Spinal Cord Lipid Research Articles

Blocking Kallikrein 6 promotes developmental myelination.

Kallikrein related peptidase 6 (Klk6) is a secreted serine protease highly expressed in oligodendrocytes and implicated in demyelinating conditions. To gain insights into the significance of Klk6 to oligodendrocyte biology, we investigated the impact of global Klk6 gene knockout on CNS developmental myelination using the spinal cord of male and female mice as a model. Results demonstrate that constitutive loss of Klk6 expression accelerates oligodendrocyte differentiation developmentally, including increases in the expression of myelin proteins such as MBP, PLP and CNPase, in the number of CC-1+ mature oligodendrocytes, and myelin thickness by the end of the first postnatal week. Co-ordinate elevations in the pro-myelinating signaling pathways ERK and AKT, expression of fatty acid 2-hydroxylase, and myelin regulatory transcription factor were also observed in the spinal cord of 7d Klk6 knockouts. LC/MS/MS quantification of spinal cord lipids showed sphingosine and sphingomyelins to be elevated in Klk6 knockouts at the peak of myelination. Oligodendrocyte progenitor cells (OPCs)-derived from Klk6 knockouts, or wild type OPCs-treated with a Klk6 inhibitor (DFKZ-251), also showed increased MBP and PLP. Moreover, inhibition of Klk6 in OPC cultures enhanced brain derived neurotrophic factor-driven differentiation. Altogether, these findings suggest that oligodendrocyte-derived Klk6 may operate as an autocrine or paracrine rheostat, or brake, on pro-myelinating signaling serving to regulate myelin homeostasis developmentally and in the adult. These findings document for the first time that inhibition of Klk6 globally, or specifically in oligodendrocyte progenitors, is a strategy to increase early stages of oligodendrocyte differentiation and myelin production in the CNS.

Neutral Lipid Cacostasis Contributes to Disease Pathogenesis in Amyotrophic Lateral Sclerosis.

Amyotrophic lateral sclerosis (ALS) is a fatal neuromuscular disease characterized by motor neuron (MN) death. Lipid dysregulation manifests during disease; however, it is unclear whether lipid homeostasis is adversely affected in the in the spinal cord gray matter (GM), and if so, whether it is because of an aberrant increase in lipid synthesis. Moreover, it is unknown whether lipid dysregulation contributes to MN death. Here, we show that cholesterol ester (CE) and triacylglycerol levels are elevated several-fold in the spinal cord GM of male sporadic ALS patients. Interestingly, HMG-CoA reductase, the rate-limiting enzyme in cholesterol synthesis, was reduced in the spinal cord GM of ALS patients. Increased cytosolic phospholipase A2 activity and lyso-phosphatidylcholine (Lyso-PC) levels in ALS patients suggest that CE accumulation was driven by acyl group transfer from PC to cholesterol. Notably, Lyso-PC, a byproduct of CE synthesis, was toxic to human MNs in vitro Elevations in CE, triacylglycerol, and Lyso-PC were also found in the spinal cord of SOD1G93A mice, a model of ALS. Similar to ALS patients, a compensatory downregulation of cholesterol synthesis occurred in the spinal cord of SOD1G93A mice; levels of sterol regulatory element binding protein 2, a transcriptional regulator of cholesterol synthesis, progressively declined. Remarkably, overexpressing sterol regulatory element binding protein 2 in the spinal cord of normal mice to model CE accumulation led to ALS-like lipid pathology, MN death, astrogliosis, paralysis, and reduced survival. Thus, spinal cord lipid dysregulation in ALS likely contributes to neurodegeneration and developing therapies to restore lipid homeostasis may lead to a treatment for ALS.SIGNIFICANCE STATEMENT Neurons that control muscular function progressively degenerate in patients with amyotrophic lateral sclerosis (ALS). Lipid dysregulation is a feature of ALS; however, it is unclear whether disrupted lipid homeostasis (i.e., lipid cacostasis) occurs proximal to degenerating neurons in the spinal cord, what causes it, and whether it contributes to neurodegeneration. Here we show that lipid cacostasis occurs in the spinal cord gray matter of ALS patients. Lipid accumulation was not associated with an aberrant increase in synthesis or reduced hydrolysis, as enzymatic and transcriptional regulators of lipid synthesis were downregulated during disease. Last, we demonstrated that genetic induction of lipid cacostasis in the CNS of normal mice was associated with ALS-like lipid pathology, astrogliosis, neurodegeneration, and clinical features of ALS.

Increasing acetyl-CoA metabolism attenuates injury and alters spinal cord lipid content in mice subjected to experimental autoimmune encephalomyelitis.

Acetate supplementation increases brain acetyl-CoA metabolism, alters histone and non-histone protein acetylation, increases brain energy reserves, and is anti-inflammatory and neuroprotective in rat models of neuroinflammation and neuroborreliosis. To determine the impact acetate supplementation has on a mouse model of multiple sclerosis, we quantified the effect treatment had on injury progression, spinal cord lipid content, phospholipase levels, and myelin structure in mice subjected to experimental autoimmune encephalomyelitis (EAE). EAE was induced by inoculating mice with a myelin oligodendrocyte glycoprotein peptide fragment (MOG35-55 ), and acetate supplementation was maintained with 4g/kg glyceryl triacetate by a daily oral gavage. Acetate supplementation prevented the onset of clinical signs in mice subject to EAE compared to control-treated mice. Furthermore, acetate supplementation prevented the loss of spinal cord ethanolamine and choline glycerophospholipid and phosphatidylserine in mice subjected to EAE compared to EAE animals treated with water. Treatment increased saturated and monounsaturated fatty acid levels in phosphatidylserine compared to controls suggesting that acetate was utilized to increase spinal cord fatty acid content. Also, acetate supplementation prevented the loss of spinal cord cholesterol in EAE animals but did not change cholesteryl esters. Treatment significantly increased GD3 and GD1a ganglioside levels in EAE mice when compared to EAE mice treated with water. Treatment returned levels of phosphorylated and non-phosphorylated cytosolic phospholipase A2 (cPLA2 ) levels back to baseline and based on FluoroMyelin™ histochemistry maintained myelin structural characteristics. Overall, these data suggest that acetate supplementation may modulate lipid metabolism in mice subjected to EAE.

Spatial elucidation of spinal cord lipid- and metabolite- regulations in amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a devastating, rapidly progressing disease of the central nervous system that is characterized by motor neuron degeneration in the brain stem and the spinal cord. We employed time of flight secondary ion mass spectrometry (ToF-SIMS) to profile spatial lipid- and metabolite- regulations in post mortem human spinal cord tissue from ALS patients to investigate chemical markers of ALS pathogenesis. ToF-SIMS scans and multivariate analysis of image and spectral data were performed on thoracic human spinal cord sections. Multivariate statistics of the image data allowed delineation of anatomical regions of interest based on their chemical identity. Spectral data extracted from these regions were compared using two different approaches for multivariate statistics, for investigating ALS related lipid and metabolite changes. The results show a significant decrease for cholesterol, triglycerides, and vitamin E in the ventral horn of ALS samples, which is presumably a consequence of motor neuron degeneration. Conversely, the biogenic mediator lipid lysophosphatidylcholine and its fragments were increased in ALS ventral spinal cord, pointing towards neuroinflammatory mechanisms associated with neuronal cell death. ToF-SIMS imaging is a promising approach for chemical histology and pathology for investigating the subcellular mechanisms underlying motor neuron degeneration in amyotrophic lateral sclerosis.

Neuroprotective action of Astragalus mongholicus aqueous extract in experimental rats suffering from spinal cord injury

Astragalus mongholicus aqueous extract (AMAE) is widely used for its medicinal properties. In the present study, we evaluated the role of AMAE on spinal cord lipid peroxidation (LPO), antioxidant status, apoptosis index and inducible nitric oxide synthases (iNOS) positive expression rate in rats. Male albino rats of Wistar strain were divided into four groups: Group I, normal control rats; Group II, model rats suffering from spinal cord injury (SCI); Group III and V, AMAE rats supplemented with AMAE. Results showed that increased spinal cord LPO, apoptosis index, iNOS positive expression rate and decreased antioxidant enzymes activities were observed in model rats (Group II). Administration of AMAE significantly dose-dependently decreased spinal cord LPO, apoptosis index, iNOS positive expression rate and increased antioxidant enzymes activities in AMAE rats. These findings demonstrated that AMAE can enhance the antioxidant status and decrease the incidence of free radical-induced LPO, and display strong neuroprotective activity in the experimental rats. Key words: Astragalus mongholicus aqueous extract, rat, spinal cord injury, inducible nitric oxide synthases (iNOS) positive expression rate.

Assessment of Oxidative Parameters in Rat Spinal Cord After Chronic Constriction of the Sciatic Nerve

Although reactive oxygen species (ROS) are involved in neuropathic pain, the direct relationship between these species and chronic constriction of sciatic nerve (CCI) has not been studied in spinal cord. Thus, this study induced CCI in rats and these animals were sacrificed 3 and 10days after the surgical procedure to determine the superoxide dismutase (SOD) and catalase activities, as well as ascorbic acid, hydrogen peroxide (H(2)O(2)) and lipid hydroperoxide levels in lumbosacral spinal cord. Von Frey Hair and hot plate tests were performed to assess the degree of mechanical and thermal hyperalgesia at days 0, 3 and 10. The results showed that CCI significantly induced mechanical and thermal hyperalgesia at days 3 and 10. Parallel there was increase in spinal cord lipid hydroperoxide at days 3 and 10 in rats submitted to CCI. In Sham rats a significant increase in this parameter occurred at day 10. H(2)O(2) decreased at day 10 only in CCI group. SOD activity was decreased in Sham and CCI groups at day 3, while catalase activity was increased in CCI rats at days 3 and 10. Ascorbic acid levels were reduced only in CCI rats at day 3. Although the role of such changes is unclear, many were not specific to neuropathic pain and the differences could be related to different degrees of central sensitization in Sham and CCI rats.

Proteomic characterization of lipid raft proteins in amyotrophic lateral sclerosis mouse spinal cord

Familial amyotrophic lateral sclerosis (ALS) has been linked to mutations in the copper/zinc superoxide dismutase (SOD1) gene. The mutant SOD1 protein exhibits a toxic gain-of-function that adversely affects the function of neurons. However, the mechanism by which mutant SOD1 initiates ALS is unclear. Lipid rafts are specialized microdomains of the plasma membrane that act as platforms for the organization and interaction of proteins involved in multiple functions, including vesicular trafficking, neurotransmitter signaling, and cytoskeletal rearrangements. In this article, we report a proteomic analysis using a widely used ALS mouse model to identify differences in spinal cord lipid raft proteomes between mice overexpressing wild-type (WT) and G93A mutant SOD1. In total, 413 and 421 proteins were identified in the lipid rafts isolated from WT and G93A mice, respectively. Further quantitative analysis revealed a consortium of proteins with altered levels between the WT and G93A samples. Functional classification of the 67 altered proteins revealed that the three most affected subsets of proteins were involved in: vesicular transport, and neurotransmitter synthesis and release; cytoskeletal organization and linkage to the plasma membrane; and metabolism. Other protein changes were correlated with alterations in: microglia activation and inflammation; astrocyte and oligodendrocyte function; cell signaling; cellular stress response and apoptosis; and neuronal ion channels and neurotransmitter receptor functions. Changes of selected proteins were independently validated by immunoblotting and immunohistochemistry. The significance of the lipid raft protein changes in motor neuron function and degeneration in ALS is discussed, particularly for proteins involved in vesicular trafficking and neurotransmitter signaling, and the dynamics and regulation of the plasma membrane-anchored cytoskeleton.

Correlation of injury severity and tissue Evans blue content, lipid peroxidation and clinical evaluation in acute spinal cord injury in rats

To demonstrate the changes in microvascular permeability occurring in association with graded acute spinal cord injury and to determine whether tissue Evans blue content is a useful indicator of the severity of spinal cord injury. The study also aimed to test the ability of the Evans blue method to demonstrate secondary injury after spinal cord contusion. In step one of the study, spinal cord lipid peroxidation levels and spinal cord Evans blue content were evaluated at 2 h post-injury in five groups of rats: a control group, a laminectomy-only group and three trauma groups (10, 50, and 100 gcm). In step two, these rats were used for Evans blue assessment following clinical examination at 24 h post-injury. The laminectomy-only group showed no difference from the control group with regard to spinal cord lipid peroxidation levels, tissue Evans blue content, and clinical findings. Increase in spinal cord tissue Evans blue content and lipid peroxidation was correlated with increasing intensity of trauma. There was a negative correlation between trauma intensity and clinical findings, and there was an increase in spinal cord tissue Evans blue content at 24 h compared with that at 2 h. Determination of spinal cord tissue Evans blue content is a reliable, rapid, simple and inexpensive method that can be used in experimental spinal cord injury to assess the severity of injury and to evaluate neuroprotection studies. The present study is the first to show that the Evans blue technique is a useful method to demonstrate secondary injury of spinal cord tissue and vasculature.

Acute phase effects of ATP-MgCl2 on experimental spinal cord injury.

The purpose of this study was to study the acute phase effects of adenosine triphosphate (ATP)-MgCl2 on experimental spinal cord clip compression injury. Spinal cord clip compression injury was performed on 36 albino Wistar rats. The rats were divided into five groups. T4-T8 total laminectomy was performed on all rats. Group 1: sham-operated group. Group 2: clip compression group. In group 3, ATP-MgCl2 (100 micro mol/kg) was given 2 min before the "clip compression injury." In group 4, ATP-MgCl2 (100 micro mol/kg) was given 5 min after the clip compression injury. In group 5, ATP MgCl2 (100 micro mol/kg) was administered 8 h after the injury. The spinal cords were excised for a length of 2 cm and deep frozen at -76 degrees C. Tissue malondialdehyde (MDA) levels were used to determine the effects of ATP-MgCl2 on spinal cord lipid peroxidation. In the groups in which ATP MgCl2 was administered after the clip compression injury (groups 4 and 5), the decrease in spinal cord MDA levels was statistically significant when compared with those of the injury group (group 2). Although MDA levels of group 4 were lower than those of group 5, this difference was not statistically significant. Administration of the ATP-MgCl2 before the clip compression injury (in group 3) did not have a statistically significant effect on lipid peroxidation when compared with the injury group (group 2). In this study, we found that ATP-MgCl2 has decreased lipid peroxidation in spinal cord injury and protected the spinal cord from secondary injury after the trauma. We concluded that ATP-MgCl2 may be used in the treatment of spinal cord injuries in conjunction with the other treatment modalities, but further investigations are mandatory.

Relationship of oxygen radical-induced lipid peroxidative damage to disease onset and progression in a transgenic model of familial ALS.

Transgenic mice that overexpress a mutated human CuZn superoxide dismutase (SOD1) gene (gly93-->ala) found in some patients with familial ALS (FALS) have been shown to develop motor neuron disease, as evidenced by motor neuron loss in the lumbar and cervical spinal regions and a progressive loss of voluntary motor activity. The mutant Cu,Zn SOD exhibits essentially normal dismutase activity, but in addition, generates toxic oxygen radicals as a result of an enhancement of a normally minor peroxidase reaction. In view of the likelihood that the manifestation of motor neuron disease in the FALS transgenic mice involves an oxidative injury mechanism, the present study sought to examine the extent of lipid peroxidative damage in the spinal cords of the TgN(SOD1-G93A)G1H mice over their life span compared to nontransgenic littermates or transgenic mice that overexpress the wild-type human Cu,Zn SOD (TgN(SOD1)N29). Lipid peroxidation was investigated in terms of changes in vitamin E and malondialdehyde (MDA) levels measured by HPLC methods and by MDA-protein adduct immunoreactivity. Four ages were investigated: 30 days (pre-motor neuron pathology and clinical disease); 60 days (after initiation of pathology, but predisease); 100 days (approximately 50% loss of motor neurons and function); and 120 days (near complete hindlimb paralysis). Compared to nontransgenic mice, the TgN(SOD1-G93A)G1H mice showed blunted accumulation of spinal cord vitamin E and higher levels of MDA (P < 0.05 at 30 and 60 days) over the 30-120 day time span. In the TgN(SOD1)N29 mice, levels of MDA at age 120 days were significantly lower than in either the TgN(SOD1-G93A)G1H or nontransgenic mice. MDA-protein adduct immunoreactivity was also significantly increased in the lumbar spinal cord at age 30, 100, and 120 days, and in the cervical cord at 100 and 120 days. The results clearly demonstrate an increase in spinal cord lipid peroxidation in the FALS transgenic model, which precedes the onset of ultrastructural or clinical motor neuron disease. However, the greatest intensity of actual motor neuronal lipid peroxidative injury is associated with the active phase of disease progression. These findings further support a role of oxygen radical-mediated motor neuronal injury in the pathogenesis of FALS and the potential benefits of antioxidant therapy.

Neuroprotective actions of glucocorticoid and nonglucocorticoid steroids in acute neuronal injury.

1. The glucocorticoid steroid methylprednisolone (MP) has been shown to enhance chronic recovery after human spinal cord injury when administered in a 24-hr high-dose regimen beginning within 8 hr. The doses of MP that affect this improved recovery have been demonstrated to inhibit posttraumatic spinal cord lipid peroxidation (LP), which has been postulated to be a key event in the secondary injury-induced degenerative cascade. 2. The molecular mechanism of action of the steroid appears to involve intercalation into the cell membrane and blockade of the propagation of peroxidative reactions. At a physiological level, the inhibition of injury-induced LP has been found to result in an attenuation of progressive posttraumatic ischemia and energy failure together with an augmented reversal of intracellular calcium accumulation. However, MP also acts directly to retard secondary neuronal degeneration as observed in studies showing the steroid's ability to slow the anterograde degeneration of experimentally injured cat soleus motor nerves. 3. The duplication of this effect by the nonsteroidal lipid antioxidant alpha-tocopherol supports the notion that is indeed a manifestation of the inhibition of posttraumatic LP. Moreover, the efficacy of MP in limiting lipid peroxidation and secondary spinal cord or motor nerve degeneration has also been duplicated by a nonglucocorticoid 21-aminosteroid tirilazad mesylate (U-74006F), which suggests the independence of the antioxidant and glucocorticoid effects of MP.

Age-related changes in brain and spinal cord lipids of the male garden lizard

The lipid composition (cholesterol, phospholipid triglyceride and fatty acids) of brain and spinal cord of the male garden lizard was traced during maturation and ageing. The total brain cholesterol content of both the tissues showed a significant rise during maturation, remaining almost constant thereafter. The free cholesterol content of the brain increased between middle and old age and that of the spinal cord increased during maturation. The esterified cholesterol content of the brain increased during maturation, the same parameter being not age-dependent in the spinal cord. While in the brain the phospholipid content increased during maturation followed by a decrease in old age, it showed a reverse trend in the spinal cord. The level of triglyceride in the brain declined during maturation followed by an increase in old age with no appreciable age change in the spinal cord. A comparison between young and old age-groups revealed a decrease in fatty acid content of the brain. A similar trend of decline was observed during maturation in the spinal cord. The pattern of age changes in the lipid profile of nervous tissue of the lizard, a non-mammalian vertebrate, almost conform to the pattern observed in a majority of mammals.

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.

Membrane lipid changes in laminectomized and traumatized cat spinal cord.

Free fatty acid (FFA), diacylglycerol (acyl2Gro), icosanoid, phospholipid, and cholesterol levels were measured in samples of cat spinal cord (L2) that were frozen in situ with vertebrae intact, at various times after laminectomy, and at various times after laminectomy with compression trauma to the spinal cord. Tissue samples either were grossly dissected into gray and white portions prior to FFA and acyl2Gro analysis or were used whole for the other lipid types. Gray matter total FFA and acyl2Gro values were abnormally high in samples frozen with vertebrae intact and in those frozen 10 min after laminectomy. This indicates that the surgical procedures resulted in some perturbation of spinal cord lipid metabolism. If the experimental animals were allowed to recover for 90 min after laminectomy, the gray matter FFA and acyl2Gro levels were greatly reduced. Compression of the spinal cord with a 170-g weight for 1, 3, or 5 min (following 90 min of recovery after laminectomy) caused significant elevations of total FFA, acyl2Gro, icosanoids, and phosphatidic acid and significant decreases in ethanolamine plasmalogens and cholesterol. Among the total FFA, arachidonic acid was found to have the largest relative increase. Comparisons of gray and white matter demonstrate that, in general, changes in white matter FFA and acyl2Gro were similar to those seen in gray matter. However, the increases in white matter levels of FFA and acyl2Gro were delayed, occurring after the elevations in gray matter. For some FFA (e.g., arachidonate), the rise in white matter occurred as gray matter levels were decreasing. This suggests that the initial alteration in spinal cord lipid metabolism after trauma was in gray matter but, with time, spread radially into white matter.

Effects of intravenous methylprednisolone on spinal cord lipid peroxidation and Na+ + K+)-ATPase activity. Dose-response analysis during 1st hour after contusion injury in the cat.

✓ The present study was undertaken to examine the ability of a single large intravenous dose of methylprednisolone (15, 30, or 60 mg/kg) to attenuate lipid peroxidation and enhance (Na+ + K+)-ATPase activity during the 1st hour after a 400 gm-cm injury to the cat spinal cord. The contusion injury was associated with a rise in the concentration of fluorescent lipid peroxy products in the injured segment at 1 hour. In addition, the accumulation of cyclic guanosine 3″,5″-monophosphate (cyclic GMP), which was used as a new index of injury-induced free radical reactions, in the injured spinal segment was twice control levels. The injury-induced increase in fluorescence and cyclic GMP content in the contused spinal segment at 1 hour was completely prevented by the administration of 15 or 30 mg/kg of methylprednisolone at 30 minutes after injury. A 60-mg/kg dose, however, did not prevent the elevation in cyclic GMP. A concomitant examination of the acute effects of glucocorticoid administration on (Na+ + K+)-ATPase activity in the injured cord revealed a striking increase of enzyme activity after the 30-mg/kg dose, but a depression in activity with the 60-mg/kg dose. These results demonstrate that a single massive dose of methylprednisolone can beneficially reduce free-radical reactions and lipid peroxidation as well as enhance the activity of neuronal (Na+ + K+)-ATPase during the early phase after spinal cord contusion. The requirement for doses to be in the range of 15 to 30 mg/kg in order to produce these neurochemical changes is consistent with other studies that have demonstrated significantly greater recovery and tissue preservation in spinal cord-injured animals treated with comparable doses of methylprednisolone soon after injury. These findings suggest the need for a rigorous approach to glucocorticoid therapy in central nervous system trauma.

Neurochemistry as a Diagnostic Aid in the Congenital Tremor Syndrome of Piglets

SUMMARY A knowledge of the chemical composition of the central nervous system can assist the neuropathologist in detecting, describing and differentiating developmental myelin disorders of the neonate. In particular, the analysis of spinal cord lipids can be used as an aid in the diagnosis of the congenital tremor syndrome (CT) of piglets. An abnormally low content of lipid (especially cerebrosides) reflects a deficiency of myelin which occurs in all four known CT types. The presence of cholesterol esters having a particular fatty acid profile denotes demyelination and this distinguishes one of two types of CT that result from transplacental virus infection and one of the two hereditary types. Thus, a fairly simple neurochemical examination of the cord taken together with the epidemiological features of outbreaks and the gross pathology of affected piglets is shown to form a reliable system for the diagnosis of the congenital tremor syndrome.

Effect of exogenous lipids on membrane-bound ceramide glycosyltransferases of rat brain

Rat brain microsomal UDP-galactose:ceramide galactosyltransferase was stimulated 5-to 8-fold when a mixture of bovine spinal cord lipid was added to the assay system. The optimal stimulation was obtained with 1 mg/tube of the lipid mixture. When the equivalent amount of lipid was added in a membrane-bound form, it was ineffective. Rat brain UDP-glucose:ceramide glucosyltransferase showed qualitatively similar but quantitatively less prominent responses to the added lipids. Among the individual lipids tested, ethanolamine phospholipid from bovine brain, at 1 mg/tube, gave the most effective stimulation of the galactosyltransferase. Synthetic dipalmitoyl-phosphatidylethanolamine, however, was ineffective. On the other hand, phosphatidylcholine from bovine brain stimulated the activity of the glucosyltransferase most effectively. Some lipids, particularly unsaturated fatty acids, were inhibitory to these glycosyltransferases. Activities of microsomal UDP-galactose:ceramide galactosyltransferase from 20- to 35-day old rat brains were stimulated more effectively by exogenous ethanolamine phospholipid than those from other developmental stages. This resulted in a shift of the maximum activity of the enzyme during development from 18 days without added ethanolamine phospholipid to 26 days with exogenous ethanolamine phospholipid. While the precise mechanism of the stimulation by exogenous lipid is difficult to assess because of the crude nature of the enzyme source, these observed phenomena might suggest a potential role of lipids in in vivo regulation of these membrane-bound synthetic enzymes.

Spinal cord lipids and myelin composition in border disease (hypomyelinogenesis congenita) of lambs.

Abstract—Spinal cords from clinically affected newborn lambs, each with muscular spasms (‘shaking’) and a ‘hairy’ birth coat, were found to be deficient in DNA and to contain less myelin and various lipid components, suggesting retarded CNS development equivalent to about 124 days conceptual age. Cerebrosides were notably deficient in whole cord and isolated myelin and contained more saturated and less unsaturated fatty acids than normal. The rate of cerebroside synthesis assayed in vitro was enhanced and taken with the very low tissue concentrations this indicated faster cerebroside turnover and a less stable myelin in the spinal cords of lambs affected with Border Disease. Marked decreases in plasmalogen concentrations, the redistribution of phospholipid fractions, the presence of about 8 per cent cholesterol in the esterified form and the characteristic fatty acid composition of these esters strongly suggest that degeneration is concomitant with myelin immaturity. Hypocupraemia, low concentrations of copper in the cerebrum and increased concentrations in spinal cord myelin are additional features of the clinical disease. The latter result may be related to myelin immaturity.

SIMULTANEOUS INCORPORATION OF ORALLY ADMINISTERED [9, 10‐3H2]OLEIC AND [1‐14C]LINOLEIC ACIDS INTO LIPIDS OF THE ADULT RAT BRAIN

Abstract—The incorporation of an orally administered mixture of [9,10‐3H2joleic acid and [1‐14C]linoleic acid into the brain and spinal cord lipids was maximal after 24 h compared with 4 h for extraneural tissue. In the latter, both acids were utilized equally well for triglyceride biosynthesis, but linoleate entered phosphatidylcholine more rapidly than oleate. Oleic acid was preferentially incorporated into newly synthesized cholesterol esters although 4 h after dosing most cholesterol esters present in serum were formed preferentially from linoleate presumably by the action of lecithin‐cholesterol acyl transferase.In neural tissue, a considerable amount of [1‐14C]linoleate was metabolized to higher polyunsaturated fatty acids, whereas in the case of oleate, 90 per cent of the tritium activity remained in monoenic acids at all time periods studied. Both acids were initially incorporated most rapidly into the lecithin fraction of brain and spinal cord, but after 7 days diacyl phosphatidylethanolamine had the highest specific activity.These data are consistent with the view that the uptake of labelled fatty acids by the brain takes place principally as free acids but that some uptake of esterified forms, probably largely as phosphatidylcholine, also occurs. The low linoleate content of the brain and probably also of cerebrospinal fluid cannot be explained on the basis of a selective restriction on the uptake of this lipid from plasma.

Neurochemistry of the spinal cord in British Saddleback piglets affected with congenital tremor, type A-IV, a second form of hereditary cerebrospinal hypomyelinogenesis.

AbstractCongenital tremor, type A‐IV is an inherited abnormality of British Saddleback piglets characterized by the presence of poorly myelinated axons throughout the CNS. This is reflected by a general lowering of the spinal cord lipid content to about half control values. In particular, cerebroside and plasmalogen levels are markedly reduced.Changes in the fatty acid composition of total lipid extracts and two isolated cerebroside fractions suggest that there is a metabolic defect in which fatty acid chain elongation, desaturation and hydroxylation are sub‐optimal.Cholesterol esters accumulate, make up about 30 per cent of total sterols and contain more than 90 per cent of C16 and C18 fatty acids. These may have arisen through the breakdown of cerebrosides containing abnormal proportions of these acids. Slightly increased levels of acid hydrolase activity appear to confirm that abnormal or immature myelin is disposed of by enhanced macrophagic activity.Differences between this and type A‐III, the sex‐linked inherited form of cerebrospinal hypomyelinogenesis are discussed and comparisons made with two forms of murine leuko‐dystrophy.