The long-term high-frequency repetitive transcranial magnetic stimulation does not induce mRNA expression of inflammatory mediators in the rat central nervous system

Repetitive transcranial magnetic stimulation (rTMS) has been applied for treatment of several diseases such as depression. However, the safety and biological effects of rTMS have not been fully elucidated. In this study, the effects of rTMS on the levels of inflammatory mediators in the central nervous system (CNS), which may be involved in neurodegenerative disorders, were investigated in comparison with the electric convulsive model. Long-term rTMS (1500 pulses at 30 Hz/day for series of 7 days) stimulation, which did not elicit convulsion, was given to rats (rTMS rats). Single high-frequency electrical stimulation (100 Hz, 0.5-ms pulse width, 1 s duration, 50 mA), which induced convulsion, was given to rats (ES rats). mRNA levels of interleukin (IL)-1beta, IL-6, cyclooxygenase (COX)-2 and inducible nitric oxide synthetase (iNOS) in the brain were evaluated by reverse transcription-polymerase chain reaction before and after these stimulations. mRNA of IL-1beta, IL-6 and COX-2 was induced in the brains of ES rats but not in the brains of long-term rTMS rats. mRNA of NOS was not induced in the brain of long-term rTMS rats. These results suggest that long-term rTMS may safe and modulate neural function without up-regulation of inflammatory mediators, which may be involved in neurodegenerative disorders. (C) 2002 Elsevier Science B.V. All rights reserved.