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X Irradiation Induces Acute Cognitive Decline via Transient Synaptic Dysfunction
Anggraeini Puspitasari1, Noriko Koganezawa1, Yuta Ishizuka1
1a Departments of Neurobiology and Behavior and.
Radiation Research
|March 30, 2016
Summary
Cranial X irradiation acutely impairs fear memory formation by causing transient synaptic dysfunction, not by affecting new neuron survival. This highlights synaptic changes as key to radiation-induced cognitive deficits.
Area of Science:
- Neuroscience
- Radiation Biology
- Cognitive Science
Background:
- Cranial X irradiation causes neurocognitive deficits and brain injury with unclear acute mechanisms.
- Radiation-induced brain injury presents acute, early, and late delayed changes, with morbidity appearing over 6 months post-irradiation.
Purpose of the Study:
- To investigate the acute effects of X radiation on synaptic function and fear memory formation.
- To elucidate the mechanisms underlying radiation-induced cognitive deficits.
Main Methods:
- Behavioral analysis and immunohistochemistry were used to examine synaptic function and adult neurogenesis.
- Drebrin immunoreactivity and the number of newly generated neurons were analyzed in irradiated brain hemispheres.
Main Results:
- Whole-brain irradiation immediately after conditioning impaired fear memory formation.
- X radiation induced transient synaptic dysfunction, evidenced by decreased drebrin immunoreactivity within 2 hours, recovering by 24 hours.
- A significant decrease in newly generated neurons was observed 8 and 24 hours post-irradiation, but not at 2 hours.
Conclusions:
- Radiation-induced synaptic dysfunction, not the death of new neurons, is the primary cause of transient memory deficits during the critical period for fear memory formation.
- The findings suggest that transient changes in synaptic plasticity in the hippocampus are crucial for understanding acute radiation effects on memory.
