Low-frequency transcranial magnetic stimulation and the expression of KCa1.1, NaV1.6, NMDAR1 and GAD65 proteins in the CA3 region of the hippocampus

Abstract

Objective To investigate whether repeated low-frequency transcranial magnetic stimulation (rTMS) can affect the expression of Kca1.1,Nav1.6,NMDAR1 and/or GAD65 protein in the pyramid layer of the CA3 region of the hippocampus.Methods Fifty rats were randomly divided into an experimental group and a sham group.The former was administered low-frequency rTMS on 14 consecutive days ; the latter were given sham stimulation for 14 days.After the protocols were completed,each group was sub-divided into 6 h,24 h,1 week,3 week and 6 week sub-groups.The rats of each sub-group were sacrificed at the corresponding time points and the expression of KCa1.1,Nav1.6,NMDAR1 and GAD65 in the CA3 region of the hippocampus was examined using immunohistochemical techniques.Results Compared with the sham group,KCa1.1-positive neuron densities increased significantly in the period 6 h to 3 weeks after rTMS.GAD65-positive neuron densities were also elevated significantly from 6 h to 3 weeks.NaV1.6-and NMDAR1-positive neuron densities decreased transiently at 6 h after the completion of the rTMS protocol.Conclusions These results show that low-frequency rTMS can upregulate the expression of KCa1.1 and GAD65,and that the effect lasts for at least 3 weeks.It transiently downregulates the expression of NaV 1.6 and NMDAR1 in the hippocampal CA3 region,at least in rats.These changes may be one of its anti-epileptic mechanisms. Key words: Transcranial magnetic stimulation; Immunohistochemistry; Neurons; Rats