Metabolism of a glutathione conjugate of 2-hydroxyoestradiol by rat liver and kidney preparations in vitro.
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ABSTRACT:
SUBMITTER: Elce JS
PROVIDER: S-EPMC1185515 | biostudies-other | 1970 Mar
REPOSITORIES: biostudies-other
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Project description:1. The isolation and partial purification of 11beta-hydroxy steroid dehydrogenase from rat and guinea-pig liver microsomes has been achieved by conventional methods. 2. The efficiency of different 11-oxygenated steroids as substrates has been examined. The relative efficiencies confirm in the main the stereochemical theory of the enzyme-coenzyme-substrate complex that was proposed earlier on the basis of studies in vivo. Delta(4)-3-Ketones and 5alpha-hydrogen steroids are readily metabolized by the enzyme. 5beta-Hydrogen steroids and Delta(4)-3-ketones with certain large alpha-substituents are metabolized to a limited extent or not at all. Halogen substitution in the 9alpha-position enhances the rate of reduction of 11-ketones but blocks the oxidation of the related 11beta-ols. 3. 9alpha-Fluorocortisol is a competitive inhibitor of the oxidation of cortisol, but 9alpha-fluorocortisone is reduced at five to ten times the initial velocity of cortisone. 4. 11beta-Hydroxy steroid dehydrogenase activity has been found in liver microsomes of rat, guinea pig, rabbit and calf. 5. Relative substrate efficiencies and K(m) values are similar in whole (debris-free) homogenates, washed microsomes and acetone-dried powders of washed microsomes. 6. A variety of conditions have been examined for the observation of 11beta-hydroxy steroid dehydrogenase activity. NADP(H) is an efficient and NAD(H) a very poor coenzyme for the reaction.
| S-EPMC1198650 | biostudies-other
Project description:BackgroundTissue hypoperfusion and inflammation in sepsis can lead to organ failure including kidney and liver. In sepsis, mortality of acute kidney injury increases by more than 50%. Which type of volume replacement should be used is still an ongoing debate. We investigated the effect of different volume strategies on inflammatory mediators in kidney and liver in an early sepsis model.Material and methodsAdult male Wistar rats were subjected to sepsis by cecal ligation and puncture (CLP) and assigned to three fluid replenishment groups. Animals received 30mL/kg of Ringer's lactate (RL) for 2h, thereafter RL (75mL/kg), hydroxyethyl starch (HES) balanced (25mL/kg), containing malate and acetate, or HES saline (25mL/kg) for another 2h. Kidney and liver tissue was assessed for inflammation. In vitro rat endothelial cells were exposed to RL, HES balanced or HES saline for 2h, followed by stimulation with tumor necrosis factor-? (TNF-?) for another 4h. Alternatively, cells were exposed to malate, acetate or a mixture of malate and acetate, reflecting the according concentration of these substances in HES balanced. Pro-inflammatory cytokines were determined in cell supernatants.ResultsCytokine mRNA in kidney and liver was increased in CLP animals treated with HES balanced compared to RL, but not after application of HES saline. MCP-1 was 3.5fold (95% CI: 1.3, 5.6) (p<0.01) and TNF-? 2.3fold (95% CI: 1.2, 3.3) (p<0.001) upregulated in the kidney. Corresponding results were seen in liver tissue. TNF-?-stimulated endothelial cells co-exposed to RL expressed 3529±1040pg/mL MCP-1 and 59±23pg/mL CINC-1 protein. These cytokines increased by 2358pg/mL (95% CI: 1511, 3204) (p<0.001) and 29pg/ml (95% CI: 14, 45) (p<0.01) respectively when exposed to HES balanced instead. However, no further upregulation was observed with HES saline. PBS supplemented with acetate increased MCP-1 by 1325pg/mL (95% CI: 741, 1909) (p<0.001) and CINC-1 by 24pg/mL (95% CI: 9, 38) (p<0.01) compared to RL. Malate as well as HES saline did not affect cytokine expression.ConclusionWe identified HES balanced and specifically its component acetate as pro-inflammatory factor. How important this additional inflammatory burden on kidney and liver function is contributing to the sepsis-associated inflammatory burden in early sepsis needs further evaluation.
| S-EPMC4795752 | biostudies-literature
Project description:Batracylin is a heterocyclic arylamine topoisomerase inhibitor with preclinical anticancer activity. Marked species differences in sensitivity to the toxicity of batracylin were observed and attributed to differential formation of N-acetylbatracylin by N-acetyltransferase. A Phase I trial of batracylin in cancer patients with slow acetylator genotypes identified a dose-limiting toxicity of hemorrhagic cystitis. To further explore the metabolism of batracylin and N-acetylbatracylin across species, detailed studies using human, rat, and dog liver microsomal and hepatocyte preparations were conducted. Batracylin or N-acetylbatracylin was incubated with microsomes and hepatocytes from human, rat, and dog liver and with CYP-expressing human and rat microsomes. Substrates and metabolites were analyzed by HPLC with diode array, fluorescence, radiochemical, or mass spectrometric detection. Covalent binding of radiolabeled batracylin and N-acetylbatracylin to protein and DNA was measured in 3-methylcholanthrene-induced rat, human, and dog liver microsomes, and with recombinant human cytochromes P450. In microsomal preparations, loss of batracylin was accompanied by formation of one hydroxylated metabolite in human liver microsomes and five hydroxylated metabolites in rat liver microsomes. Six mono- or di-hydroxy-N-acetylbatracylin metabolites were found in incubations of this compound with 3MC rat liver microsomes. Hydroxylation sites were identified for some of the metabolites using deuterated substrates. Incubation with recombinant cytochromes P450 identified rCYP1A1, rCYP1A2, hCYP1A1 and hCYP1B1 as the major CYP isoforms that metabolize batracylin and N-acetylbatracylin. Glucuronide conjugates of batracylin were also identified in hepatocyte incubations. NADPH-dependent covalent binding to protein and DNA was detected in all batracylin and most N-acetylbatracylin preparations evaluated. Microsomal metabolism of batracylin and N-acetylbatracylin results in multiple hydroxylated products (including possible hydroxylamines) and glutathione conjugates. Incubation of batracylin with hepatocytes resulted in production primarily of glucuronides and other conjugates. There was no clear distinction in the metabolism of batracylin and N-acetylbatracylin across species that would explain the differential toxicity.
| S-EPMC4948755 | biostudies-literature
Project description:Adult male rats with cannulated or ligated bile ducts were given S-(2-hydroxyoestradiol-1-yl)[(35)S]glutathione, S-(2-hydroxy[6,7-(3)H(2)]oestradiol-1-yl)glutathione or S-(2-hydroxyoestradiol-1-yl)[glycine-(3)H]glutathione by intraperitoneal injection. The recovery of radioactivity in the bile of bile duct-cannulated rats was 33-86% and in the urine of bile duct-ligated rats was 54-105%. Oestrogen thioether derivatives of glutathione, cysteinylglycine, cysteine and N-acetylcysteine were isolated from bile; only the N-acetylcysteine derivatives could be identified in the urine. The steroid moiety was characterized by microchemical tests before and after treatment with Raney nickel: 2-hydroxyoestradiol-17beta was released from the glutathione conjugate, and 2-hydroxyoestrone and 2-hydroxyoestrone 3-methyl ether from the other conjugates. From intact rats the recovery of administered radioactivity was about 15% in the urine and 5% in the faeces over a period of several days and the radioactivity appeared to be largely protein-bound. The results demonstrate that injected oestrogen-glutathione conjugate undergoes conversion into N-acetylcysteine derivatives in vivo. Oestrogen-glutathione conjugates formed in the intact rat may be excreted in an apparently non-steroidal, possibly protein-bound form, which would not be detected by current analytical techniques.
| S-EPMC1178528 | biostudies-other
Project description:Liver-like organoids that recapitulate the complex functions of the whole liver by combining cells, scaffolds, and mechanical or chemical cues are becoming important models for studying liver biology and drug metabolism. The advantages of growing cells in three-dimensional constructs include enhanced cell-cell and cell-extracellular matrix interactions and preserved cellular phenotype including, prevention of de-differentiation. In the current study, biomimetic liver constructs were made via perfusion decellularization of rat liver, with the goal of maintaining the native composition and structure of the extracellular matrix. We optimized our decellularization process to produce liver scaffolds in which immunogenic residual DNA was removed but glycosaminoglycans were maintained. When the constructs were recellularized with rat or human liver cells, the cells remained viable, capable of proliferation, and functional for 28 days. Specifically, the cells continued to express cytochrome P450 genes and maintained their ability to metabolize a model drug, midazolam. Microarray analysis showed an upregulation of genes involved in liver regeneration and fibrosis. In conclusion, these liver constructs have the potential to be used as test beds for studying liver biology and drug metabolism.
| S-EPMC5788381 | biostudies-literature
Project description:1. Rat liver supernatant preparations catalyse the reactions of some aralkyl sulphate esters with GSH to yield S-aralkylglutathione derivatives. 2. A glutathione S-transferase that catalyses these reactions has been purified 16-fold. 3. The purified enzyme preparation catalyses the release of sulphate ions from benzyl sulphate, 1-menaphthyl (naphth-1-ylmethyl) sulphate and phenanthr-9-ylmethyl sulphate only in the presence of GSH. It does not cause the release of sulphate ions from prop-1-yl sulphate, l-serine O-sulphate, phenyl sulphate or oestrone 3-sulphate even when GSH is added. 4. The stability and specificity of the enzyme and its response to inhibitors and to changes of pH were studied. 5. The activity of the preparation was compared with the activities of glutathione S-transferases described previously.
| S-EPMC1176644 | biostudies-other
Project description:1. The rates of metabolism of megestrol acetate, 17alpha-acetoxy-6alpha-methylprogesterone, 6alpha-methylprogesterone, 17alpha-acetoxyprogesterone and progesterone by liver microsome-supernatant fractions from female rats and rabbits have been compared. 2. Introduction of the 6alpha-methyl group into the progesterone molecule markedly decreased the metabolism by liver microsome-supernatant preparations in the rat but not in the rabbit. When 17alpha-acetoxy was the substituting group, metabolism was diminished in the rabbit but not in the rat preparations. Introduction of both the 6alpha-methyl and 17alpha-acetoxy groups into the progesterone molecule markedly decreased the rate of metabolism by liver microsome-supernatant preparations of both species. The Delta(6)-bond in megestrol acetate confers additional resistance to metabolism by rabbit-liver preparations. 3. It is proposed that the observed inhibition of metabolism by these substituents in the progesterone molecule partly or wholly explains the enhanced activity of megestrol acetate.
| S-EPMC1264745 | biostudies-other
Project description:A complex of haemoglobin and GSH was prepared by incubating haemoglobin with GSH and acetylphenylhydrazine. GSH could be released from the crude preparation by incubation with NADPH. However, when the haemoglobin preparation was separated from glutathione reductase by DEAE-Sephadex chromatography, NADPH no longer released GSH. Rather, the addition of a combination of either partially purified human erythrocyte or crystalline glutathione reductase and NADPH was required to release GSH from the haemoglobin-GSH complex. This complex is commonly believed to represent a mixed disulphide of GSH and the cysteine-beta-93 thiol group. This interpretation was supported by the finding that prior alkylation of available haemoglobin thiol groups prevented the formation of the complex. By using haemoglobin-[(35)S]GSH complex as a substrate, it was shown that GSH itself released the radioactivity from the complex only very slowly. In contrast, the release of [(35)S]GSH was very rapid in the presence of NADPH and glutathione reductase. This suggests that the cleavage of the haemoglobin-GSH complex is not mediated by GSH with cyclic reduction of GSSG formed, but rather proceeds enzymically through glutathione reductase.
| S-EPMC1179365 | biostudies-other
Project description:The glutathione S-transferases that were purified to homogeneity from liver cytosol have overlapping but distinct substrate specificities and different isoelectric points. This report explores the possibility of using preparative electrofocusing to compare the composition of the transferases in liver and kidney cytosol. Hepatic cytosol from adult male Sprague-Dawley rats was resolved by isoelectric focusing on Sephadex columns into five peaks of transferase activity, each with characteristic substrate specificity. The first four peaks of transferase activity (in order of decreasing basicity) are identified as transferases AA, B, A and C respectively, on the basis of substrate specificity, but the fifth peak (pI6.6) does not correspond to a previously described transferase. Isoelectric focusing of renal cytosol resolves only three major peaks of transferase activity, each with narrow substrate specificity. In the kidney, peak 1 (pI9.0) has most of the activity toward 1-chloro-2,4-dinitrobenzene, peak 2 (pI8.5) toward p-nitrobenzyl chloride, and peak 3 (pI7.0) toward trans-4-phenylbut-3-en-2-one. Renal transferase peak 1 (pI9.0) appears to correspond to transferase B on the basis of pI, substrate specificity and antigenicity. Kidney transferase peaks 2 (pI8.5) and 3 (pI7.0) do not correspond to previously described glutathione S-transferases, although kidney transferase peak 3 is similar to the transferase peak 5 from focused hepatic cytosol. Transferases A and C were not found in kidney cytosol, and transferase AA was detected in only one out of six replicates. Thus it is important to recognize the contribution of individual transferases to total transferase activity in that each transferase may be regulated independently.
| S-EPMC1186156 | biostudies-other
Project description:1. The distribution of rat-liver polyribosomes in sucrose density gradients has been investigated with regard to the effects of the preparative procedures and the physiological and pathological condition of the animal. 2. By using carefully defined conditions, three principal polyribosomal fractions have been isolated with S(20,w) values of 340, 275 and 225s in addition to the dimerized 120s and single 80s ribosomes. 3. The polyribosomes were very sensitive to treatment with ribonuclease and to mechanical stresses. 4. Incubation of dispersed hepatic cells and also cell-free preparations with puromycin in the presence of ATP and phosphoenolpyruvate caused rapid partial degradation of the polyribosomes. Treatment of the dispersed cells with actinomycin D also degraded the polyribosomes. 5. The liver polyribosomes of rats not raised under pathogen-free conditions and possibly of rats with an arthritic syndrome may be more fragile than those of healthy pathogen-free animals. 6. Treatment of pathogen-free rats with drugs stimulating liver anabolism profoundly affected the distribution of polyribosomes in sucrose density gradients.
| S-EPMC1264872 | biostudies-other