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CYP-mediated drug metabolism in the brain impacts drug response
Douglas M McMillan1, Rachel F Tyndale1
1Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health (CAMH), University of Toronto, Toronto, Ontario, Canada; Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada; Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada.
Abstract:
The functional role of cytochrome P450 (CYP) enzymes in the brain is an exciting and evolving field of research. CYPs are present and active in the brain, with heterogeneous patterns of expression, activity, and sensitivity to modulation across cell types, regions, and species. Despite total brain CYP expression being a fraction of hepatic CYP expression, the expanding literature of in vitro and in vivo experiments has provided evidence that brain CYPs can impact acute and chronic drug response, susceptibility to damage by neurotoxins, and are associated with altered personality, behaviour, and risk of neurological disease. They may also play a role in endogenous neurotransmitter and neurosteroid homeostasis. This review goes through the characterization of brain CYPs across species, the patterns of susceptibility of brain CYPs to exogenous induction, and recent preclinical evidence of the potential role of brain CYPs in vivo (e.g. CYP2D), along with the development of experiment paradigms that allow modulation of brain CYP activity without affecting CYP activity in the liver. Understanding brain CYP function, and changes therein, may provide unique strategies for the development of CNS-acting therapeutics metabolized locally in the brain, as well as therapeutics to target brain CYPs directly.
Insights
Brain cytochrome P450 (CYP) enzymes impact drug response and neurological health. Research explores their unique roles and therapeutic potential for brain-specific treatments.
Area of Science:
- Neuroscience
- Pharmacology
- Biochemistry
Background:
- Cytochrome P450 (CYP) enzymes are present and active in the brain.
- Brain CYP expression, activity, and sensitivity vary across cell types, regions, and species.
- Despite lower expression than in the liver, brain CYPs influence drug response, neurotoxicity, and neurological disease risk.
Purpose of the Study:
- To review the characterization of brain CYPs across species.
- To examine the susceptibility of brain CYPs to induction.
- To present preclinical evidence for in vivo brain CYP roles and methods to modulate their activity independently of the liver.
Main Methods:
- Literature review of in vitro and in vivo studies.
- Analysis of species-specific CYP expression and activity patterns.
- Examination of experimental paradigms for selective brain CYP modulation.
Main Results:
- Brain CYPs affect acute and chronic drug responses and neurotoxin susceptibility.
- Altered brain CYP function is linked to personality, behavior, and neurological disease.
- Brain CYPs may regulate neurotransmitter and neurosteroid homeostasis.
- Preclinical evidence highlights the in vivo role of specific CYPs (e.g., CYP2D) in the brain.
Conclusions:
- Understanding brain CYP function is crucial for developing novel therapeutics.
- Targeting brain CYPs offers potential for CNS-acting drugs metabolized locally.
- Strategies to modulate brain CYP activity without hepatic effects are emerging.