Estimation of the spatial energy deposition in CA1 pyramidal neurons under exposure to 12C and 56Fe ion beams

Abstract

a b s t r a c tThe exposure to heavy charged particles represents a significant risk to the central nervous system. In experiments with rodents, the irradiation with heavy ions induces a prolonged deficit in hippocampus-dependent learning and memory. The exact nature of these violations remains mostly unclear. In this regard, the estimation of radiation effects at the level of single neurons is of our special interest. The present study demonstrates the results of comparative calculations that are performed to clarify the early physical events in single neurons under the exposure to accelerated 12 C and 56 Fe ions with different parameters. Using the Geant4-based Monte Carlo simulations, the radiation effects are considered in terms of energy and dose deposition. The spatial patterns of energy and dose depositions within a single neural cell are produced. As additional characteristics, the spectra of the specific energy and energy imparted are estimated. Our results show that the cell morphology is an important factor determining the accumulation of radiation dose in neurons under the exposure to heavy ions. The data obtained suggest a possibility of radiation damage to synapses that are considered to play an important role in radiationinduced violations of hippocampus-dependent learning and memory.

Geometrical structures for radiation biology research as implemented in the TOPAS-nBio toolkit

“…Possible radiation targets in the neuron include the site of the genome i.e. the nucleus in the soma (Alp et al 2015, Batmunkh et al 2015). Other possible targets include organelles (e.g., mitochondria), structures 55 such as spines or the cell membranes and ion channels in the dendrites (Puspitasari et al 2016).…”

“…Possible radiation targets in the neuron include the site of the genome i.e. the nucleus in the soma (Alp et al 2015, Batmunkh et al 2015. Other possible targets include organelles (e.g.…”

The Effects of Galactic Cosmic Rays on the Central Nervous System: From Negative to Unexpectedly Positive Effects That Astronauts May Encounter

“…The radical species recombination occurring one µs after the living matter irradiation ensures the homogeneous radiolytic medium formation within the local particle’s passage region, which makes this stage one of the most destructive [ 135 ]. For heavy particles, the diameter of such a region may exceed the neuron body size (50 μm) [ 139 ]. The secondary IR effects are very diverse and include oxidative stress [ 140 ], protein folding and endoplasmic reticulum stress [ 141 ], genetic mutations [ 142 ], inflammation [ 143 ], neurogenesis inhibition (see Section 8 ), impaired neuron and glial cell morphology [ 53 , 144 ], a wide range of molecular rearrangements [ 145 , 146 ], impaired synaptic transmission and neurotransmitters metabolism [ 83 , 147 , 148 ], and finally the apoptotic death of nerve tissue cells [ 146 ].…”

Modeling of changes in the cerebral cortex under low radiation exposure

“…Эксперименты с γ-облучением животных в дозах и режимах, сопоставимых с таковыми у ликвидаторов последствий аварии на ЧАЭС, выполненные с помощью традиционных нейроморфологических и статистических методик показали достаточно высокую структурнофункциональную реактивность нейронов различных отделов головного мозга и в тоже время их высокую пластичность и резистентность по отношению к малым дозам ионизирующего излучения. Выявляемые изменения на протяжении всего эксперимента не имели линейной зависимости как от дозы γ-облучения, так и от длительности восстановительного периода, а носили ундулирующий характер с отдельными стохастическими эксцессами [2,11,16,22]. Среди нейронной популяции преобладали структурные изменения, отражающие полиморфизм функционального состояния нервных клеток (покой, возбуждение, торможение), но в ряде случаев их изменения приобретали пограничный характер, когда они уже не являлись нормой и в тоже время еще и не являлись патологией.…”