Repetitive transcranial magnetic stimulation protects hippocampal plasticity in an animal model of depression.
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.
Kim
Eun Joo
EJ
Department of Psychology, Korea University, Seoul, South Korea.
Kim
Woon Ryoung
WR
Chi
Sang Eun
SE
Lee
Kang Hee
KH
Park
Eun Hye
EH
Chae
Jeong-Ho
JH
Park
Soon Kwon
SK
Kim
Hyun Taek
HT
Choi
June-Seek
JS
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