Abstract: BACKGROUND: Acute spinal cord injury is a disease with high disability and mortality. An active and effective treatment in the acute phase is of great significance to prevent secondary injury.
OBJECTIVE: To investigate the mechanism underlying Tongfu Zhuyu therapy in the treatment of acute spinal cord injury through observing the therapeutic effect of Jiajian Didang Tang on edema and recovery of limb function after acute spinal cord injury in rats.
METHODS: A total of 60 Sprague-Dawley rats were randomly divided into sham group, model group, Didang Tang group, 2-(nicotinamide)-1,3,4-thiadiazole (TGN-020) group, and Didang Tang combined with TGN-020 group (combined group), with 12 rats in each group. Among them, the sham group only underwent laminectomy without spinal cord shock and the other groups used NYU percussion device to create an acute spinal cord injury model. After modeling, the sham and model groups did not take any treatment measures. The Didang Tang group was given 5.04 g/kg Didang Tang by intragastric administration, the TGN-020 group was given 5 mg/kg TGN-020 by intraperitoneal injection, and the combined group was given TGN-020 by intraperitoneal injection combined with Didang Tang by intragastric administration, once a day for 7 days. Basso, Beattie and Bresnahan score and Reuter score were evaluated on 1, 3, 5 and 7 days after operation. Spinal cord tissue was taken for general observation and water content measurement at 7 days after operation. The degree of tissue damage was detected by hematoxylin-eosin staining. The number of aquaporin 4/glial fibrillary acidic protein-positive cells in the spinal cord tissue was detected by immunofluorescence assay. The protein expression levels of Aquaporin 4, glial fibrillary acidic protein, chondroitin sulfate proteoglycan, and proliferating cell nuclear antigen protein in spinal cord tissue were detected by western blot.
RESULTS AND CONCLUSION: The behavioral scores showed that compared with the model group, the Basso, Beattie and Bresnahan scores were significantly increased in the three administration groups (P < 0.05), while the Reuter scores were significantly decreased (P < 0.05). Moreover, there was no significant difference among the three administration groups (P > 0.05). Compared with the model group, the water content of spinal cord tissue was significantly decreased in the three administration groups (P < 0.05), while there was no significant difference among the three administration groups (P > 0.05). Hematoxylin-eosin staining results showed that the structure of the model group was disorganized, with a lot of scar tissue and syringomyelia. Compared with the model group, the tissue structure was relatively complete in the three administration group, with a small amount of scar tissue hyperplasia and syringomyelia, and the tissue morphology was effectively improved. Immunofluorescence staining results showed that compared with the model group, the number of aquaporin 4/glial fibrillary acidic protein-positive cells was less in the three administration groups, with lower brightness and reduced degree of cell swelling (P < 0.05). However, there was no significant difference among the three administration groups (P > 0.05). Western blot results showed that compared with the model group, the expressions of aquaporin 4, glial fibrillary acidic protein, chondroitin sulfate proteoglycan, and proliferating cell nuclear antigen protein in the spinal cord tissue of the three administration groups were significantly decreased (P < 0.05). While, there was no significant difference among the three administration groups (P > 0.05). To conclude, Jiajian Didang Tang can promote the recovery of limb function in rats with acute spinal cord injury under the guidance of Tongfu Zhuyu therapy. Its mechanism may reduce edema at the injury site by inhibiting the expression of aquaporin 4, so as to effectively inhibit the activation and proliferation of reactive astrocytes and reduce the formation of glial scar.   

Key words: Tongfu Zhuyu therapy, Didang Tang, acute spinal cord injury, edema, scar, hyperblastosis, astrocyte