Objective    To observe the influence of tetrandrine (Tet) on the expressions of Bcl-2 and Bax in rats with spinal cord injury.     Methods    A total of 100 SD rats were randomly divided into sham-operation group (group A

n=10)

spinal cord injury group (group B

n=30)

methylprednisolone group (MP) group (group C

n=30) and Tet group (group D

n=30). The modified Allen method was adopted to establish the models of T9 spinal cord injury in groups B

C and D. The animals of group D received 1% 22.5 mg/kg Tet through tail vein in 24 and 48 h after operation

those of group B were injected with normal saline at same volume as in group D

and the rats from group C were given a tail vein injection of  90 mg/kg MP before and 24 and 48 h after injury. BBB score was recorded at  8 h

and 1

3

7 and 14 d after operation . Six rats from each group were killed immediately after BBB scoring

and the samples were taken from the spinal cord injury sites for HE staining. The expression levels of Bcl-2 and Bax proteins in the obtained samples were studied with immunohistochemical assay.     Results    The BBB score of groups C and D were significantly higher than that of group B at day 7 and 14 (P0.05). There was no significant difference in the score between groups C and D at each time points (P0.05). HE staining showed the spinal cord of groups C and D had fewer necrosis than that of group B (P0.05). The injury was most severe in day 3 to 7. The number of Bcl-2 positive cells in groups C and D were larger than those of group B at each time points (P0.05). However the number of Bax postive cells in groups C and D were less than those of group B at each time points (P0.05).     Conclusion    Tet is able to protect neurons from apoptosis and promote the nerve function recovery by inhibiting the expression of Bax and promoting the expression of bcl-2.