Résumé
Objective To observe the effect of repetitive transcranial magnetic stimulation (rTMS) on behavior in response to chronic but unpredictable mild stress and explore potential neuroendocrine mechanisms.Methods Forty adult SD male rats were randomly divided into a control group (n =8) and a model preparation group (n=32).The control group was given normal care while a model of depression was induced in the model preparation group through giving an unpredictable mild stimulus (CUMS).The depressive rats were randomly divided into a model group,an rTMS group and a sham rTMS group (8 cases in each group).The rTMS group and sham rTMS groups accepted the rTMS or sham stimulation for 3 weeks.The changes in behavior in each group were quantified using body weight,sucrose consumption and an open field test before and after stimulation.Enzyme-linked immunosorbent assays (Elisas) were conducted to detect plasma adrenocorticotropic hormone (ACTH) and corticosterone (CORT) levels.Reverse-transcription polymerase chain reactions (RT-PCRs) were carried out to allow the detection of mRNA expression in hypothalamus related to levels of adrenocorticotropic hormone releasing hormone (CRH).Results After the modeling there were significant differences between the model preparation group and the control group in terms of weight increase,sucrose consumption and open field test results.After rTMS the rate of weight increase,sucrose consumption and the scores in the open field test of the rTMS group had increased significantly more than in the control group.Elisas showed significantly higher plasma ACTH and CORT levels in the model group as well.The average expression of CRH mRNA in the model group was significantly higher than in either of the other two groups.Conclusions rTMS can relieve depression-like behavior induced by chronic stress,at least in rats.This may be related to a downgrading of the hyperactive functioning of the hypothalamus-pituitary-adrenal axis.
Résumé
Objective To explore the effect of repetitive transcranial magnetic stimulation (rTMS) on behaviors and hippocampal glucocorticoid receptor (GR) protein expression in chronic stress depression model rats and the possible antidepressant mechanism of rTMS. Method Seventy-five male Sprague-Dawley rats were randomly divided into the blank control group (n=15) and the stress-induced group (n=60). Singly housing and chronic unpredictable mild stress (CUMS) were used to induce the depression model in stress-induced group. Forty-five CUMS rats were selected and ran?domly divided into rTMS group (receiving 10 Hz rTMS intervention for 3 weeks), sham group (receiving pseudo rTMS treatments for 3 weeks) and depression group (with no further treatment). Body weight measurements and performance in the sucrose consumption and forced swimming test (FST) were evaluated before modeling, after modeling and after inter?vention. The GR protein and GR mRNA expression level in the hippocampus were examined after intervention. Results Compared with control group, the body weight growth rate and the sugar water preference were significantly lower in stress-induced group (P0.05), were higher than those in sham group and depression group (P<0.01). The immobility times of FST in rTMS group and control group were shorter than sham group and depression group (P<0.01). Compared with rTMS group and control group, GR and GR mRNA expression levels in the hippocampus were significantly reduced in sham group and depression group (P<0.01). Conclusion rTMS can improve depression behavior of CUMS rats, which may be associated with upregulation of GR expression in the hippocampus.