Changes in free fatty acids, phospholipids, and cholesterol following impact injury to the rat spinal cord.

Free fatty acids (FFA), phospholipid, and cholesterol levels were measured in spinal cord samples from rats subjected to low (25 g-cm), moderate (50 g-cm), or severe (100 g-cm) impact trauma to the T10 spinal segment. All degrees of injury caused early (15 min) declines in total phospholipids after trauma; phospholipid levels remained significantly below controls in rats subjected to moderate and severe injuries for up to 3 days, whereas phospholipids had returned to baseline values by 4 hr in the low injury group. Rapid and persistent decreases in cholesterol levels were observed for all injury groups. Severe trauma was associated with biphasic increases in FFA levels: levels were elevated at 5 and 15 min post-trauma and had declined by 30 min; a second elevation was observed at 1 hr, progressively increasing to reach a maximum at 24 hr, before declining over the next 6 days. Low and moderate injuries caused similar early total FFA increases; later increases were significantly smaller than in the severely injured group. Among the free fatty acids, significant increases were observed in palmitate, stearate, oleate, linoleate, linolenate, arachidonate, and docosahexaenoate. These findings indicate that traumatic spinal cord injury results in early, transient, postinjury membrane phospholipid hydrolysis, the magnitude of which is relatively independent of the severity of injury. More delayed and sustained lipid hydrolysis also occurs after trauma, the magnitude of which is related to the severity of injury.