Objective: To explore the protective effect of Mailuoning injection and hormone on spinal cord damage in radiculitis rats and to investigate the underlying mechanism as well as the evidence for substituting Mailuoning injection for hormone. Method: Wistar rats were divided into five groups randomly:normal group

sham group

model group

Mailuoning-treated group and Kangning Ketong-treated group. Filter paper placement was adopted as model method. Radioimmunologic technique was employed for blood interleukin8(IL-8) and thromboxane B2(TXB2) detetion

Nissl's staining method was used for neurons observation and immunohistochemical technique was used to examine the expression of Bax and Bcl-2 in spinal cord. Result: Compared with normal group

neurons degeneration and necrosis were normally observed in model group. Meanwhile

blood concentration of TXB2 and IL-8 was significantly increased (P<0.01)

and Bax expression was obviously up-regulated (P<0.05) in model group. Compared with model group

neurons degeneration and necrosis were greatly decreased in Mailuoning-and Kangningketong-treated group

and at the same time

IL-8 and TXB2 concentration as well as Bax-positive expression were decreased

while Bcl-2 protein was remarkably up-regulated

then ratio of Bax/Bcl-2 was obviously decreased (P<0.01). Furthermore

there was no significant difference between the above two groups. Conclusion: The experiment implied that Mailuoning injection could relieve inflammation of spinal cord in radiculit rats and protect spinal cord neurons from apoptosis

which may be one of the mechanisms of Mailuoning injection on reliving lumbocrural pain through replacing hormone in clinical practice.