTP on cells loaded with Ca-oxalate were investigated. Using permeabilized cells of both the N1E-115 neuroblastoma and DDT1MF-2 smooth muscle cell lines, 10 microM GTP activates a profound uptake of Ca2+ in the presence of oxalate, as opposed to release observed without oxalate. GTP stimulation of Ca2+ uptake was observed at oxalate concentrations (2 mM) only slightly augmenting Ca2+ uptake without GTP; with 8 mM oxalate (which alone induces linear Ca2+ accumulation) GTP still increases the rate of uptake. GTP-activated uptake in the presence of oxalate is completely reversed by 1 mM vanadate. 3% polyethylene glycol enhances the effect of GTP although GTP-activated uptake is still observed without polyethylene glycol. The Km for GTP for activation of Ca2+ uptake is 0.9 microM. Uptake is not activated by guanosine 5'-O-(3-thio)triphosphate (GTP gamma S) or guanosine 5'-(beta, gamma-imido)triphosphate (GppNHp); however, GTP gamma S (but not GppNHp) completely blocks the action of GTP. GDP gives a delayed uptake response which is blocked by ADP, indicating its action arises from conversion to GTP. In the presence of ADP, GDP blocks the action of GTP; guanosine 5'-O-(2-thio)diphosphate, which does not activate uptake, also blocks the action of GTP. These data reveal almost exact correlation between parameters affecting GTP-activated uptake and release, strongly suggesting the same process mediates both events. To explain the opposite effects of GTP in the absence and presence of oxalate, it is proposed that GTP activates a transmembrane conveyance of Ca2+ between oxalate-permeable and -impermeable compartments.

Topics: Animals; Biological Transport; Calcium; Cell Line; Cell Membrane; Guanosine Triphosphate; Kinetics; Models, Biological; Muscle, Smooth; Neuroblastoma; Neurons; Oxalates; Polyethylene Glycols

According to the two-mutation model of neuroblastoma several investigations were performed in order to find the gene carrier in a family with familial neuroblastoma. The results of these former studies are as follows: 1. Neither chromosomal analyses of the peripheral blood nor the examinations of catecholamines nor of cystathionine in the urine could mark the first step to neuroblastoma. 2. Since cystathioniuria was not only seen in blood-relations but also in relatives by marriage and since vitamin B6 deficiency was revealed, cystathioninuria was interpreted as secondary to vitamin B6 deficiency. In this study the normal values of cystathioninuria and vitamin B6 supply were examined. Furthermore the effect of oral vitamin B6 loading on cystathioninuria and oxaluria in familial neuroblastoma was investigated and the vitamin B6 supply in the neighbours of the family was analysed. The results permitted the following conclusions: 1. In 46 of 58 children and adults cystathioninuria was found in an immeasurable range by column chromatography. Only in 12 persons it could be measured quantitatively. With the exception of 6 explanable elevations no value exceeded 20 mumol/24 hr. These results show that the acceptance of the limiting value of 20 mumol/24 hr for increased cystathioninuria is justified. 2. Vitamine B6 deficiency was found in two of 7 patients. In one child this could be explained by the underlying disease. This finding supports the suggestion that vitamine B6 deficiency can relative frequently observed. 3. The examinations of cystathioninuria and oxaluria before and after loading with vitamine B6 showed different results. Whereas oxaluria decreased after loading cystathioninuria was not surely influenced. 4. The neighbours of the members with familial neuroblastoma showed mostly a reduced vitamine B6 supply. This fact could be an indication of exogenous reason of vitamine B6 deficiency in familial neuroblastoma.

Topics: Adult; Child; Cystathionine; Female; Humans; Male; Mutation; Neuroblastoma; Oxalates; Pedigree; Pyridoxine; Vitamin B Deficiency