Hannah E Frye1, Yukitoshi Izumi2, Alexis N Harris3, Sidney B Williams4, Christopher R Trousdale4, Min-Yu Sun5, Andrew D Sauerbeck6, Terrance T Kummer6, Steven Mennerick2, Charles F Zorumski2, Elliot C Nelson5, Joseph D Dougherty7, Jose A Morón8. 1. Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri; Pain Center, Washington University School of Medicine, St. Louis, Missouri; Program in Neuroscience, Washington University in St. Louis, St. Louis, Missouri. 2. Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri; Department of Neuroscience, Washington University School of Medicine, St. Louis, Missouri; Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine, St. Louis, Missouri. 3. Department of Genetics, Washington University School of Medicine, St. Louis, Missouri. 4. Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri; Pain Center, Washington University School of Medicine, St. Louis, Missouri. 5. Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri. 6. Department of Neurology, Washington University School of Medicine, St. Louis, Missouri. 7. Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri; Department of Genetics, Washington University School of Medicine, St. Louis, Missouri. 8. Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri; Pain Center, Washington University School of Medicine, St. Louis, Missouri; Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri; Department of Neuroscience, Washington University School of Medicine, St. Louis, Missouri. Electronic address: jmoron-concepcion@wustl.edu.
Abstract
BACKGROUND: CNIH3 is an AMPA receptor (AMPAR) auxiliary protein prominently expressed in the dorsal hippocampus (dHPC), a region that plays a critical role in spatial memory and synaptic plasticity. However, the effects of CNIH3 on AMPAR-dependent synaptic function and behavior have not been investigated. METHODS: We assessed a gain-of-function model of Cnih3 overexpression in the dHPC and generated and characterized a line of Cnih3-/- C57BL/6 mice. We assessed spatial memory through behavioral assays, protein levels of AMPAR subunits and synaptic proteins by immunoblotting, and long-term potentiation in electrophysiological recordings. We also utilized a super-resolution imaging workflow, SEQUIN (Synaptic Evaluation and Quantification by Imaging of Nanostructure), for analysis of nanoscale synaptic connectivity in the dHPC. RESULTS: Overexpression of Cnih3 in the dHPC improved short-term spatial memory in female mice but not in male mice. Cnih3-/- female mice exhibited weakened short-term spatial memory, reduced dHPC synapse density, enhanced expression of calcium-impermeable AMPAR (GluA2-containing) subunits in synaptosomes, and attenuated long-term potentiation maintenance compared with Cnih3+/+ control mice; Cnih3-/- males were unaffected. Further investigation revealed that deficiencies in spatial memory and changes in AMPAR composition and synaptic plasticity were most pronounced during the metestrus phase of the estrous cycle in female Cnih3-/- mice. CONCLUSIONS: This study identified a novel effect of sex and estrous on CNIH3's role in spatial memory and synaptic plasticity. Manipulation of CNIH3 unmasked sexually dimorphic effects on spatial memory, synaptic function, AMPAR composition, and hippocampal plasticity. These findings reinforce the importance of considering sex as a biological variable in studies of memory and hippocampal synaptic function.
BACKGROUND: CNIH3 is an AMPA receptor (AMPAR) auxiliary protein prominently expressed in the dorsal hippocampus (dHPC), a region that plays a critical role in spatial memory and synaptic plasticity. However, the effects of CNIH3 on AMPAR-dependent synaptic function and behavior have not been investigated. METHODS: We assessed a gain-of-function model of Cnih3 overexpression in the dHPC and generated and characterized a line of Cnih3-/- C57BL/6 mice. We assessed spatial memory through behavioral assays, protein levels of AMPAR subunits and synaptic proteins by immunoblotting, and long-term potentiation in electrophysiological recordings. We also utilized a super-resolution imaging workflow, SEQUIN (Synaptic Evaluation and Quantification by Imaging of Nanostructure), for analysis of nanoscale synaptic connectivity in the dHPC. RESULTS: Overexpression of Cnih3 in the dHPC improved short-term spatial memory in female mice but not in male mice. Cnih3-/- female mice exhibited weakened short-term spatial memory, reduced dHPC synapse density, enhanced expression of calcium-impermeable AMPAR (GluA2-containing) subunits in synaptosomes, and attenuated long-term potentiation maintenance compared with Cnih3+/+ control mice; Cnih3-/- males were unaffected. Further investigation revealed that deficiencies in spatial memory and changes in AMPAR composition and synaptic plasticity were most pronounced during the metestrus phase of the estrous cycle in female Cnih3-/- mice. CONCLUSIONS: This study identified a novel effect of sex and estrous on CNIH3's role in spatial memory and synaptic plasticity. Manipulation of CNIH3 unmasked sexually dimorphic effects on spatial memory, synaptic function, AMPAR composition, and hippocampal plasticity. These findings reinforce the importance of considering sex as a biological variable in studies of memory and hippocampal synaptic function.
Authors: Sophie K Billa; Jie Liu; Nicole L Bjorklund; Namita Sinha; Yu Fu; Patricia Shinnick-Gallagher; Jose A Morón Journal: Mol Pharmacol Date: 2010-02-16 Impact factor: 4.436
Authors: Martin B Gill; Akihiko S Kato; Matthew F Roberts; Hong Yu; He Wang; Susumu Tomita; David S Bredt Journal: J Neurosci Date: 2011-05-04 Impact factor: 6.167