Roman Vlkolinský*, Thomas Krucker?, Anna L. Smith, Tyra C. Lamp, Gregory A. Nelson and Andre Obenaus. "Effects of Lipopolysaccharide on 56Fe Radiation-Induced Impairment of Synaptic Plasticity in Mouse Hippocampus.." Radiation Research 168. (): -. (*)
Space radiation consisting of high-mass, high-Z, high-energy particles (HZE; e.g. 56Fe) represents significant health risk for astronauts and the central nervous system (CNS) may be a vulnerable target. HZE radiation may directly affect neuronal function, or during immunological challenge, it may alter immune system-to-CNS communication. To test these hypotheses, we exposed mice to accelerated iron ion particles (56Fe; 600 MeV/n; 1, 2, 4 Gy; brain only) and one month later prepared hippocampal slices to measure radiation effects on neurotransmission and synaptic plasticity in CA1 neurons. In a model of immune system-to-CNS communication these electrophysiological parameters were measured in irradiated mice additionally challenged with a peripheral immunological stressor lipopolysaccharide (LPS) injected intraperitoneally 4 h before the slice preparation. Exposure to 56Fe alone increased dendritic excitability and inhibited plasticity. In control mice (0 Gy), LPS treatment also inhibited synaptic plasticity. Paradoxically, in mice exposed to 2 Gy the LPS treatment restored synaptic plasticity to values similar to those found in controls (0 Gy, no LPS). Our results indicate that HZE radiation alters normal electrophysiological properties, and the hippocampal response to LPS.