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Study on the correlation between synaptic reconstruction and astrocyte after ischemia and the influence of electroacupuncture on rats

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Abstract

Objective

To observe the effects of electroacupuncture (EA) on the structure parameters of synapse and reactive changes of astrocyte in the marginal zone of focal cerebral ischemia in rats at different time zones so as to further explore its underlying mechanisms in the treatment of cerebral ischemia.

Methods

Ninety male Wistar rats were randomly assigned to sham-operation, model, and EA groups, with 30 animals in each group. Each group was subdivided into 1 h, as well as 1, 3, 7, and 21 days post-operation groups, with 6 animals assigned to each time point subgroup. Heat coagulation-induced occlusion of the middle cerebral artery was performed to establish a model of focal cerebral ischemia. EA was applied immediately following surgery to the EA group [4/20 Hz, 2.0–3.0 V, 1–3 mA, to Baihui (GV20) and Dazhui (GV14)] for 30 min. Treatment was performed once a day, and experimental animals were sacrificed at 1 h, as well as 1, 3, 7 and 21 days postoperation. The ultrastructure changes in synapse and astrocytes were observed by using transmission electron microscopy. Glial fibrillary acidic protein (GFAP) expression and Ca2+ of astrocytes were measured by using laser confocal scanning microscope. Excitatory amino acid transporters-2 (EAAT2) and connexin 43 (CX43) expressions were assayed with immunohistochemical method. Canonical correlation analysis was conducted between structure parameters of synapse and parameters of astrocyte in the same time and group.

Results

Broken synapses were observed following cerebral ischemia, and the numbers of synapses were significantly decreased. Compared with the model group, synaptic ultrastructure was significantly improved in the EA group. Compared with the sham-operation group, synaptic number density was significantly decreased, as were postsynaptic density thickness, synaptic cleft width and synaptic interface curvature in the EA and model groups. However, compared with the model group, postsynaptic density thickness was significantly increased in the EA group at the same time points post-operation (P <0.05, P<0.01). In addition, synaptic cleft width, synaptic number density and synaptic interface curvature were significantly increased with the passage of time (P <0.05, P<0.01). The expression of GFAP in the EA group were significantly lower than those in the model group at all the time points (P <0.05, P<0.01). OD values of EAAT2 in the EA group were significantly higher than those in the model group at the same time (P <0.05, P<0.01). Compared with that in the model group, the expressions of CX43 in the EA group increased significantly at 3 days and 7 days (P <0.05, P<0.01). Ca2+ average fluorescence intensity of astrocytes in the EA group was significantly lower than those in the model group at 1 h, 1 day, 3 days and 7 days (P <0.05, P<0.01). The changes in structure parameters of synapse were closely related to the changes of CX43, EAAT2, GFAP, Ca2+ of astrocytes by EA treatment at all the time points.

Conclusions

EA is helpful for synaptic reorganization, which may be related to its effect on intervening the activation state of astrocytes and promoting the beneficial interaction between astrocytes and synapses. Acupuncture could start the adjustment of neuron-glial network so as to promote the synaptic reorganization, which may be the key mechanism of treating cerebral ischemia.

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Authors and Affiliations

  1. Institute of Acupuncture and Moxibustion, Guangxi College of Traditional Chinese Medicine, Nanning, 530001, China

    Yan Luo  (罗 燕)

  2. College of Acupuncture & Moxibustion and Massage, Guangzhou University of Traditional Chinese Medicine, Guangzhou, 510006, China

    Neng-gui Xu  (许能贵), Wei Yi  (易 玮) & Zhong-hua Yang  (杨忠华)

  3. Depertment of Acupuncture & Moxibustion, Guangdong Province Hospital of Traditional Chinese Medicine, Guangzhou, 510120, China

    Tao Yu  (于 涛)

Authors
  1. Yan Luo  (罗 燕)
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  2. Neng-gui Xu  (许能贵)
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  3. Wei Yi  (易 玮)
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  4. Tao Yu  (于 涛)
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  5. Zhong-hua Yang  (杨忠华)
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Corresponding author

Correspondence to Neng-gui Xu  (许能贵).

Additional information

Supported by the National Basic Research Program of China (973 Program, No. 2010CB530500); National Natural Science Foundation of China (No. 30572420); Program for New Century Excellent Talents in University, Ministry of Education of China (No. NCET-04-0831)

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Luo, Y., Xu, Ng., Yi, W. et al. Study on the correlation between synaptic reconstruction and astrocyte after ischemia and the influence of electroacupuncture on rats. Chin. J. Integr. Med. 17, 750–757 (2011). https://doi.org/10.1007/s11655-011-0754-7

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  • DOI: https://doi.org/10.1007/s11655-011-0754-7

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