Postsynaptic density radiation signature following space irradiation

Area of Science:

• Neuroscience
• Space Biology
• Radiation Biology

Background:

• Space radiation poses risks to astronaut health, particularly concerning brain function.
• Understanding the brain's response to space radiation is crucial for long-duration space missions.

Purpose of the Study:

• To investigate the effects of 28Si ion irradiation on cognitive performance in mice.
• To determine if these effects are associated with alterations in hippocampal DNA methylation and gene expression.

Main Methods:

• Mice were irradiated with 28Si ions (600 MeV/n) at varying doses (0.3, 0.6, 0.9 Gy).
• Cognitive function was assessed using object recognition tests two weeks post-irradiation.
• Hippocampal DNA methylation (5hmC) and gene expression profiles were analyzed.

Main Results:

• Cognitive impairment was observed at 0.3 Gy of 28Si ion irradiation, but not at higher doses.
• Impaired cognition correlated with altered gene expression and 5hmC profiles in the hippocampus.
• A common space radiation synaptic signature involving 45 genes was identified across different ion types (proton, 56Fe, 28Si).

Conclusions:

• Low-dose 28Si ion irradiation can impair cognitive function by altering hippocampal DNA methylation and gene expression.
• Space radiation exposure induces a synaptic signature in the brain, impacting glutamatergic pathways.
• Brain response to space radiation involves synaptic remodeling, particularly in excitatory synapses.