title: Repetitive transcranial magnetic stimulation protects hippocampal plasticity in an animal model of depression.
abstract: Despite its therapeutic success in treating mood-related disorders, little is known about the mechanism by which repetitive transcranial magnetic stimulation (rTMS) alters physiological responses of neurons. Using the forced swim test (FST) in rats as a model of depression, we tested the protective effect of rTMS on synaptic plasticity, specifically, on the induction of hippocampal long-term potentiation (LTP). Male Sprague-Dawley rats were subjected to FST to induce immobility, a behavioral symptom of depression. They were subsequently treated with one of the three conditions: rTMS (rTMS: 1000 stimuli at 10Hz), sham rTMS (SHAM: acoustic stimulation only), or an antidepressant drug, fluoxetine (FLX: 10mg/kg, i.p.) for 7 days. There was a significant difference in immobility time between rTMS and SHAM groups after 7 days of treatment, but not after a single day. Following the second swim test on day 7, they were anesthetized and LTP was induced in vivo in the perforant path-dentate gyrus synapses. Another group (NAIVE) that had received no prior treatment was used as a control for LTP. The SHAM or FLX group exhibited little signs of LTP induction. On the contrary, the rTMS and NAIVE group showed a significant increase in field excitatory postsynaptic potentials after LTP induction. These results show that rTMS has an antidepressant-like effect after a relatively short period of treatment, and this effect might be mediated by a cellular process that can potentially reverse the impaired synaptic efficacy caused by the forced swim procedure.
authors.affiliation: Department of Psychology, Korea University, Seoul, South Korea.
authors.forename: Eun Joo
authors.initials: EJ
authors.lastname: Kim
authors.forename: Woon Ryoung
authors.initials: WR
authors.lastname: Kim
authors.forename: Sang Eun
authors.initials: SE
authors.lastname: Chi
authors.forename: Kang Hee
authors.initials: KH
authors.lastname: Lee
authors.forename: Eun Hye
authors.initials: EH
authors.lastname: Park
authors.forename: Jeong-Ho
authors.initials: JH
authors.lastname: Chae
authors.forename: Soon Kwon
authors.initials: SK
authors.lastname: Park
authors.forename: Hyun Taek
authors.initials: HT
authors.lastname: Kim
authors.forename: June-Seek
authors.initials: JS
authors.lastname: Choi
mesh_terms: D000818:Animals; D003863:Depression / Q000503:physiopathology / Q000628:therapy*; D004195:Disease Models, Animal; D006624:Hippocampus / Q000503:physiopathology*; D007103:Immobilization; D017774:Long-Term Potentiation; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D050781:Transcranial Magnetic Stimulation