Acta Anatomica Sinica ›› 2024, Vol. 55 ›› Issue (2): 167-173.doi: 10.16098/j.issn.0529-1356.2024.02.006

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Activation of astrocytes in distal segments of the spinal cord mediating widespread pain induced by peripheral nerve injury

JIN  Si-xuan1,2  YU  Ning1,2  SUN  Feng-run1,2  MA  Chao1,2*   

  1. 1.Department of Anatomy,Histology and Embryology,Institute of Basic Medical Sciences,Chinese Academy of Medical Sciences,School of Basic Medicine,Peking Union Medical College,Beijing 10005,China; 2.State Key Laboratory of Common Mechanism Research for Major Diseases,Beijing 10005,China
  • Received:2024-01-05 Revised:2024-01-17 Online:2024-04-06 Published:2024-04-06
  • Contact: MA Chao E-mail:machao@ibms.cams.cn

Abstract:

Objective  To discuss the relationship between activated glia cells in distal segment of the spinal cord and widespread pain.   Methods Fifty female rats were randomly divided into sham group, the chronic constriction injury of the infraorbital nerve (CCI-ION) group, CCI-ION + minocycline (Mino) group, CCI-ION + L-2-aminoadipic acid (LAA) group, and CCI-ION + normal saline (NS) group, n=10 for each group. CCI-ION model was established and Mino, LAA, and normal saline were delivered intrathecally to CCI-ION rats. Immunofluorescence staining was used to detect activated astrocytes and microglia in the medulla oblongata, cervical, thoracic, and lumbar spinal cord segments. On the 7th, 14th, 21st, 28th day, von Frey filaments were used to evaluate the mechanical withdrawal threshold of vibrissa pad, and electronic von Frey tactile pain meter was used to measure the mechanical withdrawal threshold of front paw, chest and hind paw. The radiant thermal stimulator was used to measure the thermal withdrawal threshold of hind paw.   Results After intrathecal injection of Mino to inhibit microglia, the activated microglia in each spinal cord segment decreased. Moreover, inhibiting astrocytes by using LAA significantly reduced activated astrocytes in spinal dorsal horn from distal segments. Behavioral assay showed that after intrathecal injection of Mino and LAA, the mechanical allodynia of vibrissa pad in CCI-ION rats was relieved. However, there was no significant difference (P>0.05)in the thermal and mechanical withdrawal thresholds in the hind paw of CCI-ION rats after intrathecal injection of Mino, while intrathecal injection of LAA significantly increased the thermal and mechanical withdrawal thresholds in the hind paw, indicating the relief of widespread pain induced by CCI-ION.   Conclusion The activated astrocytes in distal segments of the spinal cord mediated CCI-ION-induced widespread pain.

Key words: Chronic pain, Widespread pain, Microglia, Astrocyte, Immunofluorescence, Rat

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