Changes of Cytochrome Oxidase Activity and Mitochondrial Ultrastructure by treatment of Naloxone in the Experimental Spinal Cord Injury

Suh, Jung Keun; Chu, Jeong Wha

Abstract

Impact injuries to the surgically exposed dura overlying the lumbar cord at L2 were produced in cats. Cytochrome oxidase activities in frozen-dried sample of spinal cord gray matter were measured and analyzed as a step in the investingation of the possible effects of spinal cord trauma on mitochondria. As conservative index of mitochondria damage in gray matter resulting from inactivation on cytochrome oxidase activity, electron microscopic studies of mitochondrial ultrastructural changes in traumatized gray matter were performed. The effects of Naloxone on the alteration of the cytochrome oxidase activities and ultrastructures of the mitochondria in the gray matter were studied. A drop in cytochrome oxidase activities to approximately 50% of normal value was found as early as 15 minutes post-trauma, which greatest decrease at 1/2 hour and 1 hour post-trauma. Ultrastructural changes of the mitochondria continued to proceed with the lapse of time after the injury. Mitochondriae were slightly enlarged with decreased number of cristae at 15 minutes post-trauma. Enlargement of the mitochondria with disintegration of cristae and electron-lucent area in the matrices were observed at 1 hour and 4 hour post-trauma. As relatively less change to the mitochondrial ultrastructures was observed in the Naloxone-treated group than in the non-treated group, the results of this study suggest that Naloxone confers beneficial effects in enhancing the cytochrome-oxidase activity and preserving the mitochondrial ultrastructures from injury.