Membrane phospholipid metabolism is markedly stimulated following traumatic injury to the spinal cord. In order to understand the molecular mechanisms of the pathogenesis of spinal cord trauma, we will determine the levels of phospholipids, plasmalogens, phospholipid hydroperoxides, oxysterols, cholesterol, alpha-tocopherol, diacylglycerols, free fatty acids and eicosanoids and the activities of lipases, phospholipases, lysophospholipases and plasmalogen-specific phospholipase A2. We use a standardized contusion model of rat spinal cord injury recently developed in our center. The in vitro models include a continuation of pressure-induced injury and ischemic/hypoxic injury models. We will develop a free radical model involving the use of FeCl2, xanthine/xanthine oxidase and a combination of these two. Persistent stimulation of excitatory amino acid receptors by glutamate induces calcium entry. The effects on lipid metabolism of stimulation of pharmacologically distinct glutamate receptors will be determined. Other cultures will be treated with various pharmacological agents including: methylprednisolone and lazaroids, peroxidative injury; MK801 and APV, glutamate antagonists; MK886-5, lipoxygenase inhibitor; BW755C, lipoxygenase/cyclooxygenase inhibitor; indomethacin, a cyclooxygenase inhibitor; and GM1 ganglioside, a stimulant of neurite outgrowth. The role of Ca2+ will be determined in all in vitro models by the manipulation of intracellular Ca2+ using the intracellular Ca2+ buffer BAPTA, the extracellular Ca2+ buffer EGTA, and a low extracellular Ca2+ environment. Using these models, we will determine the mechanisms involved in spinal cord injury. Relationships to other projects: This project integrates the in vivo animal model into a project examining early events following spinal cord injury from a biochemical aspect. The role of Ca2+ in these mechanisms of the in vitro models ties into the work of Dr. Stokes on the role of energy depletion on cell survival and intracellular Ca2+ concentrations (Project 2). The studies of ganglioside effects and the roles of kinases in stimulation of lipase activities will benefit from the complementary studies of Dr. Yates (Project 5).
