title: D₂-dopaminergic receptor-linked pathways: critical regulators of CYP3A, CYP2C, and CYP2D.
abstract: Various hormonal and monoaminergic systems play determinant roles in the regulation of several cytochromes P450 (P450s) in the liver. Growth hormone (GH), prolactin, and insulin are involved in P450 regulation, and their release is under dopaminergic control. This study focused on the role of D₂-dopaminergic systems in the regulation of the major drug-metabolizing P450s, i.e., CYP3A, CYP2C, and CYP2D. Blockade of D₂-dopaminergic receptors with either sulpiride (SULP) or 4-(4-chlorophenyl)-1-(1H-indol-3-ylmethyl)piperidin-4-ol (L-741,626) markedly down-regulated CYP3A1/2, CYP2C11, and CYP2D1 expression in rat liver. This suppressive effect appeared to be mediated by the insulin/phosphatidylinositol 3-kinase/Akt/FOXO1 signaling pathway. Furthermore, inactivation of the GH/STAT5b signaling pathway appeared to play a role in D₂-dopaminergic receptor-mediated down-regulating effects on these P450s. SULP suppressed plasma GH levels, with subsequently reduced activation of STAT5b, which is the major GH pulse-activated transcription factor and has up-regulating effects on various P450s in hepatic tissue. Levels of prolactin, which exerts down-regulating control on P450s, were increased by SULP, which may contribute to SULP-mediated effects. Finally, it appears that SULP-induced inactivation of the cAMP/protein kinase A/cAMP-response element-binding protein signaling pathway, which is a critical regulator of pregnane X receptor and hepatocyte nuclear factor 1α, and inactivation of the c-Jun N-terminal kinase contribute to SULP-induced down-regulation of the aforementioned P450s. Taken together, the present data provide evidence that drugs acting as D₂-dopaminergic receptor antagonists might interfere with several major signaling pathways involved in the regulation of CYP3A, CYP2C, and CYP2D, which are critical enzymes in drug metabolism, thus affecting the effectiveness of the majority of prescribed drugs and the toxicity and carcinogenic potency of a plethora of toxicants and carcinogens.
authors: Department of Pharmacology, School of Medicine, University of Ioannina, Ioannina, Greece.
authors: Evangelos P
authors: EP
authors: Daskalopoulos
authors: Matti A
authors: MA
authors: Lang
authors: Marios
authors: M
authors: Marselos
authors: Foteini
authors: F
authors: Malliou
authors: Maria
authors: M
authors: Konstandi
mesh_terms: D000818:Animals; D014150:Antipsychotic Agents / Q000009:adverse effects / Q000494:pharmacology*; D051544:Cytochrome P-450 CYP3A / Q000378:metabolism*; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D065127:Dopamine D2 Receptor Antagonists; D004983:Ethanolamines / Q000378:metabolism; D051858:Forkhead Transcription Factors / Q000502:physiology; D005786:Gene Expression Regulation; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism; D006728:Hormones / Q000097:blood; D066298:In Vitro Techniques; D008297:Male; D008862:Microsomes, Liver / Q000187:drug effects / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000502:physiology; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000502:physiology; D051381:Rats; D017448:Receptors, Dopamine D2 / Q000502:physiology*; D050799:STAT5 Transcription Factor / Q000378:metabolism; D015398:Signal Transduction; D013469:Sulpiride / Q000009:adverse effects / Q000494:pharmacology*; D000071161:Forkhead Box Protein O1
chemical_list: D014150:Antipsychotic Agents; D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System; D065127:Dopamine D2 Receptor Antagonists; D004983:Ethanolamines; D051858:Forkhead Transcription Factors; D006728:Hormones; D009419:Nerve Tissue Proteins; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D017448:Receptors, Dopamine D2; D050799:STAT5 Transcription Factor; D013469:Sulpiride; C400322:cytochrome P-450 CYP2C subfamily; C074639:Foxo1 protein, rat; D000071161:Forkhead Box Protein O1; C010831:bufuralol; C043872:bufuralol 1'-hydroxylase