The objective of this research is to elucidate the mechanism or mechanisms by which substituted amphetamines, such as methylenedioxyamphetamine (MDA), rho-choloroamphetamine (pCA) and methylenedioxymethamphetamine (MDMA) cause a long term reduction in brain serotonin (5HT) levels and cause lesions in certain brain regions. These compounds are members of the phenylisopropylamine class of stimulants and hallucinogens that have a long history of abuse. The appearance of the methylenedioxy compounds as abused substances has caused concern because of their potential for toxicity and the lack of understanding of the detailed pharmacology. The research is centered about a model in which the drugs are metabolized either peripherally or in the brain to substance that concentrate in serotonin neurons and generate reactive electrophilic compounds and/or toxic oxygen radicals. The approach utilizes both whole animal and cell culture as the biological media and a number of chemical methods for analysis of changes in cellular properties and in the drug itself. In vivo studies investigation the metabolic N-demethylenation to catecholamines, the N-demethylation of MDMA, and the O-derivatization of catecholamine metabolites are proposed using GC/MS to analyze plasma and brain tissue extracts. The effects of heavy isotope substitution on metabolically active centers on toxicity will also be assessed as an approach to determining the metabolic pathway for toxicity. The neurochemical changes will be monitored in the whole animal by microdialysis and HPLC methodology. The data from in vivo experiments will be analyzed by pharmacokinetic modelling techniques to assess the relationship between drug levels and pharmacological response. Previous studies had demonstrated that a glutathione (GSH) adduct of a metabolite was formed in vitro and its identity and conditions for its formation will be determined. A neuroblastoma based cell line (NG108-15) has been shown to be sensitive to the toxic actions of some of the phenylisopropylamine derivatives. This line will be used to study the formation of this adduct and the biochemical sequence of toxin-induced cell death. The results of these experiments and the relevant methodology will then be applied to studies on the brains of treated animals to assess the validity of the in vitro experiments. The studies utilized techniques in pharmacokinetics, cell culture and general analytical chemistry to elucidate mechanisms.

Agency
National Institute of Health (NIH)
Institute
National Institute on Drug Abuse (NIDA)
Type
Research Project (R01)
Project #
5R01DA004206-05
Application #
3209539
Study Section
Drug Abuse Biomedical Research Review Committee (DABR)
Project Start
1986-07-01
Project End
1993-03-31
Budget Start
1991-04-01
Budget End
1992-03-31
Support Year
5
Fiscal Year
1991
Total Cost
Indirect Cost
Name
University of California Los Angeles
Department
Type
Schools of Medicine
DUNS #
119132785
City
Los Angeles
State
CA
Country
United States
Zip Code
90095
Chu, T; Kumagai, Y; DiStefano, E W et al. (1996) Disposition of methylenedioxymethamphetamine and three metabolites in the brains of different rat strains and their possible roles in acute serotonin depletion. Biochem Pharmacol 51:789-96
Lin, L Y; Kumagai, Y; Hiratsuka, A et al. (1995) Cytochrome P4502D isozymes catalyze the 4-hydroxylation of methamphetamine enantiomers. Drug Metab Dispos 23:610-4
Hiratsuka, A; Chu, T Y; Distefano, E W et al. (1995) Inactivation of constitutive hepatic cytochromes P450 by phencyclidine in the rat. Drug Metab Dispos 23:201-6
Kumagai, Y; Lin, L Y; Hiratsuka, A et al. (1994) Participation of cytochrome P450-2B and -2D isozymes in the demethylenation of methylenedioxymethamphetamine enantiomers by rats. Mol Pharmacol 45:359-65
Cho, A K; Hiramatsu, M; Kumagai, Y et al. (1993) Pharmacokinetic approaches to the study of drug action and toxicity. NIDA Res Monogr 136:213-25
Cho, A K; Hiramatsu, M; Schmitz, D A et al. (1993) A behavioral and pharmacokinetic study of the actions of phenylcyclohexyldiethylamine and its active metabolite, phenylcyclohexylethylamine. J Pharmacol Exp Ther 264:1401-5
Kumagai, Y; Lin, L Y; Philpot, R M et al. (1992) Regiochemical differences in cytochrome P450 isozymes responsible for the oxidation of methylenedioxyphenyl groups by rabbit liver. Mol Pharmacol 42:695-702
Lin, L Y; Kumagai, Y; Cho, A K (1992) Enzymatic and chemical demethylenation of (methylenedioxy)amphetamine and (methylenedioxy)methamphetamine by rat brain microsomes. Chem Res Toxicol 5:401-6
Kumagai, Y; Schmitz, D A; Cho, A K (1992) Aromatic hydroxylation of methylenedioxybenzene (MDB) and methylenedioxymethamphetamine (MDMA) by rabbit liver microsomes. Xenobiotica 22:395-403
Kumagai, Y; Wickham, K A; Schmitz, D A et al. (1991) Metabolism of methylenedioxyphenyl compounds by rabbit liver preparations. Participation of different cytochrome P450 isozymes in the demethylenation reaction. Biochem Pharmacol 42:1061-7

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