PURPOSE: Oxidative stress leads to an increased production of lipoxygenase derivatives in diabetic nephropathy. Thus, we hypothesized that lipoxygenase inhibitor, nordihydroguaiaretic acid (NDGA), ha the effects of decreasing proteinuria and preserving renal function in streptozotocin (STZ)-induced diabetic rats. METHODS: 45 Sprague-Dawley rats were divided into three groups; (A) treatment with lipoxygenase inhibitor, NDGA in diabetic nephropathy rats, (B) treatment with dimethyl sulfoxide (DMSO) as a vehicle in STZ-induced diabetic rats, (C) normal control group with subcutaneous injection of normal saline. Diabetes was induced by a single intraperitoneal injection of STZ (65 mg/kg) in rats of group A and B. After the 4th week of STZ injection, NDGA (10 mg/kg) and DMSO were given subcutaneously for another 4 weeks in group A and B respectively. RESULTS: The NDGA-treated diabetic rats exhibited significantly decreased urinary albumin excretion. Serum creatinine and blood urea nitrogen concentrations were increased in both group A and B, and tend to be higher in group B than group A. Twenty-four-hour urine creatinine clearances were increased in both group A and B after injection of STZ. Pathologic alterations of kidney were observed after injection of STZ, and then attenuated after administration of NDGA. CONCLUSION: These results suggest the potential of lipoxygenase inhibitor as a complementary therapy for the prevention and treatment of diabetic nephropathy.
Animals ; Blood Urea Nitrogen ; Creatinine ; Diabetic Nephropathies ; Dimethyl Sulfoxide ; Injections, Intraperitoneal ; Injections, Subcutaneous ; Kidney ; Lipoxygenase ; Nordihydroguaiaretic Acid ; Oxidative Stress ; Proteinuria ; Rats ; Rats, Sprague-Dawley ; Safrole ; Streptozocin

K+-Cl--cotransport (KCC) has been reported to have various cellular functions, including proliferation and apoptosis of human cancer cells. However, the signal transduction pathways that control the activity of KCC are currently not well understood. In this study we investigated the possible role of phospholipase A2 (PLA2)-arachidonic acid (AA) signal in the regulatory mechanism of KCC activity. Exogenous application of AA significantly induced K+ efflux in a dose-dependent manner, which was completely blocked by R-(+)-[2-n-butyl-6,7-dichloro-2-cyclopentyl-2,3-dihydro-1-oxo-1H-inden-5-yl]oxy]acetic acid (DIOA), a specific KCC inhibitor. N-Ethylmaleimide (NEM), a KCC activator-induced K+ efflux was significantly suppressed by bromoenol lactone (BEL), an inhibitor of the calcium-independent PLA2 (iPLA2), whereas it was not significantly altered by arachidonyl trifluoromethylketone (AACOCF3) and p-bromophenacyl bromide (BPB), inhibitors of the calcium-dependent cytosolic PLA2 (cPLA2) and the secretory PLA2 (sPLA2), respectively. NEM increased AA liberation in a dose- and time-dependent manner, which was markedly prevented only by BEL. In addition, the NEM-induced ROS generation was significantly reduced by DPI and BEL, whereas AACOCF3 and BPB did not have an influence. The NEM-induced KCC activation and ROS production was not significantly affected by treatment with indomethacin (Indo) and nordihydroguaiaretic acid (NDGA), selective inhibitors of cyclooxygenase (COX) and lipoxygenase (LOX), respectively. Treatment with 5,8,11,14-eicosatetraynoic acid (ETYA), a non-metabolizable analogue of AA, markedly produced ROS and activated the KCC. Collectively, these results suggest that iPLA2-AA signal may be essentially involved in the mechanism of ROS-mediated KCC activation in HepG2 cells.
5,8,11,14-Eicosatetraynoic Acid ; Acetophenones ; Apoptosis ; Arachidonic Acid ; Arachidonic Acids ; Cytosol ; Ethylmaleimide ; Hep G2 Cells ; Hepatoblastoma ; Humans ; Indomethacin ; Lipoxygenase ; Naphthalenes ; Nordihydroguaiaretic Acid ; Phospholipases A2 ; Prostaglandin-Endoperoxide Synthases ; Pyrones ; Reactive Oxygen Species ; Signal Transduction

In this study, we focused to identify whether eupatilin (5,7-dihydroxy-3',4',6-trimethoxyflavone), an extract from Artemisia argyi folium, prevents H2O2-induced injury of cultured feline esophageal epithelial cells. Cell viability was measured by the conventional MTT reduction assay. Western blot analysis was performed to investigate the expression of 5-lipoxygenase by H2O2 treatment in the absence and presence of inhibitors. When cells were exposed to 600 microM H2O2 for 24 hours, cell viability was decreased to 40%. However, when cells were pretreated with 25~150 microM eupatilin for 12 hours, viability was significantly restored in a concentration-dependent manner. H2O2-treated cells were shown to express 5-lipoxygenase, whereas the cells pretreated with eupatilin exhibited reduction in the expression of 5-lipoxygenase. The H2O2-induced increase of 5-lipoxygenase expression was prevented by SB202190, SP600125, or NAC. We further demonstrated that the level of leukotriene B4 (LTB4) was also reduced by eupatilin, SB202190, SP600125, NAC, or nordihydroguaiaretic acid (a lipoxygenase inhibitor) pretreatment. H2O2 induced the activation of p38MAPK and JNK, this activation was inhibited by eupatilin. These results indicate that eupatilin may reduce H2O2-induced cytotoxicity, and 5-lipoxygenase expression and LTB4 production by controlling the p38 MAPK and JNK signaling pathways through antioxidative action in feline esophageal epithelial cells.
Anthracenes ; Arachidonate 5-Lipoxygenase ; Artemisia ; Blotting, Western ; Cell Survival ; Epithelial Cells ; Flavonoids ; Hydrogen ; Hydrogen Peroxide ; Imidazoles ; Leukotriene B4 ; Lipoxygenase ; MAP Kinase Signaling System ; Nordihydroguaiaretic Acid ; p38 Mitogen-Activated Protein Kinases ; Pyridines

The selective cyclooxygenase-2 (COX-2) and 5-lipoxygenase (LOX) inhibitors might inhibit prostaglandin synthesis and reduce proteinuria. The present study was designed to investigate the anti-proteinuric effects of nordihydroguaiaretic acid (NDGA) as compared with celecoxib in puromycin aminonucleoside (PAN) nephrosis rats. Fifty five male Sprague-Dawley rats were divided into 4 groups; A, normal control; B, PAN group; C, PAN+COX-2 inhibitor (celecoxib) group; and D, PAN+5-LOX inhibitor (NDGA) group. After induction of PAN nephrosis through repeated injections of PAN (7.5 and 15 mg/100 g body weight), rats were treated with celecoxib, NDGA, or vehicle for 2 weeks. Twenty four hour urine protein excretions were significantly lower in PAN+celecoxib and PAN+NDGA groups than in PAN group. Serum creatinine (SCr) concentrations and 24 hr urine creatinine clearances (CCr) were not significantly different in the four groups. Electron microscopy showed that podocyte morphology was changed after the induction of PAN nephrosis and was recovered after celecoxib or NDGA administration. Celecoxib significantly recovered the expressions of nephrin, CD2AP, COX-2, and TGF-beta. NDGA also recovered TGF-betaexpression, but did not alter the expressions of nephrin, CD2AP and COX-2. The present study suggested that celecoxib and NDGA might effectively reduce proteinuria in nephrotic syndrome without impairing renal function.
Animals ; Anti-Inflammatory Agents, Non-Steroidal/pharmacology ; Body Weight ; Creatinine/blood ; Cyclooxygenase Inhibitors/pharmacology ; Male ; Microscopy, Electron ; Nephrosis/*chemically induced/drug therapy ; Nordihydroguaiaretic Acid/*pharmacology ; Podocytes/metabolism ; Puromycin Aminonucleoside/pharmacology/*toxicity ; Pyrazoles/*pharmacology ; Rats ; Rats, Sprague-Dawley ; Sulfonamides/*pharmacology ; Time Factors

5-Lipoxygenase inhibitor and human recombinant erythropoietin might accelerate renal recovery in cisplatin-induced acute renal failure rats. Male Sprague-Dawley rats were randomized into four groups: 1) normal controls; 2) Cisplatin group-cisplatin induced acute renal failure (ARF) plus vehicle treatment; 3) Cisplatin+nordihydroguaiaretic acid (NDGA) group-cisplatin induced ARF plus 5-lipoxygenase inhibitor treatment; 4) Cisplatin+erythropoietin (EPO) group-cisplatin induced ARF plus erythropoietin treatment. On day 10 (after 7 daily injections of NDGA or EPO), urea nitrogen and serum Cr concentrations were significantly lower in the Cisplatin+NDGA and Cisplatin+EPO groups than in the Cisplatin group, and 24 hr urine Cr clearances were significantly higher in the Cisplatin+EPO group than in the Cisplatin group. Semiquantitative assessments of histological lesions did not produce any significant differences between the three treatment groups. Numbers of PCNA(+) cells were significantly higher in Cisplatin, Cisplatin+NDGA, and Cisplatin+EPO groups than in normal controls. Those PCNA(+) cells were significantly increased in Cisplatin+NDGA group. These results suggest that EPO and also NDGA accelerate renal function recovery by stimulating tubular epithelial cell regeneration.
Animals ; Arachidonate 5-Lipoxygenase/administration & dosage ; Blood Urea Nitrogen ; Cisplatin/*toxicity ; Creatinine/urine ; Epithelial Cells/drug effects ; Erythropoietin/administration & dosage/*therapeutic use ; Kidney/metabolism ; Kidney Failure, Acute/*chemically induced/*drug therapy ; Kidney Tubules/drug effects ; Male ; Nordihydroguaiaretic Acid/*therapeutic use ; Rats ; Rats, Sprague-Dawley ; Regeneration

Reactive oxygen species (ROS) performs a pivotal function as a signaling mediator in receptor-mediated signaling. However, the sources of ROS in this signaling have yet to be determined, but may include lipoxygenases (LOXs) and NADPH oxidase. The stimulation of lymphoid cells with TNF-alpha, IL-1beta, and LPS resulted in significant ROS production and NF-kappaB activation. Intriguingly, these responses were markedly abolished via treatment with the LOXs inhibitor nordihydroguaiaretic acid (NDGA). We further examined in vivo anti-inflammatory effects of NDGA in allergic airway inflammation. Both intraperitoneal and intravenous NDGA administration attenuated ovalbumin (OVA)-induced influx into the lungs of total leukocytes, as well as IL-4, IL-5, IL-13, and TNF-alpha levels. NDGA also significantly reduced serum levels of OVA-specific IgE and suppressed OVA-induced airway hyperresponsiveness to inhaled methacholine. The results of our histological studies and flow cytometric analyses showed that NDGA inhibits OVA-induced lung inflammation and the infiltration of CD11b+ macrophages into the lung. Collectively, our findings indicate that LOXs performs an essential function in pro-inflammatory signaling via the regulation of ROS regulation, and also that the inhibition of LOXs activity may have therapeutic potential with regard to the treatment of allergic airway inflammation.
Animals ; Antioxidants/metabolism ; Asthma/complications/metabolism/pathology/physiopathology ; Bronchial Hyperreactivity/drug therapy/pathology ; Bronchial Provocation Tests ; Bronchoalveolar Lavage Fluid/cytology ; Cells, Cultured ; Drug Evaluation, Preclinical ; Humans ; Inflammation/*etiology/metabolism ; Jurkat Cells ; Lipoxygenase/*physiology ; Lipoxygenase Inhibitors/pharmacology/therapeutic use ; Lymphocytes/drug effects/metabolism ; Male ; Mice ; Mice, Inbred BALB C ; Nordihydroguaiaretic Acid/pharmacology/therapeutic use ; Reactive Oxygen Species/*adverse effects/*metabolism

Lipoxygenase is a protein with non-heme iron atom, which has been discovered in many animals and plants. Lipoxygenase which has a close relationship with human tumors, inflammatory diseases, asthma, arteriosclerosis, and toxic action of chemicals could not only di-oxygenate endogenous polyunsaturated fatty acid to yield bioactive factors such as leukotrienes(LTs), but also has co-oxidation activity to activate xenobiotics. Lipoxygenase inhibitors include hydroxamic acid derivatives, nordihydroguaiaretic acid, flavonoids, FLAP inhibitors and so on. All of them can effectively restrain the catalytic action of lipoxygenase. Literatures demonstrate that the inhibitors can block the formation of relevant bioactive factors and toxic products of xenobiotics clinically which are used to prevent and cure the relevant diseases to keep people healthy.
Animals ; Flavonoids ; pharmacology ; Humans ; Leukotrienes ; metabolism ; Lipoxygenase Inhibitors ; pharmacology ; Masoprocol ; pharmacology ; Oxidation-Reduction ; Xenobiotics ; metabolism

BACKGROUND: To evaluate the role of free fatty acids on the ischemic myocardium, influences of various free fatty acids upon transmembrane action potential and ATP-sensitive K+(KATP) channel activity were examined in the ventricular myocardium and single cardiac myocytes. METHODS: KATP channel activities were measured in the enzymatically (collagenase) isolated single rat ventricular cardiac myocytes by the method of the excised inside-out and the cell-attached patch clamp, and transmembrane action potentials were recorded using the conventional 3M-KCl microelectode techniques in the rat ventricular myocardium. RESULTS: Free fatty acids [FFAs; arachidonic acid (AA), linoleic acid (LA) and lysophosphatidylcholine (LPC)] reduced the KATP channel activity in a dose-dependent manner in the inside-out patch, and 50%-inhibition concentrations (IC50) were 88 +/- 11.2, 49 +/- 12.5, and 188 +/- 17.4 M respectively. Both frequency of channel opening and the mean open-burst duration were markedly decreased, but the amplitude of single channel currents were not changed by the FFAs. AA (50 micrometer) and LPC (50 micrometer) did not affect the dinitrophenol (DNP, 50 micrometer)-induced KATP channel activity, whereas LA (50 micrometer) had a tendency to reduce the activity. The channel inhibition effects by 10 micrometer AA in the inside-out patch were significantly augmented by diclofenac (10 micrometer), but was not changed by nordihydroguaiaretic acid. FFAs never stimulated KATP channel activity, even in the inside-out patch where KATP channel activity reduced in the presence of internal ATP (100 micrometer). Time for 90% repolarization (APD90) significantly increased during superfusion of the FFAs, to 22 (50 micrometer AA), 24 (50 micrometer LA), and 18 (50 micrometer LPC) % from those of the contol at the time of 10 min superfusion, but the other action potential characteristics were not changed by the FFAs. AA (10 micrometer) attenuated cromakalim (10 micrometer)-induced APD90 shortening effects. CONCLUSION: It was inferred that FFAs inhibit the KATP channel activity directly by themselves and/or indirectly by their metabolites in the rat ventricular cardiomyocytes, and therefore, duration of action potential lengthens to be a burden over the ischemic myocardium accounting for the injury of myocardium at the late stage of ischemia.
Action Potentials* ; Adenosine Triphosphate ; Animals ; Arachidonic Acid ; Cromakalim ; Diclofenac ; Fatty Acids, Nonesterified* ; Ischemia ; Linoleic Acid ; Lysophosphatidylcholines ; Masoprocol ; Myocardium* ; Myocytes, Cardiac ; Potassium Channels* ; Potassium* ; Rats*

This study is to investigate whether the synthesized chiral compound Nordy has influence on the function of endothelial progenitor cells (EPCs) from human umbilical cord blood induced by vascular endothelial growth factor (VEGF). EPCs were isolated from human umbilical cord blood by density gradient centrifugation. After cultured for 7 -10 days, EPCs were prepared for detecting effect of Nordy on proliferation, migration and tubule-forming activity in Matrigel induced by VEGF. Incubation of EPCs with 100 micromol L(-1) Nordy for 24 h initially inhibited the proliferative capacity of EPCs induced by VEGF (P <0.05). Moreover, 25 -50 micromol L(-1) Nordy also exhibited inhibitory effect at 48 -72 h. In addition, 25 - 100 micromol L(-1) Nordy impaired EPCs migratory and tubule-forming capacity in vitro (P < 0.05). Nordy could inhibit in EPCs the functions of proliferation, migration and tubulogenesis induced by VEGF in vitro, which might be a possible mechanism of its anti-EPCs effects.
Antineoplastic Agents ; pharmacology ; Cell Movement ; drug effects ; Cell Proliferation ; drug effects ; Cells, Cultured ; Endothelial Cells ; cytology ; Fetal Blood ; cytology ; Humans ; Masoprocol ; analogs & derivatives ; pharmacology ; Neovascularization, Physiologic ; drug effects ; Stem Cells ; cytology ; Vascular Endothelial Growth Factor A ; antagonists & inhibitors

Platelet-activating factor (PAF) enhanced interleukin-1 (IL-1) activity by the interaction with a specific receptor in rat alveolar macrophages. In this study, we investigated the role of endogenous arachidonate metabolites and intracellular calcium mobilization in the PAF-induced IL-1 activity. Alveolar macrophages were preincubated with 5-lipoxygenase and cyclooxygenase inhibitors 30 min before the addition of PAF and lipopolysaccharide (LPS). After 24 h culture, IL-1 activity was measured in the supernate of sample using the thymocyte proliferation assay. Inhibition of 5-lipoxygenase by nordihydroguaiaretic acid and AA-861 completely blocked the PAF-induced enhancement of IL-1 activity with IC50 of 2 micrometer and 5 micrometer, respectively. In contrast, the inhibition of cyclooxygenase pathway by indomethacin and ibuprofen resulted in the potentiation in PAF-induced IL-1 activity with maximal effect at 1 micrometer and 5 micrometer, respectively. In addition, leukotriene B4 and prostaglandin E2 production were observed in PAF-stimulated alveolar macrophage culture. As could be expected, 5-lipoxygenase and cyclooxygenase inhibitors abolished PAFstimulated leukotriene B4 and prostaglandin E2 production, respectively. The effects of PAF on intracellular calcium mobilization in alveolar macrophages were evaluated using the calcium-sensitive dye fura-2 at the single cell level. PAF at any dose between 10-16 and 10-8M did not increase intracellular calcium. Furthermore, there was no effective change of intracellular calcium level when PAF was added to alveolar macrophages in the presence of LPS or LPS + LTB4, and 4, 24 and 48h after treatment of these stimulants. Together, the results indicate that IL-1 activity induced by PAF is differently regulated through subsequent induction of endogenous 5-lpoxygenase and cyclooxygenase pathways, but not dependent on calcium signalling pathway.
Animals ; Arachidonate 5-Lipoxygenase ; Calcium ; Cyclooxygenase Inhibitors ; Dinoprostone ; Fura-2 ; Ibuprofen ; Indomethacin ; Inhibitory Concentration 50 ; Interleukin-1* ; Leukotriene B4 ; Lipoxygenase Inhibitors ; Macrophages, Alveolar* ; Masoprocol ; Prostaglandin-Endoperoxide Synthases ; Rats ; Thymocytes