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  • 1
    Electronic Resource
    Electronic Resource
    Distinct Developmental Patterns of Expression of Rat α1, α5, γ2S, andα12Lγ-Aminobutyric AcidA Receptor Subunit mRNAs In Vivo and In Vitro (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 59 (1992), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: We have quantitated the α1, α5, γ2S, and γ2Lγ-aminobutyric acidA (GABAA) receptor subunit mRNAs in the maturing cerebellum in vivo and in cerebellar granule neurons differentiating in vitro. Absolute amounts of mRNA were measured by reverse transcription and competitive polymerase chain reaction (PCR) analysis with appropriate internal standards. The α1 and γ2L mRNA content increased continuously during postnatal cerebellar maturation and their changes with time matched very closely those of the cerebellar granule cells differentiating in vitro. The γ2S subunit mRNA showed a relatively constant pattern of expression both in vivo and in vitro, with comparable absolute concentrations in both developmental paradigms. The α5 mRNA was initially high in vivo and decreased (eightfold) to adult levels as postnatal cerebellar development progressed. In vitro the amount of α5 GABAA receptor subunit mRNA was higher than in vivo at 3 days, increased by more than twofold by 8 days, and declined to approximately the initial values at 23 and 28 days in vitro. Collectively, the results indicate that the α1, α5, γ2S, and γ2L GABAA receptor subunit mRNAs are regulated differentially in a temporal manner during in vivo and in vitro maturation. Moreover, a comparison of the ontogenetic profiles of the γ2S and γ2L mRNAs indicates that alternative splicing of the γ2 primary RNA transcript is regulated developmentally during postnatal maturation of the rat cerebellum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1992.tb08876.x
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  • 2
    Electronic Resource
    Electronic Resource
    Endogenous Benzodiazepine Receptor Ligands in Human and Animal Hepatic Encephalopathy (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 55 (1990), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The role of endogenous benzodiazepine receptor ligands in the pathogenesis of hepatic encephalopathy was studied in humans and in rat models of hepatic encephalopathy. Endogenous benzodiazepine ligands were extracted from rat brain and human CSF by acid treatment and purification by HPLC. Detection and partial characterization of these endogenous benzodiazepine ligands were carried out using both radioreceptor binding assays and radioimmunoassays with anti-benzodiazepine antibodies. Four different benzodiazepine receptor ligands were identified in human and rat tissue, two of which may be diazepam and desmethyldiazepam, based on elution profiles and anti-benzodiazepine antibody reactivity. Human CSF and serum from patients with hepatic encephalopathy contained ∼ 10 times more endogenous benzodiazepine receptor ligand than CSF from controls or nonencephalopathic patients with liver disease. The levels of brain benzodiazepine receptor ligand compounds were also increased ∼ 10-fold in rats suffering from fulminant hepatic failure, but not in rats with portacaval shunts, a model of chronic hepatic disease. The increased concentrations of these substances could be behaviorally significant and may contribute to the pathogenesis of hepatic encephalopathy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1990.tb05790.x
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  • 3
    Electronic Resource
    Electronic Resource
    Potassium Ion Facilitation of Phosphoinositide Turnover Activation by Muscarinic Receptor Agonists in Rat Brain (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 46 (1986), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: In rat hippocampal slices kept in Krebs-Henseleit medium, an increase of K+ ions to 12 mMpotentiates the stimulation of phosphoinositide turnover elicited by carbachol and (±)-cis-methyldioxolane. Oxotremorine is inactive if tested in Krebs-Henseleit medium but it stimulates by 220% the phosphoinositide turnover when K+ is increased to 12 mM. The K+ facilitation of the carbachol stimulation of phosphoinositide turnover was blocked by pirenzepine, a muscarinic antagonist. This drug was equally potent in inhibiting the carbachol stimulation of phosphoinositide turnover both in normal and 12 mM K+ Krebs medium. This facilitatory effect of K+ appears to be preferential for muscarinic receptors, since it failed to increase the activation of phosphoinositide breakdown induced by norepinephrine and histamine. The K+ potentiation of the muscarinic stimulation of phosphoinositide turnover is not mediated by a release of one of the endogenous neurotransmitters stored in these slices because such a facilitation occurs in Ca2+ -deprived Krebs-Henseleit medium and failed to occur following a depolarizing dose of veratrine. Our experiments excluded that K+ facilitates carbachol stimulation of phosphoinositide turnover because it modifies the binding characteristics of muscarinic receptors; however, they cannot exclude that K+ acts at the receptor transducer coupling.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1986.tb01758.x
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  • 4
    Electronic Resource
    Electronic Resource
    Purification and Characterization of Naturally Occurring Benzodiazepine Receptor Ligands in Rat and Human Brain (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 58 (1992), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Chemicals that are active at the benzodiazepine receptor (endozepines) are naturally present in the CNS. These substances are present in tissue from humans and animals and in plants and fungi. Using selective extraction protocols, HPLC purification, receptor binding displacement studies, and selective anti-benzodiazepine antibodies, we have identified six or seven peaks of endozepines in rat and human brain. All material could competitively displace [3H]flunitrazepam binding to cerebellar benzodiazepine binding sites. Two peaks also competitively displaced Ro 5-4864 binding to the mitochondrial benzodiazepine binding site. Total amounts of brain endozepines were estimated to be present in potentially physiological concentrations, based on their ability to displace [3H]flunitrazepam binding. Although endozepine peaks 1 and 2 had HPLC retention profiles similar to those of nordiazepam and diazepam, respectively, gas chromatography-mass spectrometry as well as high-performance TLC revealed biologically insignificant amounts of diazepam (〈 0.02 pg/g) and nordiazepam (〈0.02 pg/g) in the purified material. Electrophysiologically, some purified endozepines positively modulated γ-aminobutyric acid (GABA) action on Cl− conductance, monitored in patch-clamped cultured cortical neurons or in mammalian cells transfected with cDNA encoding various GABAA receptor subunits. These studies demonstrate that mammalian brains contain endozepines that could serve as potent endogenous positive allosteric modulators of GABAA receptors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1992.tb10952.x
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  • 5
    Electronic Resource
    Electronic Resource
    Age-Related Bidirectional Changes in Neuropeptide Y Peptides in Rat Adrenal Glands, Brain, and Blood (1988)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 50 (1988), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Age-related changes in neuropeptide Y (NPY) regulation were studied in rat adrenal glands, brains, and blood by radioimmunoassay and biochemical characterization using reversed phase HPLC and gel filtration chromatography. NPY immunoreactivity (pmol/g tissue ± SEM) in rat adrenal glands increased from 7 ± 1 (6 weeks old) to 1,500 ± 580 (69 weeks old). Biochemical characterization by HPLC showed that this increase was due to those of NPY and methionine sulfoxide NPY. In contrast, in rat brain, NPY content decreased in an age-dependent manner specifically in striatum, hippocampus, medulla oblongata, and spinal cord and the sulfoxide form was not detected. In rat blood, the circulating level of NPY was high (3–5 pmol/ml plasma ± SEM) but did not change significantly with age or by adrenal demedullation. Only a small increase of the sulfoxide form of NPY was observed in aged rat plasma. The age-dependent changes in regulation and modification of NPY in adrenal glands and in specific brain areas may have physiological relevance in the regulation of catecholamine release from adrenal glands and some brain functions during aging.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1988.tb02492.x
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  • 6
    Electronic Resource
    Electronic Resource
    Glutamate Receptor Agonists Stimulate Nitric Oxide Synthase in Primary Cultures of Cerebellar Granule Cells (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 58 (1992), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The glutamate receptor agonist N-methyl-D-aspartate (NMDA) stimulated a rapid, extracellular Ca2+-dependent conversion of [3H]arginine to [3H]citrulline in primary cultures of cerebellar granule cells, indicating receptor-mediated activation of nitric oxide (NO) synthase. The NMDA-induced formation of [3H]citrulline reached a plateau within 10 min. Subsequent addition of unlabeled l-arginine resulted in the disappearance of 3H from the citrulline pool, indicating a persistent activation of NO synthase after NMDA receptor stimulation. Glutamate, NMDA, and kainate, but not quisqualate, stimulated both the conversion of [3H]arginine to [3H]citrulline and cyclic GMP accumulation in a dose-dependent manner. Glutamate and NMDA showed similar potencies for the stimulation of [3H]citrulline formation and cyclic GMP synthesis, respectively, whereas kainate was more potent at inducing cyclic GMP accumulation than at stimulating [3H]citrulline formation. Both the [3H]arginine to [3H]citrulline conversion and cyclic GMP synthesis stimulated by NMDA were inhibited by the NMDA receptor antagonist MK-801 and by the inhibitors of NO synthase, NG-monomethyl-L-arginine (MeArg) and NG-nitro-L-arginine (NOArg). However, MeArg, in contrast to NOArg, also potently inhibited [3H]arginine uptake. Kainate (300 μM) stimulated 45Ca2+ influx to the same extent as 100 μM NMDA, but stimulated [3H]citrulline formation to a much lesser extent, which suggests that NO synthase is localized in subcellular compartments where the Ca2+ concentration is regulated mainly by the NMDA receptor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1992.tb09315.x
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  • 7
    Electronic Resource
    Electronic Resource
    Glutamate Neurotoxicity Is Independent of Calpain I Inhibition in Primary Cultures of Cerebellar Granule Cells (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 57 (1991), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Glutamate-induced neurotoxicity and calpain activity were studied in primary cultures of rat cerebellar granule neurons and glial cells. Calpain activation, as monitored by quantitative immunoblotting of spectrin, required micromolar concentrations of Ca2+ in neuronal homogenates (calpain I) and millimolar Ca2+ concentrations in glial homogenates (calpain II). Glutamate-induced toxicity and calpain activation were observed in neuronal, but not in glial, cultures. In neurons, calpain I activation by glutamate was dose-dependent and persisted after withdrawal of neurotoxic doses of glutamate. Natural (GM1) and semisynthetic (LIGA4) gangliosides or the glutamate receptor blocker MK-801 prevented calpain I activation and delayed neuronal death elicited by glutamate. GM1 and LIGA4 had no effect on calpain I activity in neuronal homogenates, however. Furthermore, two calpain I inhibitors (leupeptin and N-acetyl-Leu-Leu- norleucinal) prevented glutamate-induced spectrin degradation, but failed to affect glutamate neurotoxicity. These results thus suggest that glutamate-induced neurotoxicity is independent of calpain I activation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1991.tb08292.x
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  • 8
    Electronic Resource
    Electronic Resource
    Subcellular Location and Neuronal Release of Diazepam Binding Inhibitor (1987)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 48 (1987), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Diazepam binding inhibitor (DBI), a peptide located in CNS neurons, blocks the binding of benzodiaze-pines and β-carbolines to the allosteric modulatory sites of γ-aminobutyric acid (GABAA) receptors. Subcellular frac-tionation studies of rat brain indicate that DBI is compartmentalized. DBI-like immunoreactivity is highly enriched in synaptosomes obtained by differential centrifugation in isotonic sucrose followed by a Percoll gradient. In synapto-somal lysate, DBI-like immunoreactivity is primarily associated with synaptic vesicles partially purified by differential centrifugation and continuous sucrose gradient. Depolarization induced by high K+ levels (50 mM) or veratridine (50 μM) released DBI stored in neurons of superfused slices of hypothalamus, hippocampus, striatum, and cerebral cortex. The high K+ level-induced release is Ca2+ dependent, and the release induced by veratridine is blocked by 1.7 μM tetrodotoxin. Depolarization released GABA and Met5-enkephalin-Arg6-Phe7 together with DBI. DBI is also released by veratridine depolarization, in a tetrodotoxin-sen-sitive fashion, from primary cultures of cerebral cortical neurons, but not from cortical astrocytes. Depolarization fails to release DBI from slices of liver and other peripheral organs. These data support the view that DBI may be released as a putative neuromodulatory substance from rat brain neurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1987.tb05632.x
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  • 9
    Electronic Resource
    Electronic Resource
    5-Hydroxytryptamine Uptake and Imipramine Binding Sites in Neurotumor NCB-20 Cells (1985)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 45 (1985), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: NCB-20 cells (neuroblastoma × fetal Chinese hamster brain hybrids) are equipped with a [3H]5-hydroxytryptamine ([3H]5-HT) uptake system and [3H]imipramine recognition sites. Approximately 80% of the radioactivity taken up by cells incubated with [3H]5-HT was identified with 5-HT. [3H]5-HT uptake was temperature-dependent, partially sodium-dependent, saturable (Km= 7.3 ± 0.6 μM; Vmax= 2.0 ± 0.6 pmol/min/mg), and inhibited by clomipramine, imipramine, fluoxetine, and desipramine, but not by iprindole, mianserin, or opipramol. Lineweaver-Burk plots showed a competitive type of inhibition by imipramine and fluoxetine. [3H]5-HT uptake was not inhibited by nisoxetine or benztropine. [3H]Imipramine binding sites had a KD of 12 ± 2 nM and a Bmax of 22 ± 7 pmol/mg protein. The binding was sodium-sensitive although to a lesser extent than that found with brain membranes. Imipramine binding was displaced by tricyclic antidepressants with the following order of potency: clomipramine 〉 imipramine 〉 fluoxetine 〉 desipramine ± iprindole = mianserin 〉 opipramol. These results suggest that imipramine binding sites are present together with the 5-HT uptake sites in NCB-20 cells and that these sites interact functionally but are different biochemically.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1985.tb04081.x
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  • 10
    Electronic Resource
    Electronic Resource
    Specific High-Affinity Binding of L-[3H]Aspartate to Rat Brain Membranes (1982)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 38 (1982), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The binding of L-[3H]aspartate was investigated in washed membranes prepared from whole rat brain. We were able to differentiate two separate binding sites differing in their Na dependence. The Na-independent binding was saturable, reversible, and optimal at 20°C and at pHs in the neutral range. The dissociation constant (Kd) at 20°C was about 200 nM. This binding site seemed to be modulated by magnesium and calcium at physiological concentrations. None of the amino acids tested was a potent competitor for Na-independent L-[3H]aspartate binding. This binding site was unevenly distributed in the rat central nervous system: cerebellum = cerebral cortex 〉 ponsmedulla 〉 spinal cord. Destruction of the intrinsic neurons of the cerebellum by injecting kainic acid 30 days before sacrifice resulted in a 53% reduction in Na-independent binding in this region. The Na-dependent binding of L-[3H]-aspartate (Kd= 484 nM) was strongly inhibited by D-aspartate, L-glutamate, D,L-aspartate β-hydroxamate; was unaffected by calcium and magnesium; and showed a different pattern of distribution: cerebral cortex 〉 cerebellum = pons-medulla = spinal cord. This binding in cerebellum was unaffected by injections of kainic acid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1982.tb07899.x
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