title: Hyperactivity and cortical disinhibition in mice with restricted expression of mutant huntingtin to parvalbumin-positive cells.
abstract: Recent evidence suggests that interneurons are involved in the pathophysiology of Huntington Disease (HD). Abnormalities in the function of interneurons expressing the calcium buffer parvalbumin (PV) have been observed in multiple mouse models of HD, although it is not clear how PV-positive interneuron dysfunction contributes to behavioral and synaptic deficits. Here, we use the cre-lox system to drive expression of mutant huntingtin (mthtt) in parvalbumin (PV)-positive neurons and find that mutant mice exhibit diffuse mthtt immunoreactivity in PV-rich areas at 10months of age and mthtt aggregates in PV-positive processes at 24months of age. At midlife, mutant mice are hyperactive and display impaired GABA release in the motor cortex, characterized by reduced miniature inhibitory events and severely blunted responses to gamma frequency stimulation, without a loss of PV-positive interneurons. In contrast, 24month-old mutant mice show normalized behavior and responses to gamma frequency stimulation, possibly due to compensatory changes in pyramidal neurons or the formation of inclusions with age. These data indicate that mthtt expression in PV-positive neurons is sufficient to drive a hyperactive phenotype and suggest that mthtt-mediated dysfunction in PV-positive neuronal populations could be a key factor in the hyperkinetic behavior observed in HD. Further clarification of the roles for specific PV-positive populations in this phenotype is warranted to definitively identify cellular targets for intervention.
authors.affiliation: Neuroscience Graduate Program, University of Alabama at Birmingham, 35294, USA; Department of Psychiatry & Behavioral Neurobiology, University of Alabama at Birmingham, 35294, USA.
authors.forename: S E
authors.initials: SE
authors.lastname: Dougherty
authors.affiliation: Department of Psychiatry & Behavioral Neurobiology, University of Alabama at Birmingham, 35294, USA.
authors.forename: J J
authors.initials: JJ
authors.lastname: Hollimon
authors.affiliation: Department of Psychiatry & Behavioral Neurobiology, University of Alabama at Birmingham, 35294, USA.
authors.forename: L J
authors.initials: LJ
authors.lastname: McMeekin
authors.affiliation: Department of Psychiatry & Behavioral Neurobiology, University of Alabama at Birmingham, 35294, USA.
authors.forename: A S
authors.initials: AS
authors.lastname: Bohannon
authors.affiliation: Department of Neurology, University of Alabama at Birmingham, 35294, USA.
authors.forename: A B
authors.initials: AB
authors.lastname: West
authors.affiliation: Department of Psychiatry & Behavioral Neurobiology, University of Alabama at Birmingham, 35294, USA.
authors.forename: M
authors.initials: M
authors.lastname: Lesort
authors.affiliation: Department of Neurobiology, University of Alabama at Birmingham, 35294, USA.
authors.forename: J J
authors.initials: JJ
authors.lastname: Hablitz
authors.affiliation: Department of Psychiatry & Behavioral Neurobiology, University of Alabama at Birmingham, 35294, USA. Electronic address: rcowell@uab.edu.
authors.forename: R M
authors.initials: RM
authors.lastname: Cowell
mesh_terms: D000367:Age Factors; D000818:Animals; D001921:Brain / Q000378:metabolism; D005260:Female; D000071058:Huntingtin Protein; D006948:Hyperkinesis / Q000378:metabolism* / Q000503:physiopathology; D053444:Inhibitory Postsynaptic Potentials; D007395:Interneurons / Q000502:physiology*; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D009044:Motor Cortex / Q000503:physiopathology*; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010320:Parvalbumins / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: C506812:Htt protein, mouse; D000071058:Huntingtin Protein; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D010320:Parvalbumins; D005680:gamma-Aminobutyric Acid
keywords: Cortical electrophysiology; GABAergic; Huntington Disease; Interneuron; Parvalbumin