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Dopaminergic Nigrostriatal System (dopaminergic + nigrostriatal_system)
Selected AbstractsCritical role of Nitric Oxide on Nicotine-Induced Hyperactivation of Dopaminergic Nigrostriatal System: Electrophysiological and Neurochemical evidence in RatsCNS: NEUROSCIENCE AND THERAPEUTICS, Issue 3 2010Vincenzo Di Matteo Nicotine, the main psychoactive ingredient in tobacco, stimulates dopamine (DA) function, increasing DA neuronal activity and DA release. DA is involved in both motor control and in the rewarding and reinforcing effects of nicotine; however, the complete understanding of its molecular mechanisms is yet to be attained. Substantial evidence indicates that the reinforcing properties of drugs of abuse, including nicotine, can be affected by the nitric oxide (NO) system, which may act by modulating central dopaminergic function. In this study, using single cell recordings in vivo coupled with microiontophoresis and microdialysis in freely moving animals, the role of NO signaling on the hyperactivation elicited by nicotine of the nigrostriatal system was investigated in rats. Nicotine induced a dose-dependent increase of the firing activity of the substantia nigra pars compacta (SNc) DA neurons and DA and 3,4-dihydroxyphenylacetic acid (DOPAC) release in the striatum. Pharmacological manipulation of the NO system did not produce any change under basal condition in terms of neuronal discharge and DA release. In contrast, pretreatments with two NO synthase (NOS) inhibitors, N-,-nitro- l -arginine methyl ester (l -NAME) and 7-nitroindazole (7-NI) were both capable of blocking the nicotine-induced increase of SNc DA neuron activity and DA striatal levels. The effects of nicotine in l -NAME and 7-NI-pretreated rats were partially restored when rats were pretreated with the NO donor molsidomine. These results further support the evidence of an important role played by NO on modulation of dopaminergic function and drug addiction, thus revealing new pharmacological possibilities in the treatment of nicotine dependence and other DA dysfunctions. [source] Evaluation of simple and complex sensorimotor behaviours in rats with a partial lesion of the dopaminergic nigrostriatal systemEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2000Pascal Barnéoud Abstract We have examined the behavioural consequences of a partial unilateral dopaminergic denervation of the rat striatum. This partial lesion was obtained by an intrastriatal 6-hydroxy-dopamine injection (6-OHDA, 20 or 10 ,g divided between two injection sites) and was compared with a unilateral complete lesion resulting from an injection of 6-OHDA (2 × 6 ,g) into the medial forebrain bundle. Quantification of striatal dopamine (DA) and its metabolites, and the immunohistochemical evaluation of the nigrostriatal DA system confirmed the complete and partial lesions. Animals with complete striatal denervation displayed both apomorphine- and amphetamine-induced rotations whereas the partial denervation elicited amphetamine-induced rotations only. However, the rates of amphetamine-induced rotation were not correlated with the size of the lesion. In contrast, the paw-reaching impairments were significantly correlated with the striatal dopaminergic depletion. When evaluated in the staircase test, animals with partial denervation were impaired exclusively for the paw contralateral to the side of the lesion. This motor deficit (50,75%) included all components of the skilled paw use (i.e. attempt, motor coordination and success) and was observed at least 12 weeks after the lesion. However, these animals were able to perform normal stepping adjustments with the impaired paw, indicating that the partial lesion induced a coordination deficit of the paw rather than a deficit of movement initiation. After a complete lesion, stepping adjustments of the contralateral paw were dramatically impaired (by 80%), an akinesia which almost certainly accounted for the great deficit in skilled paw use. The paw-reaching impairments resulting from the partial striatal denervation are proposed as a model of the early symptoms of Parkinson's disease and may be useful for the development of restorative therapies. [source] Developments in the molecular biology of DYT1 dystoniaMOVEMENT DISORDERS, Issue 10 2003Ruth H. Walker MB Abstract The identification of a mutation of the DYT1 gene as a cause of inherited dystonia has led to many insights regarding the genetics of this disorder. In addition, there is a rapidly expanding list of inherited dystonia syndromes, the genes for some of which have been identified or localized. The DYT1 mutation has been found in a variety of ethnic groups, and it may result in a range of phenotypes. To date, studies of torsinA, the protein product of the DYT1 gene, have not revealed its function, although its widespread distribution throughout the central nervous system suggests a universal role. TorsinA has structural homology to heat shock and chaperone proteins. Evidence from studies in cell cultures and Caenorhabditis elegans, and the presence of torsinA in inclusion bodies in several neurodegenerative diseases may be indicative of a function of this nature. Preliminary studies in humans with DYT1 dystonia and in DYT1 transgenic mice suggest disruption of the dopaminergic nigrostriatal system. A functional interference with neuronal signal processing induced by mutation of torsinA is consistent with current hypotheses regarding impairment of the center-surround mechanism in the striatum. © 2003 Movement Disorder Society [source] Apoptosis-inducing factor deficiency sensitizes dopaminergic neurons to parkinsonian neurotoxinsANNALS OF NEUROLOGY, Issue 2 2010Celine Perier PhD Objective Mitochondrial complex I deficits have long been associated with Parkinson disease (PD). However, it remains unknown whether such defects represent a primary event in dopaminergic neurodegeneration. Methods Apoptosis-inducing factor (AIF) is a mitochondrial protein that, independently of its proapoptotic properties, plays an essential physiologic role in maintaining a fully functional complex I. We used AIF-deficient harlequin (Hq) mice, which exhibit structural deficits in assembled complex I, to determine whether primary complex I defects linked to AIF depletion may cause dopaminergic neurodegeneration. Results Despite marked reductions in mitochondrial complex I protein levels, Hq mice did not display apparent alterations in the dopaminergic nigrostriatal system. However, these animals were much more susceptible to exogenous parkinsonian complex I inhibitors, such as 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Subtoxic doses of MPTP, unable to cause damage to wild-type animals, produced marked nigrostriatal dopaminergic degeneration in Hq mice. This effect was associated with exacerbated complex I inhibition and increased production of mitochondrial-derived reactive oxygen species (ROS) in Hq brain mitochondria. The antioxidant superoxide dismutase-mimetic compound tempol was able to reverse the increased susceptibility of Hq mice to MPTP. Supporting an instrumental role for mitochondrial-derived ROS in PD-related neurodegeneration, transgenic mice overexpressing mitochondrially targeted catalase exhibited an attenuation of MPTP-induced mitochondrial ROS and dopaminergic cell death. Interpretation Structural complex I alterations linked to AIF deficiency do not cause dopaminergic neurodegeneration but increase the susceptibility of dopaminergic neurons to exogenous parkinsonian neurotoxins, reinforcing the concept that genetic and environmental factors may interact in a common molecular pathway to trigger PD. ANN NEUROL 2010;68:184,192 [source] | |||||||||||||