Changes in free fatty acids, phospholipids, and cholesterol following impact injury to the rat spinal cord.
Explore the source record for details and available documents.
Retraction Notice↗
Biomedical subjects
P Demediuk
Publications and source records attributed to P Demediuk.
Spinal cord edema and changes in tissue content of Na+, K+, and Mg2+ after impact trauma in rats.
Changes in the tissue content of water, Na+, K+, and Mg2+ were measured in spinal cord samples from anesthetized rats subjected to impact trauma (T9 spinal segment) of varying severity: 25 g-cm (low injury), 100 g-cm (high injury). Laminectomized animals served as controls. Rats with high injury were killed at 15 min, 60 min, 4 hr, 24 hr, 3 days, or 7 days after trauma. Those with low injury were killed at 24-hr postinjury. In all groups, spinal cord tissue was rapidly removed (less than 30 sec), frozen in liquid nitrogen, and dissected into the injured segment and adjacent two caudal and rostral segments. Water content was determined as wet weight/dry weight ratios, and cations were measured by atomic absorption spectrophotometry. High injury resulted in statistically significant increases in water content as early as 15 min after trauma. There were concomitant increases in Na+ and decreases in K+ that were apparent at 15 min and were statistically significant by 60-min posttrauma. The increases in water content and Na+ were present to a similar degree in the 4-hr, 24-hr, 3-day, and 7-day groups. In contrast, tissue Mg2+ was reduced and significantly decreased at 4 hr and 24 hr; Mg2+ levels had recovered partially by 3 days and completely by 7 days. Whereas changes in the tissue content of water, Na+, and K+ occurred at 24 hr regardless of the injury severity, changes in total Mg2+ were correlated with the degree of injury. These data are consistent with the conclusion that edema formation (and associated Na+ and K+ changes) after spinal cord trauma may be an epiphenomenon and does not significantly contribute to injury progression. In contrast, reductions in Mg2+ content may represent an important factor in the development of irreversible tissue damage.
Animals↗
Traumatic spinal cord injury in rabbits decreases intracellular free magnesium concentration as measured by 31P MRS.
The mechanisms by which traumatic injury to the central nervous system cause irreversible tissue damage remain speculative. Recent reports suggest that a decrease in tissue total and free Mg2+ concentration may be an important factor in the development of such injury after experimental brain trauma. Although total Mg changes have been reported following spinal cord trauma, no studies have examined spinal cord-free Mg2+. In the present study, we have used phosphorus magnetic resonance spectroscopy to determine intracellular free Mg2+ concentration and atomic absorption spectrophotometry to measure total tissue Mg concentration in rabbit spinal cord prior to and following impact trauma. We report that intracellular free Mg2+ concentration decreases from a pre-injury value of 0.80 +/- 0.12 mM (mean +/- S.E.M.) to 0.31 +/- 0.05 mM at 2 h post-trauma. Following injury there was an associated decrease in total tissue Mg and K concentration, but no alterations in tissue Na or water content.
Animals↗
The role of excitatory amino acids and NMDA receptors in traumatic brain injury.
Brain injury induced by fluid percussion in rats caused a marked elevation in extracellular glutamate and aspartate adjacent to the trauma site. This increase in excitatory amino acids was related to the severity of the injury and was associated with a reduction in cellular bioenergetic state and intracellular free magnesium. Treatment with the noncompetitive N-methyl-D-aspartate (NMDA) antagonist dextrophan or the competitive antagonist 3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid limited the resultant neurological dysfunction; dextrorphan treatment also improved the bioenergetic state after trauma and increased the intracellular free magnesium. Thus, excitatory amino acids contribute to delayed tissue damage after brain trauma; NMDA antagonists may be of benefit in treating acute head injury.
Animals↗
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.
Animals↗
Changes in lipid metabolism, tissue cations, and water content after fluid-percussion-induced traumatic brain injury in rats.
Explore the source record for details and available documents.
Letter↗
Effect of impact trauma on neurotransmitter and nonneurotransmitter amino acids in rat spinal cord.
N-Methyl-D-aspartate (NMDA) administration exacerbates neurological dysfunction after traumatic spinal cord injury in rats, whereas NMDA antagonists improve outcome in this model. These observations suggest that release of excitatory amino acids contributes to secondary tissue damage after traumatic spinal cord injury. To further examine this hypothesis, concentrations of free amino acids were measured in spinal cord samples from anesthetized rats subjected to various degrees of impact trauma to the T9 spinal segment. Levels of excitatory and inhibitory neurotransmitter amino acids [gamma-aminobutyric acid (GABA), glutamate, aspartate, glycine, taurine] and levels of nonneurotransmitter amino acids (asparagine, glutamine, alanine, threonine, serine) were determined at 5 min, 4 h, and 24 h posttrauma. Uninjured surgical (laminectomy) control animals showed modest but significant declines in aspartate and glutamate levels, but not in other amino acids, at all time points. In injured animals, the excitatory amino acids glutamate and aspartate were significantly decreased by 5 min posttrauma, and remained depressed at 4 h and 24 h as compared with corresponding laminectomy controls. In contrast, the inhibitory amino acids, glycine, GABA, and taurine, were decreased at 5 min postinjury, had partially recovered at 4 h, and were almost fully recovered at 24 h. The nonneurotransmitter amino acids were unchanged at 5 min posttrauma and significantly increased at 4 h, with partial recovery at 24 h. At 4 h postinjury, severe trauma caused significantly greater decreases in aspartate and glutamate than did either mild or moderate injury. These findings are consistent with the postulated role of excitatory amino acids in CNS trauma.
Alanine↗
Effects of BW755C, a mixed cyclo-oxygenase-lipoxygenase inhibitor, following traumatic spinal cord injury in rats.
BW755C is an inhibitor of both cyclo-oxygenase and lipoxygenase, which has been found to have protective effects after myocardial ischemia in dogs. Impact injury to the spinal cord is associated with tissue ischemia as well as with the accumulation of eicosanoids. In the present studies we evaluated the effects of BW755C after traumatic spinal cord injury in rats. Drug treatment reduced thromboxane B2 levels and improved neurological recovery as compared to treatment with equal-volume physiological saline. The findings suggest that this drug or related compounds may be useful for the treatment of clinical spinal cord injury.
4,5-Dihydro-1-(3-(trifluoromethyl)phenyl)-1H-pyraz↗
Decline in intracellular free Mg2+ is associated with irreversible tissue injury after brain trauma.
Much of the tissue damage resulting from trauma to the central nervous system appears to result from secondary, delayed biochemical changes that follow primary mechanical injury. However, the early biochemical events remain to be elucidated. In the present studies, we have used phosphorus (31P) magnetic resonance spectroscopy (MRS) to examine in vivo, the temporal changes in brain intracellular free Mg2+ concentration following fluid percussion head injury in rats. We report that injury caused a profound and rapid decrease in intracellular free Mg2+ which was significantly correlated with the severity of injury. At high levels of injury, the decrease in intracellular free Mg2+ concentration was associated with a decrease in total Mg2+ concentration as determined by atomic absorption spectrophotometry. Prophylactic treatment with MgSO4 prevented the post-traumatic decrease in intracellular free Mg2+ and resulted in a significant improvement in acute neurological outcome. Because magnesium is essential for a number of critical enzyme reactions, including those of glycolysis, oxidative and substrate level phosphorylation, protein synthesis, and phospholipid synthesis, changes in free Mg2+ after brain trauma may represent a critical early factor leading to irreversible tissue damage.
Algorithms↗
Traumatic spinal cord injury in rats causes increases in tissue thromboxane but not peptidoleukotrienes.
Spinal cord samples from rats subjected to three different levels of impact trauma (25, 50, 100 g-cm) were examined for immunoreactive thromboxane B2 and 6-sulfidopeptide-containing leukotrienes, using specific radioimmunoassays. Trauma resulted in pronounced increases in thromboxane levels as early as 5 min after injury, with maximum values at 1 hr. Although thromboxane values then slowly declined, they remained significantly above control values for up to 7 days. Significantly smaller thromboxane values were found in rats subjected to mild injury (25 g-cm) than in those that received more severe, irreversible impact injury (50 and 100 g-cm). No statistically significant changes were observed in leukotriene levels in any of the experimental groups. These findings are consistent with the hypothesis that cyclooxygenase products of arachidonic acid metabolism may contribute to secondary injury after spinal cord trauma and provides the rationale for the use of cyclooxygenase inhibitors in the treatment of such injury.
Animals↗
Traumatic brain injury in the rat: effects on lipid metabolism, tissue magnesium, and water content.
Tissue levels of free fatty acids (FFA), total phospholipid, cholesterol, thromboxane B2, water, Na+, K+, and Mg2+ were measured in rat brain after lateral fluid-percussion brain injury of moderate severity (2.0-2.2 atm). Brains of injured animals and sham-operated controls were frozen in situ with liquid N2 at 10 min, 4 h, and 24 h postinjury and removed. The left parietal cortex, which has been shown previously histologically to be the site of maximal injury, was dissected for analysis. Traumatic injury was associated with small increases in FFA levels at 10 min and 4 h and much larger increases at 24 h postinjury. Among the FFA, the largest increases were observed in stearate, arachidonate, and docosahexaenoate. Total phospholipid and cholesterol levels were decreased significantly at all experimental time points. Thromboxane levels were markedly elevated (30-fold) at 10 min posttrauma but substantially declined by 4 h and approached control values at 24 h. Total Mg2+ levels were significantly below control values at 4 h and 24 h posttrauma. No changes in water content were observed at any of these time points. Small decreases in tissue K+ occurred at 4 h; tissue Na+ levels were found to be slightly increased only at 24 h. These results are consistent with the hypothesis that changes in lipid metabolism and Mg2+ content of brain after injury may play a role in the pathophysiology of irreversible, posttraumatic tissue damage. In contrast, significant edema formation does not occur in this model and does not, therefore, appear to be a factor in the injury process.
Animals↗
Decrease in total and free magnesium concentration following traumatic brain injury in rats.
31P magnetic resonance spectroscopy was used to determine the intracellular free Mg2+ concentration prior to and following fluid percussion induced traumatic brain injury in rats. Prior to injury, cerebral intracellular free Mg2+ concentration in the rat was 0.93 +/- 0.19 mM (mean +/- SE; n = 5). Following injury, free Mg2+ in the injured cortex declined by 70% within the first hour, and did not recover over the next 3 hours. Total Mg2+ also declined by 10% over this time period; however, there were no changes in brain Na+ or tissue water content. Because of its primary role in cellular metabolism, the early decline in tissue Mg2+ following brain trauma may be a critical factor in the development of irreversible tissue injury.
Adenosine Triphosphate↗
Alterations in tissue Mg++, Na+ and spinal cord edema following impact trauma in rats.
Alterations in water content and total tissue Na+ and Mg++ of rat spinal cord tissue were followed over time after a 100 g-cm impact injury to the T-9 spinal cord segment. Rats subjected to laminectomy but not trauma served as controls. In the injured segment there was a progressive increase in water content with increased Na+ and decreased Mg++ at 1 hour and 24 hours after trauma. At seven days, water and Na+ content remained elevated, whereas Mg++ levels had returned to preinjury baseline values. Because of its important role in many metabolic and physiological regulatory processes the early decline in Mg++ concentration after trauma may contribute to the development of secondary tissue damage after spinal cord injury.
Animals↗
Early membrane lipid changes in laminectomized and traumatized cat spinal cord.
The effects of surgical exposure (laminectomy) and compression trauma on various aspects of membrane lipid metabolism in the feline spinal cord were determined in this study. Tissue samples were frozen in situ and grossly dissected into gray and white portions prior to lipid analyses. Laminectomy alone resulted in measurable changes in spinal cord lipid metabolism, including increases in gray matter free fatty acids, diacylglycerols, and eicosanoids. A 90-min recovery period greatly reduced the levels of these compounds. Compression of the spinal cord with a 170-g weight (following a 90-min recovery period) caused very large increases in gray matter free fatty acids, diacylglycerols, and eicosanoids, and decreases in cholesterol and ethanolamine plasmalogens. Similar, but time delayed changes in these compounds were also observed in white matter.
Animals↗
Effects of methylprednisolone and the combination of alpha-tocopherol and selenium on arachidonic acid metabolism and lipid peroxidation in traumatized spinal cord tissue.
Traumatic injury of the spinal cord leads to a series of pathological events that result in tissue necrosis and paralysis. Among the earliest biochemical reactions are hydrolysis of fatty acids from membrane phospholipids, production of biologically active eicosanoids, and peroxidation of lipids. This study examines the effect of agents purported to improve recovery following spinal cord trauma, methylprednisolone sodium succinate (MPSS) and the combination of alpha-tocopherol and selenium (Se), on the posttraumatic alterations of membrane lipid metabolism. Pretreatment with either MPSS or alpha-tocopherol and Se reduced the trauma-induced release of total FFA including arachidonate in the injured spinal cord tissue. In addition, these agents decreased the postinjury levels of prostanoids. Pretreatment with either MPSS or alpha-tocopherol and Se also completely prevented the trauma-induced loss of cholesterol while inhibiting the increase of a cholesterol peroxidation product, 25-hydroxycholesterol. These data suggest that: perturbation of membrane lipid metabolism may contribute to the tissue necrosis and functional deficit of spinal cord injury and MPSS or the combination of alpha-tocopherol and Se may protect injured spinal cord tissue, at least in part, by limiting these posttraumatic membrane lipid changes.
Animals↗
Separation of phospholipids by high-performance liquid chromatography: all major classes, including ethanolamine and choline plasmalogens, and most minor classes, including lysophosphatidylethanolamine.
High-performance liquid chromatographic methods for the separation and quantitation of phospholipids were developed and shown to give sensitive, reliable measurements of tissue phospholipids, including difficult-to-resolve pairs such as choline plasmalogen (plasmenylcholine) and phosphatidylcholine, choline glycerophospholipids and sphingomyelin, phosphatidylinositol and phosphatidylserine, and phosphatidylserine and lysophosphatidylethanolamine. Separations of most phospholipids including those mentioned above are more complete than in existing procedures, and require only 40 min per injection. Utilization of the hexane-2-propanol-water system has an advantage over separation techniques that employ acidic solvents in that the plasmalogens are not hydrolyzed and a less degradative environment for labile lipids is provided. Further, a rapid high-performance liquid chromatographic procedure for the separation of intact ethanolamine plasmalogen (plasmenylethanolamine) from phosphatidylethanolamine was developed. Previous procedures have required derivatized samples or acid hydrolysis of the plasmalogen vinyl ether linkage. A slight modification of the primary method (method I) increases the resolution of lysophosphatidylethanolamine from other classes (method II). A third modification (method III) can replace the standard silicic acid column separation of lipids into neutral, glycolipid, and phospholipid fractions.
Animals↗
Phospholipids of normal and experimentally injured spinal cord of the miniature pig.
Experimental spinal cord trauma was produced in 3-month-old SS-1 miniature pigs by dropping a 25 g weight from a height of 20 cm upon the exposed spinal cord. The histological lesion consisted of edema and hemorrhage. Phospholipid concentration and composition, cholesterol concentration and phospholipid fatty acid composition were determined in whole spinal cord 3 hours after injury, and in spinal cord myelin 5 hours after injury. Three hours after injury phospholipid and cholesterol concentration were decreased by about 14% in the whole spinal cord. Trauma had no effect on the phospholipid composition of whole spinal cord and myelin. Fatty acid composition of myelin also did not change after injury, and changed very slightly in the whole spinal cord. It is concluded that edema following spinal cord trauma is much more extensive than previously assumed. Furthermore, peroxidation of membrane lipid fatty acids does not appear to be a significant factor in spinal cord pathology 3 hours after injury.
Animals↗
Mechanical damage to murine neuronal-enriched cultures during harvesting: effects on free fatty acids, diglycerides, Na+,K+-ATPase, and lipid peroxidation.
The most commonly used procedure to harvest cultured cells from petri dishes is to scrape the cells off the plates with a rubber or Teflon policeman. However, the results reported herein demonstrate that this technique, with its associated mechanical trauma, significantly perturbed cell membranes in neuronal-enriched cultures derived from the ventral half of fetal murine spinal cords. This is evidenced by liberation of free fatty acids and diglycerides, partial inhibition of Na+,K+-ATPase activity, and increased malondialdehyde production. Harvesting the cells by freezing, either on liquid nitrogen or dry ice, significantly attenuated these effects. This important observation indicates that mechanical manipulation of cultured cells during harvesting significantly affects subsequent biochemical analyses, particularly those associated with the cell membrane (e.g., membrane lipid metabolism and assay of intrinsic membrane enzymes).
Animals↗