Effects of thymoquinone on spinal cord injury in rats.

Purpose: Spinal cord injury (SCI) is a condition that causes disturbances in normal sensory, motor, and autonomic functions. During SCI, damages occur such as, contusion, compression, distraction. The aim of this study was to investigate effects of the antioxidative thymoquinone on neuron and glia cells in SCI biochemically, immunohistochemically and ultrastructurally.

Methods: Male Sprague-Dawley rats were divided into Control, SCI and SCI + Thymoquinone groups. After T10- T11 laminectomy was performed, a metal weight of 15 grams was left down the spinal tube for spinal damage. Immediately after the trauma, the muscles and skin incision were sutured. Thymoquinone was given to the rats by gavage as 30mg/kg/21days. Tissues fixed in 10% formaldehyde, embedded in paraffin wax and immunstained with Caspase-9 and phosphorylated signal transducer and activator of transcription 3 (pSTAT-3) antibodies. Remaining were stored at -80oC for biochemistry. Frozen spinal cord tissues were placed in a phosphate buffer solution and homogenized, centrifuged then used to measure malondialdehyde (MDA) levels, glutathione peroxidase (GSH) and Myeloperoxidase (MPO).

Results: In the SCI group, MDA, MPO, neuronal degeneration, vascular dilatation, inflammation, apoptotic appearance in the nucleus, loss of membrane and cristae in mitochondria, and dilatation in the endoplasmic reticulum were observed due to degeneration in the neuron structure. In the electron microscopic examination of the trauma + thymoquinone group, the membranes of the nuclei of the glial cells were thick and euchromatin, and mitochondria were shortened in length. In the SCI group, pyknosis and apoptotic changes were observed in neuronal structures and nuclei of glia cells in the substantia grisea and substantia alba region, along with positive Caspase-9 activity. An increase in Caspase-9 activity was observed in endothelial cells in blood vessels. In the SCI + thymoquinone group, Caspase-9 expression was positive in some of the cells in the ependymal canal while the cuboidal cells showed a negative Caspase-9 reaction in the majority. A few degenerated neurons in the substantia grisea region showed a positive reaction with Caspase-9. In SCI group, pSTAT-3 expression was positive in degenerated ependymal cells, neuronal structures, and glia cells. pSTAT-3 expression was positive in the endothelium and surrounding aggregated cells of the enlarged blood vessels. In the SCI+ thymoquinone group, pSTAT-3 expression was negative in most of the bipolar and multipolar neuron structures and glial cells in ependymal cells, enlarged blood vessel endothelial cells.

Conclusions: It has been thought that thymoquinone application in spinal cord injuries may be an antioxidant that can be recommended as an alternative treatment in suppressing the apoptosis of neural cells by significantly reducing the inflammation process.