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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 64 (1995), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The binding of [3H]rauwolscine to α2A- (also referred to as α2D-) and α2C-adrenoceptors in homogenates of rat cerebral cortex was measured by exploiting the selectivity of oxymetazoline for α2A-adrenoceptors. Inhibition of [3H]rauwolscine binding by oxymetazoline was modeled best assuming binding to two sites (p 〈 0.001). Competition curves for oxymetazoline were shifted rightward by the addition of GTP (250 µM) but were still fit best by a two-site model (p 〈 0.001). A concentration of oxymetazoline was calculated that would optimally antagonize [3H]rauwolscine binding (with GTP present) to oxymetazoline-sensitive α2A-adrenoceptors, minimally inhibiting binding to α2C-adrenoceptors. Subsequently, [3H]rauwolscine binding to α2A- and α2C-adrenoceptors in cortex was examined 3 weeks after destruction of noradrenergic terminals. Binding to α2C-adrenoceptors was increased significantly after treatment with 6-hydroxydopamine (6-OHDA) compared with vehicle-treated controls, whereas binding to α2A-adrenoceptors was unchanged. Pretreatment of rats with desipramine before 6-hydroxydopamine, to protect noradrenergic neurons, resulted in no changes in binding to either α2A- or α2C-adrenoceptors. Thus, α2C-adrenoceptors are regulated by changes in synaptic availability of norepinephrine. α2A-Adrenoceptors are either not regulated by synaptic norepinephrine or are located both post- and presynaptically so that up-regulation of postsynaptic α2A-adrenoceptors is offset by a loss of presynaptic α2A-adrenoceptors.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 63 (1994), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The binding of an agonist, p-[125I]iodoclonidine, and an antagonist, [3H]yohimbine, to α2-adrenoceptors was measured autoradiographically in the locus coeruleus from 10 pairs of antidepressant-free victims of suicide and age-matched controls. Agonist binding to α2-adrenoceptors was significantly greater in the locus coeruleus from victims of suicide compared with control subjects. In contrast, antagonist binding to α2-adrenoceptors in the locus coeruleus did not differ significantly between control and suicide subjects. HPLC analysis of norepinephrine in tissue sections of the locus coeruleus did not reveal any differences between control subjects and suicide victims, suggesting that differences in agonist binding are not a result of differences in retention of the endogenous agonist norepinephrine in tissue sections. The increase in agonist binding to α2-adrenoceptors in the locus coeruleus of victims of suicide links an altered expression of the high-affinity state of autoinhibitory α2-adrenoceptors with suicide.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Previously, we reported a modest but significant reduction in the concentration of neuropeptide Y in frontal cortices from victims of suicide relative to age-matched natural or accidental death control subjects. The reduction in neuropeptide Y appeared to be greatest in a subgroup of victims of suicide for which there was indirect evidence of histories of depression. We pursued these initial findings in the present study by measuring neuropeptide Y concentrations in frontal cortices from natural or accidental death control subjects and from suicide victims in whom a firm diagnosis of major depression was established by psychiatric autopsy. Because several subjects with major depression had a comorbid diagnosis of alcoholism, a group of victims of suicide that had an Axis I diagnosis of alcohol dependence was also studied. No significant differences in neuropeptide Y concentrations were observed between control subjects and victims of suicide with major depression or victims of suicide with alcohol dependence. These findings do not support a role for neuropeptide Y in major depression.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 62 (1994), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The amounts of tyrosine hydroxylase protein in locus coeruleus from nine pairs of antidepressant-free suicide victims and age-matched, sudden-death control cases were determined by quantitative blot immunolabeling of cryostat-cut sections from the caudal portion of the nucleus. In each of the nine age-matched pairs, the concentration of tyrosine hydroxylase was greater in the sample from the suicide victim, with values ranging from 108 to 172% of the matched control value (\-x = 136%). By contrast, there were no differences in the concentrations of neuron-specific enolase protein in the same set of samples. Similarly, the number of neuromelanin-containing cells, counted in sections of locus coeruleus adjacent to those taken for blot immunolabeling analyses, did not differ between the two groups. These data indicate that locus coeruleus neurons from suicide victims contain higher than normal concentrations of tyrosine hydroxylase, thus raising the possibility that the expression of tyrosine hydroxylase in locus coeruleus may be relevant in the pathophysiology of suicide.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 59 (1992), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Neuropeptide Y (NPY) was measured in postmortem brain tissue from victims of suicide and from individuals dying a sudden natural or accidental death (controls). Concentrations of NPY-immunoreactivity were measured by radioimmunoassay in frontal cortex (BA 10), temporal cortex (BA 22), caudate nucleus, and cerebellum. Concentrations of NPY-immunoreactivity were significantly lower in postmortem frontal cortex (−14%) and caudate nucleus (−27%) from suicide victims compared with age-matched controls. A subgroup of suicides with evidence of a history of depression revealed more robust reductions in concentrations of NPY-immunoreactivity in frontal cortex and caudate nucleus, as did four individuals who died from natural causes and also were described as having a possible history of depression. Concentrations of NPY-immunoreactivity in temporal cortex and cerebellum from victims of suicide or from the subgroup of subjects with a possible history of depression were not significantly different from those of age-matched controls. We suggest there is a deficit in the brain NPY system leading to region-specific reductions in peptide concentrations in subjects who have a history of depression.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 91 (2004), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Disruptions of glutamatergic and noradrenergic signaling have been postulated to occur in depressive disorders. Glutamate provides excitatory input to the noradrenergic locus coeruleus (LC). In this study, the location of immunoreactivity against neuronal nitric oxide synthase (nNOS), an intracellular mediator of glutamate receptor activation, was examined in the normal human LC, and potential changes in nNOS immunoreactivity that might occur in major depression were evaluated. Tissue containing LC, and a non-limbic, LC projection area (cerebellum) was obtained from 11 to 12 matched pairs of subjects with major depression and control subjects lacking major psychiatric diagnoses. In the LC region, nNOS immunoreactivity was found in large neuromelanin-containing neurons, small neurons lacking neuromelanin, and glial cells. Levels of nNOS immunoreactivity were significantly lower in the LC (− 44%, p 〈 0.05), but not in the cerebellum, when comparing depressed with control subjects. nNOS levels were positively correlated with brain pH values in depressed, but not control, subjects in both brain regions. Low levels of nNOS in the LC may reflect altered excitatory input to this nucleus in major depression. However, pH appears to effect preservation of nNOS immunoreactivity in subjects with depression. This factor may contribute, in part, to low levels of nNOS in depression.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Age-related changes in the gene expression of the transcription factors, Phox2a and 2b, and two marker proteins, norepinephrine transporter (NET) and dopamine β-hydroxylase (DBH), of noradrenergic neurons were characterized in the locus coeruleus (LC) and adrenal glands using in situ hybridization. Analysis of changes was performed in rats that were 1–23 months of age. Compared to 1-month-old rats, there was a 62% increase of Phox2a messenger RNA (mRNA) in the LC of 3-month-old rats, and a decline of 37% in 23-month-old rats. In contrast, levels of Phox2b mRNA in the LC remained unchanged in 3-month-old rats, but declined to a 30% reduction in 23-month-old rats. Interestingly, mRNA levels of NET in the LC decreased with increasing age to a reduction of 29%, 30% and 43% in 3-, 8- and 23-month-old rats, respectively. Similarly, DBH mRNA in the LC declined with increasing age to a 56% reduction in 23-month-old rats. mRNA levels of Phox2a, Phox2b, NET and DBH in the adrenal medulla of 23-month-old rats were significantly lower than those of 1-month-old rats. Semi-quantitative reverse transcription assays of the same genes yielded data similar to in situ hybridization experiments, with β-actin mRNA levels being unchanged across the ages. Taken together, these data reveal that reduced Phox2 mRNAs in the LC and adrenal medulla of aging rats are accompanied by a coincidental decline in mRNA levels of NET and DBH and suggest a possible relationship between Phox2 genes and the marker genes in noradrenergic neurons after birth.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 68 (1997), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: To investigate the regulation of norepinephrine transporters (NETs) in vitro, we measured the binding of the NET-selective ligand [3H]nisoxetine in homogenates of PC12 cells after exposure of intact cells to the NET inhibitor desipramine (DMI). A 3-day exposure of PC12 cells to DMI robustly reduced the Bmax, but not the KD, of [3H]nisoxetine binding to NETs. Reduction of the binding of [3H]nisoxetine was dependent on both the concentration of DMI and the time of exposure to DMI. Reduction of [3H]nisoxetine binding to NETs produced by a 1-day exposure to DMI reverted to preexposure levels 48 h after cessation of DMI exposure. Similar down-regulation of NETs was found when PC12 cells were exposed to another NET-selective drug, nisoxetine, which is structurally unrelated to DMI. In contrast, exposure of cells to the serotonin transporter-selective drug citalopram, or the NET substrate norepinephrine, had no effects on the binding of [3H]nisoxetine to NETs. The down-regulation of NETs was paralleled by a DMI-induced reduction in the uptake of [3H]norepinephrine in intact PC12 cells. It can be inferred from these data that inhibitors of the NET can down-regulate NETs directly, and do so in the absence of changes in the synaptic concentration of norepinephrine.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The effects of continuous exposure of cultured cells expressing the human norepinephrine transporter (hNET) to the hNET inhibitor desipramine on hNET expression and function were studied. Exposure of HEK-293 cells transfected stably with the hNET cDNA (293-hNET cells) to desipramine for 3 days reduced the specific binding of [3H]nisoxetine in membrane homogenates in a concentration-dependent manner. The magnitude of the reductions in [3H]nisoxetine binding to hNET was dependent on the length of time of the exposure to desipramine, reaching 77% after a 21-day exposure. The reduction of [3H]nisoxetine binding returned to control levels within 72 h after a 3-day exposure to desipramine. Reductions in [3H]nisoxetine binding to hNET were accompanied by time-dependent and exposure concentration-dependent reductions in hNET protein levels as determined by western blotting. Similar to binding, hNET protein levels returned to control levels 72 h after cessation of desipramine exposure. Northern blotting indicated that exposure of 293-hNET cells to desipramine did not significantly alter hNET mRNA levels. Uptake of [3H]norepinephrine by 293-hNET cells was markedly reduced after a 3-day exposure to desipramine. However, desipramine exposure had no effect on uptake of [3H]glutamate or [3H]-alanine. The present findings imply that down-regulation of the hNET in 293-hNET cells induced by desipramine results from a selective reduction in hNET protein levels, presumably a consequence of either a reduction in the translation of hNET mRNA or from an enhanced degradation of hNET protein.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Real estate economics 4 (1976), S. 0 
    ISSN: 1540-6229
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Economics
    Type of Medium: Electronic Resource
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