Studies on the roles of phospholipase A2 and eicosanoids in the regulation of corticotrophin secretion by rat pituitary cells in vitro

1991 ◽  
Vol 130 (1) ◽  
pp. 21-32 ◽  
Author(s):  
A. M. Cowell ◽  
R. J. Flower ◽  
J. C. Buckingham
Keyword(s):  
Arachidonic Acid ◽  
Platelet Activating Factor ◽  
Nordihydroguaiaretic Acid ◽  
Cyclooxygenase Inhibitors ◽  
Pituitary Cells ◽  
Lipoxygenase Inhibitor ◽  
Acth Secretion ◽  
Lipoxygenase Inhibitors ◽  
Prostaglandin F

ABSTRACT Dispersed anterior pituitary cells were used to investigate the possible roles of phospholipid metabolites released by phospholipase A2 (PLA2) in the control of immunoreactive ACTH (ir-ACTH) secretion in vitro. PLA2 (15 600–62 500 U/1), the PLA2 activator melittin (0·5–20 mg/l) and arachidonic acid (1 mmol/l) all produced increases in ir-ACTH release from the cells, whilst platelet-activating factor (PAF), prostaglandin F2α (PGF2α), the prostacyclin analogues iloprost and BW245C, the thromboxane A2 (TXA2) analogue U46619, and the leukotrienes LTB4 and LTC4 were ineffective in this respect. PGF2α (100 nmol/l and 1 μmol/l), iloprost (1 μmol/l) and BW245C (100 nmol/l and 1 μmol/l) depressed corticotrophin-releasing factor-41-induced ir-ACTH secretion, while the PAF antagonist BN52021 (10 and 100 μmol/l) and LTC4 (100 nmol/l and 1 μmol/l) had no discernable effects. The secretory responses of the cells to hypothalamic extracts (0·2 hypothalami/ml) and arachidonic acid (1 mmol/l) were generally unaffected by the cyclooxygenase inhibitors ibuprofen (10 and 100 μmol/l) and indomethacin (10 μmol/l), the TXA2 synthetase inhibitor imidazole (10 μmol/l–1 mmol/l), the lipoxygenase inhibitor nordihydroguaiaretic acid (10 and 100 μmol/l) and the dual cyclo-oxygenase/lipoxygenase inhibitors phenidone (1–100 μmol/l) and BW755C (10 and 100 μmol/l). They were, however, inhibited by the dual cyclo-oxygenase/lipoxygenase inhibitor eicosatetraynoic acid (10 and 100 μmol/l), which also blocks epoxygenase and PLA2 activity and by the cytochrome P450 inhibitor SKF-525A (1 mmol/l). The results suggest that the stimulatory effects of PLA2 and arachidonic acid on ir-ACTH secretion are not effected by products generated by the cyclo-oxygenase or lipoxygenase pathways but may be mediated by metabolites generated by the cytochrome P450 pathway. Journal of Endocrinology (1991) 130, 21–32

scholarly journals α-Conotoxins Enhance both the In Vivo Suppression of Ehrlich carcinoma Growth and In Vitro Reduction in Cell Viability Elicited by Cyclooxygenase and Lipoxygenase Inhibitors

Marine Drugs ◽  
2020 ◽  
Vol 18 (4) ◽  
pp. 193
Author(s):  
Alexey V. Osipov ◽  
Tatiana I. Terpinskaya ◽  
Tatsiana Yanchanka ◽  
Tatjana Balashevich ◽  
Maxim N. Zhmak ◽  
...  
Keyword(s):  
Arachidonic Acid ◽  
Antitumor Effect ◽  
Nordihydroguaiaretic Acid ◽  
Ehrlich Carcinoma ◽  
Arachidonic Acid Cascade ◽  
Lipoxygenase Inhibitor ◽  
Lipoxygenase Inhibitors ◽  
Combined Application

Several biochemical mechanisms, including the arachidonic acid cascade and activation of nicotinic acetylcholine receptors (nAChRs), are involved in increased tumor survival. Combined application of inhibitors acting on these two pathways may result in a more pronounced antitumor effect. Here, we show that baicalein (selective 12-lipoxygenase inhibitor), nordihydroguaiaretic acid (non-selective lipoxygenase inhibitor), and indomethacin (non-selective cyclooxygenase inhibitor) are cytotoxic to Ehrlich carcinoma cells in vitro. Marine snail α-conotoxins PnIA, RgIA and ArIB11L16D, blockers of α3β2/α6β2, α9α10 and α7 nAChR subtypes, respectively, as well as α-cobratoxin, a blocker of α7 and muscle subtype nAChRs, exhibit low cytotoxicity, but enhance the antitumor effect of baicalein 1.4-fold after 24 h and that of nordihydroguaiaretic acid 1.8–3.9-fold after 48 h of cell cultivation. α-Conotoxin MII, a blocker of α6-containing and α3β2 nAChR subtypes, increases the cytotoxic effect of indomethacin 1.9-fold after 48 h of cultivation. In vivo, baicalein, α-conotoxins MII and PnIA inhibit Ehrlich carcinoma growth and increase mouse survival; these effects are greatly enhanced by the combined application of α-conotoxin MII with indomethacin or conotoxin PnIA with baicalein. Thus, we show, for the first time, antitumor synergism of α-conotoxins and arachidonic acid cascade inhibitors.

scholarly journals Fundamental Concepts in the Assessment of Interaction of Biological Response Modifiers with other Agents

1992 ◽  
Vol 3 (suppl b) ◽  
pp. 60-68 ◽  
Author(s):  
William R Greco ◽  
Wlodzimierz E Dembinski
Keyword(s):  
Drug Exposure ◽  
Biological Response ◽  
Nordihydroguaiaretic Acid ◽  
Mouse Cell ◽  
Cyclooxygenase Inhibitors ◽  
Concentration Effect ◽  
Estimation Of Parameters ◽  
Surface Approach ◽  
Lipoxygenase Inhibitors

The universal response surface approach (URSA) was developed to assess the nature and intensity of drug interactions, ie, synergism. antagonism and additivity. URSA consists of fitting a concentration-effect surface to experimental data with maximum likelihood approaches, with the estimation of parameters, including: ID5os, concentration-effect slopes and the synergism-antagonism parameter α When α is positive, synergism is indicated, when α is negative, antagonism is indicated and when α is zero. additivity is indicated. URSA was applied to data from a set of 45 in vitro growth inhibition experiments with the L929 mouse cell line. The cytokine, tumour necrosis factor (TNF), was combined with one of nine eicosanoid synthesis inhibitors: indomethacin, Ro 20-5720, ibuprofen (cyclooxygenase inhibitors): nordihydroguaiaretic acid, nafazatrom, esculetin (lipoxygenase inhibitors): or BW-755C, p henidone, timegadine [cyclo- and lipoxygenase inhibitors). Five different schedules were used with various orders and durations of drug exposure. Examples of all three types of drug interaction were found for combinations of TNF with all three classes of drugs. The largest synergism found was for TNF plus BW-755C (α = 4.30±1.3 [SE]). In general, for each combination, the degree of synergism was greater for schedules in which cells were exposed to TNF before exposure to the other agent.

Effect of Lipoxygenase Inhibition on Mucous Glycoprotein Secretion from Chinchilla Middle Ear Fpithelial Cells in Vitro

1996 ◽  
Vol 105 (11) ◽  
pp. 916-921 ◽  
Author(s):  
Jizhen Lin ◽  
Youngki Kim ◽  
Frank Ondrey ◽  
Chris Lees ◽  
Steven K. Juhn
Keyword(s):  
Arachidonic Acid ◽  
Epithelial Cells ◽  
Middle Ear ◽  
Platelet Activating Factor ◽  
Lipoxygenase Inhibitor ◽  
Lipoxygenase Inhibition ◽  
Arachidonic Acid Metabolites ◽  
Acid Metabolites ◽  
Glycoprotein Secretion

Lipoxygenase is an enzyme that metabolizes arachidonic acid down to leukotrienes. Recent studies have shown that the enzyme is implicated in mucous glycoprotein (MGP) secretion stimulated by inflammatory mediators in the airways, suggesting its possible role in secretion of MGP from middle ear epithelial cells. To investigate a correlation between MGP secretion and the arachidonic acid metabolites, we examined the effects of nordihydroguaretic acid (NDGA, both a cyclooxygenase and lipoxygenase inhibitor), low-dose indomethacin (an inhibitor of cyclooxygenase), and A63162 (an inhibitor of lipoxygenase) on MGP secretion in cultured chinchilla middle ear epithelial cells. It was found that lipoxygenase inhibition led to reduction of MGP secretion from cultured chinchilla middle ear epithelial cells, while cyclooxygenase inhibition did not. Both cyclooxygenase and lipoxygenase inhibition resulted in profound blockage of MGP secretion in baseline and platelet activating factor-stimulated MGP secretion. It was concluded, therefore, that MGP secretion was linked to arachidonic acid metabolites, especially lipoxygenase products.

Arachidonic Acid Metabolites Contribute to the Irreversible Depolarization Induced by In Vitro Ischemia

2003 ◽  
Vol 90 (5) ◽  
pp. 3213-3223 ◽  
Author(s):  
E. Tanaka ◽  
S. Niiyama ◽  
S. Sato ◽  
A. Yamada ◽  
H. Higashi
Keyword(s):  
Arachidonic Acid ◽  
Nordihydroguaiaretic Acid ◽  
Arachidonic Acid Metabolism ◽  
Free Radical Scavengers ◽  
Epoxyeicosatrienoic Acid ◽  
Ca1 Neurons ◽  
Lipoxygenase Inhibitors ◽  
In Vitro Ischemia ◽  
Hippocampal Ca1

Intracellular recordings were made from hippocampal CA1 neurons in rat slice preparations. Superfusion with oxygen- and glucose-deprived medium (in vitro ischemia) produced a rapid depolarization ∼5 min after the onset of the superfusion. Even when oxygen and glucose were reintroduced immediately after rapid depolarization, the membrane depolarized further (persistent depolarization) and reached 0 mV (irreversible depolarization) after 5 min from the reintroduction. The pretreatment of the slice preparation with a phospholipase A2 (PLA2) inhibitor, para-bromophenacyl bromide, or a cytochrome P-450 inhibitor, 17-octadecynoic acid, significantly restored the membrane to the preexposure potential level after the reintroduction of oxygen and glucose. The administration of 14,15-epoxyeicosatrienoic acid or 20-hydroxyeicosatetraenoic acid did not change the latency of the rapid depolarization and did not allow the membrane potential to recover after the ischemic exposure. In contrast, after pretreatment with cyclooxygenase or lipoxygenase inhibitors, such as indomethacin, resveratrol, Dup-697, nordihydroguaiaretic acid, and 3,4-dihydrophenyl ethanol, a minority of neurons tested showed postischemic recovery from the persistent depolarization. Improved recovery was also seen after treatment with the free radical scavengers, edaravone and α-tocopherol. These results suggest that the activation of the arachidonic acid cascade via PLA2 and the free radicals produced by arachidonic acid metabolism contribute to the irreversible depolarization produced by in vitro ischemia.

A formyl peptide contracts guinea pig lung: role of arachidonic acid metabolites

1987 ◽  
Vol 63 (6) ◽  
pp. 2450-2459 ◽  
Author(s):  
S. A. Shore ◽  
N. P. Stimler-Gerard ◽  
E. Smith ◽  
J. M. Drazen
Keyword(s):  
Arachidonic Acid ◽  
Guinea Pig ◽  
Thromboxane A2 ◽  
Leukotriene B4 ◽  
Cyclooxygenase Inhibitors ◽  
Lipoxygenase Inhibitor ◽  
Synthesis Inhibitor ◽  
Leukotriene D4 ◽  
Lipoxygenase Inhibitors

We studied the role of cyclooxygenase and lipoxygenase products of arachidonic acid metabolism in mediating N-formyl-methionyl-leucyl-phenylalanine- (FMLP) induced contractions of guinea pig lung parenchymal strips. The cyclooxygenase inhibitors indomethacin (10(-5) M) and aspirin (3 X 10(-5) to 10(-4) M), the lipoxygenase inhibitor nordihydroguaiaretic acid (10(-5) to 3 X 10(-5) M), and the combined cyclooxygenase/lipoxygenase inhibitors 1-phenyl-3-pyrazolidinone (Phenidone) (3 X 10(-5) to 3 X 10(-4) M) and BW 755C (10(-5) to 10(-4) M) each caused a decrease in the maximum force induced by FMLP (Fmax) and an increase in the concentration of FMLP required to produce 50% of Fmax (EC50). The thromboxane synthesis inhibitor imidazole (3 X 10(-3) M) also decreased Fmax. The leukotriene D4 receptor antagonist FPL 55712 (5.7 X 10(-6) to 1.9 X 10(-5) M) increased the EC50 for FMLP, whereas desensitization of lung parenchymal strips to leukotriene B4 by pretreatment with this leukotriene (10(-7) M) had no effect on FMLP-induced contraction. After exposure to FMLP (10(-6) M), guinea pig lung produced (as determined by high-performance liquid chromatography and radioimmunoassay) leukotrienes C4 and B4, thromboxane A2 (as measured by its stable degradation product thromboxane B2), and prostaglandin F2 alpha. Lung strips not exposed to FMLP showed no evidence of leukotriene production. We conclude that thromboxane A2 and leukotriene C4 generated in response to FMLP mediate a substantial fraction of the force induced by this peptide in guinea pig lung parenchymal strips.

scholarly journals α-Conotoxins and α-Cobratoxin Promote, while Lipoxygenase and Cyclooxygenase Inhibitors Suppress the Proliferation of Glioma C6 Cells

Marine Drugs ◽  
2021 ◽  
Vol 19 (2) ◽  
pp. 118
Author(s):  
Tatiana I. Terpinskaya ◽  
Alexey V. Osipov ◽  
Elena V. Kryukova ◽  
Denis S. Kudryavtsev ◽  
Nina V. Kopylova ◽  
...  
Keyword(s):  
Nicotinic Acetylcholine Receptors ◽  
Acetylcholine Receptors ◽  
Glioma Cells ◽  
Nordihydroguaiaretic Acid ◽  
C6 Glioma ◽  
Cyclooxygenase Inhibitors ◽  
C6 Glioma Cells ◽  
C6 Cells ◽  
Lipoxygenase Inhibitor ◽  
Glioma C6

Among the brain tumors, glioma is the most common. In general, different biochemical mechanisms, involving nicotinic acetylcholine receptors (nAChRs) and the arachidonic acid cascade are involved in oncogenesis. Although the engagement of the latter in survival and proliferation of rat C6 glioma has been shown, there are practically no data about the presence and the role of nAChRs in C6 cells. In this work we studied the effects of nAChR antagonists, marine snail α-conotoxins and snake α-cobratoxin, on the survival and proliferation of C6 glioma cells. The effects of the lipoxygenase and cyclooxygenase inhibitors either alone or together with α-conotoxins and α-cobratoxin were studied in parallel. It was found that α-conotoxins and α-cobratoxin promoted the proliferation of C6 glioma cells, while nicotine had practically no effect at concentrations below 1 µL/mL. Nordihydroguaiaretic acid, a nonspecific lipoxygenase inhibitor, and baicalein, a 12-lipoxygenase inhibitor, exerted antiproliferative and cytotoxic effects on C6 cells. nAChR inhibitors weaken this effect after 24 h cultivation but produced no effects at longer times. Quantitative real-time polymerase chain reaction showed that mRNA for α4, α7, β2 and β4 subunits of nAChR were expressed in C6 glioma cells. This is the first indication for involvement of nAChRs in mechanisms of glioma cell proliferation.

Contributions of arachidonic acid derivatives and substance P to the sensitization of cutaneous nociceptors

1990 ◽  
Vol 64 (2) ◽  
pp. 457-464 ◽  
Author(s):  
R. H. Cohen ◽  
E. R. Perl
Keyword(s):  
Arachidonic Acid ◽  
Substance P ◽  
Receptive Fields ◽  
Lipoxygenase Inhibitor ◽  
Arterial Perfusion ◽  
Mediators Of Inflammation ◽  
Rabbit Ear ◽  
C Fiber

1. The role of presumed chemical mediators of inflammation in the heat-induced sensitization of cutaneous C-polymodal nociceptors (CPNs) was examined in a rabbit ear preparation maintained in vitro by intra-arterial perfusion with a solution free of protein and cellular elements. 2. In this preparation, CPNs consistently showed enhanced responsiveness after repeated exposure of their receptive fields to noxious levels of heat. The average magnitude of sensitization was quantitatively similar to that observed in vivo, suggesting that blood-born factors are not essential for development of sensitization. 3. Sensitization in one-half of randomly selected CPNs was blocked or reduced when the perfusate contained a cyclooxygenase inhibitor, indomethacin or dipyrone, or the dual cyclooxygenase/lipoxygenase inhibitor, BW755C, even though initial responsiveness to heat and pressure was unaltered. These observations suggest that arachidonic acid breakdown products, possibly prostaglandins, are intermediaries in the sensitization of some, but not all, C-fiber nociceptors of the skin. In addition, heat-induced sensitization for some C-fiber cutaneous nociceptors is the result of processes that are at least partially independent of those involved in excitation. 4. Substance P (SP) or the putative SP antagonists, [D-Pro2, D-Trp7.9]-SP or [D-Pro2, D-Phe7, D-Trip9]-SP, produced no significant effect on heat-responsiveness or sensitization, although ongoing activity may have marginally increased over control levels after repeated heat stimulations. We conclude that SP in an in vitro preparation is not involved in the enhancement of cutaneous C-fiber nociceptor responsiveness after repeated thermal insults.

Abstract 064: The Lipoxigenase Inhibitor Nordihydroguaiaretic Acid Prevents the Development of Hypoxia-Induced Pulmonary Hypertension in Mice

2013 ◽  
Vol 113 (suppl_1) ◽  
Author(s):  
Andrea Iorga ◽  
Gabriel Wong ◽  
Denise Mai ◽  
Jingyuan Li ◽  
Salil Sharma ◽  
...  
Keyword(s):  
Pulmonary Hypertension ◽  
Smooth Muscle ◽  
Smooth Muscle Actin ◽  
Nordihydroguaiaretic Acid ◽  
Treated Group ◽  
Oxidation Products ◽  
Lipoxygenase Inhibitor ◽  
Human Pulmonary Artery

Pulmonary hypertension (PH) is a chronic lung disease characterized by progressively elevated pulmonary arterial pressures and severe pulmonary vascular remodeling resulting from interactions between oxidized lipoprotein deposition and increased endothelial proliferation. Previously we have shown increased plasma levels of biological oxidation products such as hydroxyoctadecadienoic acids (HODEs) and hydroxyeicosatetraenoic acids (HETEs) in the rat monocrotaline model of PH. Here we investigated the role of HETEs and HODEs in the development of PH and whether their inhibition with the lipoxygenase inhibitor nordihydroguaiaretic acid (NDGA) attenuates the progression of PH. Mice were placed in a hypoxic chamber with O2 concentrations of ≤10% for 21 days and either left untreated to develop PH (n=7) or treated with NDGA daily (10mg/kg/day, i.p., n=4) from day 1. Direct RV catheterization was terminally performed to record RV pressure (RVP). Pulmonary arteriolar thickening and oxidized lipid deposition were assessed by staining lung sections with Masson’s Trichrome or with α-smooth muscle actin and E-06 (marker for oxidized low-density lipoproteins). In vitro, human pulmonary artery smooth muscle cell (hPASMC) proliferation was assessed by MTT assays in the absence or presence of 12-HETE (100ng/ml), 9-HODE (1µg/ml) and 13-HODE (1µg/ml) alone or together with NDGA (10, 25 and 50µM). In-vitro, HETE/HODE treatment increased hPASMC proliferation ~ 2-fold when compared to untreated cells and NDGA significantly inhibited the proliferative effects of all three oxidized lipids. In-vivo, NDGA treatment prevented the development of PH. RVP was lower in the NDGA-treated group vs. the PH group (24.01±1.39mmHg vs. 36.91±5.74mmHg, p<0.05) and was comparable to control normoxic mice (20.93±2.52mmHg). RV hypertrophy index was significantly elevated in the PH mice versus control mice (0.38±0.03 vs. 0.28±0.02 (p<0.001), while NDGA treatment completely prevented the development of RV hypertrophy (0.28±0.04). Lung sections demonstrated arteriolar thickening and E-06 positive deposits in the PH group, which was prevented by NDGA therapy. We conclude that oxidized fatty acid deposition and accumulation might play a role in the development of PH.

scholarly journals Arachidonic acid modulation of α1H, a cloned human T-type calcium channel

2000 ◽  
Vol 278 (1) ◽  
pp. H184-H193 ◽  
Author(s):  
Yi Zhang ◽  
Leanne L. Cribbs ◽  
Jonathan Satin
Keyword(s):  
Arachidonic Acid ◽  
Steady State ◽  
Low Voltage ◽  
Specific Inhibitor ◽  
Nordihydroguaiaretic Acid ◽  
Ca Channel ◽  
Lipoxygenase Inhibitor ◽  
Inactivation Curve ◽  
Steady State Inactivation ◽  
Window Current

Arachidonic acid (AA) and the products of its metabolism are central mediators of changes in cellular excitability. We show that the recently cloned and expressed T-type or low-voltage-activated Ca channel, α1H, is modulated by external AA. AA (10 μM) causes a slow, time-dependent attenuation of α1H current. At a holding potential of −80 mV, 10 μM AA reduces peak inward α1H current by 15% in 15 min and 70% in 30 min and shifts the steady-state inactivation curve −25 mV. AA inhibition was not affected by applying the cyclooxygenase inhibitor indomethacin or the lipoxygenase inhibitor nordihydroguaiaretic acid. The epoxygenase inhibitor octadecynoic acid partially antagonized AA attenuation of α1H. The epoxygenase metabolite epoxyeicosatrienoic acid (8,9-EET) mimicked the inhibitory effect of AA on α1H peak current. A protein kinase C (PKC)-specific inhibitor (peptide fragment 19–36) only partially antagonized the AA-induced reduction of peak α1H current and the shift of the steady-state inactivation curve but had no effect on 8,9-EET-induced attenuation of current. In contrast, PKA has no role in the modulation of α1H. These results suggest that AA attenuation and shift of α1H may be mediated directly by AA. The heterologous expression of T-type Ca channels allows us to study for the first time properties of this important class of ion channel in isolation. There is a significant overlap of the steady-state activation and inactivation curves, which implies a substantial window current. The selective shift of the steady-state inactivation curve by AA reduces peak Ca current and eliminates the window current. We conclude that AA may partly mediate physiological effects such as vasodilatation via the attenuation of T-type Ca channel current and the elimination of a T-type channel steady window current.

In vitro effects of ketoconazole on corticotrope cell morphology and ACTH secretion of two pituitary adenomas removed from patients with Nelson's syndrome

1989 ◽  
Vol 121 (2) ◽  
pp. 185-190 ◽  
Author(s):  
L.Jimenez Reina ◽  
A. Leal-Cerro ◽  
J. Garcia ◽  
P.P. Garcia-Luna ◽  
R. Astorga ◽  
...  
Keyword(s):  
Volume Density ◽  
Pituitary Cells ◽  
Acth Secretion ◽  
Nelson’S Syndrome ◽  
Human Pituitary ◽  
Human Pituitary Adenoma ◽  
Nelson's Syndrome ◽  
In Vitro Effects ◽  
Intracellular Changes

Abstract. The direct effects of ketoconazole on the secretion of ACTH by human pituitary adenoma cells from 2 patients with Nelson's syndrome were studied in vitro. Stereologically quantified, intracellular changes affect the surface density of the endoplasmic reticulum (it decreased by 73%), the volume density of the secretion granules (it decreased by 49%), and the volume density of lysosomes (it decreased by 67%). The hormone released in the culture medium decreased depending on the doses of ketoconazole used; 10 μmol/l decreased ACTH levels by 31%. These data show that ketoconazole induce marked changes on corticotrope morphology and ACTH secretion in pituitary cells obtained from patients with Nelson's syndrome.

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