Effects of magnetic stimulation on expression of SYN, GAP43, and BDNF in primary mouse hippocampal neurons

Abstract

Objective To observe the effects of magnetic stimulation on the expression of synaptophysin(SYN),growth associated protein43(GAP43),brain-derived neurotrophic factor(BDNF)in primary mouse hippocampal neurons,so as to explore the possible mechanism of magnetic stimulation in mediating synaptic plasticity.Methods Primary mouse hippocampal neurons were randomly divided into control group,sham stimulation group,and magnetic stimulation groups with various output intensities:40%(1Hz,0.76T),60%(1Hz,1.14T),and 80%(1Hz,1.52T).Cells were stimulated from the 2nd d to the 6thd after plantation;cells in the sham stimulation group was placed in the same environment,but did not accept magnetic stimulation,and cells were drawn at the same time on 7th d.Scanning electron microscopy,immune cell fluorescence,Western blotting analysis and RT-PCR methods were used to study the morphological changes of neurons and the expressions of SYN,GAP43,and BDNF at protein and mRNA levels.Results In the 40%intensity group the neurite length of neurons and neural connections between cells were both increased,and the SYN-ir,BDNF-ir COD values and protein expressions were significantly higher than those in control group(P0.05,P0.01),but GAP43-ir COD value and protein level were not significantly increased;SYN,GAP43,and BDNF mRNA expressions were also markedly higher than those in the control group(P0.05).In the 60% intensity group,the length and number of neuritis(woven into dense network)were also increased significantly compared with those in the control group(P0.01);COD values of immune reactivity for SYN,GAP43,and BDNF,and their expressions at protein and mRNA were all significantly higher(P0.01).The neuritis in the 80%intensity group had increased length and number,but with cell damage;GAP43-ir and BDNF-ir COD values and protein levels were also significantly increased(P0.05,P0.01),but SYN-ir COD value and protein expression were not significantly different from those of the control group;and SYN,GAP43,and BDNF mRNA expressions were significantly increased compared with control group(P0.05,P0.01).Conclusion Magnetic stimulation may increase SYN,GAP43 expression by promoting BDNF synthesis and secretion,and thus plays a very important role in affecting neuronal morphology,regulation of synaptic plasticity,promoting neural network construction;magnetic stimulation at different parameters results in different stimulus results.