AUTHOR=Impey Soren , Pelz Carl , Riparip Lara-Kirstie , Tafessu Amanuel , Fareh Fatema , Zuloaga Damian G. , Marzulla Tessa , Stewart Blair , Rosi Susanna , Turker Mitchell S. , Raber Jacob 

TITLE=Postsynaptic density radiation signature following space irradiation

JOURNAL=Frontiers in Physiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2023.1215535

DOI=10.3389/fphys.2023.1215535

ISSN=1664-042X

ABSTRACT=<p><bold>Introduction:</bold> The response of the brain to space radiation is an important concern for astronauts during space missions. Therefore, we assessed the response of the brain to <sup>28</sup>Si ion irradiation (600 MeV/n), a heavy ion present in the space environment, on cognitive performance and whether the response is associated with altered DNA methylation in the hippocampus, a brain area important for cognitive performance.</p><p><bold>Methods:</bold> We determined the effects of <sup>28</sup>Si ion irradiation on object recognition, 6-month-old mice irradiated with <sup>28</sup>Si ions (600 MeV/n, 0.3, 0.6, and 0.9 Gy) and cognitively tested two weeks later. In addition, we determined if those effects were associated with alterations in hippocampal networks and/or hippocampal DNA methylation.</p><p><bold>Results:</bold> At 0.3 Gy, but not at 0.6 Gy or 0.9 Gy, <sup>28</sup>Si ion irradiation impaired cognition that correlated with altered gene expression and 5 hmC profiles that mapped to specific gene ontology pathways. Comparing hippocampal DNA hydroxymethylation following proton, <sup>56</sup>Fe ion, and <sup>28</sup>Si ion irradiation revealed a general space radiation synaptic signature with 45 genes that are associated with profound phenotypes. The most significant categories were glutamatergic synapse and postsynaptic density.</p><p><bold>Discussion:</bold> The brain’s response to space irradiation involves novel excitatory synapse and postsynaptic remodeling.</p>