Circuit-Selective Striatal Synaptic Dysfunction in the Sapap3 Knockout Mouse Model of Obsessive-Compulsive Disorder

doi:10.1016/j.biopsych.2013.01.008

Biological Psychiatry

Volume 75, Issue 8, 15 April 2014, Pages 623-630

https://doi.org/10.1016/j.biopsych.2013.01.008 Get rights and content

Background

Synapse-associated protein 90/postsynaptic density protein 95-associated protein 3 (SAPAP3) is an excitatory postsynaptic protein implicated in the pathogenesis of obsessive-compulsive behaviors. In mice, genetic deletion of Sapap3 causes obsessive-compulsive disorder (OCD)-like behaviors that are rescued by striatal expression of Sapap3, demonstrating the importance of striatal neurotransmission for the OCD-like behaviors. In the striatum, there are two main excitatory synaptic circuits, corticostriatal and thalamostriatal. Neurotransmission defects in either or both of these circuits could potentially contribute to the OCD-like behaviors of Sapap3 knockout (KO) mice. Previously, we reported that Sapap3 deletion reduces corticostriatal alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid-type glutamate receptor-mediated synaptic transmission.

Methods

Whole-cell electrophysiological recording techniques in acute brain slices were used to measure synaptic transmission in the corticostriatal and thalamostriatal circuits of Sapap3 KO mice and littermate control animals. Transgenic fluorescent reporters identified striatopallidal and striatonigral projection neurons. SAPAP isoforms at corticostriatal and thalamostriatal synapses were detected using immunostaining techniques.

Results

In contrast to corticostriatal synapses, thalamostriatal synaptic activity is unaffected by Sapap3 deletion. At the molecular level, we find that another SAPAP family member, SAPAP4, is present at thalamostriatal, but not corticostriatal, synapses. This finding provides a molecular rationale for the functional divergence we observe between thalamic and cortical striatal circuits in Sapap3 KO mice.

Conclusions

These findings define the circuit-level neurotransmission defects in a genetic mouse model for OCD-related behaviors, focusing attention on the corticostriatal circuit for mediating the behavioral abnormalities. Our results also provide the first evidence that SAPAP isoforms may be localized to synapses according to circuit-selective principles.

Section snippets

Brain Slice Preparation

Animal procedures were performed according to protocol approved by the Institutional Animal Care and Use Committee of Duke University. Generation of Sapap3 KO, Drd1a-tdTomato^(tg/+) transgenic and DRD2-EGFP^(tg/+) transgenic mice has been previously described 7, 19, 20. From littermate pairs of postnatal day (P)21 to P25 Sapap3 wild-type (WT) and KO mice hemizygous for Drd1a-tdTomato and/or DRD2-EGFP transgenes, acute coronal or parahorizontal brain slices (300 μm thickness) were obtained as

In Striatopallidal MSNs, Circuit-Selective Analysis Is Necessary to Reveal Defect in Quantal Synaptic Events

Circuit-selective studies to examine thalamostriatal transmission were prompted by finding that SP MSNs had discordant effects of Sapap3 deletion on miniature and evoked EPSCs. In prior studies, we demonstrated that Sapap3 deletion reduced AMPAR-mediated evoked EPSCs in both SN and SP MSNs (6). In SN MSNs, this was accompanied by a significant reduction in the frequency of mEPSC events (6). However, in SP MSNs, we show here that mEPSCs are unaffected by Sapap3 deletion. No significant

Discussion

In the present study, we show for the first time that the activity of excitatory synapses onto striatal MSNs is circuit-selectively altered in the Sapap3 KO mouse model of obsessive-compulsive disorder. In explaining the basis for this functional divergence, we identify a novel difference in the postsynaptic molecular composition of corticostriatal and thalamostriatal synapses—SAPAP4 being present at thalamostriatal, but not corticostriatal, synapses. These observations advance both our

References (37)

M. Takeuchi et al.
SAPAPs. A family of PSD-95/SAP90-associated proteins localized at postsynaptic density
J Biol Chem
(1997)
L. Boardman et al.
Investigating SAPAP3 variants in the etiology of obsessive-compulsive disorder and trichotillomania in the South African white population
Compr Psychiatry
(2011)
L. Friedlander et al.
Neuroimaging studies of obsessive-compulsive disorder in adults and children
Clin Psychol Rev
(2006)
R.M. Smeal et al.
A rat brain slice preparation for characterizing both thalamostriatal and corticostriatal afferents
J Neurosci Methods
(2007)
Y. Smith et al.
The thalamostriatal system: A highly specific network of the basal ganglia circuitry
Trends Neurosci
(2004)
A.C. Kreitzer et al.
Striatal plasticity and basal ganglia circuit function
Neuron
(2008)
P. Barroso-Chinea et al.
Expression of vesicular glutamate transporters 1 and 2 in the cells of origin of the rat thalamostriatal pathway
J Chem Neuroanat
(2008)
M.E. Rubio et al.
Glutamate receptors are selectively targeted to postsynaptic sites in neurons
Neuron
(1997)
N. Albelda et al.
Current animal models of obsessive compulsive disorder: An update
Neuroscience
(2012)
E. Kim et al.
GKAP, a novel synaptic protein that interacts with the guanylate kinase-like domain of the PSD-95/SAP90 family of channel clustering molecules
J Cell Biol
(1997)

J.M. Welch et al.

Differential mRNA expression and protein localization of the SAP90/PSD-95-associated proteins (SAPAPs) in the nervous system of the mouse

J Comp Neurol

(2004)

E. Kim et al.

PDZ domain proteins of synapses

Nat Rev Neurosci

(2004)

M. Chen et al.

Sapap3 deletion anomalously activates short-term endocannabinoid-mediated synaptic plasticity

J Neurosci

(2011)

Y. Wan et al.

Sapap3 deletion causes mGluR5-dependent silencing of AMPAR synapses

J Neurosci

(2011)

J.M. Welch et al.

Cortico-striatal synaptic defects and OCD-like behaviours in Sapap3-mutant mice

Nature

(2007)

S. Ryu et al.

Interaction between genetic variants of DLGAP3 and SLC1A1 affecting the risk of atypical antipsychotics-induced obsessive-compulsive symptoms

Am J Med Genet B Neuropsychiatr Genet

(2011)

S. Zuchner et al.

Multiple rare SAPAP3 missense variants in trichotillomania and OCD

Mol Psychiatry

(2009)

C.M. Pennartz et al.

Corticostriatal interactions during learning, memory processing, and decision making

J Neurosci

(2009)

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Pathway-specific alterations in striatal excitability and cholinergic modulation in a SAPAP3 mouse model of compulsive motor behavior
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Deletion of the obsessive-compulsive disorder (OCD)-associated gene SAP90/PSD-95-associated protein 3 (Sapap3), which encodes a postsynaptic anchoring protein at corticostriatal synapses, causes OCD-like motor behaviors in mice. While corticostriatal synaptic dysfunction is central to this phenotype, the striatum efficiently adapts to pathological changes, often in ways that expand upon the original circuit impairment. Here, we show that SAPAP3 deletion causes non-synaptic and pathway-specific alterations in dorsolateral striatum circuit function. While somatic excitability was elevated in striatal projection neurons (SPNs), dendritic excitability was exclusively enhanced in direct pathway SPNs. Layered on top of this, cholinergic modulation was altered in opposing ways: striatal cholinergic interneuron density and evoked acetylcholine release were elevated, while basal muscarinic modulation of SPNs was reduced. These data describe how SAPAP3 deletion alters the striatal landscape upon which impaired corticostriatal inputs will act, offering a basis for how pathological synaptic integration and unbalanced striatal output underlying OCD-like behaviors may be shaped.
Acute administration of the NMDA receptor antagonists ketamine and MK-801 reveals dysregulation of glutamatergic signalling and sensorimotor gating in the Sapap3 knockout mouse model of compulsive-like behaviour
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Obsessive-compulsive disorder (OCD) is characterised by excessive intrusive thoughts that may cause an individual to engage in compulsive behaviours. Frontline pharmacological treatments (i.e., selective serotonin reuptake inhibitors (SSRIs)) leave approximately 40% of patients refractory to treatment. To investigate the possibility of novel pharmacological therapies for OCD, as well as the potential mechanisms underlying its pathology, we used the Sapap3 knockout (KO) mouse model of OCD, which exhibits increased anxiety and compulsive grooming behaviours. Firstly, we investigated whether administration of the NMDA receptor (NMDAR) antagonist ketamine (30 mg/kg), would reduce anxiety and grooming behaviour in Sapap3 KO mice. Anxiety-like behaviour was measured via time spent in the light component of the light-dark box test. Grooming behaviour was recorded and scored in freely moving mice. In line with previous works conducted in older animals (i.e. typically between 6 and 9 months of age), we confirmed here that Sapap3 KO mice exhibit an anxious, compulsive grooming, hypolocomotive and reduced body weight phenotype even at a younger age (i.e., 2-3 months of age). However, we found that acute administration of ketamine did not cause a reduction in anxiety or grooming behaviour. We then investigated in vivo glutamatergic function via the administration of a different NMDAR antagonist, MK-801 (0.25 mg/kg), prior to locomotion and prepulse inhibition assays. We found evidence of altered functional NMDAR activity, as well as sexually dimorphic prepulse inhibition, a measure of sensorimotor gating, in Sapap3 KO mice. These results are suggestive of in vivo glutamatergic dysfunction and their functional consequences, enabling future research to further investigate novel treatments for OCD.
Spinophilin Limits Metabotropic Glutamate Receptor 5 Scaffolding to the Postsynaptic Density and Cell Type Specifically Mediates Excessive Grooming
2023, Biological Psychiatry
Grooming dysfunction is a hallmark of the obsessive-compulsive spectrum disorder trichotillomania. Numerous preclinical studies have utilized SAPAP3-deficient mice for understanding the neurobiology of repetitive grooming, suggesting that excessive grooming is caused by increased metabotropic glutamate receptor 5 (mGluR5) activity in striatal direct- and indirect-pathway medium spiny neurons (MSNs). However, the MSN subtype–specific signaling mechanisms that mediate mGluR5-dependent adaptations underlying excessive grooming are not fully understood. Here, we investigated the MSN subtype–specific roles of the striatal signaling hub protein spinophilin in mediating repetitive motor dysfunction associated with mGluR5 function.
Quantitative proteomics and immunoblotting were utilized to identify how spinophilin impacts mGluR5 phosphorylation and protein interaction changes. Plasticity and repetitive motor dysfunction associated with mGluR5 action were measured using our novel conditional spinophilin mouse model in which spinophilin was knocked out from striatal direct-pathway MSNs and/or indirect-pathway MSNs.
Loss of spinophilin only in indirect-pathway MSNs decreased performance of a novel motor repertoire, but loss of spinophilin in either MSN subtype abrogated striatal plasticity associated with mGluR5 function and prevented excessive grooming caused by SAPAP3 knockout mice or treatment with the mGluR5-specific positive allosteric modulator VU0360172 without impacting locomotion-relevant behavior. Biochemically, we determined that the spinophilin-mGluR5 interaction correlates with grooming behavior and that loss of spinophilin shifts mGluR5 interactions from lipid raft–associated proteins toward postsynaptic density proteins implicated in psychiatric disorders.
These results identify spinophilin as a novel striatal signaling hub molecule in MSNs that cell subtype specifically mediates behavioral, functional, and molecular adaptations associated with repetitive motor dysfunction in psychiatric disorders.
Distinct Patterns of Abnormal Lateral Orbitofrontal Cortex Activity During Compulsive Grooming and Reversal Learning Normalize After Fluoxetine
2023, Biological Psychiatry
Patients with obsessive-compulsive disorder (OCD) display disrupted performance and abnormal lateral orbitofrontal cortex (LOFC) activity during reversal learning tasks. However, it is unknown whether compulsions and reversal learning deficits share a common neural substrate. To answer this question, we measured neural activity with in vivo calcium imaging in LOFC during compulsive grooming and reversal learning before and after fluoxetine treatment.
Sapap3 knockout (KO) mice were used as a model for OCD-relevant behaviors. Sapap3 KOs and control littermates were injected with a virus encoding GCaMP6f and implanted with gradient-index lenses to visualize LOFC activity using miniature microscopes. Grooming, reversal learning, and neural activity were measured pre- and post-fluoxetine treatment (18 mg/kg, 4 weeks).
Baseline compulsive grooming and reversal learning impairments in KOs improved after fluoxetine treatment. In addition, KOs displayed distinct patterns of abnormal LOFC activity during grooming and reversal learning, both of which normalized after fluoxetine. Finally, reversal learning–associated neurons were distributed randomly among grooming-associated neurons (i.e., overlap is what would be expected by chance).
In OCD, LOFC is disrupted during both compulsive behaviors and reversal learning, but whether these behaviors share common neural underpinnings is unknown. We found that LOFC plays distinct roles in compulsive grooming and impaired reversal learning and their improvement with fluoxetine. These findings suggest that LOFC plays separate roles in pathophysiology and treatment of different perseverative behaviors in OCD.
Deep learning-based synapse counting and synaptic ultrastructure analysis of electron microscopy images
2023, Journal of Neuroscience Methods
Synapses are the connections between neurons in the central nervous system (CNS) or between neurons and other excitable cells in the peripheral nervous system (PNS), where electrical or chemical signals rapidly travel through one cell to another with high spatial precision. Synaptic analysis, based on synapse numbers and fine morphology, is the basis for understanding neurological functions and diseases. Manual analysis of synaptic structures in electron microscopy (EM) images is often limited by low efficiency and subjective bias.
We developed a multifunctional synaptic analysis system based on several advanced deep learning (DL) models. The system achieved synapse counting in low-magnification EM images and synaptic ultrastructure analysis in high-magnification EM images.
The synapse counting system based on ResNet18 and a Faster R-CNN model had a mean average precision (mAP) of 92.55%. For synaptic ultrastructure analysis, the Faster R-CNN model based on ResNet50 achieved a mAP of 91.60%, the DeepLab v3 + model based on ResNet50 enabled high performance in presynaptic and postsynaptic membrane segmentation with a global accuracy of 0.9811, and the Faster R-CNN model based on ResNet18 achieved a mAP of 91.41% for synaptic vesicle detection.
The proposed multifunctional synaptic analysis system may help to overcome the experimental bias inherent in manual analysis, thereby facilitating EM image–based synaptic function studies.
The metabotropic glutamate receptor 5 as a biomarker for psychiatric disorders
2023, International Review of Neurobiology
The role of glutamate system in the etiology and pathophysiology of psychiatric disorders has gained considerable attention in the past two decades, including dysregulation of the metabotropic glutamatergic receptor subtype 5 (mGlu5). Thus, mGlu5 may represent a promising therapeutic target for psychiatric conditions, particularly stress-related disorders. Here, we describe mGlu5 findings in mood disorders, anxiety, and trauma disorders, as well as substance use (specifically nicotine, cannabis, and alcohol use). We highlight insights gained from positron emission tomography (PET) studies, where possible, and discuss findings from treatment trials, when available, to explore the role of mGlu5 in these psychiatric disorders. Through the research evidence reviewed in this chapter, we make the argument that, not only is dysregulation of mGlu5 evident in numerous psychiatric disorders, potentially functioning as a disease “biomarker,” the normalization of glutamate neurotransmission via changes in mGlu5 expression and/or modulation of mGlu5 signaling may be a needed component in treating some psychiatric disorders or symptoms. Finally, we hope to demonstrate the utility of PET as an important tool for investigating mGlu5 in disease mechanisms and treatment response.

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Archival ReportCircuit-Selective Striatal Synaptic Dysfunction in the Sapap3 Knockout Mouse Model of Obsessive-Compulsive Disorder

Background

Methods

Results

Conclusions

Section snippets

Brain Slice Preparation

In Striatopallidal MSNs, Circuit-Selective Analysis Is Necessary to Reveal Defect in Quantal Synaptic Events

Discussion

J Biol Chem

Compr Psychiatry

Clin Psychol Rev

J Neurosci Methods

Trends Neurosci

Neuron

J Chem Neuroanat

Neuron

Neuroscience

GKAP, a novel synaptic protein that interacts with the guanylate kinase-like domain of the PSD-95/SAP90 family of channel clustering molecules

J Cell Biol

Differential mRNA expression and protein localization of the SAP90/PSD-95-associated proteins (SAPAPs) in the nervous system of the mouse

J Comp Neurol

PDZ domain proteins of synapses

Nat Rev Neurosci

Sapap3 deletion anomalously activates short-term endocannabinoid-mediated synaptic plasticity

J Neurosci

Sapap3 deletion causes mGluR5-dependent silencing of AMPAR synapses

J Neurosci

Cortico-striatal synaptic defects and OCD-like behaviours in Sapap3-mutant mice

Nature

Interaction between genetic variants of DLGAP3 and SLC1A1 affecting the risk of atypical antipsychotics-induced obsessive-compulsive symptoms

Am J Med Genet B Neuropsychiatr Genet

Multiple rare SAPAP3 missense variants in trichotillomania and OCD

Mol Psychiatry

Corticostriatal interactions during learning, memory processing, and decision making

J Neurosci

Archival Report
Circuit-Selective Striatal Synaptic Dysfunction in the Sapap3 Knockout Mouse Model of Obsessive-Compulsive Disorder