Impairment of synaptic plasticity and novel object recognition in the hypergravity-exposed rats

Jinho Lee,Sunggu Yang,Hyerin Jeong,Doohyeong Jang,Kyu-Sung Kim

doi:10.1038/s41598-020-72639-7

Jinho Lee, Sunggu Yang + Show 3 more

Open Access

https://doi.org/10.1038/s41598-020-72639-7

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Journal: Scientific Reports	Publication Date: Sep 25, 2020
Citations: 7	License type: open-access

Affiliation: Incheon National University, Inha University

Abstract

The gravity is necessary for living organisms to operate various biological events including hippocampus-related functions of learning and memory. Until now, it remains inconclusive how altered gravity is associated with hippocampal functions. It is mainly due to the difficulties in generating an animal model experiencing altered gravity. Here, we demonstrate the effects of hypergravity on hippocampus-related functions using an animal behavior and electrophysiology with our hypergravity animal model. The hypergravity (4G, 4 weeks) group showed impaired synaptic efficacy and long-term potentiation in CA1 neurons of the hippocampus along with the poor performance of a novel object recognition task. Our studies suggest that altered gravity affects hippocampus-related cognitive functions, presumably through structural and functional adaptation to various conditions of gravity shift.

Highlights

The gravity is necessary for living organisms to operate various biological events including hippocampus-related functions of learning and memory
Postsynaptic responses were reduced under long-term HG, largely due to the impairment of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) and N-methyl-d-aspartate receptors (NMDARs)
We found that the HG group had the significant reduction in NMDAR response when compared with that of the 1G group (Fig. 3c; 1G—0.2 mV: 0.32 ± 0.04, n = 10 slices, 0.4 mV: 0.60 ± 0.10, n = 12 slices, 0.6 mV: 1.19 ± 0.04, n = 4 slices; HG—0.2 mV: 0.18 ± 0.02, n = 5 slices, 0.4 mV: 0.35 ± 0.05, n = slices, 0.6 mV: 0.57 ± 0.10, n = slices; F1,46 = 32.989, p < 0.001)

Summary

Introduction

The gravity is necessary for living organisms to operate various biological events including hippocampus-related functions of learning and memory. The effect of gravity on the hippocampus is investigated in various methods of behavioral, molecular, and electrophysiological aspects. Various effects of gravity on hippocampus-related functions from genetic to molecular, behavioral, and electrophysiological levels are summarized, based on the duration and induction method of MG and HG.

Results

Conclusion