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  • 1
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Recent research into depression has focused on the involvement of long-term intracellular processes, leading to abnormal neuronal plasticity in brains of depressed patients, and reversed by antidepressant treatment. Given a suggested decrease in noradrenergic transmission in depression, and an antidepressant induced increase in norepinephrine (NE) level, a possible role for NE in mediating alterations in neuronal morphology and plasticity was examined. Human neuroblastoma SH-SY5Y cells treated with 10−5 m NE presented an elongated granule-rich cell-body and increased number of neurites, when compared with non-treated cells. Moreover, cell survival was enhanced in the presence of NE, while proliferation was inhibited. The above effects suggest a role for NE in cell differentiation. Indeed similar effects on cell survival and neurite outgrowth were induced in SH-SY5Y cells by retinoic acid (RA), an established differentiating agent. Finally, NE treatment resulted in a progressive decrease in the pluripotent marker Oct4 and an increase in the neuronal growth cone marker, growth-associated-protein 43 (GAP-43). Alongside these effects, NE-treated cells presented alterations in the expression of 44 genes as observed in a neurobiology cDNA microarray. Among the altered genes, an increase in the expression level of two neurite-outgrowth promoting genes, neural cell adhesion molecule L1 and laminin, was confirmed by RT-PCR. Taken together, the results support a role for NE in processes of synaptic connectivity, and may point to a role for this neurotransmitter in mediating the suggested neuronal plasticity in depression and in antidepressant treatment.
    Type of Medium: Electronic Resource
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  • 2
    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: Dopamine, due to metabolism by monoamine oxidase or autoxidation, can generate toxic products such as hydrogen peroxide, oxygen-derived radicals, semiquinones, and quinones and thus exert its neurotoxic effects. Intracerebroventricular injection of dopamine into rats pretreated with the monoamine oxidase nonselective inhibitor pargyline caused mortality in a dose-dependent manner with LD50 = 90 µg. Norepinephrine was less effective with LD50 = 141 µg. The iron chelator desferrioxamine completely protected against dopamine-induced mortality. In the absence of pargyline more rats survived, indicating that the products of dopamine enzymatic metabolism are not the main contributors to dopamine-induced toxicity. Biochemical analysis of frontal cortex and striatum from rats that received a lethal dose of dopamine did not show any difference from control rats in lipid and protein peroxidation and glutathione reductase and peroxidase activities. Moreover, dopamine significantly reduced the formation of iron-induced malondialdehyde in vitro, thus suggesting that earlier events in cell damage are involved in dopamine toxicity. Indeed, dopamine inhibited mitochondrial NADH dehydrogenase activity with IC50 = 8 µM, and that of norepinephrine was twice as much (IC50 = 15 µM). Dopamine-induced inhibition of NADH dehydrogenase activity was only partially reversed by desferrioxamine, which had no effect on norepinephrine-induced inhibition. These results suggest that catecholamines can cause toxicity not only by inducing an oxidative stress state but also possibly through direct interaction with the mitochondrial electron transport system. The latter was further supported by the ability of ADP to reverse dopamine-induced inhibition of NADH dehydrogenase activity in a dose-dependent manner.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 62 (1994), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Long-term neuroleptic medication of schizophrenic patients induces extrapyramidal motor side effects, of which tardive dyskinesia (TD) is the most severe. The etiology of TD is still obscure. Recently, it was suggested that abnormal iron metabolism may play a crucial role in neuroleptic-induced dopamine D2 receptor super-sensitivity. The apparent relationship between neuroleptics and iron is further supported by the increase of iron in the basal ganglia of patients with TD. We now report on the ability of neuroleptics to alter the blood-brain barrier in the rat and to potentiate the normally limited iron transport into the brain. Thus, chronic treatment of rats with chlorpromazine and haloperidol facilitated 59Fe3+ uptake into brain cells. In contrast, clozapine, an atypical antipsychotic neuroleptic with little extrapyramidal motor side effects, caused iron sedimentation in brain blood vessels with no sign of detectable iron in the cells. Moreover, chronic treatment with chlorpromazine and haloperidol caused a 43% and 24% reduction, respectively, in liver nonheme iron, whereas clozapine induced an 81% increase. The apparent different potentials of chlorpromazine, haloperidol, and clozapine to increase iron transport into the brain from its peripheral stores may be linked to the severity of extrapyramidal motor side effects they induce and to the pathophysiology of TD.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 57 (1991), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: : The vulnerability of substantia mgral (SN) melaninized dopamine neurons to neurodegeneration in Parkinson's disease and the selective increases of iron and basal lipid peroxidation in SN indicate that iron-melanin interaction could be crucial to the pathogenesis of this disease. The present study describes, for the first time, the identification and characterization of a high-affinity (KD= 13 nM) and a lower affinity (KD= 200 nM) binding site for iron on dopamine melanin. The binding of iron to melanin is dependent on pH and the concentration of melanin Iron dictators, U74500A, desferrioxamme, and to less extent 1,10-phenanthroline and chlorpromazine, but not the Parkinson-inducing neurotoxin, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, can inhibit the binding of iron to melanin and iron-induced lipid peroxidation. Although melanin atone diminishes basal lipid peroxidation in rat cortical homogenates, it can also potentiate that initiated by iron, a reaction inhibited by desferrioxamine. In the absence of an identifiable exogenous or endogenous neurotoxin in idiopathic Parkinson's disease, iron-melanin interaction in pars compacta of SN may be a strong candidate for the cytotoxic component of oxygen radical-induced neurodegeneration of meianinized dopamine neurons.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Using energy-dispersive x-ray analysis on an electron microscope working in the scanning transmission electron microscopy mode equipped with a microanalysis system, we studied the subcellular distribution of trace elements in neuromelanin-containing neurons of the substantia nigra zona compacta (SNZC) of three cases of idiopathic Parkinson's disease (PD) [one with Alzheimer's disease (AD)] and of three controls, in Lewy bodies of SNZC, and in synthetic dopamine-melanin chemically charged or uncharged with Fe. Weak but significant Fe peaks similar to those of a synthetic melanin-Fe3+ complex were seen only in intraneuronal highly electron-dense neuromelanin granules of SNZC cells of PD brains, with the highest levels in a case of PD plus AD. whereas a synthetic melanin-Fe2+ complex showed much lower iron peaks, indicating that neuromelanin has higher affinity for Fe3+ than for Fe2+. No detectable Fe was seen in nonmelanized cytoplasm of SNZC neurons and in the adjacent neuropil in both PD and controls, in Lewy bodies in SNZC neurons in PD, and in synthetic dopamine-melanin uncharged with iron. These findings, demonstrating for the first time a neuromelanin-iron complex in dopaminergic SNZC neurons in PD, support the assumption that an iron-melanin interaction contributes significantly to dopaminergic neurodegeneration in PD and PD plus AD.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 54 (1990), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Previous studies have shown that nutritional iron deficiency in rats reduces brain iron content, resulting in dopamine D2 receptor subsensitivity, as indicated by a decrease in [3H]spiperone binding in caudate nucleus and in behavioral responses to apomorphine. Both phenomena can be reversed by iron supplementation. The possibility that neuroleptic-induced dopamine D2 receptor supersensitivity involves an alteration in brain iron content was investigated in nutritionally iron-deficient and control rats chronically treated with haloperidol (5 mg/kg daily for 14 or 21 days). Neuroleptic treatment was initiated either (a) concurrently with iron deficiency or (b) 2 weeks after the start of iron deficiency. The results show that dopamine D2 receptor subsensitivity, a feature of iron deficiency, is absent in haloperidol-treated, iron-deficient groups. On the contrary, these animals demonstrated biochemical and behavioral dopamine D2 receptor supersensitivity that is relatively greater than that observed with control, haloperidol-treated animals. Haloperidol (5 mg/kg daily for 21 days) as well as chlorpromazine (10 mg/kg daily for 21 days) caused a significant reduction (20–25%) in liver nonheme iron stores as compared with values in control rats. However, in iron-deficient rats, in which liver iron stores were almost totally depleted, haloperidol had no effect. The ability of chronic haloperidol treatment to prevent the reduction of dopamine D2 receptor number during iron deficiency may be associated with alteration of body iron status. Thus, less iron may result in an increase in free haloperidol available to the dopamine D2 receptor.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 50 (1988), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Nutritional iron deficiency induced in rats causes a significant reduction in level of brain nonheme iron and is accompanied by selective reduction of dopamine D2 receptor Bmax. Our previous studies have clearly demonstrated that these alterations can be restored to normal by supplementation with ferrous sulfate; however, neither brain nonheme iron level nor dopamine D2 receptor Bmax can be increased beyond control values even after long-term iron therapy. The possibility that iron deficiency can induce the breakdown of the blood-brain barrier (BBB) was examined. A 70 and 100% increase in brain uptake index (BUI) for l-glucose and insulin, respectively, were noted in iron-deficient rats. However, the BUI for valine was decreased by 40%, and those for l-norepinephine and glycine were unchanged. In addition, it was demonstrated that in normal rats insulin is transported into the brain. The data show that iron deficiency selectively affects the integrity of the BBB for insulin, glucose, and valine transport. Whether the effect of iron deficiency on the BBB is at the level of the capillary endothelial cell tight junction is not yet known. However, this study has shown that an important nutritional disorder (iron-deficiency anemia) has a profound effect on the BBB and brain function.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 45 (1985), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Nutritional iron deficiency induced in rats causes a selective reduction of [3H]spiperone binding in caudate nucleus. This effect can be reversed by iron supplementation in vivo. The possibility that iron may be involved in the dopamine D2 receptor was investigated by examining the effect of various iron and noniron chelators on the binding of [3H]spiperone in rat caudate nucleus. Iron chelators 1, 10-phenanthroline, 2,4,6-tripyridyl-s-triazine, α,α′-dipyridyl, and desferrioxamine mesylate inhibited the binding of [3H]spiperone. The inhibition by 1,10-phenanthroline was noncompetitive and reversible. In the presence of FeCl2 or FeCl3, the inhibitory effect of 1,10-phenanthroline was potentiated. Iron salts or chelators were without effect on the binding of [3H]dihydroalprenolol to β-adrenoreceptors in caudate nucleus; thus the action of iron chelators on the dopamine D2 receptor tends to be selective. Incubation of caudate nucleus membrane prepared from iron-deficient rats with FeCl2 or FeCl3 did not reverse the diminished binding of [3H]spiperone. The present study indicates that if iron is involved in the physiological regulation of dopamine D2 agonist-antagonist binding sites, it is more complex than hitherto considered.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 83 (2002), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Mitochondria are not only the principal source of high energy intermediates, but play an important role in intracellular calcium buffering, are main producers of reactive oxygen species, and are the source of pro- and antiapoptotic key factors. Moreover, the mitochondria are of a ubiquitous nature and the respiratory chain has a dual genetic basis, i.e. the mitochondrial and the nuclear DNAs. Thus mitochondrial impairment could provide an explanation for the tremendous heterogeneity of clinical and pathological manifestations in schizophrenia. This article reviews several independent lines of evidence that suggest an involvement of mitochondrial dysfunction in schizophrenia. Among them are altered cerebral energy metabolism, mitochondrial hypoplasia, dysfunction of the oxidative phosphorylation system and altered mitochondrial related gene expression. In addition, the interaction between dopamine, a predominant etiological factor in schizophrenia, and mitochondrial respiration is considered as a possible mechanism underlying the hyper- and hypo-activity cycling in schizophrenia. Understanding the role of mitochondria in schizophrenia may encourage novel treatment approaches, the identification of candidate genes and new insights into the pathophysiology and etiology of the disorder.
    Type of Medium: Electronic Resource
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