Cytochrome P450 2D catalyze steroid 21-hydroxylation in the brain.
mRNA of cytochrome P450 21-hydroxylase (P450c21) is expressed in the brain, but little is known about the enzymatic properties of P450c21 in the brain. In the present study, we showed, by using various recombinant cytochrome P450 (CYP)2D enzymes and anti-CYP2D4- or P450c21-specific antibodies, that rat brain microsomal steroid 21-hydroxylation is catalyzed not by P450c21, but by CYP2D isoforms. Rat CYP2D4 and human CYP2D6, which are the predominant CYP2D isoforms in the brain, possess 21-hydroxylation activity for both progesterone and 17alpha-hydroxyprogesterone. In rat brain microsomes, these activities were not inhibited by anti-P450c21 antibodies, but they were effectively inhibited by the CYP2D-specific chemical inhibitor quinidine and by anti-CYP2D4 antibodies. mRNA and protein of CYP2D4 were expressed throughout the brain, especially in cerebellum, striatum, pons, and medulla oblongata, whereas the mRNA and protein levels of P450c21 were extremely low or undetectable. These results support the idea that CYP2D4, not P450c21, works as steroid 21-hydroxylase in the brain. Allopregnanolone, a representative gamma-aminobutyric acid receptor modulator, was also hydroxylated at the C-21 position by recombinant CYP2D4 and CYP2D6. Rat brain microsomal allopregnanolone 21-hydroxylation was inhibited by fluoxetine with an IC(50) value of 2 microm, suggesting the possibility that the brain CYP2D isoforms regulate levels of neurosteroids such as allopregnanolone, and that this regulation is modified by central nervous system-active drugs such as fluoxetine.
Kishimoto
Wataru
W
Department of Chemical Biology, Osaka City University Medical School, 1-4-3 Asahimachi, Abeno-ku, Osaka 545-8585, Japan.
Hiroi
Toyoko
T
Shiraishi
Masakazu
M
Osada
Mayuko
M
Imaoka
Susumu
S
Kominami
Shiro
S
Igarashi
Takashi
T
Funae
Yoshihiko
Y
D019326:17-alpha-Hydroxyprogesterone / Q000378:metabolism; D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D001921:Brain / Q000201:enzymology*; D001923:Brain Chemistry; D019389:Cytochrome P-450 CYP2D6 / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D005473:Fluoxetine / Q000494:pharmacology; D006801:Humans; D006900:Hydroxylation; D008297:Male; D008861:Microsomes / Q000201:enzymology; D006899:Mixed Function Oxygenases / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D011280:Pregnanolone / Q000378:metabolism; D011374:Progesterone / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017367:Selective Serotonin Reuptake Inhibitors / Q000494:pharmacology; D013255:Steroid 21-Hydroxylase / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity; D014018:Tissue Distribution
D019326:17-alpha-Hydroxyprogesterone; D001189:Aryl Hydrocarbon Hydroxylases; D019389:Cytochrome P-450 CYP2D6; D005473:Fluoxetine; D006899:Mixed Function Oxygenases; D011280:Pregnanolone; D011374:Progesterone; D012333:RNA, Messenger; D011994:Recombinant Proteins; D017367:Selective Serotonin Reuptake Inhibitors; D013255:Steroid 21-Hydroxylase; C115670:Cyp2d4 protein, rat