Effects of low frequency repetitive transcranial magnetic stimulation on the behavior and cerebral monoamine neurotransmitter in the rats model of chronically depressive stress

Objective To observe the change of behavior and monoamine neurotransmitter in different cerebral areas of the rats model of chronically depressive stress after low frequency repetitive transcranial magnetic stimulation (rTMS), and to study the therapeutic effects and the mechanism of low frequency rTMS on depression. Methods Twelve male Sprague-Dawley rats were exposed to an unpredictable sequence of mild stress to establish the depression model of rats. Rats of depression model were randomly allocated to two groups: a depression model group and a magnetic stimulation group,another 6 normal rats served as the control group. Before and after the repetitive transcranial magnetic stimulation treatment, the rats were evaluated in terms of their behavior with open-field test, the consumption of sucrose solution of rats of three groups and the concentration of monoamine neurotransmitter in diffe-rent cerebral area by HPLC. Results Rats of depression model group showed no significant difference (P0.05) in level and vertical movements, consumption of sucrose solution when compared with that pre-treatment. Rats of depression model group showed a reduction in level and vertical movements in the open-field test, consumption of sucrose solution with significant difference when compared with those of the control group (P0.01).Rats of the magnetic stimulation group showed an significant increase in level and vertical movements, consumption of sucrose solution as compared with those of pre-treatment and depression model group (P0.01). Rats of the magnetic stimulation group showed no significant difference (P0.05) in level and vertical movements, consumption of sucrose solution when compared with control group. The level of 5-hydroxytryptamine in frontal brain regions, 5-hydroxytryptamine and dopamine in hippocampus,dopamine in corpus striatum, 5-hydroxytryptamine in hypothalamus in the depression model group was lower than that in the control group (P0.01). The level of 5-hydroxytryptamine in frontal brain regions, 5-hydroxytryptamine and dopamine in hippocampus, dopamine in corpus striatum, 5-hydroxytryptamine in hypothalamus in magnetic stimulation group was higher than that in depression model group (P0.01). There were no significant difference (P0.05) in level of 5-hydroxytryptamine and dopamine between magnetic stimulation group and the control group. Conclusion Low frequency rTMS can change the depressive behavior of rats with experimental depression. To regulate the level of monoamine neurotransmitter in different cerebral areas might be one of the antidepressive mechanisms of low frequency rTMS.