Effects of 1H + 16O Charged Particle Irradiation on Short-Term Memory and Hippocampal Physiology in a Murine Model

Radiat Res. 2018 Jan;189(1):53-63. doi: 10.1667/RR14843.1. Epub 2017 Nov 14.

Abstract

Radiation from galactic cosmic rays (GCR) poses a significant health risk for deep-space flight crews. GCR are unique in their extremely high-energy particles. With current spacecraft shielding technology, some of the predominant particles astronauts would be exposed to are 1H + 16O. Radiation has been shown to cause cognitive deficits in mice. The hippocampus plays a key role in memory and cognitive tasks; it receives information from the cortex, undergoes dendritic-dependent processing and then relays information back to the cortex. In this study, we investigated the effects of combined 1H + 16O irradiation on cognition and dendritic structures in the hippocampus of adult male mice three months postirradiation. Six-month-old male C57BL/6 mice were irradiated first with 1H (0.5 Gy, 150 MeV/n) and 1 h later with 16O (0.1 Gy, 600 MeV/n) at the NASA Space Radiation Laboratory (Upton, NY). Three months after irradiation, animals were tested for hippocampus-dependent cognitive performance using the Y-maze. Upon sacrifice, molecular and morphological assessments were performed on hippocampal tissues. During Y-maze testing, the irradiated mice failed to distinguish the novel arm, spending approximately the same amount of time in all three arms during the retention trial relative to sham-treated controls. Irradiated animals also showed changes in expression of glutamate receptor subunits and synaptic density-associated proteins. 1H + 16O radiation compromised dendritic morphology in the cornu ammonis 1 and dentate gyrus within the hippocampus. These data indicate cognitive injuries due to 1H + 16O at three months postirradiation.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Behavior, Animal / drug effects
  • Cosmic Radiation / adverse effects
  • Gene Expression Regulation / radiation effects
  • Hippocampus / physiology*
  • Hippocampus / radiation effects*
  • Hydrogen / adverse effects*
  • Male
  • Memory, Short-Term / radiation effects*
  • Mice
  • Mice, Inbred C57BL
  • Oxygen / adverse effects*
  • Receptors, AMPA / metabolism
  • Receptors, N-Methyl-D-Aspartate / metabolism
  • Synapses / physiology
  • Synapses / radiation effects

Substances

  • Receptors, AMPA
  • Receptors, N-Methyl-D-Aspartate
  • Hydrogen
  • Oxygen