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Croom K, Rumschlag JA, Molinaro G, Erickson MA, Binder DK, Huber KM, Razak KA. Developmental trajectory and sex differences in auditory processing in a PTEN-deletion model of autism spectrum disorders. Neurobiol Dis 2024; 200:106628. [PMID: 39111703 DOI: 10.1016/j.nbd.2024.106628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2024] [Revised: 07/31/2024] [Accepted: 08/02/2024] [Indexed: 08/16/2024] Open
Abstract
Autism Spectrum Disorders (ASD) encompass a wide array of debilitating symptoms, including severe sensory deficits and abnormal language development. Sensory deficits early in development may lead to broader symptomatology in adolescents and adults. The mechanistic links between ASD risk genes, sensory processing and language impairment are unclear. There is also a sex bias in ASD diagnosis and symptomatology. The current study aims to identify the developmental trajectory and genotype- and sex-dependent differences in auditory sensitivity and temporal processing in a Pten-deletion (phosphatase and tensin homolog missing on chromosome 10) mouse model of ASD. Auditory temporal processing is crucial for speech recognition and language development and deficits will cause language impairments. However, very little is known about the development of temporal processing in ASD animal models, and if there are sex differences. To address this major gap, we recorded epidural electroencephalography (EEG) signals from the frontal (FC) and auditory (AC) cortex in developing and adult Nse-cre PTEN mice, in which Pten is deleted in specific cortical layers (layers III-V) (PTEN conditional knock-out (cKO). We quantified resting EEG spectral power distribution, auditory event related potentials (ERP) and temporal processing from awake and freely moving male and female mice. Temporal processing is measured using a gap-in-noise-ASSR (auditory steady state response) stimulus paradigm. The experimental manipulation of gap duration and modulation depth allows us to measure cortical entrainment to rapid gaps in sounds. Temporal processing was quantified using inter-trial phase clustering (ITPC) values that account for phase consistency across trials. The results show genotype differences in resting power distribution in PTEN cKO mice throughout development. Male and female cKO mice have significantly increased beta power but decreased high frequency oscillations in the AC and FC. Both male and female PTEN cKO mice show diminished ITPC in their gap-ASSR responses in the AC and FC compared to control mice. Overall, deficits become more prominent in adult (p60) mice, with cKO mice having significantly increased sound evoked power and decreased ITPC compared to controls. While both male and female cKO mice demonstrated severe temporal processing deficits across development, female cKO mice showed increased hypersensitivity compared to males, reflected as increased N1 and P2 amplitudes. These data identify a number of novel sensory processing deficits in a PTEN-ASD mouse model that are present from an early age. Abnormal temporal processing and hypersensitive responses may contribute to abnormal development of language function in ASD.
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Affiliation(s)
- Katilynne Croom
- Graduate Neuroscience Program, University of California, Riverside, United States of America
| | - Jeffrey A Rumschlag
- Department of Otolaryngology-Head and Neck Surgery, Medical University of South Carolina, Charleston, United States of America
| | - Gemma Molinaro
- Department of Neuroscience, O'Donnell Brain Institute, UT Southwestern Medical Center, Dallas, TX, United States of America
| | - Michael A Erickson
- Psychology Department, University of California, Riverside, United States of America
| | - Devin K Binder
- Graduate Neuroscience Program, University of California, Riverside, United States of America; Biomedical Sciences, School of Medicine, University of California, Riverside, United States of America
| | - Kimberly M Huber
- Department of Neuroscience, O'Donnell Brain Institute, UT Southwestern Medical Center, Dallas, TX, United States of America
| | - Khaleel A Razak
- Graduate Neuroscience Program, University of California, Riverside, United States of America; Psychology Department, University of California, Riverside, United States of America.
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Croom K, Rumschlag JA, Erickson MA, Binder D, Razak KA. Sex differences during development in cortical temporal processing and event related potentials in wild-type and fragile X syndrome model mice. J Neurodev Disord 2024; 16:24. [PMID: 38720271 PMCID: PMC11077726 DOI: 10.1186/s11689-024-09539-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Accepted: 04/17/2024] [Indexed: 05/12/2024] Open
Abstract
BACKGROUND Autism spectrum disorder (ASD) is currently diagnosed in approximately 1 in 44 children in the United States, based on a wide array of symptoms, including sensory dysfunction and abnormal language development. Boys are diagnosed ~ 3.8 times more frequently than girls. Auditory temporal processing is crucial for speech recognition and language development. Abnormal development of temporal processing may account for ASD language impairments. Sex differences in the development of temporal processing may underlie the differences in language outcomes in male and female children with ASD. To understand mechanisms of potential sex differences in temporal processing requires a preclinical model. However, there are no studies that have addressed sex differences in temporal processing across development in any animal model of ASD. METHODS To fill this major gap, we compared the development of auditory temporal processing in male and female wildtype (WT) and Fmr1 knock-out (KO) mice, a model of Fragile X Syndrome (FXS), a leading genetic cause of ASD-associated behaviors. Using epidural screw electrodes, we recorded auditory event related potentials (ERP) and auditory temporal processing with a gap-in-noise auditory steady state response (ASSR) paradigm at young (postnatal (p)21 and p30) and adult (p60) ages from both auditory and frontal cortices of awake, freely moving mice. RESULTS The results show that ERP amplitudes were enhanced in both sexes of Fmr1 KO mice across development compared to WT counterparts, with greater enhancement in adult female than adult male KO mice. Gap-ASSR deficits were seen in the frontal, but not auditory, cortex in early development (p21) in female KO mice. Unlike male KO mice, female KO mice show WT-like temporal processing at p30. There were no temporal processing deficits in the adult mice of both sexes. CONCLUSIONS These results show a sex difference in the developmental trajectories of temporal processing and hypersensitive responses in Fmr1 KO mice. Male KO mice show slower maturation of temporal processing than females. Female KO mice show stronger hypersensitive responses than males later in development. The differences in maturation rates of temporal processing and hypersensitive responses during various critical periods of development may lead to sex differences in language function, arousal and anxiety in FXS.
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Affiliation(s)
- Katilynne Croom
- Graduate Neuroscience Program, University of California, Riverside, USA
| | - Jeffrey A Rumschlag
- Department of Otolaryngology-Head and Neck Surgery, Medical University of South Carolina, Charleston, USA
| | - Michael A Erickson
- Department of Psychology, University of California, 900 University Avenue, Riverside, USA
| | - Devin Binder
- Graduate Neuroscience Program, University of California, Riverside, USA
- Biomedical Sciences, School of Medicine, University of California, Riverside, USA
| | - Khaleel A Razak
- Graduate Neuroscience Program, University of California, Riverside, USA.
- Department of Psychology, University of California, 900 University Avenue, Riverside, USA.
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Bae HG, Wu WC, Nip K, Gould E, Kim JH. Scn2a deletion disrupts oligodendroglia function: Implication for myelination, neural circuitry, and auditory hypersensitivity in ASD. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.15.589242. [PMID: 38659965 PMCID: PMC11042360 DOI: 10.1101/2024.04.15.589242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
Autism spectrum disorder (ASD) is characterized by a complex etiology, with genetic determinants significantly influencing its manifestation. Among these, the Scn2a gene emerges as a pivotal player, crucially involved in both glial and neuronal functionality. This study elucidates the underexplored roles of Scn2a in oligodendrocytes, and its subsequent impact on myelination and auditory neural processes. The results reveal a nuanced interplay between oligodendrocytes and axons, where Scn2a deletion causes alterations in the intricate process of myelination. This disruption, in turn, instigates changes in axonal properties and neuronal activities at the single cell level. Furthermore, oligodendrocyte-specific Scn2a deletion compromises the integrity of neural circuitry within auditory pathways, leading to auditory hypersensitivity-a common sensory abnormality observed in ASD. Through transcriptional profiling, we identified alterations in the expression of myelin-associated genes, highlighting the cellular consequences engendered by Scn2a deletion. In summary, the findings provide unprecedented insights into the pathway from Scn2a deletion in oligodendrocytes to sensory abnormalities in ASD, underscoring the integral role of Scn2a -mediated myelination in auditory responses. This research thereby provides novel insights into the intricate tapestry of genetic and cellular interactions inherent in ASD.
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Croom K, Rumschlag JA, Erickson MA, Binder DK, Razak KA. Developmental delays in cortical auditory temporal processing in a mouse model of Fragile X syndrome. J Neurodev Disord 2023; 15:23. [PMID: 37516865 PMCID: PMC10386252 DOI: 10.1186/s11689-023-09496-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 07/18/2023] [Indexed: 07/31/2023] Open
Abstract
BACKGROUND Autism spectrum disorders (ASD) encompass a wide array of debilitating symptoms, including sensory dysfunction and delayed language development. Auditory temporal processing is crucial for speech perception and language development. Abnormal development of temporal processing may account for the language impairments associated with ASD. Very little is known about the development of temporal processing in any animal model of ASD. METHODS In the current study, we quantify auditory temporal processing throughout development in the Fmr1 knock-out (KO) mouse model of Fragile X Syndrome (FXS), a leading genetic cause of intellectual disability and ASD-associated behaviors. Using epidural electrodes in awake and freely moving wildtype (WT) and KO mice, we recorded auditory event related potentials (ERP) and auditory temporal processing with a gap-in-noise auditory steady state response (gap-ASSR) paradigm. Mice were recorded at three different ages in a cross sectional design: postnatal (p)21, p30 and p60. Recordings were obtained from both auditory and frontal cortices. The gap-ASSR requires underlying neural generators to synchronize responses to gaps of different widths embedded in noise, providing an objective measure of temporal processing across genotypes and age groups. RESULTS We present evidence that the frontal, but not auditory, cortex shows significant temporal processing deficits at p21 and p30, with poor ability to phase lock to rapid gaps in noise. Temporal processing was similar in both genotypes in adult mice. ERP amplitudes were larger in Fmr1 KO mice in both auditory and frontal cortex, consistent with ERP data in humans with FXS. CONCLUSIONS These data indicate cortical region-specific delays in temporal processing development in Fmr1 KO mice. Developmental delays in the ability of frontal cortex to follow rapid changes in sounds may shape language delays in FXS, and more broadly in ASD.
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Affiliation(s)
- Katilynne Croom
- Graduate Neuroscience Program, University of California, Riverside, USA
| | - Jeffrey A Rumschlag
- Department of Otolaryngology-Head and Neck Surgery, Medical University of South Carolina, Charleston, USA
| | | | - Devin K Binder
- Graduate Neuroscience Program, University of California, Riverside, USA
- Biomedical Sciences, School of Medicine, University of California, Riverside, USA
| | - Khaleel A Razak
- Graduate Neuroscience Program, University of California, Riverside, USA.
- Department of Psychology, University of California, Riverside, USA.
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Tempio A, Boulksibat A, Bardoni B, Delhaye S. Fragile X Syndrome as an interneuronopathy: a lesson for future studies and treatments. Front Neurosci 2023; 17:1171895. [PMID: 37188005 PMCID: PMC10176609 DOI: 10.3389/fnins.2023.1171895] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Accepted: 04/05/2023] [Indexed: 05/17/2023] Open
Abstract
Fragile X Syndrome (FXS) is the most common form of inherited intellectual disability (ID) and a primary genetic cause of autism spectrum disorder (ASD). FXS arises from the silencing of the FMR1 gene causing the lack of translation of its encoded protein, the Fragile X Messenger RibonucleoProtein (FMRP), an RNA-binding protein involved in translational control and in RNA transport along dendrites. Although a large effort during the last 20 years has been made to investigate the cellular roles of FMRP, no effective and specific therapeutic intervention is available to treat FXS. Many studies revealed a role for FMRP in shaping sensory circuits during developmental critical periods to affect proper neurodevelopment. Dendritic spine stability, branching and density abnormalities are part of the developmental delay observed in various FXS brain areas. In particular, cortical neuronal networks in FXS are hyper-responsive and hyperexcitable, making these circuits highly synchronous. Overall, these data suggest that the excitatory/inhibitory (E/I) balance in FXS neuronal circuitry is altered. However, not much is known about how interneuron populations contribute to the unbalanced E/I ratio in FXS even if their abnormal functioning has an impact on the behavioral deficits of patients and animal models affected by neurodevelopmental disorders. We revise here the key literature concerning the role of interneurons in FXS not only with the purpose to better understand the pathophysiology of this disorder, but also to explore new possible therapeutic applications to treat FXS and other forms of ASD or ID. Indeed, for instance, the re-introduction of functional interneurons in the diseased brains has been proposed as a promising therapeutic approach for neurological and psychiatric disorders.
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Affiliation(s)
- Alessandra Tempio
- Université Côte d’Azur, CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, Valbonne, France
- Alessandra Tempio,
| | - Asma Boulksibat
- Université Côte d’Azur, CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, Valbonne, France
| | - Barbara Bardoni
- Université Côte d’Azur, CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, Valbonne, France
- Inserm, Université Côte d’Azur, CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, Valbonne, France
- *Correspondence: Barbara Bardoni,
| | - Sébastien Delhaye
- Université Côte d’Azur, CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, Valbonne, France
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6
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Kat R, Kas MJH. Largely unaffected auditory and visual sensory processing phenotypes in the evoked potentials of Fmr1 KO2 mice. Eur J Neurosci 2022; 56:5260-5273. [PMID: 36017614 PMCID: PMC9826194 DOI: 10.1111/ejn.15808] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 07/05/2022] [Accepted: 07/06/2022] [Indexed: 01/11/2023]
Abstract
Sensory sensitivity symptoms are common in autism spectrum disorders and fragile X syndrome. Mainly in the auditory modality, disturbed processing has been found in both fragile X patients and the corresponding genetic mouse model, the Fmr1 knockout mouse. Here, we tried to replicate the auditory deficits and assess whether also visual processing is affected, using electroencephalography readouts under freely behaving conditions in the second-generation Fmr1 knockout mice. No differences between wild-type and knockout animals were found in single auditory and visual evoked potentials in response to pure sine tones and full-field light flashes. Visual sensory gating was enhanced in the early but not the late components of the evoked potentials, but no changes were found in auditory sensory gating. The higher harmonics of the synchronisation response to flickering visual stimuli seemed to be reduced with 10, but not 20 or 40 Hz, stimulation. However, this effect was not reproduced in an independent second cohort of animals. No synchronisation differences were found in response to a chirp stimulus, of which the frequency steadily increased. Taken together, this study could not reproduce earlier reported increased amplitudes in auditory responses, nor could it convincingly show that synchronisation deficits found to be present in the auditory modality also existed in the visual modality. The discrepancies within this study as well as between various studies assessing sensory processing in the Fmr1 KO raise questions about the external validity of these phenotypes and warrant careful interpretation of these phenotypes.
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Affiliation(s)
- Renate Kat
- Groningen Institute for Evolutionary Life Sciences (GELIFES)University of GroningenGroningenThe Netherlands
| | - Martien J. H. Kas
- Groningen Institute for Evolutionary Life Sciences (GELIFES)University of GroningenGroningenThe Netherlands
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Wilde M, Constantin L, Thorne PR, Montgomery JM, Scott EK, Cheyne JE. Auditory processing in rodent models of autism: a systematic review. J Neurodev Disord 2022; 14:48. [PMID: 36042393 PMCID: PMC9429780 DOI: 10.1186/s11689-022-09458-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2022] [Accepted: 08/07/2022] [Indexed: 11/19/2022] Open
Abstract
Autism is a complex condition with many traits, including differences in auditory sensitivity. Studies in human autism are plagued by the difficulty of controlling for aetiology, whereas studies in individual rodent models cannot represent the full spectrum of human autism. This systematic review compares results in auditory studies across a wide range of established rodent models of autism to mimic the wide range of aetiologies in the human population. A search was conducted in the PubMed and Web of Science databases to find primary research articles in mouse or rat models of autism which investigate central auditory processing. A total of 88 studies were included. These used non-invasive measures of auditory function, such as auditory brainstem response recordings, cortical event-related potentials, electroencephalography, and behavioural tests, which are translatable to human studies. They also included invasive measures, such as electrophysiology and histology, which shed insight on the origins of the phenotypes found in the non-invasive studies. The most consistent results across these studies were increased latency of the N1 peak of event-related potentials, decreased power and coherence of gamma activity in the auditory cortex, and increased auditory startle responses to high sound levels. Invasive studies indicated loss of subcortical inhibitory neurons, hyperactivity in the lateral superior olive and auditory thalamus, and reduced specificity of responses in the auditory cortex. This review compares the auditory phenotypes across rodent models and highlights those that mimic findings in human studies, providing a framework and avenues for future studies to inform understanding of the auditory system in autism.
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Affiliation(s)
- Maya Wilde
- The Queensland Brain Institute, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Lena Constantin
- The Queensland Brain Institute, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Peter R Thorne
- Department of Physiology, Faculty of Medical and Health Sciences, Centre for Brain Research, University of Auckland, Auckland, New Zealand.,Section of Audiology, School of Population Health, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Johanna M Montgomery
- Department of Physiology, Faculty of Medical and Health Sciences, Centre for Brain Research, University of Auckland, Auckland, New Zealand
| | - Ethan K Scott
- The Queensland Brain Institute, The University of Queensland, Brisbane, QLD, 4072, Australia.,Department of Anatomy and Physiology, School of Biomedical Sciences, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Juliette E Cheyne
- Department of Physiology, Faculty of Medical and Health Sciences, Centre for Brain Research, University of Auckland, Auckland, New Zealand.
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Chaudry S, Vasudevan N. mTOR-Dependent Spine Dynamics in Autism. Front Mol Neurosci 2022; 15:877609. [PMID: 35782388 PMCID: PMC9241970 DOI: 10.3389/fnmol.2022.877609] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 04/25/2022] [Indexed: 12/12/2022] Open
Abstract
Autism Spectrum Conditions (ASC) are a group of neurodevelopmental disorders characterized by deficits in social communication and interaction as well as repetitive behaviors and restricted range of interests. ASC are complex genetic disorders with moderate to high heritability, and associated with atypical patterns of neural connectivity. Many of the genes implicated in ASC are involved in dendritic spine pruning and spine development, both of which can be mediated by the mammalian target of rapamycin (mTOR) signaling pathway. Consistent with this idea, human postmortem studies have shown increased spine density in ASC compared to controls suggesting that the balance between autophagy and spinogenesis is altered in ASC. However, murine models of ASC have shown inconsistent results for spine morphology, which may underlie functional connectivity. This review seeks to establish the relevance of changes in dendritic spines in ASC using data gathered from rodent models. Using a literature survey, we identify 20 genes that are linked to dendritic spine pruning or development in rodents that are also strongly implicated in ASC in humans. Furthermore, we show that all 20 genes are linked to the mTOR pathway and propose that the mTOR pathway regulating spine dynamics is a potential mechanism underlying the ASC signaling pathway in ASC. We show here that the direction of change in spine density was mostly correlated to the upstream positive or negative regulation of the mTOR pathway and most rodent models of mutant mTOR regulators show increases in immature spines, based on morphological analyses. We further explore the idea that these mutations in these genes result in aberrant social behavior in rodent models that is due to these altered spine dynamics. This review should therefore pave the way for further research on the specific genes outlined, their effect on spine morphology or density with an emphasis on understanding the functional role of these changes in ASC.
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Bigras C, Villatte B, Duda V, Hébert S. The electrophysiological markers of hyperacusis: a scoping review. Int J Audiol 2022:1-11. [PMID: 35549972 DOI: 10.1080/14992027.2022.2070083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
OBJECTIVE Hyperacusis is known as a reduced tolerance to sounds perceived as normal to the majority of the population. There is currently no agreed definition, diagnostic tool, or objective measure of its occurrence. The purpose of this review is to catalogue the research to date on the use of auditory evoked potentials (AEP) to assess hyperacusis. DESIGN A step-by-step methodology was conducted following guidelines. Four databases were searched. A total of 3343 papers were identified. A final yield of 35 articles were retained for analysis. RESULTS The analysis identified four types of aetiologies to describe the hyperacusic population in AEP studies; developmental disorders (n = 19), neurological disorders (n = 3), induced hearing damage (n = 8) and idiopathic aetiology (n = 5). Electrophysiological measures were of short (n = 16), middle (n = 13) and long (n = 19) latencies, believed to reflect the activity of the ascending and descending pathways of the auditory system from periphery to cortex. CONCLUSIONS The results of this review revealed the potential use of electrophysiological measures for further understanding the mechanisms of hyperacusis. However, according to the disparity of concepts to define hyperacusis, definitions and populations need to be clarified before biomarkers specific to hyperacusis can be identified.
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Affiliation(s)
- Charlotte Bigras
- School of Speech-Language Pathology and Audiology, Université de Montréal, Montreal, Canada.,Center of Research on Brain, Language and Music (CRBLM), Montreal, Canada
| | - Bérangère Villatte
- School of Speech-Language Pathology and Audiology, Université de Montréal, Montreal, Canada.,Center of Research on Brain, Language and Music (CRBLM), Montreal, Canada
| | - Victoria Duda
- School of Speech-Language Pathology and Audiology, Université de Montréal, Montreal, Canada.,Centre de recherche interdisciplinaire en réadaptation (CRIR), Montreal, Canada
| | - Sylvie Hébert
- School of Speech-Language Pathology and Audiology, Université de Montréal, Montreal, Canada.,Center of Research on Brain, Language and Music (CRBLM), Montreal, Canada
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Castro AC, Monteiro P. Auditory Dysfunction in Animal Models of Autism Spectrum Disorder. Front Mol Neurosci 2022; 15:845155. [PMID: 35493332 PMCID: PMC9043325 DOI: 10.3389/fnmol.2022.845155] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Accepted: 03/17/2022] [Indexed: 11/16/2022] Open
Abstract
Autism spectrum disorder (ASD) is a neurodevelopmental disorder mainly characterized by social-communication impairments, repetitive behaviors and altered sensory perception. Auditory hypersensitivity is the most common sensory-perceptual abnormality in ASD, however, its underlying neurobiological mechanisms remain elusive. Consistently with reports in ASD patients, animal models for ASD present sensory-perception alterations, including auditory processing impairments. Here we review the current knowledge regarding auditory dysfunction in rodent models of ASD, exploring both shared and distinct features among them, mechanistic and molecular underpinnings, and potential therapeutic approaches. Overall, auditory dysfunction in ASD models seems to arise from impaired central processing. Depending on the model, impairments may arise at different steps along the auditory pathway, from auditory brainstem up to the auditory cortex. Common defects found across models encompass atypical tonotopicity in different regions of the auditory pathway, temporal and spectral processing impairments and histological differences. Imbalance between excitation and inhibition (E/I imbalance) is one of the most well-supported mechanisms explaining the auditory phenotype in the ASD models studied so far and seems to be linked to alterations in GABAergic signaling. Such E/I imbalance may have a large impact on the development of the auditory pathway, influencing the establishment of connections responsible for normal sound processing.
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Affiliation(s)
- Ana Carolina Castro
- Life and Health Sciences Research Institute, School of Medicine, University of Minho, Braga, Portugal
- ICVS/3B’s–PT Government Associate Laboratory, Braga, Portugal
| | - Patricia Monteiro
- Life and Health Sciences Research Institute, School of Medicine, University of Minho, Braga, Portugal
- ICVS/3B’s–PT Government Associate Laboratory, Braga, Portugal
- *Correspondence: Patricia Monteiro,
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11
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Rais M, Lovelace JW, Shuai XS, Woodard W, Bishay S, Estrada L, Sharma AR, Nguy A, Kulinich A, Pirbhoy PS, Palacios AR, Nelson DL, Razak KA, Ethell IM. Functional consequences of postnatal interventions in a mouse model of Fragile X syndrome. Neurobiol Dis 2021; 162:105577. [PMID: 34871737 DOI: 10.1016/j.nbd.2021.105577] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2021] [Revised: 10/22/2021] [Accepted: 12/02/2021] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND Fragile X syndrome (FXS) is a leading genetic cause of autism and intellectual disability with cortical hyperexcitability and sensory hypersensitivity attributed to loss and hypofunction of inhibitory parvalbumin-expressing (PV) cells. Our studies provide novel insights into the role of excitatory neurons in abnormal development of PV cells during a postnatal period of inhibitory circuit refinement. METHODS To achieve Fragile X mental retardation gene (Fmr1) deletion and re-expression in excitatory neurons during the postnatal day (P)14-P21 period, we generated CreCaMKIIa/Fmr1Flox/y (cOFF) and CreCaMKIIa/Fmr1FloxNeo/y (cON) mice, respectively. Cortical phenotypes were evaluated in adult mice using biochemical, cellular, clinically relevant electroencephalogram (EEG) and behavioral tests. RESULTS We found that similar to global Fmr1 KO mice, the density of PV-expressing cells, their activation, and sound-evoked gamma synchronization were impaired in cOFF mice, but the phenotypes were improved in cON mice. cOFF mice also showed enhanced cortical gelatinase activity and baseline EEG gamma power, which were reduced in cON mice. In addition, TrkB phosphorylation and PV levels were lower in cOFF mice, which also showed increased locomotor activity and anxiety-like behaviors. Remarkably, when FMRP levels were restored in only excitatory neurons during the P14-P21 period, TrkB phosphorylation and mouse behaviors were also improved. CONCLUSIONS These results indicate that postnatal deletion or re-expression of FMRP in excitatory neurons is sufficient to elicit or ameliorate structural and functional cortical deficits, and abnormal behaviors in mice, informing future studies about appropriate treatment windows and providing fundamental insights into the cellular mechanisms of cortical circuit dysfunction in FXS.
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Affiliation(s)
- Maham Rais
- Division of Biomedical Sciences and Biomedical Sciences Graduate Program, School of Medicine, University of California Riverside, Riverside, CA 92521, USA
| | - Jonathan W Lovelace
- Department of Psychology, University of California Riverside, Riverside, CA 92521, USA
| | - Xinghao S Shuai
- Division of Biomedical Sciences and Biomedical Sciences Graduate Program, School of Medicine, University of California Riverside, Riverside, CA 92521, USA
| | - Walker Woodard
- Division of Biomedical Sciences and Biomedical Sciences Graduate Program, School of Medicine, University of California Riverside, Riverside, CA 92521, USA
| | - Steven Bishay
- Division of Biomedical Sciences and Biomedical Sciences Graduate Program, School of Medicine, University of California Riverside, Riverside, CA 92521, USA
| | - Leo Estrada
- Division of Biomedical Sciences and Biomedical Sciences Graduate Program, School of Medicine, University of California Riverside, Riverside, CA 92521, USA
| | - Ashwin R Sharma
- Division of Biomedical Sciences and Biomedical Sciences Graduate Program, School of Medicine, University of California Riverside, Riverside, CA 92521, USA
| | - Austin Nguy
- Division of Biomedical Sciences and Biomedical Sciences Graduate Program, School of Medicine, University of California Riverside, Riverside, CA 92521, USA
| | - Anna Kulinich
- Division of Biomedical Sciences and Biomedical Sciences Graduate Program, School of Medicine, University of California Riverside, Riverside, CA 92521, USA
| | - Patricia S Pirbhoy
- Division of Biomedical Sciences and Biomedical Sciences Graduate Program, School of Medicine, University of California Riverside, Riverside, CA 92521, USA
| | - Arnold R Palacios
- Division of Biomedical Sciences and Biomedical Sciences Graduate Program, School of Medicine, University of California Riverside, Riverside, CA 92521, USA
| | | | - Khaleel A Razak
- Department of Psychology, University of California Riverside, Riverside, CA 92521, USA; Neuroscience Graduate Program, University of California Riverside, Riverside, CA 92521, USA
| | - Iryna M Ethell
- Division of Biomedical Sciences and Biomedical Sciences Graduate Program, School of Medicine, University of California Riverside, Riverside, CA 92521, USA; Neuroscience Graduate Program, University of California Riverside, Riverside, CA 92521, USA.
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Pirbhoy PS, Jonak CR, Syed R, Argueta DA, Perez PA, Wiley MB, Hessamian K, Lovelace JW, Razak KA, DiPatrizio NV, Ethell IM, Binder DK. Increased 2-arachidonoyl-sn-glycerol levels normalize cortical responses to sound and improve behaviors in Fmr1 KO mice. J Neurodev Disord 2021; 13:47. [PMID: 34645383 PMCID: PMC8513313 DOI: 10.1186/s11689-021-09394-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 09/20/2021] [Indexed: 01/08/2023] Open
Abstract
Background Individuals with Fragile X syndrome (FXS) and autism spectrum disorder (ASD) exhibit an array of symptoms, including sociability deficits, increased anxiety, hyperactivity, and sensory hyperexcitability. It is unclear how endocannabinoid (eCB) modulation can be targeted to alleviate neurophysiological abnormalities in FXS as behavioral research reveals benefits to inhibiting cannabinoid (CB) receptor activation and increasing endocannabinoid ligand levels. Here, we hypothesize that enhancement of 2-arachidonoyl-sn-glycerol (2-AG) in Fragile X mental retardation 1 gene knock-out (Fmr1 KO) mice may reduce cortical hyperexcitability and behavioral abnormalities observed in FXS. Methods To test whether an increase in 2-AG levels normalized cortical responses in a mouse model of FXS, animals were subjected to electroencephalography (EEG) recording and behavioral assessment following treatment with JZL-184, an irreversible inhibitor of monoacylglycerol lipase (MAGL). Assessment of 2-AG was performed using lipidomic analysis in conjunction with various doses and time points post-administration of JZL-184. Baseline electrocortical activity and evoked responses to sound stimuli were measured using a 30-channel multielectrode array (MEA) in adult male mice before, 4 h, and 1 day post-intraperitoneal injection of JZL-184 or vehicle. Behavior assessment was done using the open field and elevated plus maze 4 h post-treatment. Results Lipidomic analysis showed that 8 mg/kg JZL-184 significantly increased the levels of 2-AG in the auditory cortex of both Fmr1 KO and WT mice 4 h post-treatment compared to vehicle controls. EEG recordings revealed a reduction in the abnormally enhanced baseline gamma-band power in Fmr1 KO mice and significantly improved evoked synchronization to auditory stimuli in the gamma-band range post-JZL-184 treatment. JZL-184 treatment also ameliorated anxiety-like and hyperactivity phenotypes in Fmr1 KO mice. Conclusions Overall, these results indicate that increasing 2-AG levels may serve as a potential therapeutic approach to normalize cortical responses and improve behavioral outcomes in FXS and possibly other ASDs. Supplementary Information The online version contains supplementary material available at 10.1186/s11689-021-09394-x.
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Affiliation(s)
- Patricia S Pirbhoy
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, CA, 92521, USA
| | - Carrie R Jonak
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, CA, 92521, USA
| | - Rashid Syed
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, CA, 92521, USA
| | - Donovan A Argueta
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, CA, 92521, USA
| | - Pedro A Perez
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, CA, 92521, USA
| | - Mark B Wiley
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, CA, 92521, USA
| | - Keon Hessamian
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, CA, 92521, USA
| | - Jonathan W Lovelace
- Department of Psychology, University of California, Riverside, Riverside, CA, 92521, USA
| | - Khaleel A Razak
- Department of Psychology, University of California, Riverside, Riverside, CA, 92521, USA
| | - Nicholas V DiPatrizio
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, CA, 92521, USA
| | - Iryna M Ethell
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, CA, 92521, USA
| | - Devin K Binder
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, CA, 92521, USA.
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13
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Razak KA, Binder DK, Ethell IM. Neural Correlates of Auditory Hypersensitivity in Fragile X Syndrome. Front Psychiatry 2021; 12:720752. [PMID: 34690832 PMCID: PMC8529206 DOI: 10.3389/fpsyt.2021.720752] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 08/16/2021] [Indexed: 01/20/2023] Open
Abstract
The mechanisms underlying the common association between autism spectrum disorders (ASD) and sensory processing disorders (SPD) are unclear, and treatment options to reduce atypical sensory processing are limited. Fragile X Syndrome (FXS) is a leading genetic cause of intellectual disability and ASD behaviors. As in most children with ASD, atypical sensory processing is a common symptom in FXS, frequently manifesting as sensory hypersensitivity. Auditory hypersensitivity is a highly debilitating condition in FXS that may lead to language delays, social anxiety and ritualized repetitive behaviors. Animal models of FXS, including Fmr1 knock out (KO) mouse, also show auditory hypersensitivity, providing a translation relevant platform to study underlying pathophysiological mechanisms. The focus of this review is to summarize recent studies in the Fmr1 KO mouse that identified neural correlates of auditory hypersensitivity. We review results of electroencephalography (EEG) recordings in the Fmr1 KO mice and highlight EEG phenotypes that are remarkably similar to EEG findings in humans with FXS. The EEG phenotypes associated with the loss of FMRP include enhanced resting EEG gamma band power, reduced cross frequency coupling, reduced sound-evoked synchrony of neural responses at gamma band frequencies, increased event-related potential amplitudes, reduced habituation of neural responses and increased non-phase locked power. In addition, we highlight the postnatal period when the EEG phenotypes develop and show a strong association of the phenotypes with enhanced matrix-metalloproteinase-9 (MMP-9) activity, abnormal development of parvalbumin (PV)-expressing inhibitory interneurons and reduced formation of specialized extracellular matrix structures called perineuronal nets (PNNs). Finally, we discuss how dysfunctions of inhibitory PV interneurons may contribute to cortical hyperexcitability and EEG abnormalities observed in FXS. Taken together, the studies reviewed here indicate that EEG recordings can be utilized in both pre-clinical studies and clinical trials, while at the same time, used to identify cellular and circuit mechanisms of dysfunction in FXS. New therapeutic approaches that reduce MMP-9 activity and restore functions of PV interneurons may succeed in reducing FXS sensory symptoms. Future studies should examine long-lasting benefits of developmental vs. adult interventions on sensory phenotypes.
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Affiliation(s)
- Khaleel A. Razak
- Department of Psychology, University of California, Riverside, Riverside, CA, United States
- Graduate Neuroscience Program, University of California, Riverside, Riverside, CA, United States
| | - Devin K. Binder
- Graduate Neuroscience Program, University of California, Riverside, Riverside, CA, United States
- Division of Biomedical Sciences and Graduate Biomedical Sciences Program, School of Medicine, University of California, Riverside, Riverside, CA, United States
| | - Iryna M. Ethell
- Graduate Neuroscience Program, University of California, Riverside, Riverside, CA, United States
- Division of Biomedical Sciences and Graduate Biomedical Sciences Program, School of Medicine, University of California, Riverside, Riverside, CA, United States
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14
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Qiu J, Singh P, Pan G, de Paolis A, Champagne FA, Liu J, Cardoso L, Rodríguez-Contreras A. Defining the relationship between maternal care behavior and sensory development in Wistar rats: Auditory periphery development, eye opening and brain gene expression. PLoS One 2020; 15:e0237933. [PMID: 32822407 PMCID: PMC7442246 DOI: 10.1371/journal.pone.0237933] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Accepted: 08/05/2020] [Indexed: 12/18/2022] Open
Abstract
Defining the relationship between maternal care, sensory development and brain gene expression in neonates is important to understand the impact of environmental challenges during sensitive periods in early life. In this study, we used a selection approach to test the hypothesis that variation in maternal licking and grooming (LG) during the first week of life influences sensory development in Wistar rat pups. We tracked the onset of the auditory brainstem response (ABR), the timing of eye opening (EO), middle ear development with micro-CT X-ray tomography, and used qRT-PCR to monitor changes in gene expression of the hypoxia-sensitive pathway and neurotrophin signaling in pups reared by low-LG or high-LG dams. The results show the first evidence that the transcription of genes involved in the hypoxia-sensitive pathway and neurotrophin signaling is regulated during separate sensitive periods that occur before and after hearing onset, respectively. Although the timing of ABR onset, EO, and the relative mRNA levels of genes involved in the hypoxia-sensitive pathway did not differ between pups from different LG groups, we found statistically significant increases in the relative mRNA levels of four genes involved in neurotrophin signaling in auditory brain regions from pups of different LG backgrounds. These results suggest that sensitivity to hypoxic challenge might be widespread in the auditory system of neonate rats before hearing onset, and that maternal LG may affect the transcription of genes involved in experience-dependent neuroplasticity.
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Affiliation(s)
- Jingyun Qiu
- Department of Biology and Center for Discovery and Innovation, City College, City University of New York, New York, New York, United States of America
| | - Preethi Singh
- Department of Biology and Center for Discovery and Innovation, City College, City University of New York, New York, New York, United States of America
| | - Geng Pan
- Department of Biology and Center for Discovery and Innovation, City College, City University of New York, New York, New York, United States of America
| | - Annalisa de Paolis
- Department of Biomedical Engineering, City College, City University of New York, New York, New York, United States of America
| | - Frances A. Champagne
- Department of Psychology, University of Texas at Austin, Austin, Texas, United States of America
| | - Jia Liu
- Neuroscience Initiative, Advanced Science Research Center at the Graduate Center, City University of New York, New York, New York, United States of America
| | - Luis Cardoso
- Department of Biomedical Engineering, City College, City University of New York, New York, New York, United States of America
| | - Adrián Rodríguez-Contreras
- Department of Biology and Center for Discovery and Innovation, City College, City University of New York, New York, New York, United States of America
- * E-mail:
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15
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Lovelace JW, Ethell IM, Binder DK, Razak KA. Minocycline Treatment Reverses Sound Evoked EEG Abnormalities in a Mouse Model of Fragile X Syndrome. Front Neurosci 2020; 14:771. [PMID: 32848552 PMCID: PMC7417521 DOI: 10.3389/fnins.2020.00771] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 06/30/2020] [Indexed: 01/19/2023] Open
Abstract
Fragile X Syndrome (FXS) is a leading known genetic cause of intellectual disability. Many symptoms of FXS overlap with those in autism including repetitive behaviors, language delays, anxiety, social impairments and sensory processing deficits. Electroencephalogram (EEG) recordings from humans with FXS and an animal model, the Fmr1 knockout (KO) mouse, show remarkably similar phenotypes suggesting that EEG phenotypes can serve as biomarkers for developing treatments. This includes enhanced resting gamma band power and sound evoked total power, and reduced fidelity of temporal processing and habituation of responses to repeated sounds. Given the therapeutic potential of the antibiotic minocycline in humans with FXS and animal models, it is important to determine sensitivity and selectivity of EEG responses to minocycline. Therefore, in this study, we examined if a 10-day treatment of adult Fmr1 KO mice with minocycline (oral gavage, 30 mg/kg per day) would reduce EEG abnormalities. We tested if minocycline treatment has specific effects based on the EEG measurement type (e.g., resting versus sound-evoked) from the frontal and auditory cortex of the Fmr1 KO mice. We show increased resting EEG gamma power and reduced phase locking to time varying stimuli as well as the 40 Hz auditory steady state response in the Fmr1 KO mice in the pre-drug condition. Minocycline treatment increased gamma band phase locking in response to auditory stimuli, and reduced sound-evoked power of auditory event related potentials (ERP) in Fmr1 KO mice compared to vehicle treatment. Minocycline reduced resting EEG gamma power in Fmr1 KO mice, but this effect was similar to vehicle treatment. We also report frequency band-specific effects on EEG responses. Taken together, these data indicate that sound-evoked EEG responses may serve as more sensitive measures, compared to resting EEG measures, to isolate minocycline effects from placebo in humans with FXS. Given the use of minocycline and EEG recordings in a number of neurodegenerative and neurodevelopmental conditions, these findings may be more broadly applicable in translational neuroscience.
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Affiliation(s)
- Jonathan W Lovelace
- Department of Psychology and Neuroscience Graduate Program, University of California, Riverside, Riverside, CA, United States
| | - Iryna M Ethell
- Neuroscience Graduate Program, University of California, Riverside, Riverside, CA, United States.,Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, CA, United States
| | - Devin K Binder
- Neuroscience Graduate Program, University of California, Riverside, Riverside, CA, United States.,Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, CA, United States
| | - Khaleel A Razak
- Department of Psychology and Neuroscience Graduate Program, University of California, Riverside, Riverside, CA, United States.,Neuroscience Graduate Program, University of California, Riverside, Riverside, CA, United States
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16
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Pirbhoy PS, Rais M, Lovelace JW, Woodard W, Razak KA, Binder DK, Ethell IM. Acute pharmacological inhibition of matrix metalloproteinase-9 activity during development restores perineuronal net formation and normalizes auditory processing in Fmr1 KO mice. J Neurochem 2020; 155:538-558. [PMID: 32374912 DOI: 10.1111/jnc.15037] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 03/31/2020] [Accepted: 04/30/2020] [Indexed: 12/13/2022]
Abstract
Individuals with Fragile X Syndrome (FXS) and autism spectrum disorder (ASD) exhibit cognitive impairments, social deficits, increased anxiety, and sensory hyperexcitability. Previously, we showed that elevated levels of matrix metalloproteinase-9 (MMP-9) may contribute to abnormal development of parvalbumin (PV) interneurons and perineuronal nets (PNNs) in the developing auditory cortex (AC) of Fmr1 knock-out (KO) mice, which likely underlie auditory hypersensitivity. Thus, MMP-9 may serve as a potential target for treatment of auditory hypersensitivity in FXS. Here, we used the MMP-2/9 inhibitor, SB-3CT, to pharmacologically inhibit MMP-9 activity during a specific developmental period and to test whether inhibition of MMP-9 activity reverses neural oscillation deficits and behavioral impairments by enhancing PNN formation around PV cells in Fmr1 KO mice. Electroencephalography (EEG) was used to measure resting state and sound-evoked electrocortical activity in auditory and frontal cortices of postnatal day (P)22-23 male mice before and one-day after treatment with SB-3CT (25 mg/kg) or vehicle. At P27-28, animal behaviors were tested to measure the effects of the treatment on anxiety and hyperactivity. Results show that acute inhibition of MMP-9 activity improved evoked synchronization to auditory stimuli and ameliorated mouse behavioral deficits. MMP-9 inhibition enhanced PNN formation, increased PV levels and TrkB phosphorylation yet reduced Akt phosphorylation in the AC of Fmr1 KO mice. Our results show that MMP-9 inhibition during early postnatal development is beneficial in reducing some auditory processing deficits in the FXS mouse model and may serve as a candidate therapeutic for reversing sensory hypersensitivity in FXS and possibly other ASDs.
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Affiliation(s)
- Patricia S Pirbhoy
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA, USA
| | - Maham Rais
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA, USA
| | - Jonathan W Lovelace
- Department of Psychology, University of California Riverside, Riverside, CA, USA
| | - Walker Woodard
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA, USA
| | - Khaleel A Razak
- Department of Psychology, University of California Riverside, Riverside, CA, USA
| | - Devin K Binder
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA, USA
| | - Iryna M Ethell
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA, USA
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17
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Razak KA, Dominick KC, Erickson CA. Developmental studies in fragile X syndrome. J Neurodev Disord 2020; 12:13. [PMID: 32359368 PMCID: PMC7196229 DOI: 10.1186/s11689-020-09310-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 02/13/2020] [Indexed: 01/27/2023] Open
Abstract
Fragile X syndrome (FXS) is the most common single gene cause of autism and intellectual disabilities. Humans with FXS exhibit increased anxiety, sensory hypersensitivity, seizures, repetitive behaviors, cognitive inflexibility, and social behavioral impairments. The main purpose of this review is to summarize developmental studies of FXS in humans and in the mouse model, the Fmr1 knockout mouse. The literature presents considerable evidence that a number of early developmental deficits can be identified and that these early deficits chart a course of altered developmental experience leading to symptoms well characterized in adolescents and adults. Nevertheless, a number of critical issues remain unclear or untested regarding the development of symptomology and underlying mechanisms. First, what is the role of FMRP, the protein product of Fmr1 gene, during different developmental ages? Does the absence of FMRP during early development lead to irreversible changes, or could reintroduction of FMRP or therapeutics aimed at FMRP-interacting proteins/pathways hold promise when provided in adults? These questions have implications for clinical trial designs in terms of optimal treatment windows, but few studies have systematically addressed these issues in preclinical and clinical work. Published studies also point to complex trajectories of symptom development, leading to the conclusion that single developmental time point studies are unlikely to disambiguate effects of genetic mutation from effects of altered developmental experience and compensatory plasticity. We conclude by suggesting a number of experiments needed to address these major gaps in the field.
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Affiliation(s)
- Khaleel A Razak
- Department of Psychology and Graduate Neuroscience Program, University of California, Riverside, USA
| | - Kelli C Dominick
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Cincinnati, OH, USA.,Division of Child and Adolescent Psychiatry, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue MLC 4002, Cincinnati, OH, 45229, USA
| | - Craig A Erickson
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Cincinnati, OH, USA. .,Division of Child and Adolescent Psychiatry, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue MLC 4002, Cincinnati, OH, 45229, USA.
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18
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Nguyen AO, Binder DK, Ethell IM, Razak KA. Abnormal development of auditory responses in the inferior colliculus of a mouse model of Fragile X Syndrome. J Neurophysiol 2020; 123:2101-2121. [PMID: 32319849 DOI: 10.1152/jn.00706.2019] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Sensory processing abnormalities are frequently associated with autism spectrum disorders, but the underlying mechanisms are unclear. Here we studied auditory processing in a mouse model of Fragile X Syndrome (FXS), a leading known genetic cause of autism and intellectual disability. Both humans with FXS and the Fragile X mental retardation gene (Fmr1) knockout (KO) mouse model show auditory hypersensitivity, with the latter showing a strong propensity for audiogenic seizures (AGS) early in development. Because midbrain abnormalities cause AGS, we investigated whether the inferior colliculus (IC) of the Fmr1 KO mice shows abnormal auditory processing compared with wild-type (WT) controls at specific developmental time points. Using antibodies against neural activity marker c-Fos, we found increased density of c-Fos+ neurons in the IC, but not auditory cortex, of Fmr1 KO mice at P21 and P34 following sound presentation. In vivo single-unit recordings showed that IC neurons of Fmr1 KO mice are hyperresponsive to tone bursts and amplitude-modulated tones during development and show broader frequency tuning curves. There were no differences in rate-level responses or phase locking to amplitude-modulated tones in IC neurons between genotypes. Taken together, these data provide evidence for the development of auditory hyperresponsiveness in the IC of Fmr1 KO mice. Although most human and mouse work in autism and sensory processing has centered on the forebrain, our new findings, along with recent work on the lower brainstem, suggest that abnormal subcortical responses may underlie auditory hypersensitivity in autism spectrum disorders.NEW & NOTEWORTHY Autism spectrum disorders (ASD) are commonly associated with sensory sensitivity issues, but the underlying mechanisms are unclear. This study presents novel evidence for neural correlates of auditory hypersensitivity in the developing inferior colliculus (IC) in Fmr1 knockout (KO) mouse, a mouse model of Fragile X Syndrome (FXS), a leading genetic cause of ASD. Responses begin to show genotype differences between postnatal days 14 and 21, suggesting an early developmental treatment window.
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Affiliation(s)
- Anna O Nguyen
- Bioengineering Program, University of California, Riverside, California
| | - Devin K Binder
- Graduate Neuroscience Program, University of California, Riverside, California.,Division of Biomedical Sciences, University of California, Riverside, California
| | - Iryna M Ethell
- Graduate Neuroscience Program, University of California, Riverside, California.,Division of Biomedical Sciences, University of California, Riverside, California
| | - Khaleel A Razak
- Graduate Neuroscience Program, University of California, Riverside, California.,Psychology Department, University of California, Riverside, California
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