MATERIAL and METHODS: The rats were assigned randomly to one of four groups, as follows: in group I, rats underwent laminectomy; group II, myelotomy was performed after laminectomy; group III, rats received contusion after laminectomy; and group IV, myelotomy was performed 1 hour after laminectomy and contusion. In order to create a spinal cord injury, a 10-g rod was dropped from a height of 50 mm onto the exposed dura at T10 level. For the myelotomy procedure, a longitudinal 1-1.5 mm depth midline incision was made to the spinal cord. Twelve hours later, rats were decapitated, and the spinal cord tissues were removed. The obtained tissues' glutamate concentrations were measured using the HPLC technique.

RESULTS: The glutamate levels were significantly lower in group III than those of groups I and II. In group IV, glutamate levels were significantly high compared to group III and significantly low compared to group I. Between groups I and II, there was no statistically significant difference.

CONCLUSION: The study results suggest that early myelotomy significantly prevented glutamate depletion from the injured spinal cord. Compared to the normal spinal cord, there was still significant depletion in injured spinal cord with myelotomy because of the initial glutamate release until the myelotomy was performed. It was also concluded that myelotomy was not harmful to the spinal cord as it did not cause significant glutamate depletion. Keywords : Glutamate excitotoxicity, Spinal cord injury, Secondary injury, Myelotomy, Contusion, Rat