Toxic Effects of Lead and Electromagnetic Pulse Energy on Memory Mechanisms

Abstract

Abstract : Traumatic brain injury (TBI) due to explosive blast is a signature wound of combat operations, but the etiology of blast TBI is still not fully elucidated. The goal of this study was to determine whether low-level electromagnetic pulse (LEMP) energy, alone or in combination with lead (Pb), disrupts the physiological mechanisms of memory, and thus represents a potential neuropathogenic factor of explosive blasts. We examined the effects of LEMP and Pb on long-term potentiation (LTP), which is thought to be a key process of memory, using acutely prepared slices of rat hippocampus. A mathematical model of blast-generated LEMP was developed to estimate the EM energy received by the brain from a 10 kg blast from a 10 m distance and then scale the values for brain slices. An EM pulse generation system was used to expose slices to these LEMP values. In the absence of Pb, we found that single, brief (1 ms) exposures to 800 MHz or 1000 MHz LEMP significantly inhibited LTP induction, whereas 650 MHz LEMP had no effect. However, in the presence of low-level Pb (10 uM), 650 MHz LEMP effectively blocked LTP. These results suggest that LEMP may represent a pathogenic factor of blast TBI, and that low levels of Pb may increase neural susceptibility to LEMP.