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  • 2000-2004  (6)
  • 1990-1994  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 55 (1990), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The subcellular and regional distribution of endooligopeptidase (EC 3.4.22.19), an enzyme capable of generating enkephalin by single cleavage from enkephalin-containing peptides, was determined by an enzymatic assay using metorphamide and by immunochemical techniques in the CNS of the rat. The rat CNS contains a membrane-associated form of endo-oligopeptidase, an enzyme predominantly associated with the soluble fraction of brain homogenates. Sub-cellular fractionation showed that ∼17% of the total activity of the enzyme is associated with membrane fractions including synaptosomes. Synaptosomal membranes were prepared from neocortex, striatum, hypothalamus, medulla, spinal cord, and cerebellum. The amount of EC 3.4.22.19 activity solubilized by 3-([3-cholamidopropyl]dimethylammonio)-1-propanesulfonate from synaptosomal membranes was similar in neocortex, striatum, and hypothalamus, being three- to 10-fold greater than in spinal cord, cerebellum, and medulla. A polyclonal antibody exhibiting high affinity for endo-oligopeptidase was raised in rabbits against the purified rat brain enzyme and used to localize endo-oligopeptidase by Western blotting and by immunoperoxidase techniques. A strong band corresponding to the Mr of EC 3.4.22.19 was found in solubilized proteins obtained from synaptosomal membranes prepared from hypothalamus, neocortex, and striatum when subjected to Western blotting. The immunohistochemical localization of endo-oligopeptidase indicated that the immunoreactivity was confined to gray matter in regions known to be rich in peptide-containing neurons such as the striatum. In the cerebellum, a region poor in peptides, no staining could be detected. The nonuniform distribution of endo-oligopeptidase in rat brain suggests a role in neurotransmitter processing in the CNS.
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  • 2
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Substance P antagonists of the neurokinin-1 receptor type (NK1) are gaining growing interest as new antidepressant therapies. It has been postulated that these drugs exert this putative therapeutic effect without direct interactions with serotonin (5-HT) neurones. Our recent microdialysis experiment performed in NK1 receptor knockout mice suggested evidence of changes in 5-HT neuronal function (Froger et al. 2001). The aim of the present study was to evaluate the effects of coadministration of the selective 5-HT reuptake inhibitor (SSRI) paroxetine with a NK1 receptor antagonist (GR205171 or L733060), given either intraperitoneally (i.p.) or locally into the dorsal raphe nucleus, on extracellular levels of 5-HT ([5-HT]ext) in the frontal cortex and the dorsal raphe nucleus using in vivo microdialysis in awake, freely moving mice. The systemic or intraraphe administration of a NK1 receptor antagonist did not change basal cortical [5-HT]ext in mice. A single systemic dose of paroxetine (4 mg/kg; i.p.) resulted in a statistically significant increase in [5-HT]ext with a larger extent in the dorsal raphe nucleus (+ 138% over basal AUC values), than in the frontal cortex (+ 52% over basal AUC values). Co-administration of paroxetine (4 mg/kg; i.p.) with the NK1 receptor antagonists, GR205171 (30 mg/kg; i.p.) or L733060 (40 mg/kg; i.p.), potentiated the effects of paroxetine on cortical [5-HT]ext in wild-type mice, whereas GR205171 (30 mg/kg; i.p.) had no effect on paroxetine-induced increase in cortical [5-HT]ext in NK1 receptor knock-out mice. When GR205171 (300 µmol/L) was perfused by ‘reverse microdialysis’ into the dorsal raphe nucleus, it potentiated the effects of paroxetine on cortical [5-HT]ext, and inhibited paroxetine-induced increase in [5-HT]ext in the dorsal raphe nucleus. Finally, in mice whose 5-HT transporters were first blocked by a local perfusion of 1 µmol/L of citalopram into the frontal cortex, a single dose of paroxetine (4 mg/kg i.p.) decreased cortical 5-HT release, and GR205171 (30 mg/kg i.p.) reversed this effect. The present findings suggest that NK1 receptor antagonists, when combined with a SSRI, augment 5-HT release by modulating substance P/5–HT interactions in the dorsal raphe nucleus.
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  • 3
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: It has previously been shown that chronic treatment with antidepressant drugs increases neurogenesis and levels of brain-derived neurotrophic factor in the hippocampus. These changes have been correlated with changes in learning and long-term potentiation and may contribute to the therapeutic efficacy of antidepressant drug treatment. Recently, antagonists at the neurokinin-1 receptor, the preferred receptor for the neuropeptide substance P, have been shown to have antidepressant activity. Mice with disruption of the neurokinin-1 receptor gene are remarkably similar both behaviourally and neurochemically to mice maintained chronically on antidepressant drugs. We demonstrate here that there is a significant elevation of neurogenesis but not cell survival in the hippocampus of neurokinin-1 receptor knockout mice. Neurogenesis can be increased in wild-type but not neurokinin-1 receptor knockout mice by chronic treatment with antidepressant drugs which preferentially target noradrenergic and serotonergic pathways. Hippocampal levels of brain-derived neurotrophic factor are also two-fold higher in neurokinin-1 receptor knockout mice, whereas cortical levels are similar. Finally, we examined hippocampus-dependent learning and memory but found no clear enhancement in neurokinin-1 receptor knockout mice. These data argue against a simple correlation between increased levels of neurogenesis or brain-derived neurotrophic factor and mnemonic processes in the absence of increased cell survival. They support the hypothesis that increased neurogenesis, perhaps accompanied by higher levels of brain-derived neurotrophic factor, may contribute to the efficacy of antidepressant drug therapy.
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  • 4
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Some small nucleolar RNAs (snoRNAs) are exclusively expressed in the brain but they have no known role in higher brain function. We analysed the expression pattern of four brain-specific snoRNAs: MBI-36, MBII-48, MBII-52 and MBII-85, in mouse brain using in situ hybridization. All of these genes were expressed in the hippocampus and, except for MBII-85, their levels in ventral parts were higher than those in dorsal parts. Using quantitative real-time polymer chain reaction we determined hippocampal expression changes after contextual fear conditioning in mice. Ninety minutes, but not 25 h, after conditioning, we observed significant downregulation of MBII-48 and upregulation of MBII-52. Our finding that the expression of MBII-48 and MBII-52 is regulated during learning suggests that these snoRNAs have an important role in higher brain function.
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  • 5
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Substance P and neurokinin-1 receptors (NK1) modulate the respiratory activity and are expressed early during development. We tested the hypothesis that NK1 receptors are involved in prenatal development of the respiratory network by comparing the resting respiratory activity and the respiratory response to hypoxia of control mice and mutant mice lacking the NK1 receptor (NK1−/−). In vitro and in vivo experiments were conducted on neonatal, young and adult mice from wild-type and NK1−/− strains. In the wild strain, immunohistological, pharmacological and electrophysiological studies showed that NK1 receptors were expressed within medullary respiratory areas prior to birth and that their activation at birth modulated central respiratory activity and the membrane properties of phrenic motoneurons. Both the membrane properties of phrenic motoneurons and the respiratory activity generated in vitro by brainstem-spinal cord preparation from NK1−/− neonate mice were similar to that from the wild strain. In addition, in vivo ventilation recordings by plethysmography did not reveal interstrain differences in resting breathing parameters. The facilitation of ventilation by short-lasting hypoxia was similar in wild and NK1−/− neonates but was significantly weaker in adult NK1−/− mice. Results demonstrate that NK1 receptors do appear to be necessary for a normal respiratory response to short-lasting hypoxia in the adult. However, NK1 receptors are not obligatory for the prenatal development of the respiratory network, for the production of the rhythm, or for the regulation of breathing by short-lasting hypoxia in neonates.
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 3 (1991), S. 0 
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Immunocytochemical localization of a product of the proto-oncogene c-fos, Fos protein, was used to map the activity of a subset of rat spinal neurons at 3 days, 3 weeks and 3 months following section of the sciatic nerve. In a well-established experimental paradigm, the gene was induced by activation of primary afferent fibres with brief noxious sensory stimulation under anaesthetic. Central sciatic projections were demonstrated with isolectin B4 counterstain and GAP43 immunocytochemistry. In Rexed's lamina II of the spinal cord, in which there is somatotopic organization of afferent terminals, Fos-positive neurons were largely restricted to the projection area of intact peripheral nerves. Three days after a sciatic nerve lesion, the number of Fos-positive neurons in a cord region innervated by the saphenous nerve was similar to control levels, but was markedly increased by 3 weeks, remaining elevated at 3 months. Three weeks after sciatic nerve section the lectin stain in the area of sciatic representation had almost completely disappeared, and conversely GAP43 staining had greatly intensified. There was no evidence of invasion by Fos-immunoreactive cells of the area of sciatic representation. After 3 months both the size and the intensity of the lectin gap, and of the corresponding area of increased GAP43 immunoreactivity, appeared reduced. Thus a peripheral nerve lesion was followed by a delayed increase in excitability of the spinal cord as assessed by c-fos expression, so that greater numbers of second-order neurons were activated by sensory stimulation of an adjacent intact nerve. These changes may be related to the sensory abnormalities which follow nerve damage.
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  • 7
    Electronic Resource
    Electronic Resource
    [s.l.] : Macmillian Magazines Ltd.
    Nature 405 (2000), S. 180-183 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Modulation of substance P activity offers a radical new approach to the management of depression, anxiety and stress. The substance P receptor is highly expressed in areas of the brain that are implicated in these behaviours, but also in other areas such as the nucleus accumbens which ...
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  • 8
    ISSN: 1432-2013
    Keywords: In vitro Neurokinin-1 receptors Newborn mice Respiratory rhythm Substance P Transgenic mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Neurokinin-1 receptors (NK1) are present within the respiratory medullary network and in the phrenic nucleus, which controls the diaphragm. We compared the efficacy of substance P (SP) at inducing changes in respiratory frequency or the amplitude of the respiratory motor output between NK1 knockout (NK1 –/–) and wild-type mice, using the in vitro brainstem-spinal cord preparation. The in vitro respiratory frequency, as well as the variability of the rhythm and the amplitude of the motor output were similar in both lines. In wild-type mice, application of exogenous SP induced either an increase in respiratory frequency (superfusion of the medulla) or an increase of the inspiratory motor output, as defined by the integral of C4 cervical ventral root activity (superfusion of the spinal cord). These two effects were not apparent in NK1 –/– mice. In conclusion, NK1 receptors mediate the respiratory responses to SP but the lack of NK1 receptors in newborn NK1 –/– mice does not change the respiratory activity.
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