Abstract
Cytochrome P450 (P450) enzymes and ATP-binding cassette (ABC) transporters modulate the transport and metabolism of both endogenous and exogenous substrates and could play crucial roles in the human brain. In this study, we report the transcript expression profile of seven ABC transporters (ABCB1, ABCC1–C5, and ABCG2), 24 P450s (CYP1, CYP2, and CYP3 families and CYP46A1), and 14 related transcription factors [aryl hydrocarbon receptor, nuclear receptor (NR)1I2/pregnane X receptor, NR1I3/constitutive androstane receptor and NR1C/peroxisome proliferator-activated receptor, NR1H/liver X receptor, NR2B/retinoid X receptor, and NR3A/estrogen receptor subfamilies] in the whole brain, the dura mater, and 17 different encephalic areas. In addition, Western blotting and immunohistochemistry analysis were used to characterize the distribution of the P450s at the cellular and subcellular levels in some brain regions. Our results show the presence of a large variety of xenobiotic transporters and metabolizing enzymes in human brain and show for the first time their apparent selective distribution in different cerebral regions. The most abundant transporters were ABCC5 and ABCG2, which, interestingly, had a higher mRNA expression in the brain compared with that found in the liver. CYP46A1, CYP2J2, CYP2U1, CYP1B1, CYP2E1, and CYP2D6 represented more than 90% of the total P450 and showed selective distribution in different brain regions. Their presence in both microsomal and mitochondrial fractions was shown both in neuronal and glial cells in several brain areas. Thus, our study shows key enzymes of cholesterol and fatty acid metabolism to be present in the human brain and provides novel information of importance for elucidation of enzymes responsible for normal and pathological processes in the human brain.
Footnotes
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This work was supported by a grant from Servier Technology.
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Article, publication date, and citation information can be found at http://dmd.aspetjournals.org.
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doi:10.1124/dmd.109.027011.
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ABBREVIATIONS: P450, cytochrome P450; ABC, ATP-binding cassette; BBB, blood-brain barrier; PCR, polymerase chain reaction; AhR, aryl hydrocarbon receptor; NR, nuclear receptor; PPAR, peroxisome proliferator-activated receptor; LXR, liver X receptor; FXR, farnesoid X receptor; PXR, pregnane X receptor; CAR, constitutive androstane receptor; RXR, retinoid X receptor; ER, estrogen receptor; Ct, threshold cycle; PCA, principal component analysis; PC, principal component; TF, transcriptional factor; CPR, cytochrome P450 reductase; FDXR, ferredoxin reductase.
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↵ The online version of this article (available at http://dmd.aspetjournals.org) contains supplemental material.
- Accepted April 7, 2009.
- Received February 2, 2009.
- The American Society for Pharmacology and Experimental Therapeutics
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