Effect and mechanism of Tetramethylpyrazine in repair of sciatic nerve injury in rats

Abstract Objective: Observing the effects of Tetramethylpyrazine (TMP) on the expression of Collagen IV and Laminin in neurovascular basement membrane and the apoptosis of vascular endothelial cells, and to study the mechanism of TMP in the treatment of sciatic nerve injury. Methods: Sprague Dawley (SD) rats were randomly divided into control group, the model of sciatic nerve crush injury was made by means of hemostatic forceps, These rats were randomly divided into sham operation group (NC group), Tetramethylpyrazine group (TMP group, 200mg/kg), and normal saline group (NS group, 200mg/kg). Sciatic nerve function index (SFI) and grid crawling experiments were used for behavioral evaluation. hematoxylin-eosin (HE) staining was performed to observe its pathological structure and morphology. Immunohistochemistry was used to assess the expression level of Collagen IV and Laminin expression in sciatic nerve vascular basal membrane. Immunofluorescence was used to detect the expression of CD31 and Brdu receptors. The number of Circulating endothelial cells (CECs) was detected by flow cytometry. Results：Compared with the NS group, the TMP group had a significant increase in the sciatic nerve function index (P<0.01).The miss times in TMP group was significantly lower than that in NS group (P<0.01). The HE staining results of the TMP group showed irregular arrangement of some neuronal axons and Schwann cells, and more edema and rupture of cells. The proliferation of glial cells and inflammatory cells was significantly increased in TMP group. The results of immunohistochemistry showed that the expression of type IV collagen and laminin in the TMP group group was distributed around the blood vessels, vascular endothelial cells, basal membrane and glial cells after SNI. The expression of type IV collagen and laminin in TMP group increased significantly(P< 0.05). Immunofluorescence showed that compared with NS group, the apoptosis rate of TMP group was significantly decreased (P< 0.01). Flow cytometry results showed that compared with the NS group, the number of CECs in the TMP group was significantly decreased (P< 0.01).