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L Gustavsson

Publications and source records attributed to L Gustavsson.

At least 37 records · Page 2Linked to original sources
PubMed1994

Agonist-stimulated and basal phosphatidylethanol formation in neutrophils from alcoholics.

Phospholipase D has been shown to be a key enzyme in the signal transduction systems involved in neutrophil activation. In the presence of ethanol, the enzyme catalyzes a transphosphatidylation reaction through which phosphatidylethanol is formed instead of the normal product phosphatidic acid. The effects of ethanol on the formation of phosphatidylethanol and phosphatidic acid was studied in neutrophils from human alcoholics in vitro. Neutrophils were isolated and cellular lipids were labeled with [3H]oleate, whereafter the cells were preincubated with cytochalasin B. Subsequently, cells were stimulated with the chemotactic peptide formyl-Met-Leu-Phe in the presence of ethanol concentration ranging from 0 to 200 mM. In the presence of ethanol, both neutrophils from alcoholics and controls produced phosphatidylethanol, with a concomitant reduction of the production of phosphatidic acid. The amounts of phosphatidyl-ethanol and phosphatidic acid formed were dependent on the concentration of ethanol. In neutrophils from alcoholics, a higher apparent Km for the phospholipase D-mediated transphosphatidylation reaction was noted (58 mM ethanol compared with 28 mM in controls). The in vivo mass of phosphatidylethanol in recently drinking alcoholics was also analyzed in neutrophils. Measurable phosphatidyl-ethanol levels (average 5.6 pmol/10(8) neutrophils) were found in alcoholics up to 23 hr after the last intake of ethanol. Thus, in addition to the ethanol-induced changes in the normal production of phosphatidic acid, phosphatidylethanol accumulated in vivo in alcoholics may be expected to influence neutrophil function.

Adult↗
PubMed1993

Receptor-mediated phospholipase D activity in primary astroglial cultures.

Phospholipase D, an enzyme involved in signal transduction cascades, catalyses the formation of phosphatidic acid and, when ethanol is present, the formation of phosphatidylethanol. In the present study we demonstrate that stimulation of muscarinic acetylcholine receptors as well as P2-purinergic receptors induces activation of phospholipase D in primary cultures of astroglial cells. Both the hydrolysis and the transphosphatidylation reactions were stimulated by receptor agonists. Carbachol and ATP induced a rapid increase in the amount of [3H]phosphatidic acid in astroglial cells prelabelled with [3H]oleic acid. When ethanol (150 mM) was present, phosphatidylethanol was formed. Furthermore, the receptor-mediated increase in the concentration of phosphatidic acid was inhibited by ethanol, indicating that the phosphatidic acid production was indeed mediated by phospholipase D. The formation of phosphatidylethanol was concentration dependent, with a half-maximal effective concentration of 5 x 10(-5) M for carbachol and 10(-5) M for ATP. The carbachol-induced response was almost completely inhibited by atropine, indicating activation of phospholipase D via muscarinic receptors. The purinergic response is most probably mediated via P2-receptors since ADP was almost as efficient as ATP in inducing phosphatidylethanol formation, whereas AMP was significantly less potent. We conclude that astroglial cells in primary culture display muscarinic and purinergic receptors coupled to phospholipase D. The relationship to cell function needs to be further investigated.

Adenosine Triphosphate↗
PubMed1993

Phosphatidylethanol affects inositol 1,4,5-trisphosphate levels in NG108-15 neuroblastoma x glioma hybrid cells.

Phosphatidylethanol is formed by phospholipase D in animal cells exposed to ethanol. Previous reports have demonstrated that the degradation of phosphatidylethanol is slow, indicating that this lipid may be present in the cells after ethanol itself has disappeared. Accumulation of an abnormal alcohol metabolite may influence cellular functions. In the present study, cultivation of NG108-15 neuroblastoma x glioma hybrid cells in the presence of ethanol resulted in an accumulation of phosphatidylethanol and a simultaneous increase in basal inositol 1,4,5-trisphosphate levels. The direct effects of phosphatidylethanol on the phosphoinositide signal transduction system were examined through incorporation of exogenous phosphatidylethanol into membranes of ethanol-naive cells. An incorporation amounting to 2.8% of cellular phospholipids was achieved after a 5-h incubation with 30 microM phosphatidylethanol. Phosphatidylethanol was found to cause a time- and dose-dependent increase in the basal levels of inositol 1,4,5-trisphosphate. The effects on inositol 1,4,5-trisphosphate levels of exogenously added phosphatidylethanol and ethanol exposure for 2 days were not additive. No effect on bradykinin-stimulated inositol 1,4,5-trisphosphate production could be detected. However, the increase in basal inositol 1,4,5-trisphosphate levels indicates that phosphatidylethanol affects inositol 1,4,5-trisphosphate turnover and emphasizes the importance of considering phosphatidylethanol as a possible mediator of ethanol-induced effects on cellular processes.

Animals↗
PubMed1992

Mechanisms of adaptation to the effects of ethanol on activation of phospholipase C in NG 108-15 cells.

In this study the effect of different times of exposure to ethanol (1-7 days, 100 mM) on bradykinin and GTP(S)-stimulated activation of phospholipase C in NG 108-15 cells and on the binding of [3H]bradykinin to its receptors was investigated. Ethanol attenuated both agonist and GTP-analogue-induced hydrolysis of phosphoinositides for a period of up to 4 days of treatment, while exerting no effect on binding to bradykinin receptors. However, after 7 days of exposure to ethanol, the agonist-induced activation of phospholipase C was completely resistant to the inhibitory effects of alcohol. This finding correlated to a change in the affinity of the bradykinin receptor population after 7 days of treatment. The results indicate that bradykinin-induced breakdown of phosphatidylinositol 4,5-bisphosphate adapts to the effects of ethanol, after long-term treatment. Possible adaptative changes taking place at the level of the G protein(s), may induce a shift in the affinity of the receptor population and, consequently, serve as a compensatory mechanism to counteract the inhibitory effect of ethanol.

Adaptation, Physiological↗
PubMed1991

Acidic phospholipids in synaptosomal plasma membranes during repeated episodes of physical ethanol dependence in the rat.

The effects of repeated episodes of ethanol intoxication and the hyperexcitable state of withdrawal on the synaptosomal concentration of acidic phospholipids were studied in rats. There was no indication that cumulative changes in the synaptosomal acidic phospholipid composition in general occurred during multiple episodes of ethanol intoxication and withdrawal. There was, however, a statistically significant decrease in acidic phospholipid concentration (phosphatidylinositol; PI) in synaptosomal membranes from animals revealing spontaneous convulsive behaviour during ethanol withdrawal. Hypothetically this may reflect an inability to increase acidic phospholipid membrane content and thus to adaptively increase the seizure threshold during withdrawal.

Alcohol Withdrawal Delirium↗
PubMed1991

Continuous and intermittent exposure to ethanol: effect on NG 108-15 cell membrane phospholipids.

The effect of continuous and intermittent ethanol exposure on the phospholipid composition of Neuroblastoma x Glioma (NG 108-15) cell membranes was investigated. The cells were treated with ethanol for three weeks. Continuous ethanol exposure (150 mM) produced an increase (27%) in the amount of phosphatidylcholine, whereas intermittent ethanol treatment (150 mM) induced a 22% reduction of this lipid. Decreases of phosphatidylethanolamine plasmalogen (8.5%), phosphatidylinositol (16%) and phosphatidylserine (24%) were also seen after intermittent exposure. After binge administration, the concentration of total phospholipids was reduced by 17%, whereas continuous exposure produced a 19% increase. Both intermittent and continuous exposure induced a reduction in the total protein content. No changes in phosphatidic acid, sphingomyelin, phosphatidylcholine plasmalogen or phosphatidylethanolamine (diacyl form) were detected with either treatment. The importance of this study is that ethanol, irrespective of amount, can elicit different effects depending on the pattern of administration.

Animals↗
PubMed1990

Stimulation of phospholipase D activity by phorbol esters in cultured astrocytes.

The phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA) was found to stimulate phospholipase D activity in cultured primary astrocytes. Both the hydrolysis and the transphosphatidylation reaction catalyzed by phospholipase D were studied in cells labeled with [3H]glycerol. Phosphatidic acid (PA) synthesis was increased after addition of 100 nM TPA. When ethanol was present in the cell culture medium, phosphatidylethanol (Peth), a product of phospholipase D-catalyzed transphosphatidylation, was formed. The half-maximum effective concentrations (EC50) of TPA were 25 nM for PA increase as well as for Peth formation. The formation of Peth in ethanol-treated cells was accompanied by an inhibition of the TPA-induced increase in labeled PA. Increasing ethanol concentrations led to an increase in [3H]Peth and a decrease in [3H]PA. A protein kinase C inhibitor, 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H7), inhibited both the synthesis of PA and the formation of Peth observed after TPA addition to the astrocytes. Dioctanoyl-glycerol (100 microM) stimulated the formation of Peth in the presence of ethanol. In addition to the induction of Peth formation in astrocytes, TPA induced Peth formation in ethanol-treated neurons. The present results indicate that phospholipase D activity is stimulated by TPA in cultured primary brain cells. Modulation of phospholipase D activity by protein kinase C is a mechanism that may be important in signal transduction cascades.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1990

Brain lipid changes after ethanol exposure.

Ethanol interacts with brain cell membranes because of its lipid solubility. This perturbation alters the biophysical properties of the membranes. During chronic ethanol treatment, the cell membranes become resistant to the perturbing effects of ethanol, suggesting changes in the lipid composition. The most consistently found effect on lipid composition after chronic ethanol exposure has been an increase in oleic acid proportions of glycerophospholipids. There are also different changes in specific glycerophospholipids. The polyunsaturated fatty acids, docosahexaenoic acid in phosphatidylserine and arachidonic acid in phosphatidylethanolamine, were decreased. On the other hand, in phosphatidylcholine the saturated fatty acid palmitic acid was decreased after chronic ethanol exposure. Other changes found in brain after ethanol exposure are increased concentrations of acidic phospholipids and formation of abnormal phospholipids in which ethanol itself is a part of the molecule. Some of the changes found may be a result of adaptive mechanisms occurring in order to counteract the different biophysical effects of ethanol.

Animals↗
PubMed1989

Ethanol alters the transfer of arachidonic acid to ethanolamine plasmalogens in C-6 glioma cells.

In this study, the effects of ethanol exposure on uptake and metabolism of arachidonic acid by C-6 glioma cells in culture was examined. Labeled arachidonic acid was effectively taken up by the phospholipids of these cells and radioactivity was initially incorporated into phosphatidylinositols and phosphatidylcholines, reaching a peak between 4 and 6 hours. However, the labeling of ethanolamine plasmalogens continued to show an increase with time after labeled arachidonic acid has been exhausted in the medium. Since over 90% of labeled arachidonic acid was already taken up by the cells after 4 hours of exposure, the continued increase in labeling of ethanolamine plasmalogens is attributed to a transacylation mechanism. Cells grown in 150 mM ethanol for 2 days did not show a change in the overall incorporation of labeled arachidonic acid into phospholipids but showed a significant increase in labeling of ethanolamine plasmalogens, which was marked by a concomitant decrease in labeling of phosphatidylcholines. Ethanol exposure also resulted in a significant increase in the transfer of labeled arachidonic acid to triacylglycerols. Changes in phospholipid and triacylglycerol labeling pattern positively correlated with increasing ethanol concentration from 75 to 300 mM. Besides, most ethanol effects were readily noticeable after 24 hours of exposure. These data suggest a specific effect of ethanol on promoting the transacylase process for biosynthesis of ethanolamine plasmalogens as well as the acyltransferase for biosynthesis of triacylglycerols.

Arachidonic Acid↗
PubMed1989

Increase in synaptosomal acidic phospholipids after intermittent but not continuous ethanol exposure.

The aim of this study was to compare the effects of different ethanol administration procedures on synaptosomal concentrations of acidic phospholipids. The concentrations of phosphatidylinositol and phosphatidylserine were significantly increased after intermittent ethanol exposure for one week but were unaltered after one or three weeks of continuous ethanol administration. The results indicate the importance of drinking pattern for changes in synaptosomal acidic phospholipids.

Alcoholic Intoxication↗
PubMed1987

Formation of phosphatidylethanol in rat brain by phospholipase D.

The mechanism of phosphatidyl [14C]ethanol formation was studied in rat brain microsomal fraction. Phospholipase D and base-exchange enzymes were assayed with [14C]ethanol as substrate. Phospholipase D was found to catalyse the formation of phosphatidylethanol. The reaction was dependent on sodium-oleate as activating factor. Phosphatidylethanol formation by phospholipase D has previously only been reported to occur in plant tissues. Stimulation of base-exchange enzymes with calcium in the presence of [14 C]ethanol did not induce any formation of phosphatidylethanol. These findings indicate that phosphatidylethanol formation in ethanol intoxicated rats is catalysed by phospholipase D.

Animals↗
PubMed1986

Densitometric quantification of individual phospholipids. Improvement and evaluation of a method using molybdenum blue reagent for detection.

A densitometric method for simultaneous quantification of individual phospholipids based on visualization with molybdenum blue reagent is presented. Previously reported problems concerning colour instability have been solved. The method is specific for phosphorus-containing compounds and independent of the degree of fatty acid unsaturation. The molar absorptivities of most analysed phospholipids do not differ more than 10% from that for phosphatidylcholine from egg yolk. For cases of greater deviation (sphingomyelin, lysophosphatidylcholine and phosphatidylserine), analysis is accomplished by use of appropriate standard mixtures. The between-series coefficient of variation is ca. 9%. The method is compared to a preparative thin-layer chromatographic assay and another commonly used densitometric method.

Acetates↗
PubMed1986

Lipids and fatty acids in membranes from astroglial cells cultured in ethanol-containing media.

A study was undertaken to evaluate the usefulness of a primary brain cell culture for the assessment of general membrane phenomena caused by ethanol. The major aim was to study the inertness versus vulnerability of membrane lipids for 8 days of ethanol exposure. Since brain cells in cultures could be more easily influenced by nutrition than in vivo, effects of varying levels of essential fatty acids in the medium were also studied. Astroglial cells from cerebral hemispheres of newborn rats had a fatty acid composition of major phospholipids resembling that of whole brain. Addition of essential fatty acids to the medium profoundly altered the composition of cell membranes, contrary to what is found in whole animal experiments. Ethanol, in graded levels up to 75 mmol/l and added daily up to 8 days, did not significantly change the fatty acid composition of phosphatidylcholine and phosphatidylethanolamine. The ratio between neutral and acidic phospholipids diminished, which was more pronounced after 8 days of ethanol exposure than after 3 days. This study on ethanol exposure on glial cells focuses on the importance of nutritional composition of culture media and on the role of dynamics among phospholipid classes.

Animals↗
PubMed1986

Anionic glycerophospholipids in platelets from alcoholics.

Studies on ethanol-exposed animals have revealed changes in anionic phospholipids in brain membranes. The intention of this study was to investigate whether there was a similar effect on man. Assuming platelets to be an adequate model for CNS synaptosomes, concentration and fatty acid composition of anionic phospholipids, phosphatidylserine (PS) and phosphatidylositol (PI) in the platelet membrane from alcoholics after a debauche period were examined and compared to controls. Ethanol effects on neutral lipids were also analysed in order to obtain a comprehensive view. No quantitative difference was found in anionic phospholipids between alcoholics and controls. Fatty acid composition of individual phospholipids revealed significant changes which were more obvious in neutral phospholipids than in anionic. Oleic acid was increased and linoleic and arachidonic acids were decreased. After 1 week of detoxification, the abnormalities did not decrease, on the contrary they increased and total phospholipid concentration per platelet was significantly higher than in controls. It is concluded that the ethanol toxicity on bone marrow hampers the use of platelets as a model for synaptosomes but that the observed lipid abnormalities might play a major role in the impairment of platelet function in alcoholics.

Adult↗
PubMed1985

Formation of phosphatidylethanol in frozen kidneys from ethanol-treated rats.

We recently identified phosphatidylethanol (Pet) in tissues from ethanol-treated rats. Since phosphatidyl esters are formed artefactually during freezing in plants we wanted to examine if PE was elevated during freezing in animal tissues. Rats were treated with 3 g/kg of ethanol, killed after 3 h and PE was isolated from kidneys at once or after storage at 0, -5, -10, -15, -20 and -80 degrees C for 7 days. Kidneys analyzed at once or after storage at -80 degrees C had Pet equivalent to 0.02 mumol Pet/g. Storage at -10 degrees C and -15 degrees C resulted in increases of Pet to 1.5 mumol Pet/g and 1.2 mumol Pet/g, respectively. Thus, Pet is artefactually elevated during storage of tissues from ethanol-treated rats at lower freezing temperatures, reflecting considerable changes in composition of acidic phospholipids.

Animals↗