Expression of cyclooxygenase in rat spinal cord with acute contusion / 中华创伤骨科杂志

ABSTRACT

Objective To characterize the localization and expression of cyclooxygenase (COX) in thoracic spinal cord before and after acute contusion. Methods 48 Sprague Dawley rats, 250 to 300 g in weight, were used for the study. The injuries of spinal cord were induced at the T8,9 level by dropping a weight of 10.24 g form a height of 50 mm (Allen’ s model). All the animals with spinal cord injury were sacrificed at time points ranging from 2 to 48 hours (2, 4, 8, 16, 24, and 48 hours) after management. Expressions of COX- 1 and COX- 2 in the thoracic spinal cords, normal and injured, were studied with immunohistochemistry. Results COX- 1 immunoreactivity was found to constitutively express in cytoplasmof glial cells and neuropils in white matter. Tiny COX- 1 immunoreactivity was found in glial cells, neuropils and neurons in the gray substance. It was found that COX- 2 immuno- labeling expressed constitutively in cytoplasm and closely surrounding the nucleus of neurons in both ventral and dorsal horns. Contusion to the spinal cord did not result in changes of COX- 1 protein localization and expression according to evaluation of immunohistochemistry. COX- 2 immunoreactivity improved only in neurons 4 hours following contusion. The positive COX- 2 protein reactivity reached the peak 24 hours after contusion. Conclusions In contrast to their expression in the majority of peripheral tissues, both COX isoforms express constitutively in the normal rat thoracic spinal cord. The major isoform of COX involved in the secondary spinal cord injury is COX- 2 after the spinal cord is mechanically injured.