scholarly journals Dysregulation of the basal ganglia indirect pathway prior to cell loss in the Q175 mouse model of Huntington's disease

2021 ◽  
Author(s):  
Joshua Callahan ◽  
David L Wokosin ◽  
Mark D Bevan
Keyword(s):  
Basal Ganglia ◽  
Huntington's Disease ◽  
Huntington’S Disease ◽  
Ex Vivo ◽  
Cell Loss ◽  
Projection Neurons ◽  
Indirect Pathway ◽  
Cortical Input ◽  
Psychomotor Symptoms

The psychomotor symptoms of Huntington's disease (HD) are linked to degeneration of the basal ganglia indirect pathway. To determine how this pathway is perturbed prior to cell loss, optogenetic- and reporter-guided electrophysiological interrogation approaches were applied to early symptomatic 6-month-old Q175 HD mice. Although cortical activity was unaffected, indirect pathway striatal projection neurons were hypoactive in vivo, consistent with reduced cortical input strength and dendritic excitability. Downstream parvalbumin-expressing prototypic external globus pallidus (GPe) neurons were hyperactive in vivo and exhibited elevated autonomous firing ex vivo. Optogenetic inhibition of prototypic GPe neurons ameliorated the abnormal hypoactivity of postsynaptic subthalamic nucleus (STN) and putative arkypallidal neurons in vivo. In contrast to STN neurons, autonomous arkypallidal activity was unimpaired ex vivo. Together with previous studies, these findings demonstrate that basal ganglia indirect pathway neurons are highly dysregulated in Q175 mice through changes in presynaptic activity and/or intrinsic properties 6-12 months before cell loss.

scholarly journals Enhanced GABAergic Inhibition of Cholinergic Interneurons in the zQ175+/− Mouse Model of Huntington's Disease

2021 ◽  
Vol 14 ◽  
Author(s):  
Sean Austin O. Lim ◽  
D. James Surmeier
Keyword(s):  
Huntington's Disease ◽  
Huntington’S Disease ◽  
Neurodegenerative Disorder ◽  
Ex Vivo ◽  
Brain Slices ◽  
Projection Neurons ◽  
Gabaergic Inhibition ◽  
Indirect Pathway ◽  
Cholinergic Interneurons ◽  
Specific Alteration

Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder that initially manifests itself in the striatum. How intrastriatal circuitry is altered by the disease is poorly understood. To help fill this gap, the circuitry linking spiny projection neurons (SPNs) to cholinergic interneurons (ChIs) was examined using electrophysiological and optogenetic approaches in ex vivo brain slices from wildtype mice and zQ175+/− models of HD. These studies revealed a severalfold enhancement of GABAergic inhibition of ChIs mediated by collaterals of indirect pathway SPNs (iSPNs), but not direct pathway SPNs (dSPNs). This cell-specific alteration in synaptic transmission appeared in parallel with the emergence of motor symptoms in the zQ175+/− model. The adaptation had a presynaptic locus, as it was accompanied by a reduction in paired-pulse ratio but not in the postsynaptic response to GABA. The alterations in striatal GABAergic signaling disrupted spontaneous ChI activity, potentially contributing to the network dysfunction underlying the hyperkinetic phase of HD.

scholarly journals Opposing Influence of Sensory and Motor Cortical Input on Striatal Circuitry and Choice Behavior

2018 ◽  
Author(s):  
Christian R. Lee ◽  
Alex J. Yonk ◽  
Joost Wiskerke ◽  
Kenneth G. Paradiso ◽  
James M. Tepper ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Dorsal Striatum ◽  
Behavioral Effect ◽  
Projection Neurons ◽  
Cortical Input ◽  
Optogenetic Stimulation ◽  
Main Input ◽  
Opposing Effects ◽  
Stimulation Of

SummaryThe striatum is the main input nucleus of the basal ganglia and is a key site of sensorimotor integration. While the striatum receives extensive excitatory afferents from the cerebral cortex, the influence of different cortical areas on striatal circuitry and behavior is unknown. Here we find that corticostriatal inputs from whisker-related primary somatosensory (S1) and motor (M1) cortex differentially innervate projection neurons and interneurons in the dorsal striatum, and exert opposing effects on sensory-guided behavior. Optogenetic stimulation of S1-corticostriatal afferents in ex vivo recordings produced larger postsynaptic potentials in striatal parvalbumin (PV)-expressing interneurons than D1- or D2-expressing spiny projection neurons (SPNs), an effect not observed for M1-corticostriatal afferents. Critically, in vivo optogenetic stimulation of S1-corticostriatal afferents produced task-specific behavioral inhibition, which was bidirectionally modulated by striatal PV interneurons. Optogenetic stimulation of M1 afferents produced the opposite behavioral effect. Thus, our results suggest opposing roles for sensory and motor cortex in behavioral choice via distinct influences on striatal circuitry.

The Role of Hypothalamic and Neuroendocrine Changes in the Pathogenesis of Huntington’s Disease - Current Understanding and Implications for Future Treatments

2010 ◽  
Vol 5 (2) ◽  
pp. 49 ◽  
Author(s):  
åsa Petersén ◽  
Keyword(s):  
Basal Ganglia ◽  
Huntington's Disease ◽  
Huntington’S Disease ◽  
Sleep Disturbances ◽  
Neurodegenerative Disorder ◽  
Current Knowledge ◽  
Premature Death ◽  
Cell Loss ◽  
Cag Repeat ◽  
Motor Symptoms

Huntington’s disease (HD) is a hereditary neurodegenerative disorder that leads to premature death. There is no satisfactory treatment or cure. The disease is caused by an expanded CAG repeat in the huntingtin gene. The clinical features are characterised by progressive motor symptoms, including chorea, which currently defines the clinical diagnosis of the disease. The motor aspect of HD is thought to be due to dysfunction and cell loss in the striatum of the basal ganglia. Cognitive impairment and psychiatric disturbances occur early and are major components of the disease. Recent studies have shown that other non-motor symptoms and signs, such as disruption of the circadian rhythm, sleep disturbances, autonomic dysfunction and metabolic changes, are also common and occur early. Several of these non-motor features are likely results of dysfunction of the hypothalamus and neuroendocrine circuits, which are known to be central in the regulation of emotion, sleep and metabolism. Increasing numbers of reports are now redefining HD as a disease with pathology spreading beyond the basal ganglia. This article provides an overview of current knowledge based on recent clinical studies demonstrating that hypothalamic and neuroendocrine changes are important features of HD.

scholarly journals Cholinergic deficits selectively boost cortical intratelencephalic control of the striatum in Huntington’s disease

2021 ◽  
Author(s):  
Dalton Surmeier ◽  
Tristano Pancani ◽  
Michelle Day ◽  
Tatiana Tkatch ◽  
David Wokosin ◽  
...  
Keyword(s):  
Huntington's Disease ◽  
Huntington’S Disease ◽  
Acetylcholine Release ◽  
Pyramidal Tract ◽  
Projection Neurons ◽  
Mutant Huntingtin ◽  
Indirect Pathway ◽  
Cholinergic Interneurons ◽  
Triplet Expansion ◽  
Knockin Mouse

Abstract Huntington’s disease (HD) is a progressive, neurodegenerative disease caused by a CAG triplet expansion in the huntingtin gene. Although corticostriatal dysfunction has long been implicated in HD, the determinants and pathway specificity of this pathophysiology remain a matter of speculation. To help fill this gap, the zQ175+/- knockin mouse model of HD was studied using approaches that allowed optogenetic interrogation of intratelencephalic (IT) and pyramidal tract (PT) connections with principal striatal spiny projection neurons (SPNs). These studies revealed that the connectivity of IT, but not PT, neurons with direct and indirect pathway SPNs increased in early symptomatic zQ175+/- HD mice. This enhancement was attributable to reduced inhibitory control of IT terminals by striatal cholinergic interneurons (ChIs). Lowering mutant huntingtin selectively in ChIs with a virally-delivered zinc finger repressor protein normalized striatal acetylcholine release and IT functional connectivity – revealing a novel node in the network underlying corticostriatal pathophysiology in HD.

scholarly journals Imbalanced basal ganglia connectivity is associated with motor deficits and apathy in Huntington's disease

2021 ◽  
Author(s):  
Akshay Nair ◽  
Adeel Razi ◽  
Sarah Gregory ◽  
Robb R Rutledge ◽  
Geraint Rees ◽  
...  
Keyword(s):  
Basal Ganglia ◽  
Huntington's Disease ◽  
Huntington’S Disease ◽  
Bayesian Model ◽  
Empirical Bayes ◽  
Model Comparison ◽  
De Novo ◽  
Indirect Pathway ◽  
Direct Pathway ◽  
Bayesian Model Comparison

The gating of movement depends on activity within the cortico-striato-thalamic loops. Within these loops, emerging from the cells of the striatum, run two opponent pathways - the direct and indirect basal ganglia pathway. Both are complex and polysynaptic but the overall effect of activity within these pathways is thought to encourage and inhibit movement respectively. In Huntington's disease (HD), the preferential early loss of striatal neurons forming the indirect pathway is thought to lead to disinhibition giving rise to the characteristic motor features of the condition. But early HD is also associated with apathy, a loss of motivation and failure to engage in goal-directed movement. We hypothesised that in HD, motor signs and apathy may be selectively correlated with indirect and direct pathway dysfunction respectively. We used spectral dynamic casual modelling of resting state fMRI data to model effective connectivity in a model of these cortico-striatal pathways. We tested both of these hypotheses in vivo for the first time in a large cohort of patients with prodromal HD. Using an advanced approach at the group level by combining Parametric Empirical Bayes and Bayesian Model Reduction procedure to generate large number of competing models and compare them by using Bayesian model comparison. With this automated Bayesian approach, associations between clinical measures and connectivity parameters emerge de novo from the data. We found very strong evidence (posterior probability > 0.99) to support both of our hypotheses. Firstly, more severe motor signs in HD were associated with altered connectivity in the indirect pathway components of our model and, by comparison, loss of goal-direct behaviour or apathy, was associated with changes in the direct pathway component. The empirical evidence we provide here is demonstrates that imbalanced basal ganglia connectivity may play an important role in the pathogenesis of some of commonest and disabling features of HD and may have important implications for therapeutics.

Echogenicity of basal ganglia structures in different phenotypes of Huntington's disease

2014 ◽  
Vol 45 (01) ◽  
Author(s):  
C Krogias ◽  
R Hoffmann ◽  
K Straßburger-Krogias ◽  
P Klotz ◽  
G Ellrichmann ◽  
...  
Keyword(s):  
Basal Ganglia ◽  
Huntington's Disease ◽  
Huntington’S Disease ◽  
Basal Ganglia Structures

scholarly journals In Vivo Expression of Reprogramming Factor OCT4 Ameliorates Myelination Deficits and Induces Striatal Neuroprotection in Huntington’s Disease

Genes ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 712
Author(s):  
Ji-Hea Yu ◽  
Bae-Geun Nam ◽  
Min-Gi Kim ◽  
Soonil Pyo ◽  
Jung-Hwa Seo ◽  
...  
Keyword(s):  
Huntington's Disease ◽  
Huntington’S Disease ◽  
Cell Fate ◽  
Gabaergic Neurons ◽  
Oligodendrocyte Progenitor Cells ◽  
Adeno Associated Virus ◽  
In Vivo Expression ◽  
Transcription Factor 4 ◽  
Phosphate Buffered Saline

White matter atrophy has been shown to precede the massive loss of striatal GABAergic neurons in Huntington’s disease (HD). This study investigated the effects of in vivo expression of reprogramming factor octamer-binding transcription factor 4 (OCT4) on neural stem cell (NSC) niche activation in the subventricular zone (SVZ) and induction of cell fate specific to the microenvironment of HD. R6/2 mice randomly received adeno-associated virus 9 (AAV9)-OCT4, AAV9-Null, or phosphate-buffered saline into both lateral ventricles at 4 weeks of age. The AAV9-OCT4 group displayed significantly improved behavioral performance compared to the control groups. Following AAV9-OCT4 treatment, the number of newly generated NSCs and oligodendrocyte progenitor cells (OPCs) significantly increased in the SVZ, and the expression of OPC-related genes and glial cell-derived neurotrophic factor (GDNF) significantly increased. Further, amelioration of myelination deficits in the corpus callosum was observed through electron microscopy and magnetic resonance imaging, and striatal DARPP32+ GABAergic neurons significantly increased in the AAV9-OCT4 group. These results suggest that in situ expression of the reprogramming factor OCT4 in the SVZ induces OPC proliferation, thereby attenuating myelination deficits. Particularly, GDNF released by OPCs seems to induce striatal neuroprotection in HD, which explains the behavioral improvement in R6/2 mice overexpressing OCT4.

In vivo examination of the Pre- and postsynaptic dopamine neurons in huntington's disease

1996 ◽  
Vol 6 ◽  
pp. 130
Author(s):  
N. Ginovart ◽  
A. Lundin ◽  
L. Farde ◽  
C. Halldin ◽  
C.G. Swahn ◽  
...  
Keyword(s):  
Huntington's Disease ◽  
Huntington’S Disease ◽  
Dopamine Neurons
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