Search results for "Pars Compacta"
showing 10 items of 30 documents
Dopaminergic control of feline hippocampal epilepsy: A nigrophippocampal pathway
1991
Abstract Substantia nigra is a mesencephalic structure inserted along several circuits which appear to play a key role in epilepsy. In previous researches we postulated that substantia nigra pars compacta (SNpc) may be the site of a precise control of hippocampal epilepsy while substantia nigra pars reticulata (SNpr) may exert a modulation of both neocortical epilepsy and spreading of hyperactivity toward a motor target. In order to better understand mechanisms subserving nigral action in feline hippocampal epilepsy we electrically stimulated SNpc (dopaminergic), before and after sulpiride (dopamine receptor-antagonist) intravenous injection. Furthermore we compared hippocampal epileptiform…
Regional differences in mu-opioid receptor-dependent modulation of basal dopamine transmission in rat striatum
2016
Abstract The nigrostriatal dopamine system is implicated in the regulation of reward and motor activity. Dopamine (DA) release in dorsal striatum (DS) is controlled by the firing rate of DA neurons in substantia nigra pars compacta. However, influences at terminal level, such as those involving activation of mu opioid receptors (MORs), can play a key role in determining DA levels in striatum. Nonetheless, published data also suggest that the effect of opioid drugs on DA levels may differ depending on the DS subregion analyzed. In this study, in vivo microdialysis in rats was used to explore this regional dependence. Changes in basal DA levels induced by local retrodialysis application of DA…
[18F]PR04.MZ PET/CT Imaging for Evaluation of Nigrostriatal Neuron Integrity in Patients With Parkinson Disease.
2020
Introduction Degeneration of dopaminergic, nigrostriatal neurons is the hallmark of Parkinson disease (PD), and PET quantification of dopamine transporters is a widely accepted method for differential diagnosis between idiopathic PD and essential tremor. [18F]PR04.MZ is a new PET tracer with excellent imaging properties allowing for precise quantification of striatal and extrastriatal dopamine transporter. Here we describe our initial experience with [18F]PR04.MZ PET/CT in a larger cohort of healthy controls and PD patients as a proof-of-concept study for this tracer. Methods Eighteen healthy subjects, 19 early PD patients (Hoehn-Yahr I–II), and 13 moderate-advanced PD patients (Hoehn-Yahr …
Involvement of Nitric Oxide in Nigrostriatal Dopaminergic System Degeneration : A Neurochemical Study.
2009
The present study was undertaken to explore the involvement of nitric oxide (NO) in the 6-hydroxydopamine (6-OHDA) experimental model of Parkinson's disease (PD) in rats. The effect of pharmacological manipulation of the NO system was evaluated on striatal dopamine (DA) level decrease produced by the toxin. 7-nitroindazole (7-NI, 50 mg/kg i.p.; n= 5) pretreatment significantly restored the striatal DA contents. Conversely, 40 mg/kg i.p. of molsidomine (MOL, n= 5), an NO donor, significantly worsened the neurodegeneration (n= 5) and completely counteracted the neuroprotective effect of 7-NI (n= 5). Thus, a crucial role for NO in 6-OHDA induced neurodegeneration is suggested together with a p…
7-nitroindazole protects striatal dopaminergic neurons against MPP+-induced degeneration: an in vivo microdialysis study.
2007
The neuropathological hallmark of Parkinson's disease (PD) is the selective degeneration of dopaminergic (DAergic) neurons in the substantia nigra pars compacta (SNc). In this study, using a microdialysis technique, we investigated whether an inhibitor of neuronal nitric oxide synthase (nNOS), 7-nitrindazole (7-NI), could protect against DAergic neuronal damage induced by in vivo infusion of 1-methyl-4-phenylpiridinium iodide (MPP(+)) in freely moving rats. Experiments were performed over 2 days in three groups of rats: (a) nonlesioned, (b) MPP(+)-lesioned, and (c) 7-NI pretreated MPP(+)-lesioned rats. On day 1, control rats were perfused with an artificial CSF, while 1 mM MPP(+) was infuse…
Effects of Substantia Nigra pars compacta lesion on the behavioral sequencing in the 6-OHDA model of Parkinson’s disease
2019
The basal ganglia circuitry plays a crucial role in the sequential organization of behavior. Here we studied the behavioral structure of the animals after 21 days of 6-OHDA-induced lesion of the dopaminergic nigrostriatal system. Frequencies and durations of individual components of the behavioral repertoire were calculated; moreover, whether a temporal organization of the activity was present, it was investigated by using T-pattern analysis, a multivariate approach able to detect the real-time sequential organization of behavior. Six sham-depleted and six rats with unilateral 6−OHDA-lesion of the Substantia Nigra pars compacta were used. As to quantitative evaluations, the comparison betwe…
Effects of Intraaccumbens Microinjections of Quinpirole on Head Turning and Circling Movement in the Rat
1998
This study was designed to evaluate whether nucleus accumbens dopamine D2 receptors are involved in the initiation of the movement, as distinguished from its execution. For this purpose, the effects of the quinpirole-induced increase of nucleus accumbens dopamine D2 receptor activity were observed on specific parameters of the circling behavior and of its first stage, the head-turning (HT) movement. The experiments were performed on rats with unilateral 6-hydroxydopamine (6-OHDA) lesion of the pars compacta of the substantia nigra and d-amphetamine i.p. (3 mg/kg). Bilateral intraaccumbens microinjections of quinpirole (1, 5, and 10 microg/0.5 microl), an agonist of the D2 receptor family, w…
Death in the substantia nigra: a motor tragedy
2007
It is well known that the death of dopaminergic neurons of the substantia nigra pars compacta (SNc) is the pathological hallmark of Parkinson's disease (PD), the second most common and disabling condition in the expanding elderly population. Nevertheless, the intracellular cascade of events leading to dopamine cell death is still unknown and, consequently, treatment is largely symptomatic rather than preventive. Moreover, the mechanisms whereby nigral dopaminergic neurons may degenerate still remain controversial. Hitherto, several data have shown that the earlier cellular disturbances occurring in dopaminergic neurons include oxidative stress, excitotoxicity, inflammation, mitochondrial dy…
Nitric Oxide Modulation of the Dopaminergic Nigrostriatal System: Focus on Nicotine Action
2009
Nitric oxide (NO) signalling plays an important role in the integration of information processed by the basal ganglia nuclei. Accordingly, considerable evidence has emerged indicating a role for NO in pathophysiological conditions such as Parkinson’s disease (PD), schizophrenia and drug addiction. To further investigate the NO modulation of dopaminergic function in the basal ganglia circuitry, in this study we used in vivo electrophysiology and microdialysis in freely-moving rats. Pharmacological manipulation of the NO system did not cause any significant changes either in the basal firing rate and bursting activity of the dopamine (DA) neurons in the substantia nigra pars compacta (SNc) or…
Parkinson's disease and cancer: insights for pathogenesis from epidemiology .
2009
Epidemiological evidence suggests a reduced incidence of many common types of cancers in individuals with Parkinson's disease (PD). Parkinson's disease and cancer are two diseases that result from an excessive signaling by one of two forces driving cells to opposite directions. PD results from the excessive death of dopaminergic neurons in the substantia nigra pars compacta (SNc) in the brain, while uncontrolled growth is the key property of cancer. Parkinson's disease is a complex disorder, probably due in most of the cases to the interaction of environment and genes. Many genes responsible for familial forms of PD are supposed to have a supportive role in regulating or maintaining the cel…