ABSTRACT
Humans are exposed to acrylamide in their diet and cigarette smoke. Acrylamide is metabolized into glycidamide by CYP2E1. However, very few studies regarding the effects of acrylamide on cytochrome P450 and Glutathione S-Transferase (GST) isozymes have been pursued. The aim of this study is to elucidate the effects of acrylamide on cytochrome P450 and GST isozymes in HepG2 cell line. Treatment with 1.25 and 2.5 mM acrylamide caused 9.5- and 3.7-fold increases and 4.0- and 3.3-fold increases in CYP1A-associated ethoxyresorufin O-deethylase (EROD) and methoxyresorufin O-demethylase (MROD) activities, respectively. These increases were consistent with increases in mRNA and protein levels of these isozymes. Similarly, CYP2E1-associated aniline 4-hydroxylase (ANH) activity, protein levels, and mRNA levels increased 2.1- and 2.6-fold, 2.4- and 3.2-fold, and 1.4- and 1.9-fold following 1.25 and 2.5 mM acrylamide treatments, respectively. In addition, GST-mu activity was increased 2.4- and 5.1-fold by acrylamide. Moreover, GST-mu mRNA and protein levels increased twofold as a result of acrylamide treatment. In contrast, GST-pi protein and mRNA levels decreased significantly. In conclusion, human cell exposure to acrylamide causes an increase in the levels of carcinogenicity and toxicity and a disturbance in drug metabolism, possibly due to complex effects on P450 and GST isozymes.
Subject(s)
Acrylamide/toxicity , Cytochrome P-450 CYP2E1/metabolism , Gene Expression Regulation, Enzymologic , Glutathione Transferase/metabolism , RNA, Messenger/metabolism , Aniline Hydroxylase/genetics , Aniline Hydroxylase/metabolism , Carcinogenicity Tests , Cell Survival , Cytochrome P-450 CYP1A1/metabolism , Cytochrome P-450 CYP2E1/genetics , Cytochrome P-450 Enzyme System/genetics , Cytochrome P-450 Enzyme System/metabolism , Enzyme Activation/drug effects , Enzyme Assays , Gene Expression Regulation, Neoplastic , Glutathione Transferase/genetics , Hep G2 Cells , Humans , Isoenzymes/drug effects , Isoenzymes/genetics , Isoenzymes/metabolism , Toxicity TestsABSTRACT
OBJECTIVE: To investigate the effects of the ethyl acetate extract of Semen Hoveniae (ESH) on liver microsomal cytochrome P450 isoenzyme in rats. METHOD: The rats were given orally the ESH in the doses of 0.14, 0.17, 0.2 g x kg (equivalent to the crude herb) for 10 days respectively. Rat liver microsomal cytochrome P450, NADPH-Cyt C reductase, erythromycin N-demethylase (ERD), Aniline hydroxylase (ANH), aminopyrine N-demethylase (ADM) activities were quantitated by UV chromatography. The levels of mRNA expression of CYP1A1, CYP2C11, CYP2E1 and CYP3A1 were detected by semi-quantitative reverse transcripatase-polymerase chain reaction (RT-PCR). RESULT: The cytochrome P450 content, NADPH-Cyt C reductase activities and erythromycin N-demethylase (ERD) activities were not affected. Aniline hydroxylase (ANH) activities in liver were decreased by up to35.1%; aminopyrine N-demethylase (ADM) activitiesin liver were increased by up to 42.4%. The mRNA expression of CYP1A1, CYP2C11 and CYP3A1 were found to be increased markedly. CONCLUSION: A specific effect of ESH on liver microsomal cytochrome P450 isoenzyme in rats was observed in this investigation. ESH had various effects on liver microsomal cytochrome P450 isoenzyme.
Subject(s)
Cytochrome P-450 Enzyme System/metabolism , Drugs, Chinese Herbal/pharmacology , Microsomes, Liver/drug effects , Rhamnaceae/chemistry , Acetates/chemistry , Aminopyrine N-Demethylase/metabolism , Aniline Hydroxylase/genetics , Aniline Hydroxylase/metabolism , Animals , Aryl Hydrocarbon Hydroxylases/genetics , Aryl Hydrocarbon Hydroxylases/metabolism , Cytochrome P-450 CYP1A1/genetics , Cytochrome P-450 CYP1A1/metabolism , Cytochrome P-450 CYP2E1/genetics , Cytochrome P-450 CYP2E1/metabolism , Cytochrome P-450 CYP3A/genetics , Cytochrome P-450 CYP3A/metabolism , Cytochrome P-450 Enzyme System/genetics , Cytochrome P450 Family 2 , Drugs, Chinese Herbal/chemistry , Drugs, Chinese Herbal/isolation & purification , Gene Expression Regulation, Enzymologic/drug effects , Male , Microsomes, Liver/enzymology , NADPH-Ferrihemoprotein Reductase/genetics , NADPH-Ferrihemoprotein Reductase/metabolism , Plants, Medicinal/chemistry , RNA, Messenger/genetics , RNA, Messenger/metabolism , Random Allocation , Rats , Rats, Wistar , Reverse Transcriptase Polymerase Chain Reaction , Seeds/chemistry , Steroid 16-alpha-Hydroxylase/genetics , Steroid 16-alpha-Hydroxylase/metabolismABSTRACT
The molecular mechanism of cytochrome P450IIE reduction by CCl4 was reexamined by measuring its enzyme activity, immunoreactive protein contents, and mRNA levels. Aniline hydroxylase and the amounts of immunoreactive P450IIE were rapidly decreased in a time-dependent manner after a single dose of CCl4. No changes were observed in the amounts of immunoreactive P450IIC and P450IA despite significant decreases decrease in their catalytic activities. However, the decreases in P450IIE enzyme activity and immunoreactive protein by CCl4 were not accompanied by a decline in its mRNA level. The data thus suggested a post-translational reduction of P450IIE by CCl4, probably due to specific destruction of the P450IIE protein by its own substrate rather than heme moiety.
Subject(s)
Aniline Hydroxylase/genetics , Carbon Tetrachloride/pharmacology , Cytochrome P-450 Enzyme System/genetics , Microsomes, Liver/enzymology , Protein Processing, Post-Translational , RNA, Messenger/analysis , Aniline Hydroxylase/metabolism , Animals , Blotting, Northern , Blotting, Western , Carbon Tetrachloride Poisoning/enzymology , Cytochrome P-450 CYP1A1 , Cytochrome P-450 CYP2B1 , Cytochrome P-450 Enzyme System/isolation & purification , Cytochrome P-450 Enzyme System/metabolism , Male , Microsomes, Liver/drug effects , Oxidation-Reduction , Oxidoreductases/genetics , Oxidoreductases/metabolism , RNA, Messenger/genetics , Rats , Rats, Inbred StrainsABSTRACT
Hepatic microsomal enzyme activities were determined in female Wistar rats after 1 and 8 days of oral administration of high doses of rifampicin (RFP) (400 mg/kg/day). After 8 days, the level of cytochrome P-450 doubled and the activities of NADPH-cytochrome c reductase and benzphetamine N-demethylase were significantly increased. The observed changes in enzymic activities are consistent with the possibility that RFP induces a special form of cytochrome P-450, responsible for the metabolism of the antibiotic (demethylation and reduction of rifampicin quinone). Considering the role of the endoplasmic reticulum in lipid metabolism, the inducing activity of RFP might also contribute to the observed accumulation of lipids in the liver.
