scholarly journals Biochemical effects of the porphyrinogenic drug allylisopropylacetamide. A comparative study with phenobarbital

1973 ◽  
Vol 134 (4) ◽  
pp. 859-868 ◽  
Author(s):  
Manchanahalli R. Satyanarayana Rao ◽  
Govindarajan Padmanaban
Keyword(s):  
Reductase Activity ◽  
Time Lag ◽  
Liver Weight ◽  
Microsomal Protein ◽  
Female Rats ◽  
Biochemical Effects ◽  
Increase Liver Weight ◽  
Cytochrome P 450

Successive administrations of allylisopropylacetamide, a potent porphyrinogenic drug, increase liver weight, microsomal protein and phospholipid contents. There is an increase in the rate of microsomal protein synthesis in vivo and in vitro. The drug decreases microsomal ribonuclease activity and increases NADPH–cytochrome c reductase activity. Phenobarbital, which has been reported to exhibit all these changes mentioned, is a weaker inducer of δ-aminolaevulinate synthetase and increases the rate of haem synthesis only after a considerable time-lag in fed female rats, when compared with the effects observed with allylisopropylacetamide. Again, phenobarbital does not share the property of allylisopropylacetamide in causing an initial decrease in cytochrome P-450 content. Haematin does not counteract most of the biochemical effects caused by allylisopropylacetamide, although it is quite effective in the case of phenobarbital. Haematin does not inhibit the uptake of [2-14C]allylisopropylacetamide by any of the liver subcellular fractions.

scholarly journals Decreased liver cytochrome P-450 in rats caused by norethindrone or ethynyloestradiol

1977 ◽  
Vol 166 (1) ◽  
pp. 57-64 ◽  
Author(s):  
I N H White ◽  
U Muller-Eberhard
Keyword(s):  
Marked Effect ◽  
Enzyme System ◽  
Time Dependent ◽  
Female Rats ◽  
Liver Cytochrome ◽  
Mixed Function Oxidases ◽  
Green Pigments ◽  
Cytochrome P 450

1. 19-Nor-17alpha-pregna-1,3,5(10)-trien-20-yne-3,17-diol (ethynyloestradiol) or 17beta-hydroxy-19-nor-17alpha-pregn-4-en-20-yn-3-one (norethindrone) but not 17alpha-ethyl-17beta-hydroxy-19-norandrost-4-en-3-one (norethandrolone) caused a time-dependent loss of cytochrome P-450 when incubated in vitro with rat liver microsomal fractions and NADPH-generating systems. 2. The enzyme system catalysing the norethindrone-mediated loss of cytochrome P-450 had many characteristics of the microsomal mixed-function oxidases. It required NADPH and air, and was inhibited by Co. However, it was unaffected by 1 mM-compound SKF 525A. 3. In microsomal fractions from phenobarbitone-pretreated rats the norethindrone-mediated loss of cytochrome P-450 was increased relative to controls. The norethindrone-mediated cytochrome P-450 loss was less pronounced when the animals were pretreated with 3beta-hydroxy-pregn-5-en-2-one 16alpha-carbonitrile (pregnenolone 16alpha-carbonitrile). Pretreatment with 3-methylcholanthrene rendered the animals resistant to the norethindrone effect. 4. Administration in vivo [100mg/kg, intraperitoneally] of norethindrone or ethinyl oestradiol also produced a time-dependent loss of liver cytochrome P-450. Norethandrolone had a similar, though much less-marked, effect. All three steroids lead to an induction of 5-aminolaevulinate synthase and an accumulation of porphyrins in the liver. 5. The loss of cytochrome P-450 and the accumulation of porphyrins in the liver 2 h after the administration of norethindrone to female rats was similar to that seen in males. 6. Rats pretreated with phenobarbitone and given norethindrone or ethynyloestradiol (100mg/kg, intraperitoneally) formed green pigments in their livers. These had characteristics similar to the green pigments produced in the livers of rats after the administration of 2-allyl-2-isopropylacetamide. No green pigments could be extracted from the livers of control rats or those given norethandrolone, oestradiol or progesterone.

Lack of mechanism-based inactivation of rat hepatic microsomal cytochromes P450 by doxorubicin

1999 ◽  
Vol 77 (8) ◽  
pp. 589-597 ◽  
Author(s):  
Johnny Di Re ◽  
Chunja Lee ◽  
David S Riddick
Keyword(s):  
Lipid Peroxidation ◽  
Cytochrome P450 ◽  
Reductase Activity ◽  
Cytochromes P450 ◽  
Microsomal Protein ◽  
Positive Control ◽  
Male Rats ◽  
Protein Levels

Administration of the antineoplastic doxorubicin to rodents causes depression of hepatic cytochrome P450 (CYP) dependent biotransformation, an effect that has been partially attributed to the ability of doxorubicin to stimulate microsomal lipid peroxidation. Since doxorubicin can be bioactivated by the CYP/NADPH-CYP reductase system to products that bind covalently to microsomal protein, we hypothesized that doxorubicin functions as a mechanism-based inactivator of hepatic microsomal CYPs and (or) NADPH-CYP reductase under conditions in which doxorubicin-stimulated NADPH-dependent lipid peroxidation is minimized. In vitro studies were conducted with hepatic microsomes isolated from untreated and phenobarbital-treated male rats. Unlike the positive control carbon tetrachloride, doxorubicin (10 µM) did not stimulate NADPH-dependent lipid peroxidation in microsomal incubations containing EDTA (1.5 mM). Doxorubicin did not cause NADPH-dependent loss of microsomal CYP, heme, or steroid hydroxylation activities selective for CYP2A, CYP2B, CYP2C11, and CYP3A. The positive control 1-aminobenzotriazole caused marked NADPH-dependent decreases in all of these parameters. Neither doxorubicin nor 1-aminobenzotriazole caused NADPH-dependent loss of NADPH-CYP reductase activity, and neither compound altered the immunoreactive protein levels of CYP2B, CYP2C11, CYP3A, and NADPH-CYP reductase. These results indicate that a pharmacologically relevant concentration of doxorubicin does not cause direct mechanism-based inactivation of hepatic microsomal CYPs or NADPH-CYP reductase, suggesting that the ability of doxorubicin to depress hepatic CYP-mediated biotransformation in vivo is due to lipid peroxidation mediated heme destruction, altered heme metabolism, and (or) decreased expression of selected CYP enzymes.Key words: doxorubicin, cytochrome P450, mechanism-based inactivation, lipid peroxidation.

scholarly journals Metabolic activation of acetylenic substituents to derivatives in the rat causing the loss of hepatic cytochrome P-450 and haem

1978 ◽  
Vol 174 (3) ◽  
pp. 853-861 ◽  
Author(s):  
Ian N. H. White
Keyword(s):  
Covalent Binding ◽  
Metabolic Activation ◽  
Microsomal Protein ◽  
Significant Loss ◽  
Microsomal Cytochrome ◽  
Rf Values ◽  
Green Pigments ◽  
Cytochrome P 450

1. A number of acetylenic-substituted steroidal and non-steroidal compounds, including 2,2-dipropargylacetamide, pregna-2,4-dien-20-yno[2,3-d]isoxazol-17-ol (Danazol) and acetylene gas, when administered to rats in vivo brought about a decrease in the concentrations of hepatic microsomal cytochrome P-450 and haem. Abnormal haem-breakdown products, ‘green pigments’, and porphyrins accumulated in the livers of these animals. 2. For loss of microsomal cytochrome P-450 to occur in vitro, metabolic activation of the acetylenic substituent was necessary. The enzyme system responsible required NADPH and air, and was induced by pretreatment of rats with phenobarbitone; these are characteristics typical of the microsomal mixed-function oxidases. 3. When rats were dosed with 17α-ethynyl-17β-hydroxyandrost-4-en-3-one (ethynyltestosterone, 1mmol/kg) the pattern of green pigments extracted from the liver 4h after dosing and separated by t.l.c. was quite different from that in rats given 17β-hydroxy-17α-vinylandrost-4-en-3-one (vinyltestosterone), suggesting that reduction of the unsaturated triple bond to a double bond is not normally part of the metabolic activation pathway of the acetylenic substituent. 4. The green pigments extracted from the livers of rats 4h after the administration of the acetylenic-substituted compounds (1mmol/kg) when separated by silica-gel t.l.c. had variable RF values. The number and distribution of green pigments was characteristic for each compound examined. There was little correlation between the total loss of hepatic microsomal haem and the apparent intensity of the green pigments seen on the thin-layer chromatograms. 5. After incubation of [14C]acetylene in vitro with microsomal preparations from phenobarbitone-pretreated rats and a NADPH-generating system, no significant covalent binding to microsomal protein was detected over a 30min incubation period, although under similar conditions there was a significant loss of cytochrome P-450.

scholarly journals Effect of hexachlorobenzene on haem synthesis

1972 ◽  
Vol 129 (2) ◽  
pp. 381-387 ◽  
Author(s):  
C. Rajamanickam ◽  
J. Amrutavalli ◽  
M. R. S. Rao ◽  
G. Padmanaban
Keyword(s):  
Female Rats ◽  
Initial Increase ◽  
Synthetase Activity ◽  
Subsequent Increase ◽  
Sequence Of Events ◽  
Mixed Function Oxidase System ◽  
Rate Limiting ◽  
Cytochrome P 450

Several drugs are known to induce the liver microsomal mixed-function oxidase system when administered in vivo or even in vitro in cell culture. A sequence of events has been suggested in which the drug is visualized to induce δ-aminolaevulinate synthetase, the first and rate-limiting enzyme of the haem-biosynthetic pathway, which is followed by enhanced haem synthesis and cytochrome P-450 content, facilitating the increase in the drug-metabolizing activity of the liver microsomal fraction. The present studies show that the fungicide hexachlorobenzene, when administered to female rats, can lead to enhanced amounts and rate of synthesis of cytochrome P-450 under conditions when the rate of total haem synthesis has not appreciably altered. The subsequent increase in the rate of total haem synthesis as well as the initial increase in amounts of cytochrome P-450 are brought about under conditions when δ-aminolaevulinate synthetase activity remains constant. However, manifestation of porphyria due to prolonged drug administration is accompanied by a twofold increase in δ-aminolaevulinate synthetase activity. The increase in enzyme activity appears to be due to a decreased degradation rate of the enzyme.

EFFECTS OF PROLACTIN ON PITUITARY-ADRENAL FUNCTION IN INTACT AND OVARIECTOMIZED RATS

1978 ◽  
Vol 88 (4) ◽  
pp. 744-753 ◽  
Author(s):  
Silvia B. Vasquez ◽  
Julian I. Kitay
Keyword(s):  
Reductase Activity ◽  
Combined Treatment ◽  
Plasma Corticosterone ◽  
Female Rats ◽  
Ovariectomized Rats ◽  
Response To Stress ◽  
Adrenal Response ◽  
Secretion Rates

ABSTRACT The influence of prolactin treatment (100 μg/100 g body wt. sc daily for 7 days) on plasma corticosterone levels, adrenal steroid production in vitro and in vivo and pituitary-adrenal responses to stress were studied in intact and castrated female rats. Prolactin enhanced plasma corticosterone levels and corticosterone production in vitro and in vivo in intact rats after stress. Differences were abolished with ACTH treatment. In contrast, prolactin administration to ovariectomized rats inhibited plasma corticosterone response to stress. Combined treatment with ACTH reversed these findings. A greater in vitro production of corticosterone by adrenal slices and adrenal homogenates associated with an effective inhibition of adrenal 5α-reductase activity were also observed. Secretion of DHB in adrenal venous blood was decreased as well, without changes in corticosterone or THB secretion rates. However, combined treatment with prolactin and ACTH produced greater increments in secretion rates of corticosterone than those obtained with prolactin alone. The data suggest that prolactin treatment to ovariectomized rats has a dual effect: a) adrenal responsiveness to ACTH is enhanced by its effects on adrenal 5α-reductase activity, and b) pituitary-adrenal response to stress is dampered by prolactin treatment. The effects of prolactin on adrenal 5α-reductase activity and corticosterone production in vitro were paralleled in vivo only after the exogenous administration of ACTH. The presence of the gonads apparently prevented the inhibitory effect of prolactin on ACTH secretion and in turn seemed to act synergistically with prolactin to facilitate pituitary-adrenal response to stress.

Studies on the role of liver cytochrome P-450 and oestradiol metabolism in the effects of nutrition and phenobarbital on ovulation rate in the ewe

1991 ◽  
Vol 3 (6) ◽  
pp. 725 ◽  
Author(s):  
E Payne ◽  
JF Smith ◽  
BC Cope ◽  
LT McGowan
Keyword(s):  
G Protein ◽  
Dry Matter ◽  
Liver Weight ◽  
Microsomal Protein ◽  
Ovulation Rate ◽  
Protein Diet ◽  
Treatment Protocols ◽  
Low Protein ◽  
Cytochrome P 450

Coopworth ewes were differentially fed to produce 60 heavy (62 kg) and 80 light (45 kg) ewes. They were then fed a low protein (100 g protein kg-1 dry matter) pelleted ration. On Day 7 of the oestrous cycle after synchronization the following treatments were commenced in groups of 10 ewes: 4 low liveweight groups received low protein (LP), high protein (HP; 230 g protein kg-1 dry matter), LP + phenobarbital (PB; 1 g per os per day in gelatin capsules for 10 days) and LP + triacetyloleandomycin (TAO, 0.5 g day-1 in capsule for 10 days); while 3 high liveweight groups received LP, HP and HP + carbon tetrachloride (CCl4, 0.1 mL kg-1 bodyweight as a single dose). The experiment was repeated using another 7 groups of 10 ewes at an interval of 3 weeks. PB, TAO, high liveweight, and protein diet increased the ovulation rate whereas treatment with CCl4 reduced the ovulation rate. Because of the small number of ewes in some treatment protocols, only changes due to liveweight and protein diet were statistically significant. Liver weight and microsomal protein were increased by all treatments except CCl4 which caused a decrease. PB and TAO increased cytochrome P-450 and associated enzyme activities, in particular those related to cytochrome P-450p or P-450NF (including oestradiol 2-hydroxylation) in the human liver. In vitro, TAO binding indicated that the specific cytochrome was induced by PB and TAO but there were no direct effects of protein diet and liveweight. Most of the data support the theory that nutritionally induced increases in ovulation rate in ewes could result from changes in oestradiol metabolism, but the lack of induction of the specific cytochrome by protein diet and high liveweight suggests that increased ovulation caused by these factors may be the physiological response to several metabolic changes.

Effects of in vivo gonadal hormone environment on in vitro hGRF-40-stimulated GH release

1985 ◽  
Vol 249 (3) ◽  
pp. E276-E280 ◽  
Author(s):  
W. S. Evans ◽  
R. J. Krieg ◽  
E. R. Limber ◽  
D. L. Kaiser ◽  
M. O. Thorner
Keyword(s):  
Female Rats ◽  
Male Rats ◽  
Gonadal Hormone ◽  
Base Line ◽  
Pituitary Cells ◽  
Intact Male ◽  
Castrate Male ◽  
Basal Release

The effects of gender and the gonadal hormone environment on basal and stimulated growth hormone (GH) release by dispersed and continuously perifused rat anterior pituitary cells were examined. Cells from intact male and diestrus day 2 female rats and from castrate male rats either untreated or treated with testosterone (T) or 17 beta-estradiol (E2) were used. Basal GH release (ng/min per 10(7) cells; mean +/- SE) by cells from diestrus day 2 female rats was less than by cells from castrate rats treated with T (4.3 +/- 0.6 vs. 11.4 +/- 2.7, respectively; P less than 0.025). No other differences in basal release were detected. Concentration-response relationships were documented between human GH-releasing factor 40 (hGRF-40; 0.03-100 nM given as 2.5-min pulses every 27.5 min) and GH release. Mean (+/- SE) overall GH release (ng/min per 10(7) cells) above base line was greater by cells from intact male rats (496 +/- 92) than by cells from castrate (203 +/- 37.3; P less than 0.0001), castrate and T-treated (348 +/- 52.8; P = 0.008), or castrate and E2-treated (58.1 +/- 6.8; P less than 0.001) male rats or by diestrus day 2 rats (68.6 +/- 9.5; P = 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

The protective properties of synthetic porphyrin tin complexes in toxic hyperbilirubinemia

2000 ◽  
Vol 04 (03) ◽  
pp. 243-247 ◽  
Author(s):  
T. O. PHILIPPOVA ◽  
B. N. GALKIN ◽  
N. YA. GOLOVENKO ◽  
Z. I. ZHILINA ◽  
S. V. VODZINSKII
Keyword(s):  
Heme Oxygenase ◽  
Serum Bilirubin ◽  
Protoporphyrin Ix ◽  
Serum Bilirubin Level ◽  
Oxygenase Activity ◽  
Tetraphenyl Porphyrin ◽  
Tin Complexes ◽  
Cytochrome P 450

Tin complexes of meso-substituted synthetic porphyrins, namely Sn 4+-meso-tetraphenyl- porphyrin ( Sn - TPP ) and Sn 4+-meso-tetrakis(N-methyl-3-pyridyl)porphyrin tetratosylate ( Sn - TMe -3- PyP ), efficiently decrease the serum bilirubin level when injected subcutaneously at a dose of 100 μM kg−1 body weight into mice. These compounds are active during hyperbilirubinemia, induced by phenylhydrazine, hemin and tetrachloromethane, and also during autoimmune hemolytic anemia. In the latter case a decrease in serum bilirubin content was observed, as well as a decrease in the amount of blood reticulocytes which reflects a milder course of the disease. The Sn complexes under study induce, in vivo, cytochrome P-450, inhibit microsomal heme oxygenase and decrease the intensity of lipid peroxidation. At the same time, in vitro the hepatic and splenic heme oxygenase activity is blocked only when a 0.1 μM concentration of Sn - TMe -3- PyP or Sn -protoporphyrin IX is added to the incubation mixture. Sn - TPP does not affect the activity of this enzyme in vitro.

Influence of Safeners on the in vivo and in vitro Metabolism of Bentazon and Metolachlor by Grain Sorghum Shoots: a Preliminary Report

1991 ◽  
Vol 46 (9-10) ◽  
pp. 906-914 ◽  
Author(s):  
Donald E. Moreland ◽  
Frederick T. Corbin
Keyword(s):  
Grain Sorghum ◽  
In Vitro Studies ◽  
Naphthalic Anhydride ◽  
Surface Sterilization ◽  
Polar Components ◽  
In Vitro Shoots ◽  
Treated Seed ◽  
Cytochrome P 450

Abstract Metabolism of bentazon and metolachlor by excised shoots and a microsomal fraction iso­lated from the shoots, of 3-day-old, dark-grown, grain sorghum (Sorghum bicolor cv. Funk G 522 DR) seedlings was studied. The effects of seed treatments, on the subsequent metabo­lism of the herbicides, with the safeners naphthalic anhydride, oxabetrinil, and CGA 133205 were compared against surface-sterilization and Captan-treatments. Bentazon was aryl hydroxylated in both in vivo and in vitro studies with the hydroxylated derivative undergoing glycosylation only under in vivo conditions. Both shoots and microsomes isolated from shoots of safener-treated seed showed enhanced metabolism of bentazon relative to the controls. In­ hibition by tetcyclacis, a potent inhibitor of plant cytochrome P-450 monooxygenases, in both the in vivo and in vitro studies, and a requirement for NADPH in the in vitro studies suggested that the formation of hydroxybentazon was mediated by a cytochrome P-450 monooxygenase. Metolachlor was metabolized to polar material and O-desmethylmetolachlor under in vivo conditions. Only the demethylated product was formed in vitro. Shoots isolated from safener-treated seed showed enhanced formation of polar com pounds which were assumed to have arisen from conjugation with glutathione. Tetcyclacis did not affect the formation of the polar components. However, the formation of O-desmethylmetolachlor was depressed in the shoots excised from safener-treated seed under both in vivo and in vitro conditions. Tetcyclacis completely prevented formation of the demethylated metabolite. Hence, formation of this meta­bolite is considered to be P-450 mediated. The differential response obtained with the safeners, i.e., stimulation of aryl hydroxylation of bentazon and depression of metolachlor demethylation, suggests that the reactions are probably catalyzed by different cytochrome P-450 mono­oxygenases.

scholarly journals HOXA5 Expression Is Elevated in Breast Cancer and Is Transcriptionally Regulated by Estradiol

2020 ◽  
Vol 11 ◽  
Author(s):  
Imran Hussain ◽  
Paromita Deb ◽  
Avisankar Chini ◽  
Monira Obaid ◽  
Arunoday Bhan ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Female Rats ◽  
Er Positive ◽  
Gene Regulatory ◽  
Cancer Tissues ◽  
Positive Breast Cancer

HOXA5 is a homeobox-containing gene associated with the development of the lung, gastrointestinal tract, and vertebrae. Here, we investigate potential roles and the gene regulatory mechanism in HOXA5 in breast cancer cells. Our studies demonstrate that HOXA5 expression is elevated in breast cancer tissues and in estrogen receptor (ER)-positive breast cancer cells. HOXA5 expression is critical for breast cancer cell viability. Biochemical studies show that estradiol (E2) regulates HOXA5 gene expression in cultured breast cancer cells in vitro. HOXA5 expression is also upregulated in vivo in the mammary tissues of ovariectomized female rats. E2-induced HOXA5 expression is coordinated by ERs. Knockdown of either ERα or ERβ downregulated E2-induced HOXA5 expression. Additionally, ER co-regulators, including CBP/p300 (histone acetylases) and MLL-histone methylases (MLL2, MLL3), histone acetylation-, and H3K4 trimethylation levels are enriched at the HOXA5 promoter in present E2. In summary, our studies demonstrate that HOXA5 is overexpressed in breast cancer and is transcriptionally regulated via estradiol in breast cancer cells.

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