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Cognitive disruption and altered hippocampus synaptic function in Reelin haploinsufficient mice
Shenfeng Qiu1, Kimberly M Korwek, Adeola R Pratt-Davis
1Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN 37232-0615, USA.
Neurobiology of Learning and Memory
|December 27, 2005
Summary
The heterozygote reeler mouse model exhibits deficits in contextual fear learning and hippocampal plasticity, specifically impaired long-term potentiation and reduced inhibitory signaling, offering insights into cognitive disorders.
Area of Science:
- Neuroscience
- Genetics
- Cognitive Science
Background:
- The heterozygote reeler mouse (HRM) displays neuroanatomical and biochemical similarities to human cognitive disorders like schizophrenia.
- Reelin haploinsufficiency is investigated for its role in phenotypic functional differences.
Purpose of the Study:
- To comprehensively characterize hippocampal-dependent plasticity and cognitive function in the HRM.
- To identify functional differences arising from Reelin haploinsufficiency.
Main Methods:
- Behavioral tests assessing activity, coordination, nociception, anxiety, and learning (Morris water maze, contextual fear conditioning).
- Electrophysiological recordings in hippocampal CA1 synapses to evaluate synaptic plasticity (LTP, LTD) and neuronal activity.
- Analysis of glutamate receptor subunits and spontaneous excitatory/inhibitory postsynaptic currents.
Main Results:
- HRMs showed normal general activity and spatial learning but impaired contextual fear conditioning.
- Significant deficits in hippocampal CA1 synaptic plasticity, including reduced field excitatory postsynaptic potentials, impaired LTP and LTD.
- Reduced spontaneous inhibitory postsynaptic currents in CA1 pyramidal neurons, without changes in excitatory currents or glutamate receptor subunits.
Conclusions:
- HRMs exhibit specific hippocampal-dependent learning deficits linked to impaired synaptic plasticity.
- Reduced inhibitory innervation in the hippocampus may underlie the observed cognitive and plasticity impairments.
- The HRM serves as a valuable model for studying Reelin haploinsufficiency in cognitive disorders.