[The expression of c-fos and transmitter calcitonin gene-related peptide in the chronic compressive injury of the nerve root].

Objectives: To investigate the significance of c-fos oncogene morphogenetic protein's locational expression, and the correlativity between nerve transmitters calcitonin gene-related peptide (CGRP) expression and nerve root's functional change using the animal model of the chronic compressive injury in the nerve root.

Methods: The animal model of chronic compressive injury of the nerve root was established by transplanting autogenous cancellous bone into the intervertebral foramen. During different injury phase (1, 2, 4, 8, 12, 24 weeks after operation), the functional status of the nerve root was determined under the monitoring of evoked potential, and the expression changes of c-fos oncogene morphogenetic protein and nerve transmitter CGRP were detected using in situ hybridization technique and their expression intensity was determined using automatic image analytic instrument respectively.

Results: One week after operation, the c-fos expression strengthened in both anterior and posterior root fiber obviously. Two to four weeks after operation, the expression of the posterior root fiber weakened than the anterior root fiber. After 12 weeks, the anterior root fiber expression turned down obviously, however the posterior root fiber expression backed up slightly compared with that of the 8 weeks. By the time of 24 weeks after operation, the expression enhancement in all roots disappeared. CGRP expression increased obviously at the site of compressive axon of both anterior and posterior root. The expression of the posterior root axon and ganglion cell was higher than that of the anterior root axon. CGRP expression was diminished in the second week than the first week, and that was especially obvious in the posterior root and ganglion cell. But 4 weeks after operation, the expression enhanced once more, and that was more obvious inside the anterior root axon. Eight weeks after operation, the expression intensity attained the high peak. Twelve weeks after operation, the expression started the slow-moving descent.

Conclusions: The expression of c-fos gene protein is beneficial to localize the damaged part of certain nerve. During chronic injury, the degeneration of posterior root sensory fiber is earlier than the anterior root motor fiber. The expression of CGRP strengthened when the nerve fiber degenerated by the harmful stimulation, and the expression intensity is positively related with pain. That suggests when the nervous tissue is hurt, the information of warning and regulation should be sent out to our body.