Changes in 5-HT1A and NMDA binding sites by a single rapid transcranial magnetic stimulation procedure in rats

The effects of a single rapid-rate transcranial magnetic stimulation (rTMS) exposure on neurotransmitter binding sites in the rat brain 24 h after the stimulation were examined. Quantification by in vitro-autoradiography showed no differences for H-3-paroxetine binding (5-HT uptake sites) between rTMS-treated, sham and control animals. In contrast, the number of 5-HT1A binding sites (labeled with H-3-8-OH-DPAT) were selectively increased in the rTMS-group with significantly higher B-MAX values in the frontal cortex, the cingulate cortex, and the anterior olfactory nucleus. A non-specific increase in NMDA binding sites (labeled with I-125-MK-801) in rTMS and sham animals was observed in the hippocampal formation. A selective increase of these binding sites after rTMS was detected in the ventromedial hypothalamus, the basolateral amygdala and layers 5-6 of the parietal cortex. These findings imply that a single rTMS exposure can result in persistent effects on NMDA and 5-HT1A binding sites even 24 h after stimulation and therefore may be of relevance with respect to the therapeutic action of rTMS reported from clinical studies. (C) 1999 Elsevier Science B.V. All rights reserved.