scholarly journals Metabolism of arachidonic acid in nervous system of marine mollusk Aplysia californica

1991 ◽  
Vol 260 (5) ◽  
pp. R844-R848 ◽  
Author(s):  
D. Piomelli
Keyword(s):  
Arachidonic Acid ◽  
Intracellular Signaling ◽  
High Performance ◽  
Aplysia Californica ◽  
Gas Chromatography Mass Spectrometry ◽  
Neural Cells ◽  
Lipoxygenase Pathway ◽  
Marine Mollusk ◽  
Fmrf Amide ◽  
12 Lipoxygenase

Studies of the marine mollusk Aplysia californica indicate that products of the 12-lipoxygenase pathway may be involved in neuronal intracellular signaling. The nervous tissue of Aplysia has a 12-lipoxygenase activity that converts both exogenous and endogenous arachidonic acid to an array of products, which include 12-hydroperoxyeicosatetraenoic acid (12-HPETE) and its metabolites hepoxilin A3, hepoxilin B3, 12-ketoeicosatetraenoic acid, and 12-oxododecatrienoic acid. These eicosanoids were identified using a combination of high-performance liquid chromatography, ultraviolet spectrometry and gas chromatography-mass spectrometry. Generation of 12-lipoxygenase products was stimulated by application of the neurotransmitters, histamine and FMRF-amide, or by stimulation of identified neural cells. In electrophysiological studies of identified L14 and sensory neurons it was found that 12-HPETE and its metabolic products exert physiological actions that resemble those of histamine and FMRF-amide. These results suggest that products of 12-HPETE metabolism may act as second messengers in Aplysia neurons.

scholarly journals Leukotriene generation by eosinophils.

1982 ◽  
Vol 155 (2) ◽  
pp. 390-402 ◽  
Author(s):  
A Jörg ◽  
W R Henderson ◽  
R C Murphy ◽  
S J Klebanoff
Keyword(s):  
Arachidonic Acid ◽  
Calcium Ionophore ◽  
Leukotriene B4 ◽  
Arachidonic Acid Metabolism ◽  
Calcium Ionophore A23187 ◽  
Eicosatetraenoic Acid ◽  
Gas Chromatography Mass Spectrometry ◽  
Ionophore A23187 ◽  
Lipoxygenase Pathway ◽  
Leukotriene D4

Horse eosinophils purified to greater than 98% generated slow reacting substance (SRS) when incubated with the calcium ionophore A23187. On a per cell basis, eosinophils generated four to five times the SRS produced by similarly treated horse neutrophils. Eosinophil SRS production was inhibited by 5,8,11,14-eicosatetraynoic acid and augmented by indomethacin and arachidonic acid, suggesting that it was a product(s) of the lipoxygenase pathway of arachidonic acid metabolism. Compounds with SRS activity were purified by high-pressure liquid chromatography (HPLC) and identified by ultraviolet spectra, spectral shift on treatment with lipoxygenase, incorporation of [14C]arachidonic acid, gas chromatography-mass spectrometry, and comparison of retention times on HPLC to authentic standards. The eosinophil products characterized were 5-(S), 12-(R)-dihydroxy-6-cis-8, 10-trans-14-cis-eicosatetraenoic acid (leukotriene B4) and its 5-(S), 12-(R)-6-trans and 5-(S), 12-(S)-6-trans isomers, 5-(S)-hydroxy-6-(R)-S-glutathionyl-7,9-trans-11, 14-cis-eicosatetraenoic acid (leukotriene C4) and its 11-trans isomer, and 5-(S)-hydroxy-6-(R)-S-cysteinylglycine-7,9-trans-11,14-cis-eicosatetraenoic acid (leukotriene D4).

Evidence for the presence of phospholipid hydroperoxide glutathione peroxidase in human platelets: implications for its involvement in the regulatory network of the 12-lipoxygenase pathway of arachidonic acid metabolism

2000 ◽  
Vol 353 (1) ◽  
pp. 91-100 ◽  
Author(s):  
Mark SUTHERLAND ◽  
Pattabhiraman SHANKARANARAYANAN ◽  
Tankred SCHEWE ◽  
Santosh NIGAM
Keyword(s):  
Arachidonic Acid ◽  
Glutathione Peroxidase ◽  
Regulatory Network ◽  
Acid Metabolism ◽  
Human Platelets ◽  
Arachidonic Acid Metabolism ◽  
Phospholipid Hydroperoxide Glutathione Peroxidase ◽  
Lipoxygenase Pathway ◽  
Phospholipid Hydroperoxide ◽  
12 Lipoxygenase

The 12-lipoxygenase pathway of arachidonic acid metabolism in platelets and other cells is bifurcated into a reduction route yielding 12-hydroxyeicosatetraenoic acid (12-HETE) and an isomerization route forming hepoxilins. Here we show for the first time the presence of phospholipid hydroperoxide glutathione peroxidase (PHGPx) protein and its activity in platelets. The ratio of the activity of PHGPx to that of cytosolic glutathione peroxidase (GPx-1) was consistently found to be approx. 1:60 in platelets and UT7 megakaryoblasts. Moreover, short-lived PHGPx mRNA was detected in megakaryocytes but not in platelets. Carboxymethylation of selenium-containing glutathione peroxidases by iodoacetate, which results in the inactivation of PHGPx and GPx-1 without inhibition of 12-lipoxygenase, markedly altered the pattern of arachidonic acid metabolism in human platelets. Whereas the formation of 12-HETE was inhibited by 80%, a concomitant accumulation of 12-hydroperoxyeicosatetraenoic acid (12-HpETE) by two orders of magnitude as well as the formation of hepoxilins A3 and B3 were observed. The formation of hepoxilins also occurred when 12-HpETE was added to untreated platelets. In selenium-deficient UT7 cells, which were devoid of GPx-1 but not of PHGPx, the reduction of 12-HPETE was retained, albeit with a lower rate than in control cells containing GPx-1. We therefore believe that both GPx-1 and PHGPx are involved in the regulatory network of the 12-lipoxygenase pathway in platelets and other mammalian cells. Moreover, the diminution of hydroperoxide tone in platelets incubated with arachidonic acid leads primarily to the formation of 12-HETE, whereas the increase in hydroperoxide tone (a situation found under oxidative stress or selenium deficiency or on incubation with 12-HPETE) partly diverts the 12-lipoxygenase pathway from the reduction route to the isomerization route, thus resulting in the formation of hepoxilins.

Endothelial Cells Produce a Lipoxygenase Derived Chemo-Repellent which Influences Platelet/Endothelial Cell Interactions – Effect of Aspirin and Salicylate

1985 ◽  
Vol 53 (03) ◽  
pp. 306-311 ◽  
Author(s):  
M R Buchanan ◽  
R W Butt ◽  
Z Magas ◽  
J Van Ryn ◽  
J Hirsh ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Arachidonic Acid ◽  
Endothelial Cell ◽  
High Performance ◽  
Platelet Adhesion ◽  
Cell Interactions ◽  
Lipoxygenase Pathway ◽  
Associated Production ◽  
Pathway Inhibition ◽  
Layer Chromatography

SummaryWe performed experiments to determine whether endothelial cells synthesize phospholipid metabolites via the lipoxygenase pathway and whether these metabolites influence platelet/vessel wall interactions. Monolayers of cultured human endothelial cells were incubated with 14C-arachidonic acid and their cyclo-oxygenase and lipoxygenase metabolites were extracted and identified by radioimmunoassay, thin layer chromatography and high performance liquid chromatography. We found that in addition to the membrane-associated production of PGI2, endothelial cells synthesized a cytosol-associated metabolite, LOX, which was presumably derived through the lipoxygenase pathway. Inhibition of LOX was associated with an increase in PGI2 production and inhibition of PGI2 with an increase in LOX production. Under either condition, platelet adhesion to cultured endothelial cells was significantly decreased. In contrast, when both PGI2 and LOX production were inhibited, platelet adhesion to endothelial cells was enhanced. Furthermore, when LOX was bound to a thrombogenic surface, platelet adhesion was significantly decreased whereas when arachidonic acid or 12-HETE was bound to the surface, platelet adhesion was increased. We conclude that endothelial cells produce not only a cyclo-oxygenase metabolite, but also a lipoxygenase metabolite, both of which influence platelet/endothelial cell interactions.

scholarly journals Loss of miR-29b following Acute Ischemic Stroke Contributes to Neural Cell Death and Infarct Size

2013 ◽  
Vol 33 (8) ◽  
pp. 1197-1206 ◽  
Author(s):  
Savita Khanna ◽  
Cameron Rink ◽  
Reza Ghoorkhanian ◽  
Surya Gnyawali ◽  
Mallory Heigel ◽  
...  
Keyword(s):  
Cell Death ◽  
Arachidonic Acid ◽  
Ischemic Stroke ◽  
Acute Ischemic Stroke ◽  
Brain Lesion ◽  
Neural Cell ◽  
Glutathione Depletion ◽  
Lipoxygenase Inhibitor ◽  
Lipoxygenase Pathway ◽  
12 Lipoxygenase

Glutathione depletion and 12-lipoxygenase-dependent metabolism of arachidonic acid are known to be implicated in neurodegeneration associated with acute ischemic stroke. The objective of this study was to investigate the significance of miR-29 in neurodegeneration associated with acute ischemic stroke. Neural cell death caused by arachidonic acid insult of glutathione-deficient cells was preceded by a 12-lipoxygenase-dependent loss of miR-29b. Delivery of miR-29b mimic to blunt such loss was neuroprotective. miR-29b inhibition potentiated such neural cell death. 12-Lipoxygenase knockdown and inhibitors attenuated the loss of miR-29b in challenged cells. In vivo, stroke caused by middle-cerebral artery occlusion was followed by higher 12-lipoxygenase activity and loss of miR-29b as detected in laser-captured infarct site tissue. 12-Lipoxygenase knockout mice demonstrated protection against such miR loss. miR-29b gene delivery markedly attenuated stroke-induced brain lesion. Oral supplementation of α-tocotrienol, a vitamin E 12-lipoxygenase inhibitor, rescued stroke-induced loss of miR-29b and minimized lesion size. This work provides the first evidence demonstrating that loss of miR-29b at the infarct site is a key contributor to stroke lesion. Such loss is contributed by activity of the 12-lipoxygenase pathway providing maiden evidence linking arachidonic acid metabolism to miR-dependent mechanisms in stroke.

Involvement of the 12-lipoxygenase pathway of arachidonic acid metabolism in homosynaptic long-term depression of the rat hippocampus

1996 ◽  
Vol 730 (1-2) ◽  
pp. 40-46 ◽  
Author(s):  
Marlon Normandin ◽  
Joel Gagné ◽  
Julie Bernard ◽  
Robert Élie ◽  
Dom Miceli ◽  
...  
Keyword(s):  
Arachidonic Acid ◽  
Acid Metabolism ◽  
Arachidonic Acid Metabolism ◽  
Rat Hippocampus ◽  
Long Term Depression ◽  
Lipoxygenase Pathway ◽  
12 Lipoxygenase

scholarly journals Effects of reduced glutathione on the 12-lipoxygenase pathways in rat platelets

1982 ◽  
Vol 202 (3) ◽  
pp. 771-776 ◽  
Author(s):  
Wen-Chang Chang ◽  
Junko Nakao ◽  
Hajime Orimo ◽  
Sei-itsu Murota
Keyword(s):  
Arachidonic Acid ◽  
Reduced Glutathione ◽  
Maximal Activity ◽  
Tetraenoic Acid ◽  
Ph Optimum ◽  
Lipoxygenase Pathway ◽  
Cytosol Fraction ◽  
Almost All ◽  
12 Lipoxygenase ◽  
Rat Platelets

Arachidonic acid is converted into several more polar products in addition to 12-l-hydroperoxyeicosa-5,8,10,14-tetraenoic acid (12-HPETE) and 12-l-hydroxyeicosa-5,8,10,14-tetraenoic acid (12-HETE) by the cytosol fractions of rat platelets. The more polar products are formed via the lipoxygenase pathways in the same way as are 12-HPETE and 12-HETE, since their formation is not inhibited by indomethacin but by eicosa-5,8,11,14-tetraynoic acid (ETYA). The presence of 0.5–1.5mm-reduced glutathione (GSH) in the reaction mixture prevents the formation of the more polar products and produces 12-HETE as the only metabolite from arachidonic acid by the 12-lipoxygenase pathway. l-Cysteine has the same effect as GSH. However, oxidized glutathione (GSSG) and l-cystine are not able to prevent the formation of the more polar products. The results indicate that 12-HPETE peroxidase in the 12-lipoxygenase pathway is a GSH-dependent peroxidase and the more polar products might be formed from the non-enzymic breakdown of the primary 12-lipoxygenase product of 12-HPETE, owing to insufficient capability of the subsequent peroxidase system to completely reduce 12-HPETE to 12-HETE. Thus the presence of GSH in the reaction mixture offers a convenient and precise cell-free assay system for 12-lipoxygenase in rat platelets. Routine assays of 12-lipoxygenase are carried out in the presence of 1mm-GSH in the reaction mixture. The synthesis of 12-HETE by 12-lipoxygenase is linear during the first 4 min of incubation at 37°C, and has a pH optimum of 7.7. The 12-lipoxygenase reaches half-maximal activity at an arachidonate concentration of 20μm. Fractionation of cell homogenates indicates that the cytosol fraction possesses almost all the 12-lipoxygenase activity, whereas the microsomal fraction exhibits little enzyme activity.

Cerebral arteries can generate 5- and 15-hydroxyeicosatetraenoic acid from arachidonic acid

1990 ◽  
Vol 68 (7) ◽  
pp. 807-813 ◽  
Author(s):  
Richard Schulz ◽  
Sonia Jancar ◽  
David A. Cook
Keyword(s):  
Arachidonic Acid ◽  
Cerebral Artery ◽  
High Performance ◽  
Contractile Activity ◽  
Cerebral Arteries ◽  
Hydroxyeicosatetraenoic Acid ◽  
Lipoxygenase Pathway ◽  
Product Profile ◽  
Dose Dependent Increase ◽  
Dose Dependent

Products of the lipoxygenase pathway have been implicated in the development of the cerebrovascular spasm that arises after subarachnoid hemorrhage. In particular the hydroperoxyeicosatetranenoic acids (HPETEs), which are unstable and break down rapidly to the corresponding 5-hydroxy acids (HETEs), are vasoconstrictor agents that mimic some aspects of cerebrovascular spasm. It is not, however, well established whether segments of cerebral artery can manufacture these products. We have studied the lipoxygenase product profile of cerebral arteries stimulated with arachidonic acid. Rings of bovine cerebral arteries were incubated in Krebs solution containing arachidonic acid. The lipoxygenase products were studied using high performance liquid chromatography. The largest peaks had the retention times of 5- and 15-HETEs, and the identity of these peaks was confirmed using specific radioimmunoassays. Stimulation with arachidonic acid resulted in a time- and dose-dependent increase in the formation of both HETEs, with 15-HETE being most abundant. The release of both HETEs was markedly reduced in the presence of AA-861, an inhibitor of lipoxygenase, but not with the cyclooxygenase inhibitor indomethacin. These data are thus consistent with our previous suggestion that the contractile activity of arachidonic acid in cerebral arteries arises, at least in part, from HPETE formation and with a possible role for these compounds in cerebral vasospasm.Key words: arachidonic acid, cerebral artery, hydroxyeicosatetraenoic acid, lipoxygenase.

Sign in / Sign up

Export Citation Format

Share Document