The cytochrome P450 dependent mixed function oxidase system is found in many tissues of vertebrates and is responsible for the metabolism of a variety of therapeutically important drugs among them the tricyclic antidepressants. Recently our laboratory has shown the presence of cytochromes P450 forms b (P450IIB1) and c (P450IA1) using 32P DNA probes in a poly (A)+RNA hybridization assay. The hybridizable bands of both forms are inducible by phenobarbital of beta-napthoflavone, respectively, Furthermore, estrogen and the tricyclic antidepressants amitriptyline and imipramine increase the hybridization of form b. These preliminary data give rise to the hypothesis that brain cytochrome might play a role in antidepressant metabolism in brain and that estrogen levels may influence the expression of cytochromes P450 and in turn antidepressant metabolism. This proposal will test this hypothesis that brain cytochrome might play a role in antidepressant metabolism in brain and that estrogen levels may influence the expression of cytochromes P450 and in turn antidepressant metabolism. This proposal will test this hypothesis by identifying the cytochromes P450 present in brain and localizing them to specific brain areas using 32P labelled DNA or oligonucleotide probes to the various P450 isozymes. We will also characterize the effect of inducers (phenobarbital and beta-napthoflavone), antidepressant substrates (amitriptyline and imipramine), and estrogen on the expression of P450. We will also identify which P450s catalyze antidepressant metabolism in brain using purification and in vitro reconstitution of activity in assay techniques. We will assess the role of estrogen in the expression of brain cytochrome P450 by treating normal and ovarectomized rats with estrogen and other inducers and comparing P450 expression levels. These data will also be used in a correlation of estrogen responsive brain areas with those having estrogen receptors in order to assess how estrogen might exert is regulatory role on brain P450 expression. These studies may aid our understanding of the decreased efficacy of tricyclic antidepressant drugs in the treatment of post menopausal depression and provide a basis for addressing this depression.

Agency
National Institute of Health (NIH)
Institute
National Institute of Mental Health (NIMH)
Type
Research Project (R01)
Project #
1R01MH044923-01A2
Application #
3384422
Study Section
Pharmacology A Study Section (PHRA)
Project Start
1992-03-01
Project End
1996-02-29
Budget Start
1992-03-01
Budget End
1993-02-28
Support Year
1
Fiscal Year
1992
Total Cost
Indirect Cost
Name
University of Texas Health Science Center Houston
Department
Type
Schools of Medicine
DUNS #
City
Houston
State
TX
Country
United States
Zip Code
77225
Geng, J; Strobel, H W (1998) Expression, induction and regulation of the cytochrome P450 monooxygenase system in the rat glioma C6 cell line. Brain Res 784:276-83
Geng, J; Strobel, H W (1997) Expression and induction of cytochrome P-450 1A1 and P-450 2D subfamily in the rat glioma C6 cell line. Brain Res 774:11-9
Strobel, H W; Geng, J; Kawashima, H et al. (1997) Cytochrome P450-dependent biotransformation of drugs and other xenobiotic substrates in neural tissue. Drug Metab Rev 29:1079-105
Kawashima, H; Kusunose, E; Thompson, C M et al. (1997) Protein expression, characterization, and regulation of CYP4F4 and CYP4F5 cloned from rat brain. Arch Biochem Biophys 347:148-54
Thompson, C M; Bernhard, A E; Strobel, H W (1997) Barbiturate-induced expression of neuronal nitric oxide synthase in the rat cerebellum. Brain Res 754:142-6
Baum, L O; Strobel, H W (1997) Regulation of expression of cytochrome P-450 2D mRNA in rat brain with steroid hormones. Brain Res 765:67-73
Wang, H; Strobel, H W (1997) Regulation of CYP3A9 gene expression by estrogen and catalytic studies using cytochrome P450 3A9 expressed in Escherichia coli. Arch Biochem Biophys 344:365-72
Sequeira, D J; Strobel, H W (1996) In vitro metabolism of imipramine by brain microsomes: effects of inhibitors and exogenous cytochrome P450 reductase. Brain Res 738:24-31
Wang, H; Kawashima, H; Strobel, H W (1996) cDNA cloning of a novel CYP3A from rat brain. Biochem Biophys Res Commun 221:157-62
Kawashima, H; Sequeira, D J; Nelson, D R et al. (1996) Genomic cloning and protein expression of a novel rat brain cytochrome P-450 CYP2D18* catalyzing imipramine N-demethylation. J Biol Chem 271:28176-80

Showing the most recent 10 out of 17 publications