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  • (28)Silicon radiation-induced enhancement of synaptic plasticity in the hippocampus of naïve and cognitively tested mice.

(28)Silicon radiation-induced enhancement of synaptic plasticity in the hippocampus of naïve and cognitively tested mice.

Radiation research (2014-03-29)
Jacob Raber, Emil Rudobeck, Mary Campbell-Beachler, Antiño R Allen, Barrett Allen, Susanna Rosi, Gregory A Nelson, Shaila Ramachandran, Jennifer Turner, John R Fike, Roman Vlkolinsky
ABSTRACT

The space radiation environment consists of multiple species of high-energy charge particles (HZE), including (56)Fe and (28)Si nuclei, that may impact neuronal cells, but their damaging effects on the central nervous system (CNS) have been poorly defined. Hippocampus-dependent memory functions have been shown to be highly sensitive to (56)Fe HZE particles, which poses a significant risk to the cognitive performance of astronauts during space missions. While low doses of (56)Fe radiation do not induce cell death of mature neurons, they affect synaptic plasticity in the CA1 region, the principal neuronal output of the hippocampal formation involved in memory formation. The effects of (28)Si on the CNS have not been defined. Compared to behaviorally naïve mice, cognitive testing might affect synaptic plasticity and the effects of (28)Si radiation on synaptic plasticity might be modulated by prior cognitive testing. Therefore, in the current study, we quantified the effects of whole-body (28)Si radiation (600 MeV/n, 0.25 and 1 Gy) on hippocampus-dependent contextual freezing and synaptic plasticity in the CA1 region of animals not exposed (behaviorally naïve mice) and animals exposed to the contextual freezing test (cognitively tested mice). In behaviorally naïve mice exposed to 0.25 and 1 Gy of (28)Si radiation, the magnitude of long-term potentiation (LTP) was enhanced. However, in mice irradiated with 0.25 Gy contextual fear conditioning was enhanced and was associated with a further enhancement of the LTP magnitude. Such increase in synaptic plasticity was not seen in cognitively tested mice irradiated with 1 Gy. Thus, low dose (28)Si radiation has effects on synaptic plasticity in the CA1 region of the hippocampus and these effects are modulated by cognitive testing in a contextual fear-conditioning test.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Silicon, powder, −325 mesh, 99% trace metals basis
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Silicon, pieces, 99.95% trace metals basis
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Silicon, wafer (single side polished), <111>, P-type, contains boron as dopant, diam. × thickness 3 in. × 0.5 mm
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Silicon, wafer (single side polished), <100>, P-type, contains boron as dopant, diam. × thickness 2 in. × 0.5 mm
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Silicon, wafer (single side polished), <111>, N-type, contains no dopant, diam. × thickness 3 in. × 0.5 mm
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Silicon, wafer (single side polished), <111>, N-type, contains phosphorus as dopant, diam. × thickness 2 in. × 0.5 mm
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Silicon, wafer (single side polished), <100>, N-type, contains phosphorus as dopant, diam. × thickness 3 in. × 0.5 mm
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Silicon, wafer (single side polished), <100>, P-type, contains boron as dopant, diam. × thickness 3 in. × 0.5 mm
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Silicon, wafer (single side polished), <100>, N-type, contains no dopant, diam. × thickness 3 in. × 0.5 mm
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Silicon, wafer, <111>, P-type, contains boron as dopant, diam. × thickness 2 in. × 0.3 mm
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Silicon, nanopowder, <100 nm particle size (TEM), ≥98% trace metals basis
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Silicon, wafer (single side polished), <111>, N-type, contains no dopant, diam. × thickness 2 in. × 0.5 mm
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Silicon, wafer (single side polished), <100>, N-type, contains no dopant, diam. × thickness 2 in. × 0.5 mm
Silicon, disks, 15.9mm, thickness 0.38mm, single crystal, n-type, 100%
Silicon, rod, 100mm, diameter 12.7mm, single crystal - random orientation, 100%
Silicon, disks, 13mm, thickness 0.38mm, single crystal, 100%
Silicon, rod, 100mm, diameter 2.0mm, crystalline, 100%
Silicon, disks, 15.9mm, thickness 0.38mm, single crystal, n-type, 100%
Silicon, rod, 100mm, diameter 25mm, crystalline, 100%
Silicon, rod, 100mm, diameter 10.0mm, single crystal - random orientation, 100%
Silicon, rod, 50mm, diameter 2.0mm, crystalline, 100%
Silicon, sheet, 14x14mm, thickness 1.0mm, single crystal, -111, 100%
Silicon, sheet, 25x25mm, thickness 1.0mm, polycrystalline, 99.999%
Silicon, rod, 50mm, diameter 5.0mm, crystalline, 100%
Silicon, sheet, 25x25mm, thickness 1.0mm, single crystal, -100, 100%
Silicon, rod, 50mm, diameter 5mm, single crystal, -100, 99.999%
Silicon, sheet, 40x40mm, thickness 3.0mm, single crystal, p-type, 100%
Silicon, rod, 100mm, diameter 5.0mm, crystalline, 100%
Silicon, rod, 50mm, diameter 5mm, single crystal, -111, 99.999%
Silicon, sheet, 52x52mm, thickness 1.0mm, polycrystalline, 99.999%