Pulsed electromagnetic field attenuated PTSD-induced failure of conditioned fear extinction

Abstract

<em><strong>Objective(s):</strong></em> This study aimed to determine whether exposure to pulsed electromagnetic field (PEMF) can impair behavioral failure as induced by PTSD, and also its possible effects on hippocampal neurogenesis. PEMF was used as a non-invasive therapeutic tool in psychiatry.<br /><em><strong>Materials and Methods:</strong></em> Male rats were divided into Control-Sham exposed, Control-PEMF, PTSD-Sham exposed, and PTSD-PEMF groups. PTSD rats were conducted by the single prolonged stress procedures and then conditioned by the contextual fear conditioning apparatus. Control rats were only conditioned. Experimental rats were submitted to daily PEMF (7 mT, 30 Hz for 16 min/day, 14 days). Sham-exposed groups were submitted to the turned off PEMF apparatus. Fear extinction, sensitized fear and anxiety, cell density in the hippocampus, and proliferation and survival rate of BrdU-labeled cells were evaluated. <br /><em><strong>Results:</strong></em> Freezing of PTSD-PEMF rats was significantly lower than PTSD-Sham exposed. In the PTSD-PEMF, center and total crossing in open field, also the percentage of open arms entry and time in the elevated plus maze, significantly increased as compared with PTSD-Sham exposed (P<0.001). Numbers of CA1, CA3, and DG cells in PTSD-PEMF and Control-Sham exposed groups were significantly more than PTSD-Sham exposed (P<0.001). There were more BrdU-positive cells in the DG of the PTSD-PEMF as compared with the PTSD-Sham exposed. Qualitative observations showed an increased number of surviving BrdU-positive cells in the PTSD-PEMF as compared with PTSD-Sham exposed.<br /><em><strong>Conclusion:</strong></em> Using 14-day PEM attenuates the PTSD-induced failure of conditioned fear extinction and exaggerated sensitized fear, and this might be related to the neuroprotective effects of magnetic fields on the hippocampus.