A golgi study on the subthalamic nucleus of the cat

Iwahori, Nobuharu

doi:10.1002/cne.901820303

Cited by 77 publications

(34 citation statements)

References 54 publications

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“…In sections immunostained for mGluR1a, labeled dendrites were found in the cerebral peduncle (Fig. 5A), which is consistent with previous Golgi studies showing that the dendrites of neurons located along the ventral border of the STN extend ventrally into the cerebral peduncle (Iwahori, 1978;Afsharpour, 1985).…”

Section: Mglur1 and Mglur5 Are Postsynaptically Localized In Stn Neuronssupporting

confidence: 78%

Activation of Metabotropic Glutamate Receptor 5 Has Direct Excitatory Effects and Potentiates NMDA Receptor Currents in Neurons of the Subthalamic Nucleus

Awad¹,

et al. 2000

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The subthalamic nucleus (STN) is a key nucleus in the basal ganglia motor circuit that provides the major glutamatergic excitatory input to the basal ganglia output nuclei. The STN plays an important role in normal motor function, as well as in pathological conditions such as Parkinson's disease (PD) and related disorders. Development of a complete understanding of the roles of the STN in motor control and the pathophysiological changes in STN that underlie PD will require a detailed understanding of the mechanisms involved in regulation of excitability of STN neurons. Here, we report that activation of group I metabotropic glutamate receptors (mGluRs) induces a direct excitation of STN neurons that is characterized by depolarization, increased firing frequency, and increased burst-firing activity. In addition, activation of group I mGluRs induces a selective potentiation of NMDAevoked currents. Immunohistochemical studies at the light and electron microscopic levels indicate that both subtypes of group I mGluRs (mGluR1a and mGluR5) are localized postsynaptically in the dendrites of STN neurons. Interestingly, pharmacological studies suggest that each of the mGluR-mediated effects is attributable to activation of mGluR5, not mGluR1, despite the presence of both subtypes in STN neurons. These results suggest that mGluR5 may play an important role in the net excitatory drive to the STN from glutamatergic afferents. Furthermore, these studies raise the exciting possibility that selective ligands for mGluR5 may provide a novel approach for the treatment of a variety of movement disorders that involve changes in STN activity. Key words: metabotropic glutamate receptor; subthalamic nucleus; basal ganglia; Parkinson's disease; burst firing; NMDA receptor; mGluR1; mGluR5The basal ganglia (BG) are a set of subcortical nuclei that play a critical role in motor control and are a primary site of pathology in a number of movement disorders, including Parkinson's disease (PD), Tourette's syndrome, and Huntington's disease. Recent studies reveal that a key nucleus in the BG motor circuit, the subthalamic nucleus (STN), plays an especially important role in BG function. The STN is an excitatory glutamatergic nucleus in the BG and provides the major excitatory input to the BG output nuclei, the substantia nigra pars reticulata (SNr) and the internal globus pallidus. Normal motor function requires an intricate balance between excitation of the output nuclei by glutamatergic neurons from the STN and inhibition of the output nuclei by GABAergic projections from the striatum (for review, see Wichmann and DeLong, 1997).Interestingly, recent studies suggest that the major pathophysiological change that occurs in response to loss of nigrostriatal dopamine neurons in PD patients is an increase in activity of STN neurons. The resultant increase in synaptic excitation of GABAergic projection neurons in the output nuclei leads to a "shutdown" of thalamocortical projections and produces the motor impairment characteristic of PD (DeLong, 199...

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Section: Mglur1 and Mglur5 Are Postsynaptically Localized In Stn Neuronssupporting

confidence: 78%

Activation of Metabotropic Glutamate Receptor 5 Has Direct Excitatory Effects and Potentiates NMDA Receptor Currents in Neurons of the Subthalamic Nucleus

Awad¹,

et al. 2000

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“…Of interest, GABA-B -R 1 -expressing neurons are of ''small'' size in the rat LHbMS (Geisler et al, 2003), whereas they exhibit a ''large'' size in the human LHb-d (this study). As neurons of larger size often display extensive length and ramification of their dendrites (i.e., Friede, 1962;Boycott and Wassle, 1974;Iwahori, 1978) it is possible that large GABA-B -R 1 neurons have expanded dendritic trees covering an enlarged region of neuropil in the LHb-d of humans. Whether such a feature also implies increased synaptic connectivity and thus larger integration of inhibitory GABAergic signals into the LHb remains to be elucidated.…”

Section: Conserved and Divergent Organization Of The Lhb In Humansmentioning

confidence: 99%

Morphologic and immunohistochemical organization of the human habenular complex

Díaz

Bravo

Rojas

et al. 2011

J of Comparative Neurology

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The habenular complex (HbCpx) is a phylogenetically conserved brain structure located in the epithalamus of vertebrates. Despite its fundamental role in decision-making processes and the proposed link between habenular dysfunction and neuropsychiatric conditions, little is known about the structural and functional organization of the HbCpx in humans. The goal of this study was thus to provide a first systematic morphologic and immunohistochemical analysis of the human HbCpx to begin dissecting its nuclear and subnuclear organization. Our results confirmed that the human HbCpx is subdivided into medial (MHb) and lateral (LHb) nuclei, each showing a large degree of intranuclear morphologic heterogeneity. Analysis of serially stained sections using a combination of morphologic and immunohistochemical criteria allowed the distinction of five subnuclei in both the MHb and LHb. Overall, the observed subnuclear organization of the MHb in humans resembles the organization of subnuclei in the MHb of rats. The shape, relative size, and intranuclear organization of the LHb, however, show significant differences. The contribution of the LHb to the entire HbCpx is about five times larger in humans than in rats. Noteworthy, a dorsal domain of the LHb that contains afferent myelinated fibers from the stria medullaris and shows GABA-(B) -R(1) immunoreactive cells, appears substantially enlarged in humans when compared to rats. This feature seems to account for a large part of the relative growth in size of the LHb in humans and opens the intriguing possibility of an increased influence of limbic and striatal afferents into the LHb of humans.

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“…stimulation has been discussed earlier (Perkins & Stone, 1980) and is consistent with anatomical findings of reciprocal connexions between the lateral pallidum (of which the g.p. is the homologue in the rat) and the s.t.n., in higher mammals (Carpenter, Fraser & Shriver, 1968;Carpenter & Strominger, 1967;Kim et al 1976;Nauta & Cole, 1974, 1978.…”

Section: Discussionmentioning

confidence: 99%

“…cell bodies and dendrites have been observed within the p.c. in the cat and rat (Iwahori, 1978;Brown, Makman, Wolfson, Dvorkin, Warner & Katzman, 1979). Therefore stimulation of the p.c.…”

Section: Discussionmentioning

confidence: 99%

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Iontophoretic Studies on Pallidal Neurones and the Projection From the Subthalamic Nucleus

Perkins¹,

Stone²

1981

Exp Physiol

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SUMMARYThe predominant response of pallidal neurones to y-aminobutyric acid (GABA), glycine and dopamine when applied iontophoretically, was inhibition of firing rate. With dopamine some excitatory responses were observed, this never being the case with GABA or glycine. Picrotoxin reversibly blocked neuronal responses to GABA but not glycine in fourteen cases. Strychnine abolished glycine evoked inhibitions in seventeen cells while not affecting GABA responses. A number of cells were responsive to a stimulus delivered to the subthalamic nucleus (s.t.n.), an electrode array being used to establish the specificity of response to s.t.n. stimulation. In eight out of fourteen cases there was a reduction of 40% or more in the inhibitory responses following stimulation, with picrotoxin applied iontophoretically. Strychnine, conversely, had no effect on the synaptically evoked inhibition at doses that exceeded those required to antagonize iontophoretically applied glycine. Similarly, fluphenazine and naloxone administered iontophoretically or intraperitoneally (I.P.) had no effect on eight cells. The results indicate the existence of a 'GABA-ergic' link in the projection from the subthalamic nucleus to the globus pallidus, though other transmitters, but not glycine or dopamine, may contribute to the observed synaptic responses.

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A golgi study on the subthalamic nucleus of the cat

Cited by 77 publications

References 54 publications

Activation of Metabotropic Glutamate Receptor 5 Has Direct Excitatory Effects and Potentiates NMDA Receptor Currents in Neurons of the Subthalamic Nucleus

Activation of Metabotropic Glutamate Receptor 5 Has Direct Excitatory Effects and Potentiates NMDA Receptor Currents in Neurons of the Subthalamic Nucleus

Morphologic and immunohistochemical organization of the human habenular complex

Iontophoretic Studies on Pallidal Neurones and the Projection From the Subthalamic Nucleus

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