THE EFFECTS OF SELENIUM AND ALPHA-TOCOPHEROL ON THE FREE RADICALS IN AN EXPERIMENTAL MODEL OF ACUTE SPINAL CORD INJURY Nail izgi. M.D .. Mustafa Bozboga. M.D .. M. Kemal Hamamaoglu. M.D .. Murat D6~oglu. M.D .. Talat Km~. M.D .. Ali Canbolat. M.D .. Tuncay Altug. phD Department of Neurosurgery. istanbul Medical School and Experimental Medical Research and Application Center(TA). University of istanbuL istanbuL Turkey Turkish Neurosurgery 1: 119-1n. 1990 SUMMARY: Ischemia-induced lipid peroxidation is one of the most important factors produdng tissue damage in spinal cord injury. In this study a standard spinal cord injury model in rats was used and the effects of chronic admi- nistration of Selenium (3 ppm/lt water orally) before and alpha-tocopherol management (100 mg/kg. intraperito- neally) just after the trauma were investigated. For this purpose animals were divided into three groups: A (untreated controls). B (selenium-treated). C (alpha-tocopherol-treated). In group-A lipid peroxide levels incre- ased significantly one hour after the trauma. and then decreased. In group-B. this increase was not seen (P<0.05). This study has demonstrated that chronic selenium administration is effective in preventing lipid peroxide for- mation in spinal cord injury. For grup-C further investigations have been planned. KEYWORDS: alpha-tocopherol. free radicals. posttraumatic ischemia. selenium. spinal cord injury. INTRODUCTION The treatment of spinal cord injury is still a prob- lem for today's neurosurgeon. Recently there have been many experimental studies on the pathophysi- ology of acute spinal cord injury. The results of the- se studies. show that the injured spinal cord suffers not only from the direct mechanical effects of trau- ma on the neuronal and neurovascular components. but even more from the secondary effects of trauma on the vasculature and blood flow in the spinal cord (1.3.7.9.10.22). It might be possible to treat patients with spinal cord injury by preventing or reversing the undesirable effects of posttraumatic ischemia. During the past decade. a considerable research effort has been focused on the role of free radicals and lipid peroxidation in the occurence of ischemic damage (2.14.16.26). In this study. selenium and alpha-tocopherol (Vi- tamin E) known as free radical scavengers were used to investigate their therepeutic effects on spinal cord ischemia related to trauma. MATERIALS AND METHODS One hundred and twenty female Wistar rats we- ighing 180.±20gr were used. Three main groups each containing 40 rats were investigated; Group A (unt- reated controls). Group B (animals given 3 ppm sele- nium per liter of tap water. approximately 30 mlf24 hours. started 20 days before the trauma). and Gro- up C (animals administered pure alpha-tocopherol emulsion 20 mg. intraperitoneally. just after the tra- uma). Each main group was also divided into five subgroups of eight animals (AO-4. BO-4. CO-4). Surgical procedure Rats were anesthetized with intraperitoneal ad- ministration of thiopental sodium (35 mglkg). and im- mobilized in prone position. Following a T,-Tll midline indsion. the paravertebral muscles were dis- sected free. then spinous process and laminar arcs were removed between T, and T, under the surgi- cal microscope and the spinal cord was exposed. In the zero groups (AO. BO. CO). spinal cord tra- uma was not performed after laminectomy. The spinal cord was compressed at the midtho- radc level extradurally by a Ya~argil aneurysm clip (Aesculap FE 760. closing force:180..±18 gr) for one- minute. By this procedure it was possible to standar- dize spinal cord trauma in all rats as described by Ta- tor and Dolan (8).After the trauma the whole length of the thoracal vertebral column was cooled by app- lying liquid nitrogen and was removed at the first 119