title: Antiepileptic drugs affect neuronal androgen signaling via a cytochrome P450-dependent pathway.
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.
authors.affiliation: Pathologisches Institut, Abt. Neuropathologie, Neurozentrum, Universität Freiburg, Freiburg, Germany.
authors.forename: Marcel
authors.initials: M
authors.lastname: Gehlhaus
authors.forename: Nina
authors.initials: N
authors.lastname: Schmitt
authors.forename: Benedikt
authors.initials: B
authors.lastname: Volk
authors.forename: Ralf P
authors.initials: RP
authors.lastname: Meyer
mesh_terms: D000818:Animals; D000927:Anticonvulsants / Q000494:pharmacology*; D045744:Cell Line, Tumor; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics / Q000378:metabolism; D051544:Cytochrome P-450 CYP3A / Q000235:genetics / Q000378:metabolism*; D065692:Cytochrome P-450 CYP3A Inhibitors; D015870:Gene Expression / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000502:physiology*; D015151:Immunoblotting; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D007654:Ketoconazole / Q000494:pharmacology; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D020932:Nerve Growth Factor / Q000494:pharmacology; D016900:Neurofilament Proteins / Q000378:metabolism; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D016716:PC12 Cells; D010634:Phenobarbital / Q000494:pharmacology; D010672:Phenytoin / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000235:genetics; D051381:Rats; D011944:Receptors, Androgen / Q000235:genetics / Q000378:metabolism*; D020218:Response Elements / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects*; D014162:Transfection
chemical_list: D000927:Anticonvulsants; D065692:Cytochrome P-450 CYP3A Inhibitors; D007527:Isoenzymes; D008565:Membrane Proteins; D016900:Neurofilament Proteins; D034741:RNA, Small Interfering; D011944:Receptors, Androgen; D010672:Phenytoin; D020932:Nerve Growth Factor; C496508:Cyp3a11 protein, mouse; D051544:Cytochrome P-450 CYP3A; D015500:Chloramphenicol O-Acetyltransferase; D007654:Ketoconazole; D010634:Phenobarbital