[Effect of electroacupuncture at "Zusanli" (ST36) on TREM2-mediated microglial activation in amyotrophic lateral...

To observe the effect of electroacupuncture (EA) at "Zusanli" (ST36) on amyotrophic lateral sclerosis (ALS) in mouse models based on myeloid cell trigger receptor 2 (TREM2)-mediated microglial activation.

Thirty-six SPF-grade male human mutant superoxide dismutase 1 (SOD1-G93A) transgenic mice were divided into a model group, an EA group, and a drug group, 12 mice in each group. Besides, 12 wide-type littermates were collected as a control group. In the EA group, EA was performed at the "Zusanli" (ST36), with an intermittent wave, at the frequency of 15 Hz, and for 10 min each intervention; once every other day, 3 interventions a week and for 4 continuous weeks. In the drug group, the intragastric administration of riluzole solution was given at 8 mg/kg, once daily, for 4 continuous weeks. After intervention completion, behavioral assessment of mice was conducted using rotarod test and wire hang test. With HE and Nissl staining adopted, morphology of motor neurons in the anterior horn of the spinal cord was observed. Immunofluorescence was used to detect the fluorescence intensity of TREM2 in the anterior horn of spinal cord. Western blot analysis was performed to measure the protein expression of interleukin (IL)-1β, γ interferon (IFN-γ), IL-4 and IL-10 in spinal cord tissue. Flow cytometry was used to analyze the proportion of CD86⁺ and CD206⁺ in spinal cord monocyte suspension.

Compared with the control group, in the model group, motor neurons in the anterior horn of the spinal cord exhibited disordered arrangement; accompanied by nuclear pyknosis and cytoplasmic shrinkage; the latency to fall in the rotarod test and the cut-off time in the wire hang test were shortened, fluorescence intensity of TREM2 in the spinal anterior horn, the protein expression of IL-1β, IFN-γ, IL-4, and IL-10, and the proportion of CD86⁺ and CD206⁺ in spinal cord tissue increased(P<0.01). When compared with the model group, in the EA and drug groups, motor neurons in the anterior horn of the spinal cord were arranged regularly; nuclear pyknosis and chromatolysis were attenuated, and the structural integrity of neurons was improved; the latency to fall and the the cut-off time were prolonged, fluorescence intensity of TREM2 in the spinal anterior horn was reduced, the protein expression of IL-1β and IFN-γ decreased, and that of IL-4, and IL-10 increased in the spinal cord tissue; the proportion of CD86⁺ in spinal cord tissue was reduced and that of CD206⁺ elevated(P<0.01, P<0.05). Compared with the drug group, the EA group showed the increase of protein expression of IL-1β,and the decrease of IL-4, IL-10 in the spinal cord tissue and the proportion of CD206⁺ (P<0.05).

Electroacupuncture at "Zusanli" (ST36) exhibits a certain improvements in motor function of SOD1-G93A transgenic mice. The underlying mechanism may be related to attenuating neuroinflammation via the modulation of microglial activation mediated by TREM2.