title: Altered sensory experience exacerbates stable dendritic spine and synapse loss in a mouse model of Huntington's disease.
abstract: A key question in Huntington's disease (HD) is what underlies the early cognitive deficits that precede the motor symptoms and the characteristic neuronal death observed in HD. The mechanisms underlying cognitive symptoms in HD remain unknown. Postmortem HD brain and animal model studies demonstrate pathologies in dendritic spines and abnormal synaptic plasticity before motor symptoms and neurodegeneration. Experience-dependent synaptic plasticity caused by mechanisms such as LTP or novel sensory experience potentiates synaptic strength, enhances new dendritic spine formation and stabilization, and may contribute to normal cognitive processes, such as learning and memory. We have previously reported that under baseline conditions (without any sensory manipulation) neuronal circuitry in HD (R6/2 mouse model) was highly unstable, which led to a progressive loss of persistent spines in these mice, and that mutant huntingtin was directly involved in the process. Here, we investigated whether pathological processes of HD interfere with the normal experience-dependent plasticity of dendritic spines in the R6/2 model. Six weeks of two-photon in vivo imaging before and after whisker trimming revealed that sensory deprivation exacerbates loss of persistent-type, stable spines in R6/2 mice compared with wild-type littermates. In addition, sensory deprivation leads to impaired transformation of newly generated spines into persistent spines in R6/2 mice. As a consequence, reduced synaptic density and decreased PSD-95 protein levels are evident in their barrel cortical neurons. These data suggest that mutant huntingtin is implicated in maladaptive synaptic plasticity, which could be one of the plausible mechanisms underlying early cognitive deficits in HD.
authors.affiliation: Neural Plasticity and Repair Unit, Wallenberg Neuroscience Center, Department of Experimental Medical Sciences, Lund University, BMC A10, 22184 Lund, Sweden, and.
authors.forename: Reena Prity
authors.initials: RP
authors.lastname: Murmu
authors.affiliation: Neural Plasticity and Repair Unit, Wallenberg Neuroscience Center, Department of Experimental Medical Sciences, Lund University, BMC A10, 22184 Lund, Sweden, and.
authors.forename: Wen
authors.initials: W
authors.lastname: Li
authors.affiliation: Neural Plasticity and Repair Unit, Wallenberg Neuroscience Center, Department of Experimental Medical Sciences, Lund University, BMC A10, 22184 Lund, Sweden, and.
authors.forename: Zsuzsanna
authors.initials: Z
authors.lastname: Szepesi
authors.affiliation: Neural Plasticity and Repair Unit, Wallenberg Neuroscience Center, Department of Experimental Medical Sciences, Lund University, BMC A10, 22184 Lund, Sweden, and Neuroscience Institute, College of Life and Health Sciences, Northeastern University, Shenyang 110015, People's Republic of China jia-yi.li@med.lu.se jiayili@mail.neu.edu.cn.
authors.forename: Jia-Yi
authors.initials: JY
authors.lastname: Li
mesh_terms: D000818:Animals; D049229:Dendritic Spines / Q000235:genetics / Q000473:pathology*; D004195:Disease Models, Animal; D006801:Humans; D006816:Huntington Disease / Q000235:genetics / Q000473:pathology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008822:Mice, Transgenic; D009473:Neuronal Plasticity / Q000502:physiology*; D012683:Sensory Deprivation / Q000502:physiology*; D013569:Synapses / Q000473:pathology*; D014738:Vibrissae / Q000502:physiology
keywords: Huntington's disease; cognitive dysfunction; dendritic spines; sensory deprivation; synaptic plasticity