ABSTRACT
Objective To investigate the effects of low frequency repetitive transcranial magnetic stimulation (rTMS) on motor function and excitability of motor cortex in Parkinson's disease (PD) patients and to study the mechanism of PD from the electrophysiology. Methods Twenty-eight patients with PD received 1 Hz rTMS therapy for 15 d. Thirty normal volunteers were enrolled as controls. Unified Parkinson's Disease Rating Scale (UPDRS) and motor evoked potential (MEP) were adopted as assessment indicators. The excitability of motor cortex was assessed by rest motor threshold (RMT), central motor conduction time (CMCT) and the amplitude of MEP. Results The initial RMTs and CMCTs of PD patients were significantly lower than those of the controls, but MEP amplitudes were not significantly different. After rTMS treatment, motor function of PD patients improved, RMTs increased and CMCTs prolonged. Conclusion In PD patients, motor function disorder and increased motor cortical excitability were observed. Low frequency rTMS may inhibit these changes to some extent.
ABSTRACT
Objective To investigate the effect and its underlying mechanism of repetitive transcranial magnetic stimulation(rTMS)on dopaminergic neurons and glial cell line-derived neurotrophic factor(GDNF)in the substantia nigra(SN)in mice with Parkinson's disease(PD). Methods Thirty-two male C57 BL/6J mice were randomly divided into a normal saline group,a sham-rTMS group,a PD model group and an rTMS group,with 8 mice in each group. All the mice except those in the normal saline group were administered with 4 times of subcutaneous in jection of 1-methyl,4-phenyl-1,2,3,6 tetrahydropyridine(MPTP)15 mg/kg at 2-hour intervals in 1 day to induce neuronal injury in the SN and to establish acute mice PD model.The mice in the rTMS group received 5 trains of 1 Hz rTMS for 25 s,at the intensity of 1 Tesla(T)daily for 2 weeks.After rTMS,the effect of rTMS on PD mice was observed by immunohistoehemieal technique with regard to the expression of tyrosine hydroxylase(TH)and GDNF in the SN,and the quantitative analysis was performed by an advanced image-analysis system. Results Compared with normal saline group,the number of TH and GDNF immunoreaetive(TH-ir and GDNF-ir)cells and the corrected optical density(COD)values of PD model group and sham-rTMS group were significantly lower(P＜0.01);Com pared with PD model and sham-rTMS groups,the numbers of TH and GDNF positive cells and COD values in rTMS group were significantly higher(P＜0.05).There was a significant positive correlation between the count of TH-ir and that of GDNF-ir cells(r=0.836,P＜0.01).The correlation between the COD values of TH-ir and that of GD-NF-ir cells was also significant(r=0.921,P＜0.01).Conclusion rTMS markedly increased the number and the COD values of TH-positive dopaminergic neurons and simultaneously increased the number and the COD value of GD NF-ir cells in the SN of PD mice.These findings suggest that rTMS has neuroprotective effects on dopaminergic neurons in the MPTP-induced PD mice,which might be mediated by up-regulation of the expression of GDNF protein in the SN.
ABSTRACT
Objective To observe the toxic effects of Rotenone on PC12 cells.Methods MTT assay was used to detect the toxic effect of Rotenone.The apoptosis rate and membrane potential of mitochondria were examined by flowctyometry (FCM).Results PC12 cells viability decreased after exposed to Rotenone for 72 hours.Although the apoptosis rate was very low,the G1 phase cells increased and membrane potential decreased as the increase of Rotenone concentration.Mitochondrial membrane potential decreased with a concentration dependent manner.Conclusion Low level and long term exposure of rotenone may induce the membrane potential of mitochondria of PC12 cells decrease,it indicated that rotenone may induce an apoptotic process with the mitochondrial membrane potential decrease in the early stage.