Effect of ultra‑wide‑band electromagnetic pulses on blood‑brain barrier permeability in rats

The restrictive nature of the blood brain barrier (BBB) brings a particular challenge to the treatment of central nervous system (CNS) disorders. The effect of ultra‑wide band electromagnetic pulses (UWB‑EMPs) on BBB permeability was examined in the present study in order to develop a safe and effective technology that opens the BBB to improve treatment options for CNS diseases. Rats were exposed to a single UWB‑EMP at various field strengths (50, 200 or 400 kV/m) and the BBB was examined using albumin immunohistochemistry and Evans blue staining at different time periods (0.5, 3, 6 and 24 h) after exposure. The expression and distribution of zonula occludens 1 (ZO‑1) were evaluated using western blotting to identify a potential mechanism underlying BBB permeability. The results showed that the BBB permeability of rats exposed to UWB‑EMP increased immediately following UWM‑EMP treatment and peaked between 3 and 6 h after UWB‑EMP exposure, returning to pre‑exposure levels 24 h later. The data suggested that UWB‑EMP at 200 and 400 kV/m could induce BBB opening, while 50 kV/m UWB‑EMP could not. The levels of ZO‑1 in the cerebral cortex were significantly decreased at 3 and 6 h after exposure; however, no change was observed in the distribution of ZO‑1. The present study indicated that UWB‑EMP‑induced BBB opening was field strength‑dependent and reversible. Decreased expression of ZO‑1 may be involved in the effect of UWB‑EMP on BBB permeability.