title: (28)silicon radiation impairs neuronal output in CA1 neurons of mouse ventral hippocampus without altering dendritic excitability.
abstract: An unavoidable complication of space travel is exposure to radiation consisting of high-energy charged particles (HZE), such as Fe and Si nuclei. HZE radiation can affect neuronal functions at the level of the synapse or neuronal soma without inducing significant neuronal death. Different radiation species impart distinct patterns of radiation damage depending on their track structure, dose rate and fluence. Moreover, structural differences exist along the dorsoventral axis of the hippocampus that may underlie different radiosensitivities within the same neuronal field (e.g., the CA1 pyramidal cell population of the hippocampus). In this study we tested the functional effects of low doses of (28)Si radiation on excitability and synaptic plasticity in hippocampal slices prepared strictly from the ventral hippocampus. We used extracellular electrophysiological techniques to record field excitatory postsynaptic potentials (EPSPs) and population spikes in hippocampal CA1 neurons from C57BL/6J male mice 3 months after exposure to (28)Si radiation (600 MeV/n; 0.25 and 1 Gy, whole body). In irradiated mice we found prominent decrements in population spike amplitudes and reduced maximal neuronal output without changes in dendritic field EPSP. Reduced field EPSP vs. population spike ratios indicate radiation-induced impairment of the EPSP-spike (E-S) coupling. This effect was not associated with significant changes in the magnitude of short- and long-term synaptic plasticity [long-term potentiation (LTP)]. These data confirm that irradiation with (28)Si particles at relatively low doses alters the properties of the hippocampal network, which can limit its connectivity with other brain centers.
authors.affiliation: Department of Basic Sciences, Division of Radiation Research, School of Medicine, Loma Linda University, Loma Linda, California 92354.
authors.forename: Emil
authors.initials: E
authors.lastname: Rudobeck
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Nelson
authors.forename: Irina V
authors.initials: IV
authors.lastname: Sokolova
authors.forename: Roman
authors.initials: R
authors.lastname: Vlkolinský
mesh_terms: D000818:Animals; D056547:CA1 Region, Hippocampal / Q000166:cytology / Q000187:drug effects / Q000528:radiation effects*; D003712:Dendrites / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D019706:Excitatory Postsynaptic Potentials; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009474:Neurons / Q000187:drug effects / Q000528:radiation effects*; D011868:Radioisotopes / Q000494:pharmacology*; D012825:Silicon / Q000494:pharmacology*
chemical_list: D011868:Radioisotopes; D012825:Silicon