ABSTRACT
Objective To explore the effects of repetitive transcranial magnetic stimulation (rTMS) on the improve?ment of depressive behavior and the hippocampus brain derived neurotrophic factor (BDNF) expression in chronic stress-induced depression rats. To further investigate the possible molecular mechanism of rTMS treatment for depres?sion. Methods Forty male Sprague-Dawley rats of SPF grade were randomly divided into the blank control group (n=8) and the stress-induced group (n=30). Singly housing and chronic unpredictable mild stress (CUMS) were used to induce the depression model in stress-induced group. Twenty-four model rats were divided into three groups:model group (with no further treatment), rTMS group (receiving 10 Hz rTMS intervention for 3 weeks) and shame group (receiving pseudo TMS treatments for 3 weeks). Weight measurement, sucrose consumption test and open-field test were used to assess the behavior changes. The rat hippocampal CA3 area of BDNF positive staining cell number and expression levels of BDNF mRNA in hippocampus were examined after intervention. Results The weight reduction rate, score of sucrose consump?tion test and the score of open field test were significantly higher in rTMS group than in model group (P<0.05). The num? ber of BDNF staining positive cells in the hippocampal CA3 area was lower in model group and shame group than in the blank control group whereas was higher in the rTMS group than in the model group (P<0.01). Compared with the model group, the BDNF mRNA relative expression was significantly increased in the hippocampus of rTMS group (P<0.01). Conclusion rTMS can improve depressive behaviors of CUMS rats probably through the increase in expression of BDNF in the hippocampal neurons and neuronal regeneration.
ABSTRACT
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.
ABSTRACT
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.
ABSTRACT
Objective To explore the effects of repetitive transcranial magnetic stimulation on behaviors and hippocampus neuronal apoptosis in rats with chronic stress-induced depression.Methods 40 male SD rats of SPF grade were randomly divided into normol control group (n =8) and model preparation group (n =30) after screening.Rats in model preparation group were singly housed and given chronic unpredictable mild stress(CUMS) to build depression model.Excluding unsuccessful modeling rats,the model preparation group was divided into three groups:model group(n=8,without any treatment),rTMS group (n=8,with the intervention of 10 Hz rTMS) and shame group (n=8,simulation of rTMS environment without rTMS stimulus).The changes of behaviors in each group were detected by weight measurement,sucrose consumption test and open-field test.The changes of morphology of hippocampal neurons were detected by Nissl's staining.The changes of Bax in hippocampal neuron were detected by Immunohistochemical staining.Results (1) Behavioral results showed stress for 21 d could make rat behavior scores decrease significantly(all P＜0.05),and rTMS intervention could significantly improve their behavior scores (all P＜0.01).Compared with model group,the weight reduction rate (0.32±0.05)％,the score of sucrose consumption test(7.03 ± 1.02) and the score of open field test(8212.41 ± 1416.15,8.75 ± 1.58) in rTMS group was higher(P ＜0.01).(2) Nissl staining showed stress for 21 d could make the number of hippocampal CA3 neurons was reduced,cell morphology was poor,and the number of Nissl bodies was reduced.rTMS intervention could increase the number of hippocampal CA3 neurons,cell morphology was integral and the number of Nissl bodies was increased.(3) Immunohistochemistry results showed stress for 21 d could cause the number of Bax cell were significantly increased(P＜0.01),and rTMS intervention can make the number of Bax cell were significantly lower(P＜0.01).Conclusion rTMS intervention improves the depressive behavior in chronic stress depression model rats and inhibits the apoptosis,which might work through inhibition of neuron apoptosis and decline of Bax expression in hippoeampal neurons.