Molecular characterization of an arachidonic acid epoxygenase in rat brain astrocytes
- PMID: 8623121
- DOI: 10.1161/01.str.27.5.971
Molecular characterization of an arachidonic acid epoxygenase in rat brain astrocytes
Abstract
Background and purpose: Brain parenchymal tissue metabolizes arachidonic acid (AA) via the cytochrome P450 (P450) epoxygenase to epoxyeicosatrienoic acids (EETs). EETs dilate cerebral arterioles and enhance K+ current in vascular smooth muscle cells from large cerebral arteries. Because of the close association between astrocytes and the cerebral microcirculation, we hypothesized that brain epoxygenase activity originates from astrocytes. This study was designed to identify and localize an AA epoxygenase in rat brain astrocytes. We also tested the effect of EETs on whole-cell K+ current in rat cerebral microvascular smooth muscle cells.
Methods: A functional assay was used to demonstrate endogenous epoxygenase activity of intact astrocytes in culture. Oligonucleotide primers derived from the sequence of a known hepatic epoxygenase, P450 2C11, were used in reverse transcription/polymerase chain reaction of RNA isolated from cultured rat astrocytes. The appropriate size reverse transcription/polymerase chain reaction product was cloned into a plasmid vector and sequenced. A polyclonal peptide antibody was raised against P450 2C11 and used in Western blotting and immunocytochemical staining of cultured astrocytes. A voltage-clamp technique was used to test the effect of EETs on whole-cell K+ current recorded from rat cerebral microvascular muscle cells.
Results: Based on elution time of known standards and inhibition by miconazole, an inhibitor of P450 AA epoxygenase, cultured astrocytes produce 11,12- and 14,15-EETs when incubated with AA. The sequence of a cDNA derived from RNA isolated from cultured rat astrocytes was 100% identical to P450 2C11. Immunoreactivity to glial fibrillary acidic protein, a marker for astrocytes, colocalized with 2C11 immunoreactivity in double immunochemical staining of cultured astrocytes. EETs enhanced outward K+ current in muscle cells from rat brain microvessels.
Conclusions: Our results demonstrate that a P450 2C11 mRNA is expressed in astrocytes and may be responsible for astrocyte epoxygenase activity. Given the vasodilatory effect of EETs, our findings suggest a role for astrocytes in the control of cerebral microcirculation mediated by P450 2C11-catalyzed conversion of AA to EETs. The mechanism of EET-induced dilation of rat cerebral microvessels may involve activation of K+ channels.
Similar articles
-
Hypoxic preconditioning and tolerance via hypoxia inducible factor (HIF) 1alpha-linked induction of P450 2C11 epoxygenase in astrocytes.J Cereb Blood Flow Metab. 2005 Aug;25(8):939-48. doi: 10.1038/sj.jcbfm.9600085. J Cereb Blood Flow Metab. 2005. PMID: 15729289
-
Dual regulation of the cerebral microvasculature by epoxyeicosatrienoic acids.Trends Cardiovasc Med. 2001 Jan;11(1):38-42. doi: 10.1016/s1050-1738(01)00082-2. Trends Cardiovasc Med. 2001. PMID: 11413051 Review.
-
Functional hyperemia in the brain: hypothesis for astrocyte-derived vasodilator metabolites.Stroke. 1998 Jan;29(1):229-34. doi: 10.1161/01.str.29.1.229. Stroke. 1998. PMID: 9445355 Review.
-
Role of P-450 arachidonic acid epoxygenase in the response of cerebral blood flow to glutamate in rats.Stroke. 1997 May;28(5):1066-72. doi: 10.1161/01.str.28.5.1066. Stroke. 1997. PMID: 9158651
-
Inhibition of brain P-450 arachidonic acid epoxygenase decreases baseline cerebral blood flow.Am J Physiol. 1996 Oct;271(4 Pt 2):H1541-6. doi: 10.1152/ajpheart.1996.271.4.H1541. Am J Physiol. 1996. PMID: 8897950
Cited by
-
A Narrative Review of the Published Pre-Clinical Evaluations: Multiple Effects of Arachidonic Acid, its Metabolic Enzymes and Metabolites in Epilepsy.Mol Neurobiol. 2024 Jun 6. doi: 10.1007/s12035-024-04274-6. Online ahead of print. Mol Neurobiol. 2024. PMID: 38842673 Review.
-
Fatty acid binding proteins are novel modulators of synaptic epoxyeicosatrienoic acid signaling in the brain.Sci Rep. 2023 Sep 14;13(1):15234. doi: 10.1038/s41598-023-42504-4. Sci Rep. 2023. PMID: 37709856 Free PMC article.
-
Astrocytes amplify neurovascular coupling to sustained activation of neocortex in awake mice.Nat Commun. 2022 Dec 22;13(1):7872. doi: 10.1038/s41467-022-35383-2. Nat Commun. 2022. PMID: 36550102 Free PMC article.
-
Lipids as Regulators of Cellular Senescence.Front Physiol. 2022 Mar 4;13:796850. doi: 10.3389/fphys.2022.796850. eCollection 2022. Front Physiol. 2022. PMID: 35370799 Free PMC article. Review.
-
Hormone-sensitive lipase is localized at synapses and is necessary for normal memory functioning in mice.J Lipid Res. 2022 May;63(5):100195. doi: 10.1016/j.jlr.2022.100195. Epub 2022 Mar 15. J Lipid Res. 2022. PMID: 35300984 Free PMC article.
MeSH terms
Substances
Grants and funding
LinkOut - more resources
Full Text Sources
Miscellaneous