Expression of calcitonin gene-related peptide in anterior and posterior horns of the spinal cord after brachial plexus injury.

This study shows the expression pattern of calcitonin gene-related peptide (CGRP) in the anterior and posterior horns of the spinal cord after brachial plexus injury. The animals were divided into three injury groups: group 1, right C(7) anterior root avulsion; group 2, right C(7) anterior root avulsion and cut right C(5)-T(1) posterior roots; and group 3, right C(7) anterior root avulsion plus right hemitransection between the C(5) and C(6) segments of the spinal cord. These animals were killed at 1, 3, 7 and 14 days after injury. In the anterior horn of all three injured groups, the expression of CGRP increased progressively from day 1 to day 7 (p<0.05), peaked on day 7, and then began to decrease slowly. In the posterior horn of all three injured groups, the expression of CGRP decreased gradually from day 1 to day 14 after the operation and was significantly lower on day 14 compared to day 1. At each time point (days 1, 3, 7 and 14), the expression of CGRP was the highest in group 1 and the lowest in group 2, with significant differences among the three groups. The CGRP in the anterior horn of the spinal cord was derived from the cell bodies of motor neurons and was possibly involved in repair mechanisms and regeneration after nerve injury. However, the CGRP in the posterior horn was mainly derived from the posterior root ganglion and was possibly associated with the conduction of noxious stimulation.