Effects of electromagnetic pulses on the blood-brain barrier of rats

Animals were exposed to EMP with field intensity 25, 50, 100, 200 and 400 kV/m, and 25, 50, 100 and 200 pulses; duration between every two pulses is 2s. Firstly, an Evans blue (EB) and fluorescent microscope were used to observe the changes in the permeability of BBB after exposed to different combinations of the parameters. Secondly, an electron microscope was used to investigate the effects of EMP on the ultrastructure of different areas in the hippocampus and the marginal division of the brain after injection of lanthanum nitrate. Results showed that the permeability of the BBB of the rat can be changed after exposure to EMP with a significant dose-effect relationship. With the increasing of field intensity and raising of pulse number, the number and the area of spots increased so too the intensity of fluorescent colorations. Morphological changes in BBB and nervous tissue after EMP exposure also showed dose-effect relationship. The lanthanum nitrate granules appeared in the tissue of the cortex, hippocampus and hypothalamus in the EMP exposed group. The process of the granules crossing through the tight junction of capillary vessels and the phagocytosis of the granules in the endothelium cells were presented. Exposure to EMP can lead to increased permeability of BBB and could damage the endothelium cells of the capillary, resulting in increases of the perivascular space of the capillary.