Antiepileptic Drugs Affect Neuronal Androgen Signaling via a Cytochrome P450-Dependent Pathway
- Pathologisches Institut, Abteilung Neuropathologie, Neurozentrum, Universitätsklinik Freiburg, Freiburg, Germany
- Address correspondence to:
Dr. Ralf P. Meyer, Pathologisches Institut, Abt. Neuropathologie, Neurozentrum, Universität Freiburg, Breisacherstraße 64, D-79106 Freiburg, Germany. E-Mail: ralf.meyer{at}uniklinik-freiburg.de
Abstract
Recent data imply an important role for brain cytochrome P450 (P450) in endocrine signaling. In epileptic patients, treatment with P450 inducers led to reproductive disorders; in mouse hippocampus, phenytoin treatment caused concomitant up-regulation of CYP3A11 and androgen receptor (AR). In the present study, we established specific in vitro models to examine whether CYP3A isoforms cause enhanced AR expression and activation. Murine Hepa1c1c7 cells and neuronal-type rat PC-12 cells were used to investigate P450 regulation and its effects on AR after phenytoin and phenobarbital administration. In both cell lines, treatment with antiepileptic drugs (AEDs) led to concomitant up-regulation of CYP3A (CYP3A11 in Hepa1c1c7 and CYP3A2 in PC-12) and AR mRNA and protein. Inhibition of CYP3A expression and activity by the CYP3A inhibitor ketoconazole or by CYP3A11-specific short interfering RNA molecules reduced AR expression to basal levels. The initial up-regulation of AR signal transduction, measured by an androgen-responsive element chloramphenicol-acetyltransferase reporter gene assay, was completely reversed after specific inhibition of CYP3A11. Withdrawal of the CYP3A11 substrate testosterone prevented AR activation, whereas AR mRNA expression remained up-regulated. In addition, recombinant CYP3A11 was expressed heterologously in PC-12 cells, thereby eliminating any direct drug influence on the AR. Again, the initial up-regulation of AR mRNA and activity was reduced to basal levels after silencing of CYP3A11. In conclusion, we show here that CYP3A2 and CYP3A11 are crucial mediators of AR expression and signaling after AED application. These findings point to an important and novel function of P450 in regulation of steroid hormones and their receptors in endocrine tissues such as liver and brain.
Footnotes
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This study was supported by the Deutsche Forschungsgemeinschaft (DFG Me 1544/4-1) and the Forschungskommission of the University Hospital Freiburg (MEY 375/05 and MEY 465/06).
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Parts of this study were presented as follows: Gehlhaus M, Schmitt N, Hagemeyer CE, Knoth R, Volk B, and Meyer RP (2004) Anticonvulsive drugs modulate steroid hormone signalling in hippocampus of mouse brain, in Proceedings of the 15th International Symposium on Microsomes and Drug Oxidations, 15th International Symposium on Microsomes and Drug Oxidations; 2004 July 4–9; Mainz, Germany, and Gehlhaus M, Schmitt N, Hock M, Knoth R, Volk B, and Meyer RP (2006) Cytochrome P450 CYP3A11 links neuroactive drugs to androgen signalling in hepatic and neural cell lines, Proceedings of the 16th International Symposium on Microsomes and Drug Oxidations, 16th International Symposium on Microsomes and Drug Oxidations; 2006 September 3–7; Budapest, Hungary.
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Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
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doi:10.1124/jpet.107.120303.
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ABBREVIATIONS: P450, cytochrome P450; AED, antiepileptic drug; AR, androgen receptor; NGF, nerve growth factor; siRNA, short interfering RNA; NFpan, neurofilament pan; PCR, polymerase chain reaction; Q-PCR, quantitative PCR; CAT, chloramphenicol-acetyltransferase; ELISA, enzyme-linked immunosorbent assay; MMTV, mouse mammary tumor virus; ARE, androgen-responsive element; GFP, green fluorescent protein; bp, base pair; RT, reverse transcriptase; FL3a11, full-length cytochrome P450 3a11; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; mAR, mouse AR; rAR, rat AR.
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- Received January 22, 2007.
- Accepted May 14, 2007.
- The American Society for Pharmacology and Experimental Therapeutics
