scholarly journals The role of cytochrome P-450 in cholesterol biogenesis and catabolism

1972 ◽  
Vol 128 (2) ◽  
pp. 237-242 ◽  
Author(s):  
Sandra D. Atkin ◽  
Eileen D. Palmer ◽  
P. D. English ◽  
B. Morgan ◽  
M. A. Cawthorne ◽  
...  
Keyword(s):  
Cholesterol Metabolism ◽  
Carbon Disulphide ◽  
Normal Serum ◽  
Liver Cholesterol ◽  
Drug Metabolizing Enzyme ◽  
Metabolizing Enzyme ◽  
Cytochrome P 450

1. Adjuvant-induced arthritis in rats is accompanied by a loss of activity of the drug-metabolizing enzyme system and a decrease in hepatic cytochrome P-450. 2. Arthritic rats have normal serum and liver cholesterol concentrations. 3. The rate of biogenesis of cholesterol in vivo and in vitro from either [14C]acetate or [14C]mevalonate in arthritic rats was the same as or greater than that found in control rats. 4. Treatment of rats with carbon disulphide (1ml/kg) resulted in a loss of drug-metabolizing-enzyme activity and increased cholesterol biogenesis. 5. The activity of cholesterol 7α-hydroxylase in adjuvant-induced arthritic rats did not differ significantly from that in control rats. 6. Rats fed with cholestyramine had an elevated hepatic cholesterol 7α-hydroxylase activity, but neither the concentration of cytochrome P-450 nor the activity of the drug-hydroxylating enzyme, aminopyrine demethylase, was affected. 7. The relationships between drug hydroxylation and cholesterol metabolism are discussed.

scholarly journals Generation of tetracycline-controllable CYP3A4-expressing Caco-2 cells by the piggyBac transposon system

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Moe Ichikawa ◽  
Hiroki Akamine ◽  
Michika Murata ◽  
Sumito Ito ◽  
Kazuo Takayama ◽  
...  
Keyword(s):  
Small Intestine ◽  
Drug Absorption ◽  
Cell Model ◽  
Negative Effects ◽  
Piggybac Transposon ◽  
Drug Metabolizing Enzyme ◽  
Metabolizing Enzyme ◽  
Cyp3a4 Expression

AbstractCaco-2 cells are widely used as an in vitro intestinal epithelial cell model because they can form a monolayer and predict drug absorption with high accuracy. However, Caco-2 cells hardly express cytochrome P450 (CYP), a drug-metabolizing enzyme. It is known that CYP3A4 is the dominant drug-metabolizing enzyme in human small intestine. In this study, we generated CYP3A4-expressing Caco-2 (CYP3A4-Caco-2) cells and attempted to establish a model that can simultaneously evaluate drug absorption and metabolism. CYP3A4-Caco-2 cells were generated by piggyBac transposon vectors. A tetracycline-controllable CYP3A4 expression cassette (tet-on system) was stably transduced into Caco-2 cells, thus regulating the levels of CYP3A4 expression depending on the doxycycline concentration. The CYP3A4 expression levels in CYP3A4-Caco-2 cells cultured in the presence of doxycycline were similar to or higher than those of adult small intestine. The CYP3A4-Caco-2 cells had enough ability to metabolize midazolam, a substrate of CYP3A4. CYP3A4 overexpression had no negative effects on cell proliferation, barrier function, and P-glycoprotein activity in Caco-2 cells. Thus, we succeeded in establishing Caco-2 cells with CYP3A4 metabolizing activity comparable to in vivo human intestinal tissue. This cell line would be useful in pharmaceutical studies as a model that can simultaneously evaluate drug absorption and metabolism.

Effect of Splenectomy on the Activity of Drug-Metabolizing Enzymes in the Liver of Rats

1971 ◽  
Vol 49 (3) ◽  
pp. 161-166 ◽  
Author(s):  
Jules Brodeur ◽  
Claude Marchand
Keyword(s):  
Indirect Evidence ◽  
Female Rats ◽  
Microsomal Enzymes ◽  
Drug Metabolizing Enzyme ◽  
Effect Of Splenectomy ◽  
Maximal Induction ◽  
Metabolizing Enzyme ◽  
Cytochrome P 450 ◽  
Liver Microsomal Enzymes

Splenectomy was performed in adult female rats in order to investigate the influence of removal of the spleen on liver microsomal enzymes and cytochrome P-450 in vitro, as well as on the pharmacological activity of certain drugs in intact animals. Splenectomy significantly decreases the amount of cytochrome P-450 at 1 and 4 days after the operation, but not at 7 days. The activity of the enzymes catalyzing the metabolism of parathion, p-nitroanisole, and zoxazolamine is also decreased 4 days after splenectomy, whereas that of the enzymes involved in the metabolism of hexobarbital is unchanged. The maximal induction by phenobarbital of the enzymatic activities catalyzing the metabolism of parathion, p-nitroanisole, and zoxazolamine is prevented by splenectomy. Splenectomy exerts very little effect on plasma levels of hexobarbital and hexobarbital sleeping time; however, in both control and phenobarbital-pretreated rats, splenectomy results in a marked increase in the duration of zoxazolamine paralysis. These results indicate that splenectomy exerts inhibitory effects on certain liver microsomal enzymes, and provide some indirect evidence in support of the view that the hepatic blood supply is important for maintaining normal levels of drug-metabolizing enzyme activity in the liver.

Cytochrome P-450 and Peroxidase Oxidize Detoxication Products of Carcinogenic Aristolochic Acids (Aristolactams) to Reactive Metabolites Binding to DNA in vitro

1995 ◽  
Vol 60 (12) ◽  
pp. 2189-2199 ◽  
Author(s):  
Marie Stiborová ◽  
Eva Frei ◽  
Heinz H. Schmeiser ◽  
Manfred Wiessler
Keyword(s):  
Dna Adducts ◽  
Microsomal Cytochrome ◽  
Aristolochic Acids ◽  
Nuclease P1 ◽  
Order Of Magnitude ◽  
Prostaglandin H ◽  
Cytochrome P 450

We report the analysis of DNA adducts formed from aristolactams I and II, which are the final metabolites derived from carcinogenic aristolochic acids in vivo, after their oxidation by microsomal cytochrome P-450 and horseradish peroxidase in vitro. DNA adducts were detected and quantified using the nuclease P1-enhanced variation of the 32P-postlabeling assay. Quantitative analysis revelead that the extent of modification of DNA by aristolactams activated by peroxidase was more than one order of magnitude higher than for activation by microsomal cytochrome P-450. Peroxidase catalyzes the formation of active oxygen in the presence of NADH, H2O2 and aristolactams. Aristolactams are also oxidized by mammalian peroxidase prostaglandin H synthase. The possible role of aristolactams in carcinogenesis induced by aristolochic acid is discussed.

scholarly journals FMO1 catalyzes the production of taurine from hypotaurine

2019 ◽  
Author(s):  
Sunil Veeravalli ◽  
Ian R. Phillips ◽  
Rafael T. Freire ◽  
Dorsa Varshavi ◽  
Jeremy R. Everett ◽  
...  
Keyword(s):  
De Novo ◽  
Cysteic Acid ◽  
Muscle Disorders ◽  
H Nmr ◽  
Drug Metabolizing Enzyme ◽  
Anti Oxidant ◽  
Metabolizing Enzyme ◽  
Skeletal Muscle Disorders

ABSTRACTTaurine is one of the most abundant amino acids in mammalian tissues. It is obtained from the diet and by de novo synthesis, from cysteic acid or hypotaurine. Despite the discovery in 1954 that the oxygenation of hypotaurine produces taurine, the identification of an enzyme catalyzing this reaction has remained elusive. In large part this is due to the incorrect assignment, in 1962, of the enzyme as a NAD-dependent hypotaurine dehydrogenase. For more than 55 years the literature has continued to refer to this enzyme as such. Here we show, both in vivo and in vitro, that the enzyme that oxygenates hypotaurine to produce taurine is flavin-containing monooxygenase 1 (FMO1). Metabolite analysis of the urine of Fmo1-null mice by 1H NMR spectroscopy revealed a build-up of hypotaurine and a deficit of taurine in comparison with the concentrations of these compounds in the urine of wild-type mice. In vitro assays confirmed that FMO1 of human catalyzes the conversion of hypotaurine to taurine utilizing either NADPH or NADH as co-factor. FMO1 has a wide substrate range and is best known as a xenobiotic- or drug-metabolizing enzyme. The identification that the endogenous molecule hypotaurine is a substrate for the FMO1-catalyzed production of taurine resolves a long-standing mystery. This finding should help establish the role FMO1 plays in a range of biological processes in which taurine or its deficiency is implicated, including conjugation of bile acids, neurotransmitter, anti-oxidant and anti-inflammatory functions, the pathogenesis of obesity and skeletal muscle disorders.

scholarly journals Acquired granulocyte abnormality during drug allergic reactions: possible role of complement activation

Blood ◽  
1977 ◽  
Vol 49 (1) ◽  
pp. 3-8
Author(s):  
TK Bowers ◽  
PR Craddock ◽  
HS Jacob
Keyword(s):  
Steroid Therapy ◽  
Complement Activation ◽  
Normal Serum ◽  
Heat Inactivation ◽  
Boyden Chamber ◽  
Systemic Lupus Erythematosis ◽  
Hemolytic Complement Activity

A profound defect in granulocyte chemotaxis was documented in an otherwise healthy 21-yr-old man who failed to localize granulocytes to an area of cellulitis during an allergic reaction to cephalothin. During the period of drug allergy, characterized by urticaria, eosinophilia, and profound hypocomplementemia, in vitro migration of the patient's granulocytes in the Boyden chamber was markedly impaired. Although devoid of hemolytic complement activity, the patient's serum possessed supranormal chemotactic activity, even following heat inactivation, suggesting the presence of chemotactically active complement split products. Chemotactic function improved concomitantly with steroid therapy and normalization of serum complement levels, and was entirely normal following clinical recovery and cessation of steroid therapy. The chemotactic abnormality noted in the patient's cells was reproduced in normal granulocytes by preincubation either with patient serum or with cobra venom-activated fresh (but not heated) normal serum, suggesting that in vivo exposure of granulocytes to activated complement was responsible for the patient's abnormal chemotactic response. This mechanism may contribute to the increased infection propensity noted in other conditions characterized by in vivo complement activation, such as rheumatoid arthritis and systemic lupus erythematosis.

Comparison of in vivo and in vitro methods for assessing the effects of phenobarbital on the hepatic drug-metabolizing enzyme system

1985 ◽  
Vol 29 (2-3) ◽  
pp. 95-105 ◽  
Author(s):  
Robert W. Chadwick ◽  
M. Frank Copeland ◽  
Gary P. Carlson ◽  
Bruce A. Trela ◽  
Bernard M. Most
Keyword(s):  
Enzyme System ◽  
Hepatic Drug ◽  
In Vitro Methods ◽  
Drug Metabolizing Enzyme ◽  
Metabolizing Enzyme

scholarly journals Acquired granulocyte abnormality during drug allergic reactions: possible role of complement activation

Blood ◽  
1977 ◽  
Vol 49 (1) ◽  
pp. 3-8 ◽  
Author(s):  
TK Bowers ◽  
PR Craddock ◽  
HS Jacob
Keyword(s):  
Steroid Therapy ◽  
Complement Activation ◽  
Normal Serum ◽  
Heat Inactivation ◽  
Boyden Chamber ◽  
Systemic Lupus Erythematosis ◽  
Hemolytic Complement Activity

Abstract A profound defect in granulocyte chemotaxis was documented in an otherwise healthy 21-yr-old man who failed to localize granulocytes to an area of cellulitis during an allergic reaction to cephalothin. During the period of drug allergy, characterized by urticaria, eosinophilia, and profound hypocomplementemia, in vitro migration of the patient's granulocytes in the Boyden chamber was markedly impaired. Although devoid of hemolytic complement activity, the patient's serum possessed supranormal chemotactic activity, even following heat inactivation, suggesting the presence of chemotactically active complement split products. Chemotactic function improved concomitantly with steroid therapy and normalization of serum complement levels, and was entirely normal following clinical recovery and cessation of steroid therapy. The chemotactic abnormality noted in the patient's cells was reproduced in normal granulocytes by preincubation either with patient serum or with cobra venom-activated fresh (but not heated) normal serum, suggesting that in vivo exposure of granulocytes to activated complement was responsible for the patient's abnormal chemotactic response. This mechanism may contribute to the increased infection propensity noted in other conditions characterized by in vivo complement activation, such as rheumatoid arthritis and systemic lupus erythematosis.

scholarly journals Cholesterol Synthesis Increased in the MMI-Induced Subclinical Hypothyroidism Mice Model

2017 ◽  
Vol 2017 ◽  
pp. 1-6
Author(s):  
Yongfeng Song ◽  
Xiujuan Zhang ◽  
Wenbin Chen ◽  
Ling Gao
Keyword(s):  
Subclinical Hypothyroidism ◽  
Cholesterol Synthesis ◽  
Cholesterol Metabolism ◽  
Thyroid Stimulating Hormone ◽  
Normal Serum ◽  
Control Group ◽  
Mice Model

Subclinical hypothyroidism (SCH) is defined as increased serum thyroid-stimulating hormone (TSH) concentrations and normal serum thyroid hormone (TH) levels as well as an increased serum cholesterol level, which is an important cause of secondary hypercholesterolemia and cardiovascular diseases. Some studies have demonstrated a direct effect of TSH on cholesterol metabolism via in vivo and in vitro experiments. However, because no suitable SCH model has been established until now, the changes in cholesterol synthesis that occur in SCH patients remain unknown. Here, we establish an SCH mouse model by using long-term low-dose MMI administered in drinking water. Compared with the control group, the MMI-treated mice had elevated circulating TSH levels, but the serum FT3 levels in these mice did not change. Additionally, the TC levels increased in both the serum and liver of the experimental mice. Both the protein expression and activity of hepatic HMGCR, the rate-limiting enzyme for cholesterol synthesis in the liver, increased in these mice. We also found that the SCH mice had decreased phospho-HMGCR and phospho-AMPK expression, while the expression of AMPK showed no change. In conclusion, we established a suitable SCH model in which cholesterol synthesis is increased.

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