Department of Pharmacokinetics and Drug Metabolism

Research profile
The Department of Pharmacokinetics and Drug Metabolism study objectives include pharmacokinetics of psychotropic drugs (antidepressants and neuroleptics), an involvement of cytochrome P450 isoenzymes in the metabolism of these drugs and endogenous neuroactive substrates as well as an influence of the nervous system on the expression of this enzyme.
Studies concerning pharmacokinetics and metabolism of psychotropics are carried out using animal and clinically derived material. They include four stages of the drug's fates in the body: absorption from the site of administration, cytochrome P450-dependent metabolism, distribution (transport and penetration across the blood-brain barrier) and elimination from the body.
Studies on cytochrome P450-associated metabolism of psychotropic drugs and endogenous substrates are carried out in human and animal enzyme preparations. Particular attention is paid to the involvement of this enzyme in alternative pathways of neurotransmitter synthesis (e.g. dopamine formation from tyramine, serotonin synthesis from 5-methoxytryptamine or melatonin), which may constitute new targets for psychotropic drug action.
Our research involves also the direct impact of psychotropic drugs (drug-enzyme interaction) on brain and liver P450 expression and metabolic activity. The results of these studies help to understand pharmacokinetic interactions between drugs and their effects on metabolism of endogenous substances (e.g. neurotransmitters, steroids, arachidonic acid).
We are also interested in the involvement of brain and peripheral neurotransmitters in the regulation of cytochrome P450 expression, including neuroendocrine mechanisms. These studies aim to understand the role of nervous system in the physiological and molecular regulation of hepatic and cerebral cytochrome P450 and to explain the influence of psychotropic drugs on this enzyme, which may be considered as a novel aspect of drug action.
The results of the above research allows to gain a better understanding of physiological and pharmacological role of cytochrome P450 in brain and liver, and the influence of psychotropic drugs. Studies conducted in our department are intended to assess the ability of psychotropic drugs to reach their site of action in the brain and their influence on metabolism of endogenous (understanding the new mechanisms of drug action) and exogenous (understanding the possible interactions between drugs) neuroactive substrates.

Research methods
The Department of Pharmacokinetics and Drug Metabolism uses in vivo (systemic or intra-cerebral administration of substances, brain microdialysis), ex vivo (preparation of microsomal fractions) and in vitro (determination of drug and neurotransmitter concentration, enzymatic reactions and measurement of specific substrates and metabolites, measurement of enzyme expression, determination of hormone and cytokine levels) research methods.

Pharmacokinetic and biochemical methods:
- measurement of drugs and their metabolite concentration in biological material (plasma, brain, other tissues) using high-performance liquid chromatography (HPLC) with UV or fluorimetric detection and liquid chromatography coupled to LC / ESI-MS / MS tandem mass spectrometry;
- determination of monoaminergic neurotransmitters and their metabolite levels in plasma and brain structures, using high-performance liquid chromatography (HPLC) with electrochemical (coulometric) detection;
- in vitro measurement of cytochrome P450 isoenzymes activity, using recombinant cytochrome P450 isoenzymes (human and rat), liver and brain microsomes, hepatocytes and neuronal cells. Determination of specific substrates related to cytochrome P450 isoenzymes and their metabolites formed during enzymatic reaction using high performance liquid chromatography (HPLC) with UV or fluorimetric detection and liquid chromatography coupled to tandem mass spectrometry (LC/ESI-MS/MS);
- measurement of brain and liver expression of cytochrome P450, nuclear receptors and transcription factors: protein content (Western blotting) and mRNA (qRT-PCR);
- determination of serum hormones and cytokines (ELISA).

- stereotactic implantation of cannula into the brain structures;
- intra-cerebral drug administration;
- brain microdialysis;
- brain dissection;
- preparation of brain and liver microsomes (differential centrifugation).

The most important recent discoveries
(1) Studies performed using brain microdialysis technique following administration of 5-methoxytryptamine or melatonin, with application of serotonin synthesis inhibitors of a classical (tryptophan hydroxylase inhibitor) and an alternative (CYP2D inhibitors) pathway, revealed that cytochrome P450 isoform 2D (CYP2D) is involved in the synthesis of serotonin in the brain, which occurs in the following biochemical transformation cycle: melatonin → 5-methoxytryptamine → serotonin.

 (2) In vivo studies, performed after injury and activation of the brain serotonergic system, have demonstrated, that serotonergic system is involved in the neuroendocrine regulation of cytochrome P450 expression in the liver.

More publications
  • , Przemysław Danek, MSc

  • The role of the brain serotonergic system in the expression and activity of liver cytochrome P450., Marta Rysz, PhD

  • , Przemysław Danek, MSc
    Monday, 30 November -0001