Functional role of cytochrome p-450 2a3 in N-nitrosomethylbenzylamine metabolism in rat esophagus
| Autor: | Peter S. Carlton, Rajaram Gopalakrishnan, Gary D. Stoner, Mark A. Morse, Ashok Gupta |
|---|---|
| Rok vydání: | 2002 |
| Předmět: |
Male
medicine.medical_specialty Health Toxicology and Mutagenesis Toxicology Dimethylnitrosamine Mixed Function Oxygenases Cytochrome P-450 CYP2A6 Esophagus Organ Culture Techniques Cytochrome P-450 Enzyme System In vivo Coumarins Internal medicine Gene expression medicine Animals RNA Messenger Enzyme inducer Lung Carcinogen Biotransformation Unspecific monooxygenase biology Reverse Transcriptase Polymerase Chain Reaction Cytochrome P450 Anticoagulants Cytochrome P-450 CYP2E1 CYP2E1 Rats Inbred F344 Rats medicine.anatomical_structure Endocrinology biology.protein Carcinogens Aryl Hydrocarbon Hydroxylases |
| Zdroj: | Journal of toxicology and environmental health. Part A. 65(15) |
| ISSN: | 1528-7394 |
| Popis: | Previous in vitro studies demonstrated that the rat esophageal carcinogen N-nitrosomethylbenzylamine (NMBA) is metabolically activated by cytochrome P-450s (CYP) 2A3 and 2E1. However, the in vivo role of these P-450s in the metabolism of NMBA has not been fully evaluated. In this study, the effects of single and multiple doses of NMBA were investigated on CYP2A3 and CYP2E1 mRNA expression in the rat esophagus and lung. Seven- to 8-wk old male Fischer 344 rats were administered a single subcutaneous dose of NMBA at either 0.5 mg/kg or 2 mg/kg body weight, after which the rats were sacrificed at 1, 3, 6, 12, 24, 48, and 72 h. In the multiple-dose experiment, 2 groups of rats were dosed with 0.5 mg/kg body weight NMBA 3 times per week for 1 wk or 3 wk. The animals were sacrificed 24 h following the last treatment. Semiquantitative reverse-transcription polymerase chain reaction (RT-PCR) analysis demonstrated a reduction of CYP2A3 mRNA expression in lung and esophagus from NMBA-treated animals compared to dimethyl sulfoxide (DMSO)-treated vehicle controls. This reduction in CYP2A3 mRNA was significant at 48 h in the esophagus and at 24 and 48 h in the lung following a single dose of 2 mg/kg body weight NMBA. In contrast, CYP2E1 mRNA expression remained unchanged in rat lung following NMBA treatment and no consistent pattern of expression could be observed in the esophagus. In the multiple-dose study, a 32% and 25% reduction in esophageal CYP2A3 mRNA expression was observed at 1 and 3 wk, respectively. Similar reductions in CYP2A3 mRNA expression were also observed in the lung. Further, esophageal explants derived from animals pretreated with NMBA in vivo demonstrated a reduced ability to metabolize the carcinogen in vitro as compared to explants from vehicle control animals. Taken together, these data provide further support for a potential role of CYP2A3 in NMBA metabolism in the rat esophagus. Data suggest that CYP2A3 levels in the rat esophagus can be a determinant of its ability to metabolize this carcinogen in vivo. |
| Databáze: | OpenAIRE |
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