Protective effects of repetitive transcranial magnetic stimulation in a rat model of transient cerebral ischaemia: a microPET study
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Repetitive transcranial magnetic stimulation (rTMS) is a noninvasive method to excite neurons in the brain. However, the underlying mechanism of its therapeutic effects in stroke remains unclear. The aim of this study was to investigate the neuroprotective effect of high-frequency rTMS in a rat model of transient cerebral ischaemia using positron emission tomography (PET).
Sprague-Dawley rats (n=30) were anaesthetized with chloral hydrate and subjected to 90 min of intraluminal middle cerebral artery occlusion (MCAO) with subsequent reperfusion in three groups: control (n=10), rTMS (n=10), or sham-rTMS groups (n=10). In the rTMS group, rTMS was given 1 h after ischaemia and every 24 h for 7 days after MCAO. In all three groups, small-animal PET (microPET) imaging with 18F-FDG was used to evaluate brain glucose metabolism. Apoptotic molecules were measured in the infarct margin using immunohistochemical staining.
The neurological scores of the rats in the rTMS group were higher than in those of the control group over the whole 7-day observation period. The total, cortical and striatal infarct volumes were significantly less in the rTMS group than in the control group, as measured by 2,3,5-triphenyltetrazolium chloride staining. 18F-FDG microPET images showed significantly higher standardized uptake values in the cortex and striatum in the rTMS group than in the control group in the affected hemisphere. The number of cells positive for caspase-3 was significantly lower in the rTMS group than in the control group, while the Bcl-2/Bax ratio was significantly higher in the rTMS group than in the control group.
rTMS therapy increased glucose metabolism and inhibited apoptosis in the ischaemic hemisphere. 18F-FDG PET could be used to monitor rTMS therapy in transient cerebral ischaemia in animal studies and in future clinical trials.
KeywordsRepetitive transcranial magnetic stimulation (rTMS) Cerebral ischaemia Apoptosis Glucose metabolism microPET
This study was supported by grants from the National Science Foundation of China (NSFC) (nos. 30672396, 30600194), a key project grant from the Ministry of Science and Technology of China (MOST; no. 2006DFB32940), and a project grant from the Science and Technology Department of Zhejiang Province (no. 2009C33134).
- 11.Plesni N. Role of mitochondrial proteins for neuronal cell death after focal cerebral ischemia. Acta Neurochir Suppl 2004;89:15–9.Google Scholar
- 28.Paxinos G, Watson C. The rat brain in stereotaxic coordinates. 4th ed. San Diego: Academic Press; 1998.Google Scholar
- 36.Müller MB, Toschi N, Kresse AE, et al. Long-term repetitive transcranial magnetic stimulation increases the expression of brain-derived neurotrophic factor and cholecystokinin mRNA, but not neuropeptide tyrosine mRNA in specific areas of rat brain. Neuropsychopharmacology 2000;23:205–15.CrossRefPubMedGoogle Scholar