During surgery, Stereoplan coordinates of the tip of the central macroelectrodes were compared with intended coordinates along the central trajectory at 4 levels: (1) 10 mm above the anatomical target, (2) in the target, (3) in the substantia nigra pars reticulata, and (4) at the depth of contact 1. 
Most neurons in the external and internal segments of the globus pallidus and the substantia nigra pars reticulata (GPe, GPi and SNr) are characterized by a high-frequency discharge (HFD) rate (50-80 Hz) which, in most GPe neurons, is also interrupted by pauses.
We analyzed recordings from three BG locations: the external part of the globus pallidus (GPe), the substantia nigra pars reticulata (SNr), and dopaminergic neurons from the substantia nigra pars compacta (SNc) during performance of a probabilistic visuo-motor task.
Inhibitory responses of rat nigral dopaminergic neurons by stimulation of afferents from striatum, globus pallidus, or pars reticulata have been shown to be mediated predominantly or exclusively by GABA(A) receptors. Striatal-evoked inhibition exhibited a slower onset and a weaker initial component compared with inhibition from globus pallidus or substantia nigra pars reticulata.
In addition, EAAC1 protein was found to be increased in the substantia nigra pars reticulata of the lesioned rats but not in the striatum. An increase in the EAAC1 level in the substantia nigra pars reticulata may increase GABA synthesis and enhance GABAergic neurotransmission.
The third, newly modeled, pathway involves medium spiny projection neurons (MSPNs) of the striatal matrix, whose axons corelease GABA and substance P, both at synapses with GABAergic neurons in the substantia nigra pars reticulata (SNr) and with distal dendrites (in SNr) of DA neurons whose somas are located in ventral SNc.
Using c-Fos expression as a high-resolution marker of neuronal activation, congenic mice demonstrated significantly less neuronal activity associated with ethanol withdrawal than background strain mice in the substantia nigra pars reticulata (SNr), subthalamic nucleus (STN), rostromedial lateral globus pallidus, and ventral pallidum.
Methamphetamine (3 mg/kg, i.p.) induced Fos-like immunoreactivity (FLI) dominantly in the striatum and the globus pallidus (GP) on the intact side as well as in the substantia nigra pars reticulata (SNr) on the lesioned side in the 6-OHDA rats.
Of particular note is the compartmentalization of the iron-enrichment in this region; the pars reticulata contains higher levels of stainable iron as compared to the pars compacta.
These brain areas contain a high concentration of serotonin (5-HT), with the substantia nigra pars reticulata receiving the greatest input.
DARP32+ neurons projecting to the globus pallidus were strongly GFP+ with both vectors, whereas those projecting to the substantia nigra pars reticulata (SNpr) were efficiently labeled by the CMV but poorly by the tetON vector.
The substantia nigra pars reticulata (SNr) forms a principal output from the basal ganglia.
Of the 12 other brain regions measured, three showed VP NMDA-induced enhancements in Fos-ir: the frontal cortex, entopeduncular nucleus and substantia nigra pars reticulata, all regions associated with the basal ganglia.
In the present study we assessed the anticonvulsant efficacy and safety of bilateral allotransplantation of genetically engineered striatal GABAergic rat cell lines into the substantia nigra pars reticulata (SNr).
Stimulation of kappa-opioid receptors in the substantia nigra pars reticulata (SNPR) increases the locomotor activity of young rats: an effect blocked by systemic administration of a D2-like receptor agonist.
After dopamine loss, synchronous oscillatory activity emerges in the subthalamic nucleus and substantia nigra pars reticulata in phase with cortical slow oscillations.
GABAergic projections emitted from the entopeduncular nucleus (ENT) and the substantia nigra pars reticulata (SNr) innervate different thalamic nuclei and they are known to be hyperactive after dopaminergic depletion.
The direct projection from the substantia nigra pars reticulata (SNr) to the superior colliculus (SC) mediates the inhibition.
There was severe neuronal loss bilaterally in the anterior part of the pallidum and in the substantia nigra, pars reticulata. This first clinico-pathological case of a self-activation deficit illustrates the dissociation between motor and behavioral symptoms in lesions of the pallido-nigral complex, with the behavioral symptoms being related to lesions of the substantia nigra, pars reticulata and of the anterior part of the pallidum..
An opposite pattern was found in the substantia nigra pars reticulata where D1 binding was higher in WKY rats compared to WIS rats (p<0.05).
Lastly, we consider the contribution of brain nuclei, such as the substantia nigra pars reticulata (SNR), that are capable of modulating seizures and exert their influence over the seizure onset zone (and neighboring areas) from a relatively great-in neuroanatomical terms-distance.
Single neurons and local field potentials were simultaneously recorded in the motor cortex, the striatum, and the substantia nigra pars reticulata (SNr) of freely moving rats, and high-voltage spindles (HVSs) were used to compare signal transmission before and after dopaminergic depletion.
In the present study, the effects of a single or subchronic systemic administration of the dopamine D1/D5-preferring receptor agonist SKF-81297 on GAD65, GAD67, PPD and vGAT mRNA levels in the striatum and GABA(A) receptor alpha1 subunit mRNA levels in the substantia nigra, pars reticulata, were measured in rats with a unilateral 6-hydroxydopamine (6-OHDA) lesion.
The microdialysis probes were unilaterally lowered into the globus pallidus (GP) and the substantia nigra pars reticulata (SNr).
By in situ hybridization, we detected cellular expression of CRF-BP mRNA in the VTA; no such expression was seen in neighboring substantia nigra pars compacta (SNC) or substantia nigra pars reticulata.
We found that the zebra finch LSt projects to the GP, substantia nigra pars reticulata (SNr) and pars compacta (SNc), but not the thalamus.
To obtain quantitative information on neuronal spike descriptors, we systematically analysed neuronal spikes in the STN and substantia nigra pars reticulata (SNr) in 31 sides of the brain in awake patients undergoing stereotactic neurosurgery for DBS electrode implantation.
The substantia nigra pars reticulata (SNR) controls seizures in a sex-specific manner.
A remarkable c-fos expression was found in the lesioned side of GP, subthalamic nucleus (STN), and substantia nigra pars reticulata (SNr) of rats that received the ACPD or DHPG injection, compared to rats treated with L-AP-4 or phosphate buffer-injection.
The substantia nigra pars reticulata (SNr) is the primary output nucleus for the basal ganglia (BG) in the rat.
By contrast, definite GAD-immunoreactivity was confirmed in SP-containing boutons in the substantia nigra pars reticulata even in specimens treated with a conventional fixative, indicating that negligible GAD labeling in CeA is not ascribed to methodological problems such as interference by the presence of SP but actually reflects low GAD content.
In 8-month-old LXRbeta-/- mice there was activation of microglia in the substantia nigra pars reticulata and aggregates of ubiquitin and TDP-43 in the cytoplasm of large motor neurons in the lumbar spinal cord.
Those that express dopamine D2 receptors (D2+) project to the globus pallidus external and are thought to inhibit movement, whereas those that express dopamine D1 receptors (D1+) project to the substantia nigra pars reticulata and are thought to facilitate movement.
In contrast, ethanol decreased proenk mRNA expression in the substantia nigra pars compacta and pars reticulata 2 h after drug exposure.
AIM: The substantia nigra pars reticulata (SNr) constitutes one of the output centers of the basal ganglia, and its abnormal activity is believed to contribute to some basal ganglia motor disorders.
The substantia nigra pars reticulata (SNr) is the primary output nucleus for the basal ganglia (BG) in the rat.
A hallmark of the GABA projection neurons of the substantia nigra pars reticulata (SNr), a key basal ganglia output nucleus, is its depolarized membrane potential and rapid spontaneous spikes that encode the basal ganglia output.
The SN comprises two major regions, the SN pars compacta (SNc) consisting of dopaminergic projection neurons, and the SN pars reticulata (SNr) consisting of GABAergic parvalbumin-positive projection neurons. These results show marked GABA(A)R subunit hetereogeneity in the SN, suggesting that GABA exerts quite different effects on pars compacta and pars reticulata neurons in the human SN via GABA(A) receptors of different subunit configurations..
The thalamic lateral posterior nucleus (LP) of the hooded rat is regarded as a relay nucleus for the transmission of information from visuomotor-related structures such as the superior colliculus, pedunculopontine tegmental nucleus (PPT) and substantia nigra, pars reticulata, to visual cortical areas as well as the striatum.
The present study was performed to assess changes in neuronal activity of ipsilateral and contralateral subthalamic nucleus (STN), substantia nigra pars reticulata (SNr), and PPN in the unilateral 6-hydroxydopamine (6-OHDA) rat model of advanced PD under urethane anesthesia.
In this study, vervet monkeys that received two doses of METH (2 mg/kg, intramuscularly, 6 h apart) showed at 1 month, iron increases in substantia nigra pars reticulata and globus pallidus, with concurrent increases of ferritin-immunoreactivity and decreases of tyrosine hydroxylase-immunoreactivity in substantia nigra.
Further, we investigated the role of the substantia nigra pars reticulata (SNR) in control of barrel rotations using localized bilateral microinfusions of GABA(A) or GABA(B) receptor agonists (muscimol or baclofen, respectively) or an N-methyl-D-aspartate (NMDA) receptor antagonist (AP7).
GABA(B) receptors inhibit and dopamine D1 receptors stimulate the release of GABA from striatal terminals in the pars reticulata of the substantia nigra. Here we have studied the interaction between both classes of receptors by exploring the effect of GABA(B) receptors upon the stimulation of depolarization-induced [ (3)H]GABA release induced by the activation of D1 receptors in slices of the pars reticulata of the rat substantia nigra.
rAAV-mediated human parkin was expressed in the nigrostriatal tract, the substantia pars reticulata, and the subthalamic nucleus.
Moreover, in contralateral nucleus lateralis thalami pars posterior, ipsi- and contralateral nucleus medialis dorsalis thalami, and ipsilateral substantia nigra, pars reticulata (SNr), kappa receptors were increased; mu receptor densities were decreased in nucleus ventralis thalami, pars posterior (VThP), and SNr.
Instead, upregulated, functional alpha4* receptors localize to the GABAergic neurons of the VTA and substantia nigra pars reticulata.
Studies of the effects of dopamine in the basal ganglia have focused on the striatum, whereas the functions of dopamine released in the internal pallidal segment (GPi) or in the substantia nigra pars reticulata (SNr) have received less attention.
Pharmacological inhibition and high-frequency stimulation (HFS) of the substantia nigra pars reticulata (SNr) suppress seizures in different animal models of epilepsy.
In the substantia nigra, immunoreactivities for TRPC3 and TRPC7 were prominent in the cell bodies and several processes in the pars compacta and pars reticulata.
In these rats, DHPG activates an 'alternative' circuit: NAcc-->substantia nigra pars reticulata-->ventro-medial thalamus-->prefrontal cortex, which is not activated in control rats.
722, 181-184] we have assumed that exogenously administered L-dihydroxyphenylalanine (L-DOPA) is converted into dopamine (DA) in serotonergic (5-HT) fibers within the striatum (ST) and the substantia nigra pars reticulata (SNR).
The activity of CNS 7056 at brain benzodiazepine receptors in vivo was measured in rats using extracellular electrophysiology in the substantia nigra pars reticulata. CNS 7056 (intravenous) caused a dose-dependent inhibition of substantia nigra pars reticulata neuronal firing and recovery to baseline firing rates was reached rapidly. Inhibition of substantia nigra pars reticulata firing and the inhibition of the effects of CNS 7056 by flumazenil show that it acts at the brain benzodiazepine receptor..
The effects of selective group III mGluR agonists (1S,3R,4S)-1-aminocyclopentane-1,3,4-tricarboxylic acid (ACPT-I) and L-(+)-2-amino-4-phosphonobutyric acid (L-AP4) infused into the globus pallidus (GP) or the substantia nigra pars reticulata (SNr) were thus studied in rat models of PD.
In the present study, we analyzed the localization of D1a receptors within the rat substantia nigra pars reticulata (SNr) using specific D1a immunochemistry at the ultrastructural level and RT-PCR.
In Sprague-Dawley rats with 6-hydroxydopamine (6-OHDA)-induced nigrostriatal lesions, approximately 50% substantia nigra pars reticulata (SNpr) units show abnormal cortically driven slow oscillations of discharge.
In situ hybridization data and a direct comparison of SN neurons expressing tyrosine hydroxylase (TH) and/or the beta-gal marker for EphB1 revealed that EphB1 is not expressed in TH+ neurons of pars compacta (SNc), but is restricted to neurons in pars reticulata (SNr).
A typically mammalian appearance of the catecholaminergic nuclei was observed, however, the anterior hypothalamic groups (A15 dorsal and ventral), the dorsal and dorsal caudal subdivisions of the ventral tegmental area (A10d and A10dc), and the ventral (pars reticulata) substantia nigra (A9v) were not present.
GABA cells are present in the ventral and dorsal thalamic nuclei, and in the ventral thalamus form a remarkable continuum with GABA cells of the two segments of the globus pallidus and pars reticulata of the substantia nigra..
We report here that subchronic haloperidol administration after a high-dose regimen of METH produces a heretofore unrecognized toxicity to GABAergic cells, as reflected by GAD67 mRNA expression histochemistry, in the rat substantia nigra pars reticulata (SNr) through an acute and persistent augmentation of glutamate release, NMDA receptor activation, and DNA fragmentation.
The vast majority of these arise from the neostriatum, the external globus pallidus and the substantia nigra pars reticulata. However, in vivo, synaptic responses elicited by stimulation of neostriatal or pallidal afferents, or antidromic activation of nigral pars reticulata GABAergic projection neurons are mediated predominantly or exclusively by GABA(A) receptors. The GABAergic inputs from the axon collaterals of the pars reticulata projection neurons seem to be a particularly important source of a GABA(A) tone to the dopaminergic neurons, inhibition of which leads to burst firing. The globus pallidus exerts powerful control over the pars reticulata input, and through the latter, disynaptically over the dopaminergic neurons. Inhibition of pallidal output leads to a slight decrease in firing of the dopaminergic neurons due to disinhibition of the pars reticulata neurons whereas increased firing of pallidal neurons leads to burst firing in dopaminergic neurons that is associated with a modest increase in spontaneous firing rate and a significant increase in extracellular levels of dopamine in the neostriatum.
Together with the internal segment of the globus pallidus (GP(i)), the pars reticulata of the substantia nigra (SNr) provides a main output nucleus of the basal ganglia (BG) where the final stage of information processing within this system takes place.
To study the effects of high-frequency STN stimulation on one of the main output pathways of the basal ganglia, single-unit recordings of the neuronal activity of the substantia nigra pars reticulata (SNr) were performed before, during, and after the application of STN electrical stimulation in eight PD patients.
We measured the effects of cocaine, methylphenidate, 2beta-propanoyl-3beta-(4tolyl) tropane (PTT), fluoxetine, amphetamine, methamphetamine, 3,4-methylenedioxymethamphetamine (MDMA), phentermine and fenfluramine on dopamine and serotonin uptake following electrically stimulated release in mouse caudate-putamen and substantia nigra pars reticulata slices.
At the cellular level, GlyRs are present only in discrete populations of neurons immunoreactive for choline acetyltransferase (ChAT), parvalbumin, and calretinin in the human striatum, on a subpopulation of parvalbumin- and calretinin-positive neurons in the globus pallidus, and in the substantia nigra GlyRs are present on approximately three-fourths of all pars compacta and one-third of all pars reticulata neurons. At the subcellular level in the substantia nigra pars reticulata (SNr), GlyRs show a localized distribution on the soma and dendrites that partially complements but does not overlap with the distribution of gamma-aminobutyric acid (GABA)A receptors.
We inserted cannulae in the NAcc and microdialysis probes in the NAcc, ventral pallidum (VP), substantia nigra pars reticulata (SNr), medio-dorsal thalamus (MDT), ventro-medial thalamus (VMT) or prefrontal cortex (PFCx).
Significant increase of VGLUT3 immunoreactivity was observed in the perikarya of GABAergic substantia nigra pars reticulata neurons (+14.7%) although VGLUT3 protein was not modulated in the nigral tissues.
This pathway provides a direct GABAergic connection by which the striatum inhibits the output regions of the basal ganglia, i.e., the internal globus pallidus and the substantia nigra pars reticulata.
Physiological concentrations of ketone bodies (beta-hydroxybutyrate or acetoacetate) reduced the spontaneous firing rate of neurons in slices from rat or mouse substantia nigra pars reticulata.
In a series of now classic experiments, an output structure of the basal ganglia (BG)--the substantia nigra pars reticulata (SNr)--was shown to be involved in the generation of saccades made in particular behavioral contexts, such as when memory was required for guidance.
The cut-off level of 1.2-fold showed the clearest change in MSD between the STN and the pars reticulata of substantia nigra.
We previously had shown that: (1) serial GABAergic connections from the CD to the superior colliculus (SC) via the substantia nigra pars reticulata (SNr) exert powerful control over the initiation of saccadic eye movement and (2) these GABAergic neurons encode target position and are strongly influenced by expected reward, while dopaminergic neurons in the substantia nigra pars compacta (SNc) encode only reward-related information.
Using in vivo microdialysis, we found a temporal correlation between the expression of l-DOPA-induced AIMs and an increased GABA outflow within the substantia nigra pars reticulata.
The neurons of many basal ganglia nuclei, including the external and internal globus pallidus (GPe and GPi, respectively) and the substantia nigra pars reticulata (SNr) are characterized by their high-frequency (50-100 spikes/s) tonic discharge (HFD).
Here, we examine the initiation and spread of action potentials in dopaminergic neurons of the substantia nigra pars reticulata and reveal that the displacement of the axon to a dendritic site allows highly compartmentalized electrical signaling.
We recorded single neurons and local field potentials (LFPs) simultaneously in the motor cortex, striatum and substantia nigra pars reticulata (SNr) of the freely moving rat.
It is known that the substantia nigra pars reticulata (SNr) receives GABAergic inputs mainly from the striatum and sends GABAergic outputs to the thalamus.
Here we report that neurons in gerbil (Meriones unguiculatus) substantia nigra pars reticulata (SNr), whose "neuronal" phenotype was confirmed via electrophysiology, biocytin-labeling, histology, and in situ hybridization, are also devoid of NeuN-immunoreactivity as assayed with the widely used monoclonal antibody A60.
The cortico-basal ganglia-thalamo-cortical loop with projections from frontal cortex to striatum, then to globus pallidus or to substantia nigra pars reticulata, to thalamus and back to cortex, provides the anatomical substrate for this function.
Striatal projection neurons target the substantia nigra pars reticulata (direct pathway) or the lateral globus pallidus (indirect pathway).
The evolution of the nigrostriatal lesion was accompanied by complex changes in the metabolic activity of the other basal ganglia nuclei investigated (substantia nigra pars reticulata, entopeduncular nucleus, globus pallidus and subthalamic nucleus), which led, ultimately, to a generalized, metabolic hyperactivity, ipsilaterally to the lesion.
The GABAergic projections from substantia nigra pars reticulata (SNR) to thalamocortical neurons of the ventral medial (VM) thalamic nucleus provide a potent network for the control of absence seizures by basal ganglia.
Levodopa reversed the lesion-induced increase in the expression of cytochrome oxidase mRNA in the subthalamic nucleus and glutamate decarboxylase mRNA in the pars reticulata of the substantia nigra.
Kir3.1 immunoreactivity was found in SNc fibers and some neurons of the substantia nigra pars reticulata (SNr).
The aim of the present study was to determine whether (1S,3R,4S)-1-aminocyclo-pentane-1,3,4-tricarboxylic acid (ACPT-1), an agonist of group III mGluRs, injected bilaterally into the globus pallidus (GP), striatum or substantia nigra pars reticulata (SNr), can attenuate the haloperidol-induced catalepsy in rats, and whether that effect was related to modulation of proenkephalin (PENK) or prodynorphin (PDYN) mRNA expression in the striatum.
Also in the ventral tegmental area and substantia nigra pars reticulata quantitative analysis of the density of receptors shows a significant reduction in [ 3H]SR141716A binding.
The loss of dopamine neurons combined or not with the subsequent administration of L-DOPA in patients with Parkinson's disease or in experimental models of the disease results in altered GABAergic signaling throughout the basal ganglia, including the striatum and the substantia nigra, pars reticulata.
It has been shown in rats with HE that hypolocomotion is due to excessive activation of metabotropic glutamate receptors (mGluRs) in substantia nigra pars reticulata.
We obtained whole-cell recordings from neurons in the substantia nigra pars reticulata in rat brain slices and labeled them with biocytin, followed by immunocytochemical staining for parvalbumin and calretinin. Reconstructions revealed that all parvalbumin- and calretinin-positive neurons issued at least one axon collateral, which ramified within the substantia nigra pars reticulata and/or pars compacta. In sum, the parvalbumin- and calretinin-containing GABAergic neurons of the substantia nigra pars reticulata cannot be differentiated on the basis of their electrophysiological properties, morphological properties, or target nuclei, and both parvalbumin- and calretinin-containing projection neurons issue local axon collaterals that arborize within the substantia nigra..
In vivo electrophysiology and microdialysis were used to investigate the physiological role of 5-HT(2C) receptors in the control of substantia nigra pars reticulata (SNr) function.
The importance of the substantia nigra pars reticulata (SNPr), striatum (STR) and superior colicullus (SC) in the blockade of experimental seizures is well known.
Immunofluorescent studies revealed that, although SP+ fibers arborised more densely in the pars reticulata (SNr) than in the pars compacta (SNc), the two nigral divisions harbored numerous neurons expressing NK-1R and NK-3R.
Spike train recordings from striatum, subthalamic nucleus (STN), globus pallidus (GP), and substantia nigra pars reticulata (SNpr) were paired with simultaneous local field potential (LFP) recordings from SNpr or motor cortex ipsilateral to a unilateral lesion of substantia nigra dopamine neurons in urethane-anesthetized rats.
Using in situ hybridization immunohistochemistry co-labeling, PMAT mRNA was found in various neuron subtypes, including glutamatergic neurons of the hippocampus, mitral cells of the olfactory bulbs and GABAergic neurons in the substantia nigra pars reticulata and hypothalamus.
These brain areas contain the highest concentration of serotonin (5-HT), with the substantia nigra pars reticulata receiving the greatest input.
To study the modulation of excitability by the outward current pulses, we recorded from GABAergic pars reticulata neurons of mice at postnatal days 12-16. In this instance, the phasic, spike-independent activation of SK channels supports pauses to interrupt autonomous discharge in juvenile GABAergic pars reticulata neurons..
In this study, we analyzed the effects of STN-HFS on motor behavior in intact or hemiparkinsonian rats (6-hydroxydopamine lesion of the substantia nigra pars compacta) and investigated the correlation between these effects and extracellular glutamate (Glu) and GABA levels, assessed by intracerebral microdialysis in the substantia nigra pars reticulata (SNr).
We have examined the morphology of the somatodendritic domain of projection neurons located in different sectors of rat substantia nigra pars reticulata (SNr) or having distinct axonal arborizations.
Neural activity was recorded simultaneously in the sensorimotor cortex (Ctx), hippocampus, amygdala, substantia nigra pars reticulata (SNr) and the subthalamic nucleus (STN).
Similarly, the STN and the substantia nigra pars reticulata (SNr) showed increased activity in Parkinson's disease (PD) animal models.
The present study, using in vivo microdialysis, investigated the effects of a single or subchronic administration of L-DOPA to adult rats with a unilateral 6-OHDA lesion of dopamine neurons on GABA release in the substantia nigra, pars reticulata (SNr).
GABAergic activation of substantia nigra pars reticulata (SNR) at postnatal day (PN) 15 has sex-specific features on seizure control in vivo and electrophysiological responses in vitro.
Dopamine (DA) neurons located in the substantia nigra pars compacta release DA not only via axonal terminals, affecting neurotransmission within the striatum, but also via dendrites, some of which densely protrude into the substantia nigra pars reticulata (SNr).
RESULTS: Extracellular glutamate is increased in substantia nigra pars reticulata (SNr) of PCS rats.
PURPOSE: The substantia nigra pars reticulata (SNR) is known to play a role in gating and control of seizures.
Further experiments indicated that 2-AG is the endocannabinoid mediating short-term retrograde signalling also at other synapses: orlistat abolished DSI in the rat cerebellum, DSI in the mouse substantia nigra pars reticulata and depolarization-induced suppression of excitation in the mouse cerebellum..
A large number of BrdU-positive cells were found in the striatum and its output structures (globus pallidus, entopeduncular nucleus, and substantia nigra pars reticulata) in L-DOPA-treated rats that had developed dyskinesia. In addition, dyskinetic rats exhibited a significant increase in total blood vessel length and a visible extravasation of serum albumin in the two structures in which endothelial proliferation was most pronounced (substantia nigra pars reticulata and entopeduncular nucleus).
Electrolytic or chemical lesions of the substantia nigra, pars reticulata (SNpr), decreased the freezing and escape behaviors thresholds elicited by electrical stimulation of the IC, and increased the behavioral responses evoked by the GABAA blockade in the same sites of the mesencephalic tectum (MT) electrically stimulated.
To understand the events underlying the clinical efficacy of deep brain stimulation (DBS) of the subthalamic nucleus (STN), electrophysiological recordings and microdialysis evaluations were carried out in the substantia nigra pars reticulata (SNr), one of the two basal ganglia (BG) nuclei targeted by STN output, in patients with Parkinson's disease (PD).
DA increased the alpha-synuclein content 1 week after the lesion (but not at the later times analyzed) in tyrosine hydroxylase-positive and in non-dopaminergic fibers of pars reticulata.
Twenty days after HS enhanced BDZ binding was restricted in the cingulated, frontal, anterior and posterior parietal cortices, as well as in substantia nigra pars reticulata, whereas decreased values were found in accumbens nucleus and substantia nigra pars compacta.
For comparison with the PC, labeled neurons were examined in the basolateral amygdala, substantia nigra pars reticulata, and the hippocampal formation.
It is hypothesized that substantia nigra pars reticulata neurons become overactive during a deficit of dopamine transmission. In this study, we examined how acute dopamine receptor blockade (SCH23390 and eticlopride) affects impulse activity of substantia nigra pars reticulata neurons and their response to iontophoretic gamma-amino-n-butyric acid in awake, unrestrained rats. As substantia nigra pars reticulata neurons are autoactive and resistant to tonic increases in gamma-amino-n-butyric acid input, changes in their responsiveness to phasic gamma-amino-n-butyric acid inputs, not tonic increase discharge rate, may underlie movement disturbance following dopamine deficit..
The substantia nigra contains two main compartments: the pars compacta and the pars reticulata.
The substantia nigra pars reticulata (SNR) represents an endogenous seizure suppressing system, which may be targeted to develop treatments for generalized or multifocal epilepsies.
The substantia nigra pars reticulata (SNr) is a key basal ganglia output nucleus.
The substantia nigra pars reticulata (SNR) plays an important age- and sex-specific role in control of clonic seizures.
In the dorsal striatum, MSNs can be distinguished based on the organization of their connectivity to substantia nigra pars reticulata (SNpr) and internal segment of the globus pallidus (GPi), which, in turn, control thalamocortical neurons.
The substantia nigra pars reticulata (SNR) is involved in movement and seizure control.
Besides the superior colliculus, the pedunculopontine tegmental nucleus (PPN) is one of three main target regions of basal ganglia output activity and is reciprocally connected with the substantia nigra pars reticulata (SNr), which is critically involved in seizure propagation and manipulation.
Here we examined the effects of DBS of the substantia nigra pars reticulata (SNr) on amygdala-kindled seizures.
The subthalamic nucleus (STN) plays an important role in movement control by exerting its excitatory influence on the substantia nigra pars reticulata (SNR), a major output structure of the basal ganglia.
We used single-unit recording coupled with iontophoresis to examine impulse activity and responses of substantia nigra pars reticulata (SNr) neurons to GABA, glutamate (GLU), and dopamine (DA) in rats in awake, unrestrained conditions and during chloral hydrate anesthesia.
Neurochemical and neurophysiological studies have indicated that the activity of the GABAergic projection from the striatum to the substantia nigra pars reticulata is reduced in kindled rats, but the exact mechanisms involved in this observation are not known.
The substantia nigra pars reticulata (SNR) plays important roles in movement and, in an age- and sex-dependent manner, in seizure control.
Since electrophysiological correlates of L-dopa-induced dyskinesia (LID) are almost unknown, changes of striatal dopamine (DA) transmission and electrophysiological activity of the substantia nigra pars reticulata (SNr) were recorded before and after acute L-dopa administration in sham-operated and 6-hydroxydopamine (6-OHDA)-lesioned rats that were previously treated with vehicle or L-dopa for 10 days.
Simultaneous recording of single unit activity in the striatum (STR), globus pallidus (GP), substantia nigra pars reticulata (SNr), and STN revealed a variety of neural responses during behaviorally effective HFS of the STN.
We investigated the effects of a selective lesion of the substantia nigra pars reticulata (SNr), obtained by stereotaxic injection of ibotenic acid, on the cortical expression of Fos protein induced by striatal infusion of dopamine, D1-like agonist SKF 38393, in Sprague-Dawley rats.
Immunolabeling showed that presumptive striatal terminals in globus pallidus externus, globus pallidus internus and substantia nigra pars reticulata that colocalized SP and ENK were scarce.
These regions include the amygdaloid complex, caudate putamen, globus pallidus, substantia nigra pars reticulata, suprachiasmatic nucleus, and the anterior part of the subventricular zone.
Neurons in the caudate nucleus and the substantia nigra pars reticulata are extremely sensitive to the positional difference in expected reward, which leads to a bias in excitability between the superior colliculi such that the saccade to the to-be-rewarded position occurs more quickly.
Furthermore, hyperactivity observed in the subthalamic nucleus, pedunculopontine nucleus, and substantia nigra pars reticulata of PD rat models was dramatically reduced by the grafting of N2-derived cells.
Previous studies have shown that GABA binding is reduced in the substantia nigra pars reticulata (SNr) of both epileptic and pre-epileptic gerbils compared with controls, suggesting that reduced expression of GABAA receptors in SNr might be epileptogenic in this model.
Twenty days after HS enhanced BDZ binding was restricted in the cingulated, frontal, anterior and posterior parietal cortices, as well as in substantia nigra pars reticulata, whereas decreased values were found in accumbens nucleus and substantia nigra pars compacta.
Single unit activity from 64 microelectrodes in the striatum (STR), globus pallidus (GP), subthalamic nucleus (STN) and substantia nigra pars reticulata (SNr) was recorded simultaneously before and after a unilateral DA lesion induced by microinjection of 6-hydroxydopamine (6-OHDA) into the medial forebrain bundle.
When the patterns of immunohistochemical localization of mGluRs in monkeys administered systemically with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) were analysed in comparison with normal controls, we found that expression of mGluR1alpha, but not of other subtypes, was significantly reduced in the internal and external segments of the globus pallidus and the substantia nigra pars reticulata.
Virtually nothing is known about the ontogeny of substantia nigra, pars reticulata projections to the midbrain superior colliculus, even though this pathway is critical for the basal ganglia modulation of midbrain-mediated visuomotor behaviors. In anterograde experiments, dye placements into each substantia nigra, pars reticulata resulted in an iterative series of labeled patches, aligned medial-to-lateral across the intermediate and deep superior colliculus, a pattern reminiscent of the adult. Uncrossed neonatal axons had simple linear morphologies with few branch points; by contrast, crossed axons displayed more extensive terminal arbors that were distributed diffusely throughout the rostrocaudal extent of the contralateral superior colliculus In the final series of experiments, one dye was placed unilaterally in the substantia nigra, pars reticulata, while the second dye was positioned in the predorsal bundle, in order to bilaterally label superior colliculus output neurons.
To test this hypothesis we examined the effect of the alpha 2 adrenergic agonist, clonidine, and antagonist, rauwolscine, on the efflux of [ 3H]-GABA and [ 3H]-noradrenaline from brain slices of the rat substantia nigra pars reticulata.
RESULTS: At peak acute ethanol-withdrawal ethanol-withdrawn D2 and B6 mice differed in neural activation within the basal ganglia, including the subthalamic nucleus and the two major output nuclei of the basal ganglia (the medial globus pallidus and the substantia nigra pars reticulata).
Intraneuronal gene expression of cytochrome oxidase subunit I (COI), a metabolic index of neuronal activity, was increased in the subthalamic nucleus, substantia nigra pars reticulata and decreased in frontal cortical areas, but paradoxically unchanged in the striatum, globus pallidus, entopeduncular nucleus and ventrolateral thalamic nucleus.
Both "low" and "high" sensitized groups demonstrated heightened Fos expression relative to acutely challenged rats in the medial and central amygdala, as well as rostroventrolateral medulla, whereas Fos-IR in the locus coeruleus and substantia nigra pars reticulata was significantly increased only in the "high" sensitized group compared to acute.
These changes cause an inhibition of neurons in the substantia nigra pars reticulata and subsequent disinhibition of neurons in the superior colliculus and pedunculopontine nucleus (including its cholinergic cells).
Here we report on how different levels of mesencephalic DA denervation affect substantia nigra pars reticulata (SNpr) neuronal activity in the rat and its relationship to akinesia (stepping test).
The effects of activating dopaminergic D1 and D2 class receptors of the subthalamic projections that innervate the pars reticulata of the subtantia nigra (SNr) were explored in slices of the rat brain using the whole cell patch-clamp technique.
In the present report, fast-scan cyclic voltammetry was used to identify the monoamines that were released by electrical stimulation in mouse brain slices containing ventral tegmental area (VTA), substantia nigra (SN) -pars compacta (SNc) and -pars reticulata (SNr).
The ionotropic, N-methyl-D-aspartate receptor antagonist MK-801 increased cell survival in the substantia nigra pars compacta (SNc) and corrected the metabolic hyperactivity (increased cytochrome oxidase activity) of the ipsilateral substantia nigra pars reticulata (SNr) associated with the lesion, but showed no effects on the 6-OHDA-induced hyperactivity of the subthalamic nucleus (STN).
Microrecordings helped to identify neurons in peduncolopontine nucleus and the adjacent substantia nigra pars reticulata.
As both nigrostriatal dopamine depletion and lesioning of the PPN were shown to induce akinesia and parkinsonism, the present study was performed in order to investigate the changes in neuronal activity of the subthalamic nucleus (STN) and the substantia nigra pars reticulata (SNr) after unilateral ibotenic acid lesioning of the PPN and after unilateral 6-hydroxydopamine lesioning of the substantia nigra pars compacta (SNc).
Axons from neurons of the rat substantia nigra pars reticulata (SNr) and pars lateralis (SNl) were traced after injecting their cell body with biotinylated dextran amine.
Neurons in substantia nigra pars reticulata express the messenger RNA for SK2 but not for SK3 subunits that form small-conductance, Ca2+-dependent K+ channels in dopamine neurons. To determine pathways for the activation of small-conductance, Ca2+-dependent K+ channels in substantia nigra pars reticulata neurons of rats and mice, we studied effects of the selective blocker of small-conductance, Ca2+-dependent K+ channels, apamin (0.01 or 0.3 microM). Apamin diminished the afterhyperpolarization following each action potential and induced burst discharges in substantia nigra pars reticulata neurons. Sensitization of ryanodine receptors by caffeine silenced substantia nigra pars reticulata neurons. We conclude that SK2 channels in substantia nigra pars reticulata neurons are activated by Ca2+ influx through at least two types of Ca2+ channels in the membrane and by ryanodine receptor-mediated Ca2+ release from intracellular stores.
Loss of tyrosine hydroxylase expression was accompanied by increased iron and ferritin levels in glial cells of the substantia nigra pars reticulata.
Through their repetitive discharge, GABAergic neurons of the substantia nigra pars reticulata (SNr) tonically inhibit the target nuclei of the basal ganglia and the dopamine neurons of the midbrain.
Furthermore, either naltrexone or naloxonazine microinjected in the substantia nigra, pars reticulata (SNpr), caused a significant increase in the defensive thresholds elicited by electrical stimulation of the continuum comprised by dorsolateral aspects of the periaqueductal gray matter (dlPAG) and deep layers of the superior colliculus (dlSC), as compared with controls. Labeled neurons of the midbrain tectum send inputs with varicosities to ipsi and contralateral dlSC/dlPAG and ipsilateral substantia nigra, pars reticulata and compacta, in which the anterograde and retrograde tracing from a single injection indicates that the substantia nigra has reciprocal connections with the dlSC/dlPAG featuring close axo-somatic and axo-dendritic appositions in both locations.
A series of experiments was conducted to investigate the locomotor effects of local injections of ethanol and the ethanol metabolite, acetaldehyde, into substantia nigra pars reticulata (SNr).
On the other hand, when orexin was injected into either the PPN (8 cats) or the substantia nigra pars reticulata (SNr, 4 cats), an increased stimulus intensity at the PPN was required to induce muscle atonia.
The STN neurons send glutamatergic projections to the output structures of basal ganglia, including the substantia nigra pars reticulata (SNr) and the entopeduncular nucleus, and also innervate the globus pallidus (GP).
The effects of neuroleptics and the impact of STN HFS applied at parameters alleviating neuroleptic-induced catalepsy were analyzed in the substantia nigra pars reticulata (SNR), a major basal ganglia output structure, by recording the neuronal firing pattern and the responses evoked by cortical stimulation.
Twenty-four of 27 reconstructed axons arborized into the three main striatal targets (external pallidum, globus pallidus, and substantia nigra pars reticulata), a finding that is at odds with the concept of a dual striatofugal system. Axons of striosomal neurons formed several columnar terminal fields in the substantia nigra pars reticulata.
Nuclei within the basal ganglia (BG), in particular the substantia nigra pars reticulata (SNr), subthalamic nucleus (STN) and caudate nucleus, are known to be involved in the generation of rapid or saccadic eye movements.
We publish here descriptions of the excitatory sensory responses and receptive field properties of the visual, auditory, somatosensory and multisensory caudate nucleus and substantia nigra pars reticulata neurons.
OBJECT: Deep brain stimulation (DBS) of subcortical nuclei such as the subthalamic nucleus (STN) or the substantia nigra pars reticulata (SNR) may provide an alternative therapy for intractable epilepsy.
An autoradiography approach indicated that there was a reduction in [ 3H]SCH 23390 binding in substantia nigra pars compacta (SNpc), substantia nigra pars reticulata (SNpr) and ventrolateral striatum in MPTP-treated rats 21 days after the surgery.
Neuronal loss in SNpc was confirmed in coronal sections stained with cresyl violet and revealed extension of lesion towards SN pars reticulata, in SNpc-infused animals.
To provide direct evidence for substantia nigra pars reticulata (SNr) control of oro-facio-lingual muscle activity, high-frequency electrical microstimulation (mainly trains of 20, 333-Hz cathodal pulses at 40-60 microA) and GABA microinjection (1-5 microl of 10 mM GABA in saline) were carried out using a three-barreled microelectrode at the same SNr site in lightly anesthetized, chronically decorticated rats (n=39). We referred to this site as the substantia nigra pars reticulata oro-facio-lingual (SNr-ofl) region.
The occurrence of spheroids has been described in the globus pallidus (GP) and substantia nigra pars reticulata (SNr) of aged rhesus monkeys.
Lesion and microinfusion studies suggest that the substantia nigra pars reticulata (SNR) seizure-controlling network could play a key role.
The lowest stimulation induced by galanin was recorded in diverse areas of the cortex, striatum, hippocampus and substantia nigra pars reticulata.
After focal ischemic or excitotoxic lesions of the cortex and/or striatum, secondary changes have been observed in the thalamus, substantia nigra pars reticulata, hippocampus and spinal cord. In the thalamus, substantia nigra pars reticulata and hippocampus, an expression of proinflammatory cytokine like tumor necrosis factor-alpha and interleukin-1beta is induced.
A large number of PSA-positive cells were detected in the substantia nigra pars reticulata of some patients with PD.
The substantia nigra pars reticulata, the area with the highest expression of ATP-sensitive potassium channels in the brain, plays a pivotal role in suppressing the propagation of generalized seizures by its silence.
We showed previously that 1 h of HFS-STN in normal rats increases extracellular glutamate (Glu) level in the output nuclei of the STN, the globus pallidus (GP), and the substantia nigra pars reticulata (SNr), consistent with an increase in the activity of STN neurons.
Furthermore, the MRI analysis reveals a significantly lower volume (-9%) of the anterior striatum of DAT-KO mice, while the volume of other dopamine-related structures such as the posterior striatum and the substantia nigra pars reticulata is unchanged in comparison to wild type littermates.
When lactacystin was administered at a high concentration, the striatum was simultaneously involved, and alpha-synuclein-immunopositive extracytoplasmic granules appeared extensively within the SN pars reticulata (SNpr).
The purpose of this study was to compare in adult rats with a unilateral 6-hydroxydopamine (6-OHDA) lesion the effects of an acute or chronic (for 3 or 7 days) injection of L-DOPA on mRNA levels encoding for glutamic acid decarboxylase (GAD65 and GAD67) in the striatum and GABA(A) receptor alpha1, beta2 and gamma2 subunits in the substantia nigra, pars reticulata (SNr), by in situ hybridization histochemistry.
Inappropriate output from the substantia nigra pars reticulata (SNr) is known to exacerbate seizures, but the precise neuronal mechanisms underlying abnormal activity in SNr remain unclear.
The effects of NMDA and MK-801 injected into the substantia nigra pars reticulata on jaw movements evoked by dopamine D1/D2 receptor stimulation in the ventrolateral striatum were examined in freely moving rats, by using a magnet-sensing system combined with intracerebral drug microinjection technique. Bilateral injections of NMDA (0.01 and 0.05 microg/0.2 microl in each side) into the substantia nigra pars reticulata, which alone did not produce jaw movements, reduced the repetitive jaw movements evoked by the dopamine D1/D2 receptor agonist mixture in a dose-dependent manner. Injection of the non-competitive NMDA receptor antagonist, MK-801 (0.1 and 0.5 microg/0.2 microl in each side), into the substantia nigra pars reticulata, which alone did not produce jaw movements, prevented the dopaminergic jaw movements in a dose-dependent manner. Moreover, other behaviors such as grooming, rearing, yawning, vacuous chewing, and locomotor activity that occurred after injections of the dopamine receptor agonist mixture were not significantly altered by the bilateral injections of NMDA or MK-801 into the substantia nigra pars reticulata. Given our previous results showing that both agonist and antagonist of GABA(A) receptors injected into the substantia nigra pars reticulata inhibit the jaw movements elicited by dopamine D1/D2 receptor stimulation in the ventrolateral striatum, the present results suggest that there are complex functional interactions between NMDA and GABA(A) receptors within the substantia nigra pars reticulata that may be responsible for the common profiles in the effects of NMDA and GABA(A) receptor agents..
The aim of the present study was to determine the effects of such a lesion on glutamate within the substantia nigra pars reticulata (SN-PR) and the effect of subchronic administration of the dopamine D-1/D-2 agonist, apomorphine, on extracellular glutamate within both the striatum and the SN-PR using in vivo microdialysis.
The injection of trkB-IgG fusion proteins did not modify the effects of kainate in the substantia nigra pars reticulata.
BDNF-/- mice also had aberrant tyrosine hydroxylase (TH) positive cell bodies in the pars reticulata.
GDNF-positive fibers are identified not only within intrinsic striatal neuropil, but also in fibers within the major striatal efferent targets: the globus pallidus, the entopeduncular nucleus, and the SN pars reticulata.
We used unilateral SN pars reticulata (SNR) infusions of the GABA agonist muscimol to induce circling and deoxyglucose autoradiography mapping in adult and postnatal day (PN) 15 male and female rats to determine its substrates.
The present study describes the thalamic innervation coming from the rat parafascicular nucleus (PF) onto striatal and subthalamic efferent neurons projecting either to the globus pallidus (GP) or to the substantia nigra pars reticulata (SNr) by using a protocol for multiple neuroanatomical tracing.
This inhibition is made mainly through GABAergic neurons from substantia nigra, pars reticulata (SNpr), that sends outputs toward neural networks of the deep layers of the superior colliculus and dorsal periaqueductal gray matter involved with the organization of fear-like responses.
The control of seizures can be influenced by the substantia nigra pars reticulata (SNR) in an age- and sex-specific manner.
METH increased striatonigral GABAergic transmission, as evidenced by increased striatal GAD65 mRNA expression and extracellular GABA concentrations in substantia nigra pars reticulata (SNr).
Although there is no evidence that STN is responsible for driving eye movements, it may have a role in either sensory feedback, corollary discharge, or in focusing the substantia nigra pars reticulata to allow a saccade to occur through disinhibition of the superior colliculus..
substantia nigra pars reticulata (SNr) is a major output nucleus of the basal ganglia that receives GABAergic projections from neostriatum and globus pallidus.
Analysis of the behavioral and biochemical results of the experiment revealed a significant negative correlation between the ligand binding in the substantia nigra pars reticulata (SNR), and the number of entries into the central sector of the open field (r=-0.48, p<0.05), as well as the positive correlation between time spent in the central sector of the open field and [ 3H]-raclopride binding within nucleus accumbens septi (r=0.57, p<0.05).
The bilateral microinjection of CBX (0.001-0.50 microg/0.5 microl) into the inferior colliculi, the substantia nigra (pars reticulata or compacta) and the inferior olivary complex was able to reduce the seizure severity score in a dose-dependent manner.
Local field potentials (LFPs) were simultaneously recorded in the subthalamic nucleus (STN), globus pallidus (GP) and substantia nigra pars reticulata (SNr), together with the ipsilateral frontal electrocorticogram (ECoG) of anaesthetized rats.
A significant increase in [ (3)H] (2-D-penicillamine, 5-D-penicillamine)-enkephalin binding was observed in the substantia nigra pars reticulata 1 h after ethanol treatment.
The substantia nigra pars reticulata (SNr) is thought to act as a seizure-gating mechanism in kindling and other epilepsy models.
Recordings of neural activity in the dorsolateral striatum and the substantia nigra pars reticulata indicate preferential activation during syntactic sequences over more random sequences.
Injection of phenytoin (390 pmol/200 nl), muscimol (90 pmol/200 nl), baclofen (500 pmol/200 nl) into the substantia nigra (SN) pars reticulata, protected rats from convulsions evoked by unilateral focal injection of bicuculline into the area tempestas by 50, 80, and 100%, respectively.
The principal GABAergic inputs to the dopaminergic neurons of the substantia nigra originate from neurons of the neostriatum, globus pallidus and substantia nigra pars reticulata.
A multiple-channel, single unit recording method was used to record neuronal activity in the dorsal lateral striatum, the globus pallidus, the subthalamic nucleus, and the substantia nigra pars reticulata simultaneously during spontaneous movement and treadmill locomotion.
The substantia nigra pars reticulata (SNr) plays a key role in basal ganglia function.
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