1
|
Domingues MF, Callai-Silva N, Piovesan AR, Carlini CR. Soluble Epoxide Hydrolase and Brain Cholesterol Metabolism. Front Mol Neurosci 2020; 12:325. [PMID: 32063836 PMCID: PMC7000630 DOI: 10.3389/fnmol.2019.00325] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 12/17/2019] [Indexed: 12/15/2022] Open
Abstract
The bifunctional enzyme soluble epoxide hydrolase (sEH) is found in all regions of the brain. It has two different catalytic activities, each assigned to one of its terminal domains: the C-terminal domain presents hydrolase activity, whereas the N-terminal domain exhibits phosphatase activity. The enzyme’s C-terminal domain has been linked to cardiovascular protective and anti-inflammatory effects. Cholesterol-related disorders have been associated with sEH, which plays an important role in the metabolism of cholesterol precursors. The role of sEH’s phosphatase activity has been so far poorly investigated in the context of the central nervous system physiology. Given that brain cholesterol disturbances play a role in the onset of Alzheimer’s disease (AD) as well as of other neurodegenerative diseases, understanding the functions of this enzyme could provide pivotal information on the pathophysiology of these conditions. Moreover, the sEH phosphatase domain could represent an underexplored target for drug design and therapeutic strategies to improve symptoms related to neurodegenerative diseases. This review discusses the function of sEH in mammals and its protein structure and catalytic activities. Particular attention was given to the distribution and expression of sEH in the human brain, deepening into the enzyme’s phosphatase activity and its participation in brain cholesterol synthesis. Finally, this review focused on the metabolism of cholesterol and its association with AD.
Collapse
Affiliation(s)
- Michelle Flores Domingues
- Graduate Program in Cellular and Molecular Biology, Center of Biotechnology, Universidade Federal do Rio Grande do Sul, UFRGS, Porto Alegre, Brazil.,Laboratory of Neurotoxins, Brain Institute (BRAINS-InsCer), Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil
| | - Natalia Callai-Silva
- Laboratory of Neurotoxins, Brain Institute (BRAINS-InsCer), Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil.,Graduate Program in Medicine and Health Sciences, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil
| | - Angela Regina Piovesan
- Laboratory of Neurotoxins, Brain Institute (BRAINS-InsCer), Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil
| | - Celia Regina Carlini
- Graduate Program in Cellular and Molecular Biology, Center of Biotechnology, Universidade Federal do Rio Grande do Sul, UFRGS, Porto Alegre, Brazil.,Laboratory of Neurotoxins, Brain Institute (BRAINS-InsCer), Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil.,Graduate Program in Medicine and Health Sciences, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil
| |
Collapse
|
2
|
Sakayori N, Kikkawa T, Tokuda H, Kiryu E, Yoshizaki K, Kawashima H, Yamada T, Arai H, Kang JX, Katagiri H, Shibata H, Innis SM, Arita M, Osumi N. Maternal dietary imbalance between omega-6 and omega-3 polyunsaturated fatty acids impairs neocortical development via epoxy metabolites. Stem Cells 2015; 34:470-82. [DOI: 10.1002/stem.2246] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Revised: 09/30/2015] [Accepted: 10/09/2015] [Indexed: 12/31/2022]
Affiliation(s)
- Nobuyuki Sakayori
- Department of Developmental Neuroscience; Center for Neuroscience, United Centers for Advanced Research and Translational Medicine, Tohoku University School of Medicine; Miyagi Japan
- Research Fellow of the Japan Society for the Promotion of Science; Tokyo Japan
| | - Takako Kikkawa
- Department of Developmental Neuroscience; Center for Neuroscience, United Centers for Advanced Research and Translational Medicine, Tohoku University School of Medicine; Miyagi Japan
| | - Hisanori Tokuda
- Institute for Health Care Science, Suntory Wellness Ltd; Osaka Japan
| | - Emiko Kiryu
- Department of Developmental Neuroscience; Center for Neuroscience, United Centers for Advanced Research and Translational Medicine, Tohoku University School of Medicine; Miyagi Japan
| | - Kaichi Yoshizaki
- Department of Developmental Neuroscience; Center for Neuroscience, United Centers for Advanced Research and Translational Medicine, Tohoku University School of Medicine; Miyagi Japan
| | - Hiroshi Kawashima
- Institute for Health Care Science, Suntory Wellness Ltd; Osaka Japan
| | - Tetsuya Yamada
- Department of Metabolism and Diabetes; Tohoku University School of Medicine; Miyagi Japan
| | - Hiroyuki Arai
- Department of Health Chemistry; Graduate School of Pharmaceutical Sciences, University of Tokyo; Tokyo Japan
| | - Jing X. Kang
- Department of Medicine; Massachusetts General Hospital and Harvard Medical School; Massachusetts USA
| | - Hideki Katagiri
- Department of Metabolism and Diabetes; Tohoku University School of Medicine; Miyagi Japan
| | - Hiroshi Shibata
- Institute for Health Care Science, Suntory Wellness Ltd; Osaka Japan
| | - Sheila M. Innis
- Department of Paediatrics; Child and Family Research Institute, University of British Columbia; Vancouver Canada
| | - Makoto Arita
- Department of Health Chemistry; Graduate School of Pharmaceutical Sciences, University of Tokyo; Tokyo Japan
- Laboratory for Metabolomics, Center for Integrative Medical Sciences, RIKEN; Kanagawa Japan
| | - Noriko Osumi
- Department of Developmental Neuroscience; Center for Neuroscience, United Centers for Advanced Research and Translational Medicine, Tohoku University School of Medicine; Miyagi Japan
| |
Collapse
|
3
|
Shewchuk BM. Prostaglandins and n-3 polyunsaturated fatty acids in the regulation of the hypothalamic-pituitary axis. Prostaglandins Leukot Essent Fatty Acids 2014; 91:277-87. [PMID: 25287609 DOI: 10.1016/j.plefa.2014.09.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Revised: 08/23/2014] [Accepted: 09/11/2014] [Indexed: 12/26/2022]
Abstract
The hypothalamic-pituitary (H-P) axis integrates complex physiological and environmental signals and responds to these cues by modulating the synthesis and secretion of multiple pituitary hormones to regulate peripheral tissues. Prostaglandins are a component of this regulatory system, affecting multiple hormone synthesis and secretion pathways in the H-P axis. The implications of these actions are that physiological processes or disease states that alter prostaglandin levels in the hypothalamus or pituitary can impinge on H-P axis function. Considering the role of prostaglandins in mediating inflammation, the potential for neuroinflammation to affect H-P axis function in this manner may be significant. In addition, the mitigating effects of n-3 polyunsaturated fatty acids (n-3 PUFA) on the inflammation-associated synthesis of prostaglandins and their role as substrates for pro-resolving lipid mediators may also include effects in the H-P axis. One context in which neuroinflammation may play a role is in the etiology of diet-induced obesity, which also correlates with altered pituitary hormone levels. This review will survey evidence for the actions of prostaglandins and other lipid mediators in the H-P axis, and will address the potential for obesity-associated inflammation and n-3 PUFA to impinge on these mechanisms.
Collapse
Affiliation(s)
- Brian M Shewchuk
- Department of Biochemistry and Molecular Biology, Brody School of Medicine, East Carolina University, Greenville, NC 27834, United States.
| |
Collapse
|
4
|
Silva MPD, Cedraz-Mercez PL, Varanda WA. Effects of nitric oxide on magnocellular neurons of the supraoptic nucleus involve multiple mechanisms. Braz J Med Biol Res 2014; 47:90-100. [PMID: 24519124 PMCID: PMC4051181 DOI: 10.1590/1414-431x20133326] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Accepted: 10/22/2013] [Indexed: 01/24/2023] Open
Abstract
Physiological evidence indicates that the supraoptic nucleus (SON) is an
important region for integrating information related to homeostasis of body
fluids. Located bilaterally to the optic chiasm, this nucleus is composed of
magnocellular neurosecretory cells (MNCs) responsible for the synthesis and
release of vasopressin and oxytocin to the neurohypophysis. At the cellular
level, the control of vasopressin and oxytocin release is directly linked to the
firing frequency of MNCs. In general, we can say that the excitability of these
cells can be controlled via two distinct mechanisms: 1) the intrinsic membrane
properties of the MNCs themselves and 2) synaptic input from circumventricular
organs that contain osmosensitive neurons. It has also been demonstrated that
MNCs are sensitive to osmotic stimuli in the physiological range. Therefore, the
study of their intrinsic membrane properties became imperative to explain the
osmosensitivity of MNCs. In addition to this, the discovery that several
neurotransmitters and neuropeptides can modulate their electrical activity
greatly increased our knowledge about the role played by the MNCs in fluid
homeostasis. In particular, nitric oxide (NO) may be an important player in
fluid balance homeostasis, because it has been demonstrated that the enzyme
responsible for its production has an increased activity following a hypertonic
stimulation of the system. At the cellular level, NO has been shown to change
the electrical excitability of MNCs. Therefore, in this review, we focus on some
important points concerning nitrergic modulation of the neuroendocrine system,
particularly the effects of NO on the SON.
Collapse
Affiliation(s)
- M P da Silva
- Departamento de Fisiologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão PretoSP, Brasil, Departamento de Fisiologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brasil
| | - P L Cedraz-Mercez
- Departamento de Fisiologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão PretoSP, Brasil, Departamento de Fisiologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brasil
| | - W A Varanda
- Departamento de Fisiologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão PretoSP, Brasil, Departamento de Fisiologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brasil
| |
Collapse
|
5
|
Iliff JJ, Fairbanks SL, Balkowiec A, Alkayed NJ. Epoxyeicosatrienoic acids are endogenous regulators of vasoactive neuropeptide release from trigeminal ganglion neurons. J Neurochem 2010; 115:1530-42. [PMID: 20950340 DOI: 10.1111/j.1471-4159.2010.07059.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Epoxyeicosatrienoic acids (EETs) are bioactive eicosanoids produced from arachidonic acid by cytochrome P450 epoxygenases. We previously described the expression of cytochrome P450-2J epoxygenase in rat trigeminal ganglion neurons and that EETs signaling is involved in cerebrovascular dilation resulting from perivascular nerve stimulation. In this study, we evaluate the presence of the EETs signaling pathway in trigeminal ganglion neurons and their role in modulating the release of calcitonin gene-related peptide (CGRP) by trigeminal ganglion neurons. Liquid chromatography tandem mass spectrometry identified the presence of each of the four EETs regio-isomers within primary trigeminal ganglion neurons. Stimulation for 1 h with the transient receptor potential vanilloid-1 channel agonist capsaicin (100 nmol/L) or depolarizing K(+) (60 mmol/L) increased CGRP release as measured by ELISA. Stimulation-evoked CGRP release was attenuated by 30 min pre-treatment with the EETs antagonist 14,15-epoxyeicosa-5(Z)-enoic acid (14,15-EEZE, 10 μmol/L). K(+) stimulation elevated CGRP release 2.9 ± 0.3-fold above control levels, whereas in the presence of 14,15-EEZE K(+)-evoked CGRP release was significantly reduced to 1.1 ± 0.2-fold above control release (p < 0.01 anova, n = 6). 14,15-EEZE likewise attenuated capsaicin-evoked CGRP release from trigeminal ganglion neurons (p < 0.05 anova, n = 6). Similarly, pre-treatment with the cytochrome P450 epoxygenase inhibitor attenuated stimulation-evoked CGRP release. These data demonstrate that EETs are endogenous constituents of rat trigeminal ganglion neurons and suggest that they may act as intracellular regulators of neuropeptide release, which may have important clinical implications for treatment of migraine, stroke and vasospasm after subarachnoid hemorrhage.
Collapse
Affiliation(s)
- Jeffrey J Iliff
- Department of Anesthesiology and Perioperative Medicine, Oregon Health & Science University, Portland, Oregon 97239-3098, USA
| | | | | | | |
Collapse
|
6
|
Jiang H, Anderson GD, McGiff JC. Red blood cells (RBCs), epoxyeicosatrienoic acids (EETs) and adenosine triphosphate (ATP). Pharmacol Rep 2010; 62:468-74. [PMID: 20631410 DOI: 10.1016/s1734-1140(10)70302-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2009] [Revised: 04/22/2010] [Indexed: 02/05/2023]
Abstract
In addition to serving as carriers of O(2), red blood cells (RBCs) regulate vascular resistance and the distribution of microvascular perfusion by liberating adenosine triphosphate (ATP) and epoxyeicosatrienoic acids (EETs) upon exposure to a low O(2) environment. Therefore, RBCs act as sensors that respond to low pO(2) by releasing millimolar amounts of ATP, a signaling molecule, and lipid mediators (EETs). The release of EETs occurs by a mechanism that is activated by ATP stimulation of P2X(7) receptors coupled to ATP transporters, which should greatly amplify the circulatory response to ATP. RBCs are reservoirs of EETs and the primary sources of plasma EETs, which are esterified to the phospholipids of lipoproteins. Levels of free EETs in plasma are low, about 3% of circulating EETs. RBC EETs are produced by direct oxidation of arachidonic acid (AA) esterified to glycerophospholipids and the monooxygenase-like activity of hemoglobin. On release, EETs affect vascular tone, produce profibrinolysis and dampen inflammation. A soluble epoxide hydrolase (sEH) regulates the concentrations of RBC and vascular EETs by metabolizing both cis- and trans-EETs to form dihydroxyeicosatrienoic acids (DHETs). The function and pathophysiological roles of trans-EETs and erythro-DHETs has yet to be integrated into a physiological and pathophysiological context.
Collapse
Affiliation(s)
- Houli Jiang
- Department of Pharmacology, New York Medical College, Valhalla, NY 10595, USA
| | | | | |
Collapse
|
7
|
Iliff JJ, Jia J, Nelson J, Goyagi T, Klaus J, Alkayed NJ. Epoxyeicosanoid signaling in CNS function and disease. Prostaglandins Other Lipid Mediat 2009; 91:68-84. [PMID: 19545642 DOI: 10.1016/j.prostaglandins.2009.06.004] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2009] [Revised: 06/09/2009] [Accepted: 06/10/2009] [Indexed: 10/20/2022]
Abstract
Epoxyeicosatrienoic acids (EETs) are arachidonic acid metabolites of cytochrome P450 epoxygenase enzymes recognized as key players in vascular function and disease, primarily attributed to their potent vasodilator, anti-inflammatory and pro-angiogenic effects. Although EETs' actions in the central nervous system (CNS) appear to parallel those in peripheral tissue, accumulating evidence suggests that epoxyeicosanoid signaling plays different roles in neural tissue compared to peripheral tissue; roles that reflect distinct CNS functions, cellular makeup and intercellular relationships. This is exhibited at many levels including the expression of EETs-synthetic and -metabolic enzymes in central neurons and glial cells, EETs' role in neuro-glio-vascular coupling during cortical functional activation, the capacity for interaction between epoxyeicosanoid and neuroactive endocannabinoid signaling pathways, and the regulation of neurohormone and neuropeptide release by endogenous EETs. The ability of several CNS cell types to produce and respond to EETs suggests that epoxyeicosanoid signaling is a key integrator of cell-cell communication in the CNS, coordinating cellular responses across different cell types. Under pathophysiological conditions, such as cerebral ischemia, EETs protect neurons, astroglia and vascular endothelium, thus preserving the integrity of cellular networks unique to and essential for proper CNS function. Recognition of EETs' intimate involvement in CNS function in addition to their multi-cellular protective profile has inspired the development of therapeutic strategies against CNS diseases such as cerebral ischemia, tumors, and neural pain and inflammation that are based on targeting the cellular actions of EETs or their biosynthetic and metabolizing enzymes. Based upon the emerging importance of epoxyeicosanoids in cellular function and disease unique to neural systems, we propose that the actions of "neuroactive EETs" are best considered separately, and not in aggregate with all other peripheral EETs functions.
Collapse
Affiliation(s)
- Jeffrey J Iliff
- Department of Anesthesiology and Perioperative Medicine, Oregon Health & Science University, Portland, OR, USA
| | | | | | | | | | | |
Collapse
|
8
|
Marowsky A, Burgener J, Falck JR, Fritschy JM, Arand M. Distribution of soluble and microsomal epoxide hydrolase in the mouse brain and its contribution to cerebral epoxyeicosatrienoic acid metabolism. Neuroscience 2009; 163:646-61. [PMID: 19540314 DOI: 10.1016/j.neuroscience.2009.06.033] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2008] [Revised: 06/05/2009] [Accepted: 06/07/2009] [Indexed: 12/17/2022]
Abstract
Epoxide hydrolases comprise a family of enzymes important in detoxification and conversion of lipid signaling molecules, namely epoxyeicosatrienoic acids (EETs), to their supposedly less active form, dihydroxyeicosatrienoic acids (DHETs). EETs control cerebral blood flow, exert analgesic, anti-inflammatory and angiogenic effects and protect against ischemia. Although the role of soluble epoxide hydrolase (sEH) in EET metabolism is well established, knowledge on its detailed distribution in rodent brain is rather limited. Here, we analyzed the expression pattern of sEH and of another important member of the EH family, microsomal epoxide hydrolase (mEH), in mouse brain by immunohistochemistry. To investigate the functional relevance of these enzymes in brain, we explored their individual contribution to EET metabolism in acutely isolated brain cells from respective EH -/- mice and wild type littermates by mass spectrometry. We find sEH immunoreactivity almost exclusively in astrocytes throughout the brain, except in the central amygdala, where neurons are also positive for sEH. mEH immunoreactivity is abundant in brain vascular cells (endothelial and smooth muscle cells) and in choroid plexus epithelial cells. In addition, mEH immunoreactivity is present in specific neuronal populations of the hippocampus, striatum, amygdala, and cerebellum, as well as in a fraction of astrocytes. In freshly isolated cells from hippocampus, where both enzymes are expressed, sEH mediates the bulk of EET metabolism. Yet we observe a significant contribution of mEH, pointing to a novel role of this enzyme in the regulation of physiological processes. Furthermore, our findings indicate the presence of additional, hitherto unknown cerebral epoxide hydrolases. Taken together, cerebral EET metabolism is driven by several epoxide hydrolases, a fact important in view of the present targeting of sEH as a potential therapeutic target. Our findings suggest that these different enzymes have individual, possibly quite distinct roles in brain function and cerebral EET metabolism.
Collapse
Affiliation(s)
- A Marowsky
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstr. 190, CH-8057 Zurich, Switzerland.
| | | | | | | | | |
Collapse
|
9
|
Athirakul K, Bradbury JA, Graves JP, DeGraff LM, Ma J, Zhao Y, Couse JF, Quigley R, Harder DR, Zhao X, Imig JD, Pedersen TL, Newman JW, Hammock BD, Conley AJ, Korach KS, Coffman TM, Zeldin DC. Increased blood pressure in mice lacking cytochrome P450 2J5. FASEB J 2008; 22:4096-108. [PMID: 18716027 DOI: 10.1096/fj.08-114413] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The cytochrome P450 (CYP) enzymes participate in a wide range of biochemical functions, including metabolism of arachidonic acid and steroid hormones. Mouse CYP2J5 is abundant in the kidney where its products, the cis-epoxyeicosatrienoic acids (EETs), modulate sodium transport and vascular tone. To define the physiological role of CYP2J5 in the kidney, knockout mice were generated using a conventional gene targeting approach. Cyp2j5 (-/-) mice develop normally and exhibit no overt renal pathology. While renal EET biosynthesis was apparently unaffected by the absence of CYP2J5, deficiency of this CYP in female mice was associated with increased blood pressure, enhanced proximal tubular transport rates, and exaggerated afferent arteriolar responses to angiotensin II and endothelin I. Interestingly, plasma 17beta-estradiol levels were reduced in female Cyp2j5 (-/-) mice and estrogen replacement restored blood pressure and vascular responsiveness to normal levels. There was no evidence of enhanced estrogen metabolism, or altered expression or activities of steroidogenic enzymes in female Cyp2j5 (-/-) mice, but their plasma levels of luteinizing hormone and follicle stimulating hormone were inappropriately low. Together, our findings illustrate a sex-specific role for CYP2J5 in regulation of blood pressure, proximal tubular transport, and afferent arteriolar responsiveness via an estrogen-dependent mechanism.
Collapse
Affiliation(s)
- Krairerk Athirakul
- Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Mosset P, Grée R, Falck JR. Synthesis of Two Intermediate Phosphonium Salts for 5,20 and 15,20-DiHetes. SYNTHETIC COMMUN 2006. [DOI: 10.1080/00397918908050711] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
11
|
Jiang H. Erythrocyte-derived epoxyeicosatrienoic acids. Prostaglandins Other Lipid Mediat 2006; 82:4-10. [PMID: 17164127 DOI: 10.1016/j.prostaglandins.2006.05.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2006] [Revised: 05/16/2006] [Accepted: 05/18/2006] [Indexed: 11/25/2022]
Abstract
Red blood cells (RBCs) are reservoirs for cis- and trans-epoxyeicosatrienoic acids (EETs) that can be released. The sources of EET release from RBCs include direct synthesis from arachidonic acid, peroxidation of phospholipids and EETs esterified into cellular phospholipids. The release of EETs from RBCs can be through cytosolic phospholipase A2 (PLA2), secretory PLA2 and other responses associated with ATP release from RBCs. The erythrocyte ATP, purinergic receptors, ATP-binding cassette transporters, PLA2 and cytoskeleton rearrangement may all participate in EET release in the microcirculatory deformation of RBCs. EETs are vasodilatory and are candidate endothelium-derived hyperpolarizing factors. Due to the anti-hypertensive, fibrinolytic, and anti-thrombotic properties of EETs, their release from RBCs is replete with implications for the control of circulation and rheological characteristics of the circulating blood.
Collapse
Affiliation(s)
- Houli Jiang
- Department of Pharmacology, New York Medical College, Valhalla, New York 10595, USA.
| |
Collapse
|
12
|
Sarkis A, Ito O, Mori T, Kohzuki M, Ito S, Verbalis J, Cowley AW, Roman RJ. Cytochrome P-450-dependent metabolism of arachidonic acid in the kidney of rats with diabetes insipidus. Am J Physiol Renal Physiol 2005; 289:F1333-40. [PMID: 16014574 DOI: 10.1152/ajprenal.00188.2005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This study compared the renal metabolism of arachidonic acid in Brattleboro (BB) (vasopressin deficient) and Long-Evans (LE) control rats and the effects of a cytochrome P-450 (CYP) inhibitor 1-aminobenzotriazole (ABT) on renal function in these animals. The production of 20-hydroxyeicosatetraenoic acid (20-HETE) by renal cortical and outer medullary microsomes was significantly greater in BB than in LE rats (155 +/- 16 vs. 92 +/- 13 and 59 +/- 7 vs. 33 +/- 3 pmol.min(-1).mg protein(-1)). Renal cortical epoxygenase activity was not different in these strains. The expression of CYP4A proteins was 58 and 78% higher in the renal cortex and outer medulla of BB than in LE rats. Chronic treatment of BB rats with a vasopressin type 2 receptor agonist for 1 wk normalized the renal production of 20-HETE. Chronic blockade of the formation of 20-HETE and EETs with ABT had little effect on renal function in LE rats. However, urine flow increased by 54% and urine osmolarity decreased by 33% in BB rats treated with ABT. Plasma levels of oxytocin fell significantly from 7.2 +/- 1.3 to 3.9 +/- 1.0 pg/ml. The effects of ABT in BB rats were attenuated by chronic infusion of oxytocin (0.7 ng.min(-1).100 g(-1)) to maintain fixed high plasma levels of this hormone. These results indicate that the expression of CYP4A protein and the renal formation of 20-HETE are elevated in the kidney of BB rats due to a lack of vasopressin and that chronic blockade of the formation of 20-HETE and EETs with ABT promotes water excretion in vasopressin-deficient BB rats by reducing the circulating levels of oxytocin, which is a weak vasopressin agonist.
Collapse
Affiliation(s)
- Albert Sarkis
- Department of Physiology, Medical College of Wisconsin, Milwaukee, 53226, USA
| | | | | | | | | | | | | | | |
Collapse
|
13
|
Knigge U, Kjaer A, Kristoffersen U, Madsen K, Toftegaard C, Jørgensen H, Warberg J. Histamine and prostaglandin interaction in regulation of oxytocin and vasopressin secretion. J Neuroendocrinol 2003; 15:940-5. [PMID: 12969238 DOI: 10.1046/j.1365-2826.2003.01079.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Prostaglandins and histamine in the hypothalamus are involved in the regulation of oxytocin and vasopressin secretion, and appear to be involved in the mediation of pituitary hormone responses to immunochallenges. Therefore, we investigated in conscious male rats: (i) whether blockade of H1 or H2 receptors affected the oxytocin and vasopressin responses to prostaglandins and (ii) whether blockade of prostaglandin synthesis affected the oxytocin and vasopressin responses to histamine or to Escherichia coli lipopolysaccharide (LPS), in order to determine any interaction between prostaglandins and histamine in the hypothalamus. Oxytocin secretion was dose-dependently stimulated by intracerebroventricular infusion of 1 or 5 microg of PGE1, PGE2 or PGF2alpha, with PGE2 being the most potent of the compounds used. Prior central infusion of the H1 receptor antagonist mepyramine or the H2 receptor antagonist cimetidine significantly inhibited the oxytocin response to all three prostaglandins by approximately 50%. Vasopressin secretion was increased by PGE1 but not by PGE2 or PGF2alpha. The stimulatory effect of PGE1 was almost annihilated by prior administration of mepyramine or cimetidine. Central infusion of histamine or immunochallenge with LPS administered intraperitoneally increased oxytocin and vasopressin secretion four- and two-fold, respectively. Pretreatment with systemic injection of the prostaglandin synthesis inhibitor indomethacin dose-dependently reduced the oxytocin response and prevented the vasopressin response to histamine or LPS. We conclude that histamine and PGE1, PGE2 or PGF2alpha interact in the regulation of oxytocin secretion, whereas histamine and only PGE1 interact in the regulation of vasopressin secretion. Furthermore, histamine as well as LPS may affect oxytocin and vasopressin neurones via activation of prostaglandins, probably in the hypothalamic supraoptic nucleus.
Collapse
Affiliation(s)
- U Knigge
- Department of Medical Physiology, Division of Endocrinology and Metabolism, The Panum Institute, University of Copenhagen, Denmark.
| | | | | | | | | | | | | |
Collapse
|
14
|
Snyder GD, Krishna UM, Falck JR, Spector AA. Evidence for a membrane site of action for 14,15-EET on expression of aromatase in vascular smooth muscle. Am J Physiol Heart Circ Physiol 2002; 283:H1936-42. [PMID: 12384472 DOI: 10.1152/ajpheart.00321.2002] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Epoxyeicosatrienoic acids (EETs) are synthesized in the endothelial cells of vascular tissues. They are released from the endothelial cells and produce relaxation of the smooth muscle cells by hyperpolarization. The present findings demonstrate that EETs also regulate aromatase activity in vascular smooth muscle cells. Exposure of cultured rat aortic smooth muscle cells to either 1 microM 14,15-EET or 1 microM 11,12-EET inhibits dibutyryl cAMP-induced aromatase activity by 80-100%. 11,12-Dihydroxyeicosatrienoic acid, the hydration product of 11,12-EET, has no effect on dibutyryl cAMP-induced vascular smooth muscle aromatase activity. In contrast to 14,15-EET, the N-methylsulfanilamide derivative of 14,15-EET (14,15-EET-SA) was neither metabolized nor incorporated into cell lipids, but it retained the ability to inhibit cAMP-induced aromatase activity. Furthermore, the 14,15-EET-SA inhibition of cAMP-induced aromatase activity persisted when the sulfanilamide derivative of 14,15-EET was covalently tethered to silica beads (average diameter, 0.5 microm), which restricted 14,15-EET-SA from entering the cell. These data are consistent with the presence of a receptor for EETs in the plasma membrane and support the hypothesis that the inhibition of aromatase by EETs is initiated by the interaction of EET with the putative plasma membrane receptor.
Collapse
MESH Headings
- 8,11,14-Eicosatrienoic Acid/analogs & derivatives
- 8,11,14-Eicosatrienoic Acid/pharmacokinetics
- Animals
- Aorta, Thoracic/cytology
- Aromatase/metabolism
- Carbon Radioisotopes
- Cell Membrane/enzymology
- Cells, Cultured
- Enzyme Activation/drug effects
- Microspheres
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/enzymology
- Rats
- Rats, Sprague-Dawley
- Vasodilator Agents/pharmacokinetics
Collapse
Affiliation(s)
- Gary D Snyder
- Department of Biochemistry, 4-403 BSB, University of Iowa, Iowa City, IA 52242, USA.
| | | | | | | |
Collapse
|
15
|
Abstract
Recent studies have indicated that arachidonic acid is primarily metabolized by cytochrome P-450 (CYP) enzymes in the brain, lung, kidney, and peripheral vasculature to 20-hydroxyeicosatetraenoic acid (20-HETE) and epoxyeicosatrienoic acids (EETs) and that these compounds play critical roles in the regulation of renal, pulmonary, and cardiac function and vascular tone. EETs are endothelium-derived vasodilators that hyperpolarize vascular smooth muscle (VSM) cells by activating K(+) channels. 20-HETE is a vasoconstrictor produced in VSM cells that reduces the open-state probability of Ca(2+)-activated K(+) channels. Inhibitors of the formation of 20-HETE block the myogenic response of renal, cerebral, and skeletal muscle arterioles in vitro and autoregulation of renal and cerebral blood flow in vivo. They also block tubuloglomerular feedback responses in vivo and the vasoconstrictor response to elevations in tissue PO(2) both in vivo and in vitro. The formation of 20-HETE in VSM is stimulated by angiotensin II and endothelin and is inhibited by nitric oxide (NO) and carbon monoxide (CO). Blockade of the formation of 20-HETE attenuates the vascular responses to angiotensin II, endothelin, norepinephrine, NO, and CO. In the kidney, EETs and 20-HETE are produced in the proximal tubule and the thick ascending loop of Henle. They regulate Na(+) transport in these nephron segments. 20-HETE also contributes to the mitogenic effects of a variety of growth factors in VSM, renal epithelial, and mesangial cells. The production of EETs and 20-HETE is altered in experimental and genetic models of hypertension, diabetes, uremia, toxemia of pregnancy, and hepatorenal syndrome. Given the importance of this pathway in the control of cardiovascular function, it is likely that CYP metabolites of arachidonic acid contribute to the changes in renal function and vascular tone associated with some of these conditions and that drugs that modify the formation and/or actions of EETs and 20-HETE may have therapeutic benefits.
Collapse
Affiliation(s)
- Richard J Roman
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA.
| |
Collapse
|
16
|
Nithipatikom K, Grall AJ, Holmes BB, Harder DR, Falck JR, Campbell WB. Liquid chromatographic-electrospray ionization-mass spectrometric analysis of cytochrome P450 metabolites of arachidonic acid. Anal Biochem 2001; 298:327-36. [PMID: 11700990 DOI: 10.1006/abio.2001.5395] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Arachidonic acid (AA) can be metabolized by cytochrome P450 (CYP) enzymes to many biologically active compounds including 5,6-, 8,9-, 11,12-, and 14,15-epoxyeicosatrienoic acids (EETs), their corresponding dihydroxyeicosatrienoic acids (DHETs), and 20-hydroxyeicosatetraenoic acid (20-HETE). These eicosanoids are potent regulators of vascular tone. We developed a liquid chromatography-electrospray ionization-mass spectrometry method to simultaneously determine 5,6-, 8,9-, 11,12-, and 14,15-EETs; 5,6-, 8,9-, 11,12-, and 14,15-DHETs; and 20-HETE. [2H8]EETs, [2H8]DHETs, and [2H2]20-HETE were used as internal standards. These compounds are readily separated on a C18 reverse-phase column using water:acetonitrile with 0.005% acetic acid as a mobile phase. The internal standards, [2H8]EETs, [2H8]DHETs, and [2H2]20-HETE, eluted slightly faster than the natural eicosanoids. The samples were ionized by electrospray with fragmentor voltage of 120 V and detected in a negative mode. The negative ion detection gave a lower background than the positive ion detection for these compounds. These eicosanoids exhibited high abundance of the ions corresponding to [M - 1]-. The m/z = 319, 337, and 319 ions were used for quantitation of EETs, DHETs, and 20-HETE, respectively. The detection limits using selected ion monitoring of these compounds are about 1 pg per injection. The position of functional groups and water content of mobile phase had a significant effect on the sensitivity of detection. Water content of 40% was found to give maximal sensitivity. The method was used to determine EETs, DHETs, and 20-HETE in bovine coronary artery endothelial cells, dog plasma, rat astrocytes, and rat kidney microsome samples.
Collapse
Affiliation(s)
- K Nithipatikom
- Department of Pharmacology & Toxicology, Cardiovascular Research Center, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, Wisconsin 53226, USA
| | | | | | | | | | | |
Collapse
|
17
|
Qu W, Bradbury JA, Tsao CC, Maronpot R, Harry GJ, Parker CE, Davis LS, Breyer MD, Waalkes MP, Falck JR, Chen J, Rosenberg RL, Zeldin DC. Cytochrome P450 CYP2J9, a new mouse arachidonic acid omega-1 hydroxylase predominantly expressed in brain. J Biol Chem 2001; 276:25467-79. [PMID: 11328810 DOI: 10.1074/jbc.m100545200] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A cDNA encoding a new cytochrome P450 was isolated from a mouse brain library. Sequence analysis reveals that this 1,958-base pair cDNA encodes a 57-58-kDa 502-amino acid polypeptide that is 70-91% identical to CYP2J subfamily P450s and is designated CYP2J9. Recombinant CYP2J9 was co-expressed with NADPH-cytochrome P450 oxidoreductase (CYPOR) in Sf9 cells using a baculovirus system. Microsomes of CYP2J9/CYPOR-transfected cells metabolize arachidonic acid to 19-hydroxyeicosatetraenoic acid (HETE) thus CYP2J9 is enzymologically distinct from other P450s. Northern analysis reveals that CYP2J9 transcripts are present at high levels in mouse brain. Mouse brain microsomes biosynthesize 19-HETE. RNA polymerase chain reaction analysis demonstrates that CYP2J9 mRNAs are widely distributed in brain and most abundant in the cerebellum. Immunoblotting using an antibody raised against human CYP2J2 that cross-reacts with CYP2J9 detects a 56-kDa protein band that is expressed in cerebellum and other brain segments and is regulated during postnatal development. In situ hybridization of mouse brain sections with a CYP2J9-specific riboprobe and immunohistochemical staining with the anti-human CYP2J2 IgG reveals abundant CYP2J9 mRNA and protein in cerebellar Purkinje cells. Importantly, 19-HETE inhibits the activity of recombinant P/Q-type Ca(2+) channels that are known to be expressed preferentially in cerebellar Purkinje cells and are involved in triggering neurotransmitter release. Based on these data, we conclude that CYP2J9 is a developmentally regulated P450 that is abundant in brain, localized to cerebellar Purkinje cells, and active in the biosynthesis of 19-HETE, an eicosanoid that inhibits activity of P/Q-type Ca(2+) channels. We postulate that CYP2J9 arachidonic acid products play important functional roles in the brain.
Collapse
Affiliation(s)
- W Qu
- Division of Intramural Research, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
18
|
Nithipatikom K, Pratt PF, Campbell WB. Determination of EETs using microbore liquid chromatography with fluorescence detection. Am J Physiol Heart Circ Physiol 2000; 279:H857-62. [PMID: 10924087 DOI: 10.1152/ajpheart.2000.279.2.h857] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Epoxyeicosatrienoic acids (EETs) are cytochrome P-450 metabolites of arachidonic acid involved in the regulation of vascular tone. The method of microbore column high-performance liquid chromatography with fluorescence detection was developed to determine 14,15-EET, 11, 12-EET, and the mixture of 8,9-EET and 5,6-EET. Tridecanoic acid (TA) was used as an internal standard. EETs were reacted with 2-(2, 3-naphthalimino)ethyl trifluoromethanesulfonate (NT) to form highly fluorescent derivatives. A C(18) microbore column and a water-acetonitrile mobile phase were used for separation. Samples were excited at 259 nm, and the fluorescence was detected at 395 nm. The overall recoveries were 88% for EETs and 40% for TA. EETs were detected in concentrations as low as 2 pg (signal-to-noise ratio = 3). The method was used to determine the EET production from endothelial cells (ECs). Bradykinin and methacholine (10(-6) M) stimulated an increase in the production of EETs by ECs two- and fivefold, respectively. This sensitive method may be used for determination of EETs at low concentrations normally detected in complex biological samples.
Collapse
MESH Headings
- 8,11,14-Eicosatrienoic Acid/analogs & derivatives
- 8,11,14-Eicosatrienoic Acid/analysis
- 8,11,14-Eicosatrienoic Acid/metabolism
- Animals
- Bradykinin/pharmacology
- Cattle
- Cells, Cultured
- Chromatography, High Pressure Liquid/methods
- Coronary Vessels
- Endothelium, Vascular/chemistry
- Endothelium, Vascular/cytology
- Endothelium, Vascular/metabolism
- Methacholine Chloride/pharmacology
- Microchemistry
- Spectrometry, Fluorescence/methods
Collapse
Affiliation(s)
- K Nithipatikom
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
| | | | | |
Collapse
|
19
|
Zhang L, Karpinski E, Benishin CG. Prostaglandin E2 modulates a non-inactivating potassium current in rat neurohypophyseal nerve terminals. Neurochem Int 1999; 35:345-55. [PMID: 10517695 DOI: 10.1016/s0197-0186(99)00073-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A non-inactivating voltage dependent K+ channel current was observed in neuro-hypophyseal nerve terminals. This current was sensitive to inhibition by 4-aminopyridine and tetraethyl ammonium chloride, but was not sensitive to inhibition by alpha- or beta-dendrotoxin. Prostaglandin E2 (PGE2) modulated the voltage-dependent K+ channel, through a receptor-mediated process, as indicated by meclofenamate sensitivity, and this involved the activation of G protein(s), as indicated by sensitivity to guanosine-5'-O-(2-thiodiphosphate) (GDPfS). After short periods of incubation (e.g. 5 min), PGE2 increased the non-inactivating current. Following longer incubation periods with PGE2 (e.g. 20 min), the non-inactivating current declined. Forskolin and the cyclic adenosine monophosphate (AMP) analogs 8-bromo- and dibutyryl cyclic AMP, and Sp-cyclic AMPs inhibited the current, but did not mimic the increase in current caused by PGE2. Also, the cyclic AMP antagonist Rp-cyclic AMPs did not block the increase in current induced by PGE2. These results indicate that activation of cyclic AMP-dependent protein kinase (PKA) is not involved in mediating the stimulatory actions of PGE2. These observations provide evidence that PGE2 may contribute to the regulation of hormone release from the posterior pituitary by modulating K+ channels. However, the post-receptor mechanisms of subcellular signal transduction underlying this effect remain unknown.
Collapse
Affiliation(s)
- L Zhang
- Department of Physiology, University of Alberta, Edmonton, Canada
| | | | | |
Collapse
|
20
|
Kozak W, Archuleta I, Mayfield KP, Kozak A, Rudolph K, Kluger MJ. Inhibitors of alternative pathways of arachidonate metabolism differentially affect fever in mice. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 275:R1031-40. [PMID: 9756531 DOI: 10.1152/ajpregu.1998.275.4.r1031] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Inhibitors of cyclooxygenases prevent fever. The purpose of this study was to test the hypothesis that selective and dual inhibitors of the other enzyme systems of arachidonic acid oxygenation (i.e., lipoxygenase and epoxygenase) affect the time course or magnitude of fever in mice. Swiss Webster mice kept at 30 degreesC ambient temperature were implanted with biotelemeters to monitor body temperature. Fever was induced by intraperitoneal injection of lipopolysaccharide at doses from 10 micrograms/kg to 2.5 mg/kg. Phenidone (20-30 mg/kg ip), a dual lipoxygenase and cyclooxygenase inhibitor, prevented fever in these mice, but esculetin (1-10 mg/kg ip), a selective inhibitor of lipoxygenases, did not affect fever. Intramuscular injection of nordihydroguaiaretic acid (10-20 mg/kg), a dual lipoxygenase and epoxygenase inhibitor, as well as SKF-525A (5 mg/kg ip) and clotrimazole (20 mg/kg im), inhibitors of the cytochrome P-450/epoxygenase pathway, augmented fever in mice. Indomethacin (5 mg/kg ip), an inhibitor of cyclooxygenase, suppressed the exacerbation of fever due to clotrimazole, suggesting that the epoxygenase inhibitor-induced potentiation of fever in mice is a prostaglandin-mediated effect. From this study, we hypothesize that the cytochrome P-450/epoxygenase branch of the arachidonate cascade is involved in antipyresis and in controlling the upper limit of fever.
Collapse
Affiliation(s)
- W Kozak
- Lovelace Respiratory Research Institute, Inhalation Toxicology Laboratory, Albuquerque, New Mexico 87185, USA
| | | | | | | | | | | |
Collapse
|
21
|
Abstract
The hypothalamo-hypophyseal system is supplied with two types of specialized glial cells that interact in neuroendocrine functional dynamics: the tanycytes and the pituicytes. Tanycytes are the dominating glial cells within the median eminence. Similar to radial glia, they extend from the floor of the third ventricle to the neurohemal surface of the median eminence. Pituicytes, as specialized astrocytes, are the main glial cells of the neural lobe. They are in intimate contact with the perivascular space of the sinusoidal vessels. Morphological similarities between the two cell types focus on their interaction with terminal branches of hypothalamic neurons in both regions of the neurohypophysis, the median eminence and the neural lobe. Release of hypothalamic hormones is apparently influenced by pituicytes and tanycytes. For instance, both types of cells are capable of closing or opening the access to the vessels. Thereby, in contrast to the "blood-brain-barrier" function of astrocytes, pituicytes and tanycytes display "brain-blood-barrier" functions. Pituicytes are characterized by the expression of specific membrane-bound receptors for opioids, vasopressin, and beta-adrenoceptors, indicating that they receive input by numerous neuroactive substances. Integration of these incoming signals may result in a regulation of neurosecretion, especially by morphological changes and by modulation of extracellular ion concentrations. Comparable modulatory mechanisms of tanycytes have not yet been elucidated in a convincing manner. Besides possible regulatory functions, tanycytes are considered to possess guiding functions for hypothalamic axons and to be involved in transport mechanisms between ventricle and blood vessels of the portal system.
Collapse
Affiliation(s)
- W Wittkowski
- Institut für Anatomie der Universität Münster, Germany
| |
Collapse
|
22
|
Nithipatikom K, Falck JR, Bhatt RK, Hanke CJ, Campbell WB. Determination of 14,15-epoxyeicosatrienoic acid and 14,15-dihydroxyeicosatrienoic acid by fluoroimmunoassay. Anal Biochem 1997; 246:253-9. [PMID: 9073364 DOI: 10.1006/abio.1997.2014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A fluoroimmunoassay (FIA) for 14,15-epoxyeicosatrienoic acid (14,15-EET) and 14,15-dihydroxyeicosatrienoic acid (14,15-DHET), cytochrome P450 epoxygenase products of arachidonic acid, was developed using fluorescence polarization. 14-15-EET was hydrolyzed and analyzed as 14,15-DHET. 14,15-DHET was conjugated to thyroglobulin and a specific antibody was raised in rabbits. Both [3H8]14,15-DHET in radioimmunoassay or fluorescein-labeled 14,15-DHET (14, 15-DHET*) in FIA bound to this antibody and were competitively displaced by 14,15-DHET. The binding activity and cross-reactivity of 14,15-DHET antibody were also studied by RIA compared to FIA. The antibody cross-reacted < or = 1% with 11,12-DHET and 14,15-EET and < 0.1% with other regioisomeric DHETs and arachidonic acid metabolites. The detection limit of 14,15-DHET was 2 pg/0.6 ml by FIA. Using this method, we found that A23187 stimulated the production of 14,15-EET by endothelial cells by angiotensin II stimulated 14,15-EET release from zona glomerulosa cells. The production of 14,15-EET in these samples was confirmed by gas chromatography/mass spectrometry. These studies demonstrate a sensitive and specific FIA for 14,15-EET and 14,15-DHET and that agonists stimulate the release of these eicosanoids in two cell types, bovine coronary artery endothelial cells and bovine zona glomerulosa cells.
Collapse
Affiliation(s)
- K Nithipatikom
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee 53226, USA
| | | | | | | | | |
Collapse
|
23
|
Zeldin DC, Foley J, Boyle JE, Moomaw CR, Tomer KB, Parker C, Steenbergen C, Wu S. Predominant expression of an arachidonate epoxygenase in islets of Langerhans cells in human and rat pancreas. Endocrinology 1997; 138:1338-46. [PMID: 9048644 DOI: 10.1210/endo.138.3.4970] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Our laboratory recently described a new human cytochrome P450 arachidonic acid epoxygenase (CYP2J2) and the corresponding rat homolog (CYP2J3). Immunoblotting studies using a polyclonal antibody raised against recombinant human CYP2J2 confirmed CYP2J protein expression in human and rat pancreatic tissues. Immunohistochemical staining of formalin-fixed paraffin-embedded rat and human pancreas using the anti-CYP2J2 IgG and avidin-biotin-peroxidase detection revealed that CYP2J2 protein expression was highly localized to cells in the islets of Langerhans, with minimal staining in pancreatic exocrine cells. Colocalization studies using antibodies to the glucagon, insulin, somatostatin, and pancreatic polypeptide as markers for alpha-, beta-, delta-, and PP cells, respectively, showed that CYP2J protein expression was abundantly present in all four cell types, but was highest in the glucagon-producing alpha-cells. Direct evidence for the epoxidation of arachidonic acid by pancreatic cytochrome P450 was provided by documenting, for the first time, the presence of epoxyeicosatrienoic acids in vivo in human and rat pancreas by gas chromatography/mass spectrometry. Importantly, the levels of immunoreactive CYP2J2 in different human pancreatic tissues were highly correlated with endogenous epoxyeicosatrienoic acid concentrations. We conclude that human and rat pancreas contain an arachidonic acid epoxygenase belonging to the CYP2J subfamily that is highly localized to islet cells. These data together with previous work showing effects of epoxyeicosatrienoic acids in stimulating insulin and glucagon secretion from isolated rat pancreatic islets support the hypothesis that epoxygenase products may be involved in stimulus-secretion coupling in the pancreas.
Collapse
Affiliation(s)
- D C Zeldin
- Laboratory of Pulmonary Pathobiology, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA.
| | | | | | | | | | | | | | | |
Collapse
|
24
|
Oliw EH, Bylund J, Herman C. Bisallylic hydroxylation and epoxidation of polyunsaturated fatty acids by cytochrome P450. Lipids 1996; 31:1003-21. [PMID: 8898299 DOI: 10.1007/bf02522457] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Polyunsaturated fatty acids can be oxygenated by cytochrome P450 to hydroxy and epoxy fatty acids. Two major classes of hydroxy fatty acids are formed by hydroxylation of the omega-side chain and by hydroxylation of bisallylic methylene carbons. Bisallylic cytochrome P450-hydroxylases transform linoleic acid to 11-hydroxylinoleic acid, arachidonic acid to 13-hydroxyeicosa-5Z,8Z,11Z,14Z-tetraenoic acid, 10-hydroxyeicosa-5Z,8Z,11Z,14Z-tetraenoic acid and 7-hydroxyeicosa-5Z,8Z,11Z,14Z-tetraenoic acid and eicosapentaenoic acid to 16-hydroxyeicosa-5Z,8Z,11Z,14Z,17Z-pent aenoic acid, 13-hydroxyeicosa-5Z,8Z,11Z,14Z,17Z-pent aenoic acid and 10-hydroxyeicosa-5Z,8Z,11Z,14Z,17Z-pent aenoic acid as major metabolites. The bisallylic hydroxy fatty acids are chemically unstable and decompose rapidly to cis-trans conjugated hydroxy fatty acids during acidic extractive isolation. Bisallylic hydroxylase activity appears to be augmented in microsomes induced by the synthetic glucocorticoid dexamethasone and by some other agents, but the P450 gene families of these hydroxylases have yet to be determined. The fatty acid epoxides, which are formed by cytochrome P450, are chemically stable, but are hydrolyzed to diols by soluble epoxide hydrolases. Epoxidation of polyunsaturated fatty acids is a prominent pathway of metabolism in the liver and the renal cortex and epoxy-genase activity appears to be under homeostatic control in the kidney. Many arachidonate epoxygenases have been identified belonging to the CYP2C gene subfamily. Epoxygenases have also been found in the central nervous system, endocrine organs, the heart and endothelial cells. Epoxides of arachidonic acid have been found to exert pharmacological effects on many cells.
Collapse
Affiliation(s)
- E H Oliw
- Department of Pharmaceutical Biosciences, Uppsala University Biomedical Center, Sweden
| | | | | |
Collapse
|
25
|
Boersma CJ, Van Leeuwen FW. Neuron-glia interactions in the release of oxytocin and vasopressin from the rat neural lobe: the role of opioids, other neuropeptides and their receptors. Neuroscience 1994; 62:1003-20. [PMID: 7845582 DOI: 10.1016/0306-4522(94)90339-5] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The release of the neurohormones oxytocin and vasopressin from the neural lobe into the circulation is regulated in a complex manner, which has only been partly elucidated. At the level of the neural lobe, regulation of release can occur by various endogenous compounds that act on specific receptors present on the nerve terminals themselves. In addition, release may be modulated by an alternative pathway in which the local glia cells, the pituicytes, are involved. It is especially the latter pathway that is discussed in detail in this commentary.
Collapse
Affiliation(s)
- C J Boersma
- Graduate School Neurosciences Amsterdam, The Netherlands
| | | |
Collapse
|
26
|
Abstract
Polyunsaturated fatty acids can be oxygenated by P450 in different ways--by epoxidation, by hydroxylation of the omega-side chain, by allylic and bis-allylic hydroxylation and by hydroxylation with double bond migration. Major organs for these oxygenations are the liver and the kidney. P450 is an ubiquitous enzyme. It is therefore not surprising that some of these reactions have been found in other organs and tissues. Many observations indicate that P450 oxygenates arachidonic acid in vivo in man and in experimental animals. This is hardly surprising. omega-Oxidation was discovered in vivo 60 years ago. It was more unexpected that biological activities have been associated with many of the P450 metabolites of arachidonic acid, at least in pharmacological doses. Epoxygenase metabolites of arachidonic acid have attracted the largest interest. In their critical review on epoxygenase metabolism of arachidonic acid in 1989, Fitzpatrick and Murphy pointed out some major differences between the PGH synthase, the lipoxygenase and the P450 pathways of arachidonic acid metabolism. Their main points are still valid and have only to be modified slightly in the light of recent results. First, lipoxygenases show a marked regiospecificity and stereospecificity, while many P450 seem to lack this specificity. There are, however, P450 isozymes which catalyse stereospecific epoxidations or hydroxylations. Many hydroxylases and at least some epoxygenases also show regiospecificity, i.e. oxygenate only one double bond or one specific carbon of the fatty acid substrate. In addition, preference for arachidonic acid and eicosapentaenoic acid may occur in the sense that other fatty acids are oxygenated with less regiospecificity. A more important difference is that prostaglandins and leukotrienes affect specific and well characterised receptors in cell membranes, while receptors for epoxides of arachidonic acid or other P450 metabolites have not been characterised. Nevertheless, epoxides of arachidonic acid have been found to induce a large number of different pharmacological effects. In some systems, effects have been noted at pm concentrations which might conceivably be in the physiological concentration range of these epoxides, e.g. after release from phospholipids by phospholipase A2. An intriguing possibility is that the effects of [Ca]i on different ion channels might possibly explain their biological actions. In situations when pharmacological doses are used, metabolism to epoxyprostanoids or other interactions with PGH synthase could also be of importance. Finally, one report on a specific receptor for 14R,15S-EpETrE in mononuclear cell membranes has just been published.(ABSTRACT TRUNCATED AT 400 WORDS)
Collapse
Affiliation(s)
- E H Oliw
- Department of Pharmaceutical Biosciences, Uppsala University, Sweden
| |
Collapse
|
27
|
Kankofer M, Hoedemaker M. Role of Eicosanoids in the Regulation of the Periparturient Period in Cattle. Reprod Domest Anim 1993. [DOI: 10.1111/j.1439-0531.1993.tb00724.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
28
|
Kankofer M, Hoedemaker M. Role of Eicosanoids in the Regulation of the Periparturient Period in Cattle. Reprod Domest Anim 1993. [DOI: 10.1111/j.1439-0531.1993.tb01153.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
29
|
Fujimoto N, Kaneko T, Eguchi N, Urade Y, Mizuno N, Hayaishi O. Biochemical and immunohistochemical demonstration of a tightly bound form of prostaglandin E2 in the rat brain. Neuroscience 1992; 49:591-606. [PMID: 1501767 DOI: 10.1016/0306-4522(92)90229-u] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Basal levels of prostaglandin E2 in the rat brain were determined by radioimmunoassay to be 0.68-0.79 pmol/g brain. About one-third of the prostaglandin E2 (0.23-0.28 pmol/g) was resistant to extraction with ethanol, but could be recovered with a mixture of ethanol and 1 N HCl (9:1, v/v), indicating that a tightly bound form of prostaglandin E2 exists in the brain. The amount of the bound form of prostaglandin E2 was almost unchanged by pentylenetetrazole-induced convulsion or by transcardial perfusion with a formaldehyde solution, although these treatments resulted in 40- to 80-fold increases in prostaglandin E2 content extracted with ethanol at neutral pH. A polyclonal antibody against prostaglandin E2-albumin conjugates recognized the bound form of prostaglandin E2, giving a punctate appearance in many neuronal cell bodies in the brain. Although almost all of the neuronal perikarya were immunoreactive for prostaglandin E2, intense immunoreactivity was observed in the mitral cell layer of the olfactory bulb, layer V of the cerebral neocortex, anterodorsal and reticular nuclei of the thalamus, supraoptic, paraventricular, accessory neurosecretory and lateral mammaillary nuclei of the hypothalamus, mesencephalic trigeminal nucleus, nucleus of the trapezoid body and deep cerebellar nuclei. When the cerebral neocortical regions were observed electron microscopically, immunoreaction products were seen as fine granules which were clustered into small patches in the cytoplasm of neuronal cell bodies and proximal dendrites. No immunoreaction products were seen in glial cells or endothelial cells. These results suggest that prostaglandin E2 is involved in fundamental processes of neurons.
Collapse
Affiliation(s)
- N Fujimoto
- Department of Biotechnology Research Institute, Fuji Chemical Industries, Takaoka, Japan
| | | | | | | | | | | |
Collapse
|
30
|
Seki K, Hirai A, Noda M, Tamura Y, Kato I, Yoshida S. Epoxyeicosatrienoic acid stimulates ADP-ribosylation of a 52 kDa protein in rat liver cytosol. Biochem J 1992; 281 ( Pt 1):185-90. [PMID: 1731754 PMCID: PMC1130659 DOI: 10.1042/bj2810185] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
In rat liver cytosol, rapid ADP-ribosylation of a 52 kDa protein by endogenous ADP-ribosyltransferase(s) was observed. This ADP-ribosylation was stimulated dose-dependently by 14,15-epoxyeicosatrienoic acid (14,15-EET), one of the metabolites of arachidonic acid by NADPH-dependent cytochrome P-450 mono-oxygenase. This stimulatory effect required the presence of GTP or its non-hydrolysable analogues, guanosine 5'-[beta gamma-imido]triphosphate or guanosine 5'-[gamma-thio]triphosphate. Of four regioisomeric EETs, 14,15-EET was the most potent. No stimulatory effect was observed with addition of 14,15-dihydroxyeicosatrienoic acid, a stable metabolite of 14,15-EET. The 52 kDa protein was not ADP-ribosylated by cholera toxin A subunit and pertussis toxin, and was not recognized by anti-Gs alpha and anti-Gi alpha antibodies. However, the 52 kDa protein could be photoaffinity-labelled with 8-azidoguanosine 5'-[alpha-32P]triphosphate. These results suggest that the 52 kDa protein is neither Gs nor Gi, though it may have a GTP-binding site. These results contribute to the understanding of the role of mono-oxygenase metabolites of arachidonic acid in intracellular signal transduction.
Collapse
Affiliation(s)
- K Seki
- 2nd Department of Internal Medicine, Chiba University School of Medicine, Japan
| | | | | | | | | | | |
Collapse
|
31
|
Heizer ML, McKinney JS, Ellis EF. 14,15-Epoxyeicosatrienoic acid inhibits platelet aggregation in mouse cerebral arterioles. Stroke 1991; 22:1389-93. [PMID: 1750047 DOI: 10.1161/01.str.22.11.1389] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
BACKGROUND AND PURPOSE Epoxygenase metabolites of arachidonic acid are produced by several tissues and have been shown to inhibit in vitro platelet aggregation. The purpose of the present investigation was to determine whether 14,15- or 8,9-epoxyeicosatrienoic acid, epoxygenase derivatives of arachidonic acid, affect the speed of platelet aggregation in in vivo mouse cerebral arterioles. METHODS We performed a craniectomy in 116 anesthetized male mice and observed the pial arterioles by microscopy. We induced in situ platelet aggregation using a mercury light and intravascularly injected fluorescein dye. RESULTS Indomethacin (0.5 mg/kg i.p.), a known cyclooxygenase inhibitor, and 14,15-epoxyeicosatrienoic acid (0.3 mg/kg i.v.) increased the time necessary for the light plus dye to induce the first arterial platelet aggregate by 35% and 26%, respectively, whereas 8,9-epoxyeicosatrienoic acid (0.3 mg/kg i.v.) had no effect. Analysis of mouse serum by radioimmunoassay showed that the degree of inhibition of platelet aggregation by indomethacin and epoxyeicosatrienoic acids correlated with the degree of inhibition of thromboxane production. CONCLUSIONS We conclude that 14,15-epoxyeicosatrienoic acid is a potent inhibitor of in vivo platelet aggregation but cannot conclusively confirm that its effect on aggregation occurs via its reduction of platelet thromboxane A2. Because epoxyeicosatrienoic acids are produced by several tissues, including brain and vascular tissue, they may be important in vivo modulators of platelet aggregation and hemostasis.
Collapse
Affiliation(s)
- M L Heizer
- Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond
| | | | | |
Collapse
|
32
|
Madhun ZT, Goldthwait DA, McKay D, Hopfer U, Douglas JG. An epoxygenase metabolite of arachidonic acid mediates angiotensin II-induced rises in cytosolic calcium in rabbit proximal tubule epithelial cells. J Clin Invest 1991; 88:456-61. [PMID: 1650793 PMCID: PMC295359 DOI: 10.1172/jci115325] [Citation(s) in RCA: 106] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Previous studies from this and other laboratories have shown that angiotensin II (AII) induces [Ca2+]i transients in proximal tubular epithelium independent of phospholipase C. AII also stimulates formation of 5,6-epoxyeicosatrienoic acid (5,6-EET) from arachidonic acid by a cytochrome P450 epoxygenase and decreases Na+ transport in the same concentration range. Because 5,6-EET mimics AII with regard to Na+ transport, it effects on calcium mobilization were evaluated. [Ca2+]i was measured by video microscopy with the fluorescent indicator fura-2 employing cultured rabbit proximal tubule. AII-induced [Ca2+]i transients were enhanced by arachidonic acid and attenuated by ketoconazole, an inhibitor of cytochrome P450 epoxygenases. Arachidonic acid also elicited a [Ca2+]i transient that was attenuated by ketoconazole. 5,6-EET augmented [Ca2+]i similar to that seen with AII, but was unaffected by ketoconazole. By contrast, the other regioisomers (8,9-, 11,12-, and 14,15-EET) were much less potent. [Ca2+]i transients resulted from influx through verapamil- and nifedipine-sensitive channels. These results suggest a novel mechanism for AII-induced Ca mobilization in proximal tubule involving cytochrome P450-dependent arachidonic acid metabolism and Ca influx through voltage-sensitive channels.
Collapse
Affiliation(s)
- Z T Madhun
- Department of Medicine, University Hospitals of Cleveland, Ohio
| | | | | | | | | |
Collapse
|
33
|
Yoshida S, Hirai A, Tamura Y, Yoshida S. Possible involvement of arachidonic acid metabolites of cytochrome P450 monooxygenase pathway in vasopressin-stimulated glycogenolysis in isolated rat hepatocytes. Arch Biochem Biophys 1990; 280:346-51. [PMID: 2369126 DOI: 10.1016/0003-9861(90)90340-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Arachidonic acid (AA) is reported to be metabolized by three major pathways, i.e., cyclooxygenase (CO), lipoxygenase (LO), and NADPH-dependent cytochrome P450 monooxygenase (MO) pathways. Monooxygenase metabolites of AA have been proposed to play an important role in hormone action in various cells. Recently it was reported that the MO pathway may exist in rat liver. The present study was carried out to investigate the role of MO metabolites in vasopressin-induced glycogenolysis in isolated rat hepatocytes. The pretreatment of isolated rat hepatocytes with eicosatetraynoic acid (ETYA), an inhibitor of CO, LO, and MO pathways, and ketoconazole and SKF 525A, inhibitors of the MO pathway, dose-dependently reduced vasopressin-induced phosphorylase activation, while the pretreatment with indomethacin, an inhibitor of the CO pathway, had no effect. The increment of cytosolic calcium concentration in vasopressin-stimulated hepatocytes was also dose-dependently decreased by ETYA, ketoconazole, and SKF 525A. In vitro addition of epoxyeicosatrienoic acid (EET) dose-dependently increased both phosphorylase a activity and cytosolic calcium concentration. 14,15-EET was the most potent among four regioisomeric EETs. These results suggest that MO metabolites of AA, most likely EETs, may be involved in vasopressin-induced glycogenolysis probably via the activation of phosphorylase by increasing the cytosolic calcium concentration.
Collapse
Affiliation(s)
- S Yoshida
- The Second Department of Internal Medicine, School of Medicine, Chiba University, Japan
| | | | | | | |
Collapse
|
34
|
Hjelle JT, Guenthner TM, Bell K, Whalen R, Flouret G, Carone FA. Inhibition of catalase and epoxide hydrolase by the renal cystogen 2-amino-4,5-diphenylthiazole and its metabolites. Toxicology 1990; 60:211-22. [PMID: 2315942 DOI: 10.1016/0300-483x(90)90144-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Subchronic feeding of 2-amino-4,5-diphenylthiazole (DPT) to rats results in the development of renal cysts and has been used as a model system to study polycystic kidney disease. Because previous studies revealed changes in renal enzymes following DPT administration, a possible direct effect of DPT and its phenolic metabolites on catalase and a related enzyme, epoxide hydrolase, was examined. Experiments with three in vitro systems (suspensions of rabbit renal tubules, rat kidney homogenates, and commercially obtained bovine liver catalase) revealed direct inhibition of catalase activity by the diphenolic metabolite (diOH- DPT: 2-amino-4,5di(4'-hydroxyphenyl)-thiazole), the known renal cystogen nordihydroquaiaretic acid (NDGA) 2-amino-4(4'-hydroxyphenyl),5-phenyl-thiazole (4OH-DPT), and the known catalase inhibitor 3-amino-1,2,4-triazole; DPT did not inhibit catalase activity. Following oral administration to rats of the DPT congeners, 4OH-DPT caused the greatest decrease in both renal catalase and cytosolic epoxide hydrolase activities and the shortest time to onset of cystic lesions. In vitro, mouse liver cytosolic epoxide hydrolase activity was substantially inhibited by 4OH-DPT and dioH-DPT, and NDGA, but not by 2-amino-4-phenyl,5-(4'-hydroxyphenyl)-thiazole (5OH-DPT) or DPT itself. Microsomal epoxide hydrolase (mEH) activity was inhibited by 4OH-DPT, unaffected by DPT or dioH-DPT, and stimulated 2-fold by 5OH-DPT. Finally, mEH activity was substantially higher in samples of normal human kidney than in samples of kidney derived from a patient with autosomal recessive polycystic kidney disease; no differences were observed in cEH activity in these samples. Although the role of altered catalase and epoxide hydrolase activities in cystogenesis is unknown, DPT-induced cyst formation is associated with loss of these enzyme activities in kidney tissue. To our knowledge, this is the first report of an in vivo diminution of cytosolic epoxide hydrolase activity by xenobiotics.
Collapse
Affiliation(s)
- J T Hjelle
- Department of Basic Sciences, University of Illinois College of Medicine, Peoria 61656
| | | | | | | | | | | |
Collapse
|
35
|
Hirt DL, Capdevila J, Falck JR, Breyer MD, Jacobson HR. Cytochrome P450 metabolites of arachidonic acid are potent inhibitors of vasopressin action on rabbit cortical collecting duct. J Clin Invest 1989; 84:1805-12. [PMID: 2556446 PMCID: PMC304058 DOI: 10.1172/jci114365] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
AA is metabolized by a cytochrome P450, NADPH-dependent epoxygenase to four regioisomeric epoxyeicosatrienoic acids (EETs). The EETs are further hydrated enzymatically to their respective diols, vic-dihydroxyeicosatrienoic acids (DHETs). We studied the effect of pretreatment with DHETs on 10 microU/cm2 arginine vasopressin (AVP)-stimulated hydraulic conductivity (Lp) (Lp x 10(-7) cm/atm/s, mean +/- SE) in rabbit cortical collecting ducts (CCDs) perfused in vitro at 37 degrees C. At 10(-6) M all four DHETs were potent inhibitors of the hydroosmotic effect of AVP. 14,15-DHET was the most potent isomer; it reduced AVP-induced Lp from a control value of 234.75 +/- 11.7, n = 17, to a value of 95.2 +/- 8.39, n = 5, P less than 0.0001, a reduction of AVP-mediated water flow of 60%. The inhibitory effect of 14,15-DHET was dose dependent and significant to nanomolar concentrations. 14,15-DHET at 10(-7) M was as potent an inhibitor of AVP's activity as was 10(-7) M PGE2. AVP's hydroosmotic effect is mediated through its intracellular second messenger, cAMP. 8-p-Chlorophenylthio-cAMP (CcAMP) at 10(-4) M induced a peak Lp of 189.6 +/- 11.0, n = 8; pretreatment with 10(-6) M 14,15-DHET reduced CcAMP-peak Lp to 132.0 +/- 13.4, n = 5, P less than 0.01, demonstrating a post-cAMP effect. Gas chromatography/mass spectroscopy suggests that EETs are present in extracts purified from CCDs. We conclude that cytochrome P450 epoxygenase eicosanoids are potent inhibitors of the hydroosmotic effect of vasopressin and are endogenous constituents of normal CCDs, the major target tissue for AVP.
Collapse
Affiliation(s)
- D L Hirt
- Department of Medicine, Veterans Administration Medical Center, Nashville, Tennessee 37232
| | | | | | | | | |
Collapse
|
36
|
Nishimura M, Hirai A, Omura M, Tamura Y, Yoshida S. Arachidonic acid metabolites by cytochrome P-450 dependent monooxygenase pathway in bovine adrenal fasciculata cells. PROSTAGLANDINS 1989; 38:413-30. [PMID: 2510214 DOI: 10.1016/0090-6980(89)90124-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
[1-14C]Arachidonic acid was incubated with microsomes of bovine adrenal fasciculata cells in the presence of 1 mM NADPH for 30 min at 37 degrees C. The metabolites were separated and purified by reverse phase high performance liquid chromatography, and identified by gas chromatography-mass spectrometry. Identified metabolites were four dihydroxyeicosatrienoic acids (DHTs) (5,6-, 8,9-, 11,12-, 14,15-DHTs), 20-hydroxyeicosatetraenoic acid and eicosatetradioic acid. The formation of these metabolites was dependent on NADPH and inhibited by SKF-525A. 14,15-DHT was also formed by isolated bovine adrenal fasciculata cells. These results indicate that cytochrome P-450 dependent arachidonate monooxygenase pathway may exist in bovine adrenal fasciculata cells. Addition of the chemically synthesized epoxyeicosatrienoic acids (EETs) to isolated bovine adrenal fasciculata cells stimulated cortisol production. Among four regioisomeric EETs, 14,15-EET was most potent and stimulated steroidogenesis in a dose-related manner over a range of 0.5 to 5.0 microM.
Collapse
Affiliation(s)
- M Nishimura
- Second Department of Internal Mediciné, School of Medicine, Chiba University, Japan
| | | | | | | | | |
Collapse
|
37
|
Snowdowne KW, Rosenoer L, Yu E, Cashman JR. Eicosanoids evoke the release of amylase and increase cytoplasmic calcium in rat parotid cells. Biochem Biophys Res Commun 1989; 161:379-84. [PMID: 2471532 DOI: 10.1016/0006-291x(89)91608-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The effects of various eicosanoids on cytoplasmic calcium and the release of amylase were examined in isolated rat parotid cells. Arachidonate and several of its metabolites increased amylase release and elevated cytoplasmic calcium. Melittin, a stimulator of arachidonate mobilization, and lyso-phosphatidylcholine also released amylase and elevated calcium. These results suggest that the metabolites of arachidonate may have an important role in amylase secretion.
Collapse
Affiliation(s)
- K W Snowdowne
- Department of Biochemistry, School of Dentistry, University of the Pacific, San Francisco, CA 94115
| | | | | | | |
Collapse
|
38
|
Snyder GD, Yadagiri P, Falck JR. Effect of epoxyeicosatrienoic acids on growth hormone release from somatotrophs. THE AMERICAN JOURNAL OF PHYSIOLOGY 1989; 256:E221-6. [PMID: 2563927 DOI: 10.1152/ajpendo.1989.256.2.e221] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Growth hormone secretion was stimulated in vitro by products of arachidonic acid epoxygenase, the epoxyeicosatrienoic acids. 5,6-Epoxyeicosatrienoic and 14,15-epoxyeicosatrienoic acid stimulated growth hormone release from an enriched population of somatotrophs (approximately 85%) by twofold. Inhibition of arachidonic acid metabolism by indomethacin did not affect growth hormone-releasing hormone stimulation of growth hormone release. In contrast, pretreatment of somatotrophs with an 11,12-isonitrile analogue of arachidonic acid that inhibits arachidonic acid epoxygenase, resulted in a 20-25% inhibition of growth hormone-releasing hormone-stimulated growth hormone release. 14,15-Epoxyeicosatrienoic acid stimulated a concentration-dependent increase (twofold) in the cytoplasmic concentration of adenosine 3',5'-cyclic monophosphate (cAMP) in the somatotrophs. 14,15-Epoxyeicosatrienoic acid also rapidly increased the intracellular free calcium concentration in somatotrophs from resting levels (approximately 80 nM) to greater than 250 nM. Growth hormone-releasing hormone increased the free intracellular calcium to 160-180 nM. Preincubation of somatotrophs with somatostatin inhibited growth hormone-releasing hormone-stimulated growth hormone secretion, cAMP accumulation, and 14,15-epoxyeicosatrienoic acid stimulated cAMP accumulation. These data are suggestive that the epoxyeicosatrienoic acids may have a role in the secretion of growth hormone.
Collapse
Affiliation(s)
- G D Snyder
- Department of Obstetrics and Gynecology, University of Iowa, Iowa City 52242
| | | | | |
Collapse
|
39
|
Cashman JR. 5,6-Epoxyeicosatrienoic acid stimulates growth hormone release in rat anterior pituitary cells. Life Sci 1989; 44:1387-93. [PMID: 2716476 DOI: 10.1016/0024-3205(89)90396-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The effect of arachidonic acid and some of its metabolites have been examined in rat anterior pituitary cells for their ability to release growth hormone. The cytochrome P-450 metabolite, 5,6-epoxyeicosatrienoic acid is a much more effective growth-hormone releasing agent than 15-hydroxyeicosatetraenoic acid, 15-hydroxyeicosatetraenoic acid methyl ester, 5-hydroxyeicosatetraenoic acid or arachidonic acid. The release of growth hormone is rapid, dose-dependent and reaches an apparent saturation after eight minutes. These studies described herein provide evidence that lipoxygenase and cyclooxygenase products of arachidonic acid are less potent while cytochrome P-450 products are more potent in the release of growth hormone from anterior pituitary cells.
Collapse
Affiliation(s)
- J R Cashman
- Department of Pharmaceutical Chemistry, School of Pharmacy, University of California, San Francisco 94143-0446
| |
Collapse
|
40
|
Capdevila JH, Mosset P, Yadagiri P, Lumin S, Falck JR. NADPH-dependent microsomal metabolism of 14,15-epoxyeicosatrienoic acid to diepoxides and epoxyalcohols. Arch Biochem Biophys 1988; 261:122-33. [PMID: 3341770 DOI: 10.1016/0003-9861(88)90111-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The arachidonic acid epoxygenase metabolite 14,15-epoxyeicosatrienoic acid is further metabolized by rat liver microsomal fractions to regioisomeric diepoxides and epoxyalcohols. Diepoxides result from epoxidation at the 5,6-, 8,9-, or 11,12-olefins. Hydroxylation leading to epoxyalcohols with a cis, trans-conjugated dienol occurs at carbons 5, 8, 9, or 12. Structural assignments were established by chromatographic and mass spectral comparisons with synthetic standards. The reaction requires NADPH and is inhibited by typical cytochrome P-450 inhibitors. Analysis of the time course of product formation during arachidonic acid oxidation by rat liver microsomal fractions indicated that all four regioisomeric epoxyeicosatrienoic acids can be further metabolized by the enzyme system.
Collapse
Affiliation(s)
- J H Capdevila
- Division of Nephrology, Vanderbilt Medical School, Nashville, Tennessee 37232
| | | | | | | | | |
Collapse
|
41
|
NEGRO-VILAR A, VALENCA MM. Transmembrane Signals and Neural Peptide Release: Role of Protein Kinase C Activators and Arachidonic Acid. Ann N Y Acad Sci 1987. [DOI: 10.1111/j.1749-6632.1987.tb29506.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
42
|
Rabier M, Chavis C, Crastes de Paulet A, Damon M. Arachidonic acid metabolism in a cloned strain of rat pituitary tumor cells: correlation between 15 hydroxyeicosatetraenoic acid release and the prolactin secretory process. PROSTAGLANDINS, LEUKOTRIENES, AND MEDICINE 1987; 27:27-42. [PMID: 3108904 DOI: 10.1016/0262-1746(87)90057-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
We investigated the involvement of arachidonic acid metabolites in basal and thyrotropin releasing hormone (TRH) stimulated prolactin release by GH3 cells, a cloned strain of rat pituitary tumor cells. GH3 cells spontaneously released 9 and 15 HETEs and the 15 HETE release was greater than that of 9 HETE. When the cells were challenged by 10(-5) M AA, they were able to produce 5, 9, 12 and 15 HETEs. 10(-6) M TRH only stimulated the release of the two metabolites synthesized by the basal cells (15 and 9 HETEs). This release depended on the length of stimulation by TRH. When both AA and TRH were added, there was an increase in 15 and 9 HETE production. In all cases, more 15 HETE was released than other metabolites. In dose-response studies using TRH concentrations of 10(-6) M to 10(-12) M, the highest level of 9 HETE release was obtained at 10(-11) M TRH and the highest release of 15 HETE was at 10(-9) M TRH. PRL secretion by GH3 cells challenged by TRH showed the same pattern as 15 HETE release, and the correlation between PRL and 15 HETE was significant (p less than 0.001). These data indicate that 15 HETE is the lipoxygenase metabolite released in the largest amounts by GH3 cells and suggest some physiological interaction between 15 HETE and TRH in the control of PRL secretion.
Collapse
|
43
|
Negro-Vilar A, Valenca MM, Culler MD. Transmembrane signals and intracellular messengers mediating LHRH and LH secretion. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1987; 219:85-108. [PMID: 3124526 DOI: 10.1007/978-1-4684-5395-9_5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- A Negro-Vilar
- Reproductive Neuroendocrinology Section, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709
| | | | | |
Collapse
|
44
|
Ennis MD, Baze ME. Asymmetric total synthesis of 14(R),15(S)-, 14(S),15(R)-, 14(R),15(R)-, and 14(S),15(S)-epoxyeicosatrienoic acids. Tetrahedron Lett 1986. [DOI: 10.1016/s0040-4039(00)85390-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
45
|
Mosset P, Yadagiri P, Lumin S, Capdevila J, Falck J. Arachidonate epoxygenase: Total synthesis of both enantiomers of 8,9- and 11,12-epoxyricosatrienoic acid. Tetrahedron Lett 1986. [DOI: 10.1016/s0040-4039(00)85391-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
46
|
Valenca MM, Conte D, Negro-Vilar A. Diacylglycerol and phorbol esters enhance LHRH and prostaglandin E2 secretion from median eminence nerve terminals in vitro. Brain Res Bull 1985; 15:657-9. [PMID: 3910172 DOI: 10.1016/0361-9230(85)90215-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The present experiments were designed to evaluate the role of protein kinase C activation on the secretion of the neural peptide, LHRH, from hypothalamic nerve terminals in vitro. Two specific protein kinase C activators, diacylglycerol (1,2-didecanoylglycerol, DiC10) and a phorbol ester (12,13-dibutyrate, PDBu) were used as probes. In addition to LHRH, secretion of prostaglandin E2 (PGE2) was also measured, since previous studies from our laboratory indicate that this arachidonic acid metabolite is intimately involved in the LHRH secretory process. PDBu at a dose of 200 nM significantly enhanced LHRH secretion from median eminence nerve terminals; in addition, a more modest but significant stimulation of PGE2 release was also observed. DiC10 (100 microM), on the other hand, enhanced PGE2 release but had no clear effect on LHRH secretion. Release of LHRH, however, was clearly stimulated when the lipoxygenase inhibitor nordihydroguaiaretic acid was added to the medium, suggesting that some arachidonic acid metabolites are inhibitory to LHRH secretion. The results indicate that protein kinase C activation leads to an enhanced secretion of LHRH. In addition, they suggest that 1,2-diacylglycerol may also activate the formation of arachidonoyl residues inhibitory to LHRH release.
Collapse
|