Differential Effect of Amyloid Beta1-40 on Short-term and Long-term Plasticity in Dentate Gyrus of a Rat Model of Alzheimer Disease

Tourandokht Baluchnejadmojarad | Mehrdad Roghani | Javad Fahanik-Babaei

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URL :   http://research.shahed.ac.ir/WSR/WebPages/Report/PaperView.aspx?PaperID=158412
Date :  2020/07/28
Publish in :    Basic and Clinical Neuroscience


Keywords :Alzheimer disease, Amyloid beta, Synaptic plasticity

Abstract :

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Introduction: Synaptic plasticity is inappropriately affected by neurodegenerative diseases, including Alzheimer Disease (AD). In this study, we examined the effect of intrahippocampal amyloid-beta (Aβ1-40) on dentate gyrus Long-term Potentiation (LTP) and presynaptic shortterm plasticity in a rat model of AD. Methods: The experimental groups in this research included the control with no treatment, sham-operated receiving the vehicle (normal saline), and Aβ-lesioned groups. For modeling AD, aggregated Aβ1-40 (10 μg/2 μl on each side) was injected into the hippocampal CA1. Three weeks later, Population Spike (PS) amplitude and slope ratios were determined at different Inter-pulse Intervals (IPI) of 10, 20, 30, and 50 ms as a valid indicator of the shortterm presynaptic facilitation and/or depression. In addition, PS amplitude and slope were taken as an index of long-term synaptic plasticity after application of High-frequency Stimulation (HFS) to induce LTP in the medial perforant-dentate gyrus pathway. Results: No significant differences were noted amongst the experimental groups regarding fEPSP slope and paired-pulse indices as indicators of short-term plasticity. In contrast, fEPSP slope and PS amplitude significantly decreased following the application of HFS in Aβ-injected group. In addition, there was no significant difference between the control and sham-operated groups regarding the mentioned parameters. Conclusion: Findings of this study clearly demonstrated that microinjection of Aβ1-40 into the CA1 could impair LTP in dentate gyrus but could not modify short-term plasticity.