Repetitive Transcranial Magnetic Stimulation Ameliorates Cognitive Impairment by Enhancing Neurogenesis and Suppressing Apoptosis in the Hippocampus in Rats with Ischemic Stroke

Cognitive impairment is a serious mental deficit caused by stroke that can severely affect the quality of a survivor's life. Repetitive transcranial magnetic stimulation (rTMS) is a well-known rehabilitation modality that has been reported to exert neuroprotective effects after cerebral ischemic injury. In the present study, we evaluated the therapeutic efficacy of rTMS against post-stroke cognitive impairment (PSCI) and investigated the mechanisms underlying its effects in a middle cerebral artery occlusion (MCAO) rat model. The results showed that rTMS ameliorated cognitive deficits and tended to reduce the sizes of cerebral lesions. In addition, rTMS significantly improved cognitive function via a mechanism involving increased neurogenesis and decreased apoptosis in the ipsilateral hippocampus. Moreover, brain-derived neurotrophic factor (BDNF) and its receptor, tropomyosin-related kinase B (TrkB), were clearly upregulated in ischemic hippocampi after treatment with rTMS. Additionally, further studies demonstrated that rTMS markedly enhanced the expression of the apoptosis-related B cell lymphoma/leukemia gene 2 (Bcl-2) and decreased the expression of the Bcl-2-associated protein X (Bax) and the number of TUNEL-positive cells in the ischemic hippocampus. Both protein levels and mRNA levels were investigated. Our findings suggest that after ischemic stroke, treatment with rTMS promoted the functional recovery of cognitive impairments by inhibiting apoptosis and enhancing neurogenesis in the hippocampus and that this mechanism might be mediated by the BDNF signaling pathway

Adjustable Trifunctional Mid-Infrared Metamaterial Absorber Based on Phase Transition Material VO₂

In this paper, we demonstrate an adjustable trifunctional absorber that can achieve the conversion of broadband, narrowband and superimposed absorption based on the phase transition material vanadium dioxide (VO2) in the mid-infrared domain. The absorber can achieve the switching of multiple absorption modes by modulating the temperature to regulate the conductivity of VO2. When the VO2 film is adjusted to the metallic state, the absorber serves as a bidirectional perfect absorber with switching capability of wideband and narrowband absorption. The superposed absorptance can be generated while the VO2 layer is converted to the insulating state. Then, we introduced the impedance matching principle to explain the inner mechanism of the absorber. Our designed metamaterial system with a phase transition material is promising for sensing, radiation thermometer and switching devices

Infarct volume assessed by TTC staining 1 day after the tMCAO.

<p>(A) Position of SVZ in the coronal section of brain. Areas imaged for immunofluorescence studies are indicated by box. (B) Coronal brain section stained by TTC 1 day after tMCAO. The white areas without deep red-staining indicate ischemic areas. SVZ, subventricular zone.</p

Antagomir-25 injection resulted in decreased proliferation of NSCs 7days after tMCAO.

<p>Panels A–C show staining of Brdu⁺(red)/Nestin⁺(green) positive cells in the ipsilateral SVZ from rTMS (A), antagomir-25/rTMS (B), and control antagomir/rTMS (C) groups(Bar = 20 µm). (D) Quantification analysis of the number of Brdu⁺/Nestin⁺ positive cells in the ipsilateral SVZ at 7 days after tMCAO. ^#<b>P</b> = 0.006 versus rTMS group; ^*<b>P</b> = 0.013 versus Scr group. SVZ, subventricular zone.</p

Experimental protocol.

<p>Experimental protocol.</p

Effects of Ant-25 and Scr on p21 and p57 in the ischemic cortex 7 days after surgery.

<p>(A) Electrophoresis of p21, p57 and GAPDH on gel. (B) Relative levels of p21 and p57 protein from the different groups. ^#<b>P</b> = 0.018 compared to the rTMS group; ^*<b>P</b> = 0.012 compared to the Scr group.</p

Neurobehavioral function was improved by rTMS after cerebral ischemia.

<p>NSSs were improved in MCAO rats treated with rTMS as compared with other groups. Data are presented as mean±SD. ^&P<0.001 versus Sham group. ^*P = 0.005 for MCAO group between day 7 and day 1. ^**P<0.001 for rTMS group between day 7 and day 1. ^#P = 0.019 between rTMS group and MCAO group 7 days after surgery.</p

Expression changes of p57 and PTEN in the ipsilateral cortex 7 days after surgery.

<p>(A) Electrophoresis of p57, PTEN and GAPDH on gel. (B) The ratio of the target genes to GAPDH in different groups. ^#<b>P</b> = 0.005 for p57 compared to the Sham group; ^#<b>P</b> = 0.004 for PTEN compared to the Sham group; ^*<b>P</b> = 0.007 for PTEN compared to MCAO group.</p

Confocal image of Brdu (red) and Nestin (green) co-immunofluorescence staining in the ipsilateral SVZ 7 days after surgery.

<p>Panels A–C show staining of Brdu⁺/Nestin⁺ positive cells in the ipsilateral SVZ from Sham (A), MCAO (B), and rTMS (C) groups (Bar = 20 µm). (D) Quantification analysis of the number of Brdu⁺/Nestin⁺ positive cells in the ipsilateral SVZ 7 days after surgery. Brdu positive cells were labeled red (E), Nestin positive cells were labeled green (F) and Brdu⁺/Nestin⁺ positive cells were double-labeled (G), Bar = 20 µm. ^#<b>P<</b>0.001 for rTMS group versus Sham group; ^*<b>P</b> = 0.001 for rTMS group versus MCAO group. ^&<b>P</b> = 0.044 for MCAO group versus Sham group. SVZ, subventricular zone.</p