Abstract: Objective To explore the degeneration of motor end plates (MEP) by observing the expression of calcitonin gene-relative peptide (CGRP) and acetylcholine esterase (AChE) in the MEP after different types of spinal cord injury. Methods 60 adult female Wistar rats were randomly assigned to 3 groups: sham group, completely transection group and contusion group. The content of AChE in the MEP was detected with Karnovsky-Roots staining and the expression of CGRP was then determined with immunohistochemistry. Results The content of both AChE and CGRP significantly decreased after either type of spinal cord injury. However, their activity gradually recovered to the normal level in the contusion group, but not in the transection group. Moreover, the changes of CGRP occurred earlier than those of AChE. Conclusion The motor end plate degenerates differently after different kinds of spinal cord injury in adult rat, CGRP and AChE are related to the degeneration of MEP.

Key words: spinal cord injury (SCI), motor end plates (MEP), calcitonin gene-related peptide (CGRP), acetylcholine esterase (AChE), rats