Effects of iloprost on vasospasm after experimental spinal cord injury: an electron and light microscopic study

It has been increasingly reported that traumatic and ischemic insults to the spinal cord may produce tissue damage through both direct and indirect mechanisms. In spite of many theories about post-traumatic spinal cord injury, there is still no satisfactory account of the exact mechanism. Vasospasm may be related to the trauma and release of vasoconstrictor or vasoactive amines. This study aims at studying the possible protective mechanisms of iloprost, a stable analogue of prostacyclin, after spinal cord injury on the rabbit. Forty-two adult male rabbits (New Zealand albino) were inflicted injuries by epidural application of an aneurysm clip to the spinal cord. Twenty-one rabbits received an i.v. infusion of 25 microg kg(-1) x h(-1) iloprost. The remaining twenty-one rabbits received an i.v. infusion of saline as the control group. Intravenous treatment started immediately after the infliction of the spinal cord injury and lasted for 1 h. Iloprost treatment had no side effects on the general physiological parameters in the rabbits. Control and iloprost treatment groups were divided into three sub-groups. The first group of animals was deeply anesthetized and spinal cords were removed 15 min after treatment. Second and third group animals were sacrificed in the 3rd and 24th hours respectively. All spinal cords were removed for light and electron microscopic examination. The width of anteriolar smooth muscle cells and the ultrastructural analysis of sulcal arterioles and venules in the ventral median fissure of spinal cords treated by iloprost revealed less thickening in all groups especially on the 24th hour group (p < 0.01), but less thickening was observed on the 3rd hour group. Iloprost-treated groups had limited edema and moderate protection of myelin and axons. These results suggest that iloprost treatment after spinal cord injury has a highly protective effect, and the possible protective effect of iloprost is resolution of vasospasm due to spinal cord injury.