BACKGROUND:Previous studies have confirmed that Wen-Shen-Tong-Du Decoction can promote the recovery of spinal cord injury by inhibiting pyroptosis of splenic B cells,promoting the phagocytosis of myelin debris by microvascular endothelial cells,affecting the migration and infiltration of microglia,promoting the recovery of damaged neurons,and decreasing neuronal apoptosis after spinal cord injury,but the mechanism of this is still not clear. OBJECTIVE:To investigate the effect of Wen-Shen-Tong-Du Decoction on the triggering receptor expressed on myeloid cells 2(TREM2)and PI3K/Akt signaling pathways in mice following spinal cord injury. METHODS:Thirty-six C57BL/6 mice were selected and randomly divided into a sham-operation group,a model group and a Wen-Shen-Tong-Du Decoction group,with 12 mice in each group.In the model and Wen-Shen-Tong-Du Decoction groups,mouse models of T10 spinal cord injury were prepared by the modified Allen's method.On the 1st day after modeling,the Wen-Shen-Tong-Du Decoction group was given Wen-Shen-Tong-Du Decoction by gavage,and the sham-operation group and the model group were given saline by gavage once a day for 28 days.During the drug administration period,mouse motor function was evaluated by Basso Mouse Scale score and inclined plane test.On the 7th and 28th days after modeling,hematoxylin-eosin staining was used to observe the histopathological changes in the spinal cord tissue of the mice;immunofluorescence double staining was used to detect the protein expression of ionized calcium binding adaptor molecule 1(IBA1)and TREM2;and western blot assay was used to detect the expression of TREM2,PI3K,p-PI3K,Akt,p-Akt,Bcl2,Bax and Caspase3 in spinal cord tissue. RESULTS AND CONCLUSION:Basso Mouse Scale scores and inclined plane test results indicated that the motor function of the mouse hindlimbs was declined after spinal cord injury,and Wen-Shen-Tong-Du Decoction significantly improved motor function in mice with spinal cord injury.Hematoxylin-eosin staining results revealed that Wen-Shen-Tong-Du Decoction significantly ameliorated the pathological structure of spinal cord tissue compared with the model group,manifesting as reduced degrees of dorsal white matter and neuronal atrophy,decreased cytoplasmic vacuolization,and reduced inflammatory cell infiltration.Immunofluorescence double staining results showed that on the 7th day after modeling,the protein expression of IBA1 and TREM2 in the model group was lower than that in the sham-operation group(P＜0.05),and the protein expression of IBA1 and TREM2 in the Wen-Shen-Tong-Du Decoction group was higher than that in the model group(P＜0.05);on the 28th day after modeling,the protein expression of TREM2 in the model group was lower than that in the sham-operation group(P＜0.05),and the protein expression of TREM2 in the spinal cord tissue of the mice in the Wen-Shen-Tong-Du Decoction group was higher than that in the model group(P＜0.05).Western blot results analysis demonstrated that on the 7th day after modeling,compared with the sham-operation group,the model group exhibited a significant reduction in TREM2,PI3K,and Bcl2/Bax(P＜0.05),as well as a significant increase in p-Akt,Bax and p-Akt/Aktp-PI3K(P＜0.05);compared with the model group,the Wen-Shen-Tong-Du Decoction group showed a significant increase in TREM2,PI3K,p-PI3K,Akt,p-Akt,Bcl2,p-PI3K/PI3K,p-Akt/Ak,and Bcl2/Bax(P＜0.05),as well as a significant decrease in Bax and Caspase3 protein expression(P＜0.05).On the 28th day after modeling,compared with the sham-operation group,the model group exhibited a significant reduction in TREM2,PI3K,p-PI3K,Akt,p-Akt,Bcl2 and Bcl2/Bax(P＜0.05),as well as a significant increase in Bax protein expression(P＜0.05);compared with the model group,the Wen-Shen-Tong-Du Decoction group showed a significant increase in TREM2,PI3K,Akt,p-Akt,Bcl2,and Bcl2/Bax(P＜0.05),as well as a significant decrease in Bax protein expression(P＜0.05).To conclude,Wen-Shen-Tong-Du Decoction may activate the PI3K/Akt signaling pathway by up-regulating the expression of TREM2 protein in microglia,and then inhibit neuronal apoptosis,thus exerting neuroprotective effects and promoting the repair of spinal cord injury.