[Animal Modeling]-Changes in the activation state and types of microglia in the spinal dorsal horn in the early stage after sciatic nerve injury in rats

  Objective: To study the changes in the activation state and types of microglia in the spinal dorsal horn after sciatic nerve injury.

  Method: Rats were randomly divided into control group (n=24) and experimental group (n=24). The experimental group used the method of ligating the backbone of the sciatic nerve to construct a rat model of sciatic nerve injury. Measure the behavioral data of pain in rats, collect materials on the 1, 7, and 14 days after surgery, and use immunofluorescence staining to detect the changes of microglia in different activated states of the rat's lumbar spinal dorsal horn; verify the different types by qRT-PCR Trends of microglia related markers.

  Result: Rats in the sham operation group had no significant changes in the morphology and number of microglia in the spinal dorsal horn within 14 days after the operation, and there were no significant changes in microglia markers. On the 1st postoperative day, there was no significant change in the morphology and number of microglia in CCI rats, but the pro-inflammatory (M1 type) markers increased, suggesting the activation of M1 microglia. At 7 and 14 days after operation, the number of microglia in CCI rats increased significantly. The detection of markers showed that the activation of M1 type was the main type, and the activation of anti-inflammatory (M2 type) microglia was not obvious.

  Conclusion: Rat spinal dorsal horn microglia start to activate early after sciatic nerve injury, and the activation lasts for at least two weeks after surgery. During this period, M1 type microglia are mainly activated.