Ethylmorphine N-demethylase Activity Research Articles

Cerebral Pharmacokinetics of Ipsapirone in Rats After Different Routes of Administration

Ipsapirone, a putative non-benzodiazepine anxiolytic, was extensively metabolized in rats to 1-(2-pyrimidinyl)piperazine (1-PP) which accumulated in the brain. Neither the route of administration (i.p. or p.o.), nor prolonged administration of ipsapirone or 1-PP affected their accumulation in the rat brain. The cytochrome P450 level and ethylmorphine N-demethylase activity in rat liver microsomes were unchanged by chronic treatment with ipsapirone or 1-PP. The results indicate that 1-PP may contribute to the alpha 2-adrenoceptor antagonism of ipsapirone in rats and that chronic treatment with the drug does not affect its biotransformation to 1-PP.

Sex-related differences in rat liver microsomal enzymes and their induction by doxapram.

The effects of doxapram on the hepatic microsomal mono-oxygenase system of male and female rats were investigated. Male and female rats were administered doxapram (10-120 mg kg-1 day-1, i.p.) for 4 days. In female rats, administration of doxapram (20, 40, 60, 80, 100 and 120 mg kg-1) elevated the parameters in a dose-dependent manner while doxapram (100 and 120 mg kg-1) elevated the levels of cytochrome P450 and hexobarbitone hydroxylase in male rats. Doxapram (40 mg kg-1) caused induction of hepatic drug metabolism typified by an increase of hepatic microsomal cytochrome P450 content and activities of hexobarbitone hydroxylase, benzphetamine N-demethylase and ethylmorphine N-demethylase in female rats, but no change in male rats. These findings were supported by the results of SDS/polyacrylamide-gel electrophoresis. However, 7-ethoxycoumarin O-de-ethylase and arylhydrocarbon hydroxylase activities were significantly increased in male rats. NADPH-cytochrome c reductase and NADH-cytochrome c reductase activities, and cytochrome b5 content were unaffected in rats of both sexes. The sex-dependent cytochrome P450 species may be selectively sensitive to the action of doxapram.

In vivo effects of Diosgenin, isolated from Asparagus officinalis, compared to Phenobarbital in rats

Event Abstract Back to Event In vivo effects of Diosgenin, isolated from Asparagus officinalis, compared to Phenobarbital in rats Magdalena Kondeva-Burdina1*, Mitka Mitcheva1, Ilina Krasteva2 and Stefan Nikolov2 1 Medical University-Sofia, Department of Pharmacology, Pharmacotherapy and Toxicology, Bulgaria 2 Medical University-Sofia, Department of Pharmacognosy and Botany, Bulgaria Diosgenin is a well-known antihypercholesterolemic agent. Biliary cholesterol secretion is mediated by different transporters and is stimulated by cholesterol and non-cholesterol steroids – Cholate and Diosgenin. It is known that nuclear receptors CAR and PXR take part in the regulation of hepatic drug metabolism. There are data that Diosgenin increased the expression of lipid-sensing nuclear receptor Pregnane X Receptor (PXR). Phenobarbital (PB) and Phenytoin are the most well known activators of PXR and CAR. PXR has been shown to take part in the regulation of hepatic metabolism – especially biochemically and genetically activation of CYP3A genes. According to these data, it is interesting to investigate in vivo the possible effect of Diosgenin, isolated from Asparagus officinalis, on the activity of some drug-metabolizing enzyme systems, compared to Phenobarbital in rats. Rats were treated with Diosgenin (50 mg/kg p.o./6 days) and Phenobarbital (75 mg/kg i.p./4 days). The total quantity of Cytochrome P450, enzyme activity of Ethylmorphine N-demethylase (EMND) (CYP3A) and Aniline Hydroxilase (AH) (CYP2E1) were measured spectrophotometrically in isolated rat microsomes. As marker of lipid peroxidation and cell protection, we measured the quantity of malondialdehyde (MDA) and reduced glutathione (GSH). Diosgenin and Phenobarbital, administered alone, increased statistically significant, compared to control, the total amount of Cytochrome P450 – with 36% and with 85%, respectively; the activity of EMND with 58% and with 184%, respectively. Diosgenin didn’t influenced the AH activity compared to Phenobarbital. Both Diosgenin and Phenobarbital have no statistically significant effect on GSH level. On the quantity of MDA, Diosgenin has no effect, while Phenobarbital increased it with 27%. Our results showed that Diosgenin, isolated from Astragalus officinalis, exhibited inducible effect similar to the effect of Phenobarbital on the activity of some drug-metabolizing enzyme systems. Keywords: Diosgenin, Phenobarbital, induction, drug-metabolizing enzymes Conference: 8th Southeast European Congress on Xenobiotic Metabolism and Toxicity - XEMET 2010, Thessaloniki, Greece, 1 Oct - 5 Oct, 2010. Presentation Type: Poster Topic: Xenobiotic metabolism Citation: Kondeva-Burdina M, Mitcheva M, Krasteva I and Nikolov S (2010). In vivo effects of Diosgenin, isolated from Asparagus officinalis, compared to Phenobarbital in rats. Front. Pharmacol. Conference Abstract: 8th Southeast European Congress on Xenobiotic Metabolism and Toxicity - XEMET 2010. doi: 10.3389/conf.fphar.2010.60.00145 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 28 Oct 2010; Published Online: 04 Nov 2010. * Correspondence: Dr. Magdalena Kondeva-Burdina, Medical University-Sofia, Department of Pharmacology, Pharmacotherapy and Toxicology, Sofia, Bulgaria, magdalenakondeva@hotmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Magdalena Kondeva-Burdina Mitka Mitcheva Ilina Krasteva Stefan Nikolov Google Magdalena Kondeva-Burdina Mitka Mitcheva Ilina Krasteva Stefan Nikolov Google Scholar Magdalena Kondeva-Burdina Mitka Mitcheva Ilina Krasteva Stefan Nikolov PubMed Magdalena Kondeva-Burdina Mitka Mitcheva Ilina Krasteva Stefan Nikolov Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Experimental study on the effects of 7-nitroindazol, selective inhibitor of neuronal nitric oxide synthase (nNOS), on some brain and hepatic biochemical parameters

Event Abstract Back to Event Experimental study on the effects of 7-nitroindazol, selective inhibitor of neuronal nitric oxide synthase (nNOS), on some brain and hepatic biochemical parameters Vessela Vitcheva1*, Rumyana Simeonova1 and Mitka Mitcheva1 1 Medical University, Department of Pharmacology, Pharmacotherapy and Toxicology, Bulgaria 7-nitroindazole (7-NI) is a selective nNOS inhibitor, which has been proved to have a beneficial effect on different physical processes and behaviors, related to drug abuse, such as tolerance, withdrawal, neurotoxicity and reward. However there are no information available for its toxicity and hepatic biotransformation. The objective of the following study was to investigate the effects of 7-NI on rat brain and liver, after multiple alone administartion. Male Wistar rats were treated with 7-NI (25 mg/kg i.p.) for 5 days. 24 hours after the last administration brains and livers were taken for biochemical assay. Being an inhibitor of nNOS, 7-NI significantly decreased the enzyme activity by 41%. For tracing the possible toxic effect of the compound, the quantity of malondialdehyde (MDA) and the level of reduced glutathion (GSH) were measured both in the brain and in the liver. Multiple administration of 7-NI did not affect the MDA quantity, neither in the brain, nor in the liver that corresponds with the literature data about the positive effect of 7-NI on lipid peroxidation. On the other hand, the GSH level was depleated by 43% in the brain and by 27% in the liver, which suggest a toxic effect of 7-NI. The chemical structure of 7-NI, benzpyrazole, which is a part of the structure of such substrates of cytochrome P 450 as antichelmintes, suggests hepatic metabolism of the compound. The cytochrome P 450 quantity and the activity of ethylmorphine-N-demethylase (EMND) and anilinehydroxilase (AH), were also assessed. 7-NI decreased P 450 quantity by 30% and AH activity by 26%. At the same time EMND activity remained unchanged. On the basis of these results we proved a hepatic metabolism of 7-NI that might be responsible for the detected GSH depletion in the liver and could be regarded as a precondition for hepatic drug interactions. Keywords: 7-nitroindazole, nNOS inhibitor, Brain, Liver Conference: 8th Southeast European Congress on Xenobiotic Metabolism and Toxicity - XEMET 2010, Thessaloniki, Greece, 1 Oct - 5 Oct, 2010. Presentation Type: Oral Topic: Xenobiotic toxicity Citation: Vitcheva V, Simeonova R and Mitcheva M (2010). Experimental study on the effects of 7-nitroindazol, selective inhibitor of neuronal nitric oxide synthase (nNOS), on some brain and hepatic biochemical parameters. Front. Pharmacol. Conference Abstract: 8th Southeast European Congress on Xenobiotic Metabolism and Toxicity - XEMET 2010. doi: 10.3389/conf.fphar.2010.60.00213 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 28 Oct 2010; Published Online: 04 Nov 2010. * Correspondence: Dr. Vessela Vitcheva, Medical University, Department of Pharmacology, Pharmacotherapy and Toxicology, Sofia, Bulgaria, vesselavitcheva@yahoo.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Vessela Vitcheva Rumyana Simeonova Mitka Mitcheva Google Vessela Vitcheva Rumyana Simeonova Mitka Mitcheva Google Scholar Vessela Vitcheva Rumyana Simeonova Mitka Mitcheva PubMed Vessela Vitcheva Rumyana Simeonova Mitka Mitcheva Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Upregulation of CYP2e1 and CYP3a activities in histamine-deficient histidine decarboxylase gene targeted mice.

Histamine is a biogenic amine with multiple physiological functions. Its importance in allergic inflammation is well characterized; moreover, it plays a role in the regulation of gastric acid production, various hypothalamic functions, such as food uptake, and enhancing TH2 balance during immune responses. Using histidine decarboxylase gene targeted (HDC(-/-)) BALB/c mice, we studied the effect of the absence of histamine on four cytochrome p450 enzyme activities. Their selective substrates were measured: ethoxyresorufin O-dealkylase activity of CYP1A, pentoxyresorufin O-dealkylase activity of CYP2B, chlorzoxazone 6-hydroxylase activity of CYP2E1 and ethylmorphine N-demethylase activity of CYP3A. The results indicate a significant elevation of CYP2E1 and CYP3A activities, however, no change in CYP1A and CYP2B activities was seen in HDC targeted mice compared to wild type controls with identical genetic backgrounds.

Quantitative structure–activity relationships in a series of endogenous and synthetic steroids exhibiting induction of CYP3A activity and hepatomegaly associated with increased DNA synthesis

The results of a quantitative structure–activity relationship (QSAR) study on a total of 14 steroids exhibiting induction of a CYP3A-associated activity and increase in liver weight/DNA synthesis is reported. It is found that different, but related, structural descriptors correlate with increase in ethylmorphine N-demethylase activity ( r=0.92) and with the increase in liver weight ( r=0.78) and DNA synthesis ( r=0.78). Although there is a strong correlation between increase in liver weight and DNA content ( r=0.999), neither of these correlated with ethylmorphine N-demethylase activity. These findings are discussed in the light of CYP3A induction, substrate specificity and inhibition; a proposed model of human CYP3A4 based on sequence homology with CYP102, a bacterial P450 of known crystal structure, demonstrates the possible mode of interaction between substrates and inhibitors within the putative active site.

Purification and characterization of the hepatic CYP2C and 3A isozymes from phenobarbitone pretreated rhesus monkey.

Hepatic P450s, named M-3 and M-4 were purified from phenobarbitone pretreated rhesus monkey. These demonstrated polypeptide molecular mass of 50 and 52.5 kDa and specific content of 12 and 20 nmol P450/mg protein, respectively. Both the isozymes demonstrated low spin state of heme. Antibodies raised against M-3 inhibited the activity of aminopyrine, erythromycin and ethylmorphine N-demethylase in the microsomes obtained from PB pretreated rhesus monkey by 76, 40 and 35%, respectively. M-4 did the same by 69, 85 and 79%, respectively. These observations indicated M-3 and M-4 to be the members of CYP2C and 3A subfamilies, respectively. These results were substantiated by the observations that M-3 metabolized aminopyrine whereas M-4 metabolized aminopyrine, erythromycin and ethylmorphine in the reconstituted system. Microsomal lipids and cytochrome b5 enhanced the rate of these reactions. Further confirmation to the identity of these isozymes was provided by N-terminal amino acid sequences. The first 10 N-terminal amino acid residues of M-3 were 90% similar to CYP2C20 and 2C9 and that of M-4 were 100 and 90% similar to CYP3A8 and 3A5, respectively. In conclusion, two isozymes of hepatic P450 purified from PB pretreated rhesus monkey belong to CYP2C and 3A subfamilies.

Ethylmorphine N-demethylase activity as a marker for cytochrome P450 CYP3A activity in rat hepatic microsomes

The purpose of this study was to evaluate the selectivity and sensitivity of ethylmorphine N-demethylase (EMD) as an indicator of chemically-induced cytochrome P450 CYP3A activity in liver microsomes of rats following treatment with selective enzyme inducers. Male and female Sprague–Dawley (CD®) rats were dosed with either pregnenolone-16 α-carbonitrile (PCN; 50 mg/kg per day for 5 days), phenobarbital (PB; 100 mg/kg per day for 4 days), beta-naphthoflavone ( βNF; 100 mg/kg per day for 3 days), clofibrate (CF; 300 mg/kg per day for 14 days), isoniazid (ISO; 100 mg/kg per day for 3 days), or dexamethasone (DEX; 50 mg/kg per day for 4 days). Microsomes were isolated, frozen and subsequently assayed for protein, cytochrome P450 content and EMD activity. In males, significant elevations ( P<0.01) in EMD activity were observed in microsomes from PB-, DEX- and PCN-dosed animals compared with untreated controls. Microsomes from ISO- and βNF-dosed males showed a reduction ( P<0.05) in EMD activity when compared with control microsomes, and CF was without effect. In females, EMD activities were significantly increased in microsomes from PCN, DEX and PB-dosed but not βNF, ISO, or CF-dosed animals. As expected on the basis of sex-related differences in gene expression, EMD activities in untreated animals were considerably higher in males than females, attributable to constitutive CYP3A and CYP2C11 activities. The selectivity of EMD for induced CYP3A was confirmed on the basis of inhibition studies with selected steroid substrates of CYP3A, polyclonal anti-CYP3A1 antibodies and triacetyloleandomycin (TAO), a selective inhibitor of CYP3A. In conclusion, for both sexes, the greatest elevations (≈3–13-fold) in EMD activity were observed in microsomes from rats dosed with DEX, a potent archetypal inducer with lesser but significant increases noted for PCN and PB, indicating that EMD is a reliable indicator of induced rat hepatic cytochrome P450 CYP3A activity.

Effects of horminone on liver mixed function mono-oxygenases and glutathione enzyme activities of Wistar Rat

The present study reports on the effects of horminone on serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, on hepatic cytochrome P450 (P450) and cytochrome b 5 (cyt b 5) contents and on the activities of NADPH-cytochrome P450 reductase (NR), mixed function mono-oxygenases (MFO), glutathione- S-transferase (GST) and glutathione reductase (GR) of Wistar male rat. Horminone is a diterpenoid quinone (7,12-dihydroxyabiet-8,12-diene-11,14-dione) present in several species of the Labiatae family and used as medicinal plants in folk medicine. In this study, horminone was administered by the intraperitoneal route (i.p.) at a concentration of 1 or 10 mg/kg to each group of six mice, using water as a vehicle. On the one hand, results showed that horminone increased serum ALT and AST levels and cyt b 5 content and induced the activities of ethylmorphine N-demethylase (EMD). On the other hand, horminone decreased P450 content and inhibited the activities of 7-ethoxyresorufin O-deethylase (ERD), 7-ethoxycoumarin O-deethylase (ECD), aniline 4-hydroxylase (AH) and NR. Based on these results, the possibility of toxic effects occurring after administration of plant extracts containing horminone must be considered.

Effects of cytochrome P450 inducers on tamoxifen genotoxicity in female mice in vivo

We recently reported that administration of the antiestrogen tamoxifen (TAM) gives rise to two groups of DNA adducts in female mouse liver in vivo, as measured by 32P-postlabeling, and provided evidence that 4-hydroxytamoxifen and α-hydroxytamoxifen are proximate carcinogenic metabolites leading to group I and group II adducts, respectively (Randerath et ed., Carcinogenesis 15: 2087-2094, 1994). Because cytochrome P450 (CYP) enzymes play an important role in TAM metabolism, in this investigation we tested the hypothesis that induction of liver CYP enzymes may affect TAM metabolism profoundly, resulting in increased or decreased TAM-DNA adduct formation in vivo. To this end, we treated female ICR mice with TAM either alone or in combination with one of several classic CYP inducers, i.e. phenobarbital (PB), ß-naphthoflavone (BNF), and pregnenolone-16α-carbonitrile (PCN), and determined the levels of 32P-postlabeled TAM-DNA adducts and the activities of several CYP-dependent enzymes. Each of the inducers greatly diminished levels of group II, but did not affect group I adducts. TAM elicited induction of benzphetamine N-demethylase activity in liver, while activities of other enzymes were not affected. TAM, when given in combination with BNF, elicited a synergistic induction of ethoxyresorufin O-deethylase (EROD) (CYP1A1) and methoxyresorufin O-demethylase (MROD) (CYP1A2) activities. Likewise, PCN given along with TAM caused synergistic induction of EROD and ethylmorphine N-demethylase activities. There was no synergism between PB and TAM, however. Overall, the results further support the existence of two pathways of TAM metabolism to DNA-reactive electrophiles and strongly suggest that the classic CYP inducers tested enhance detoxication of TAM to non-genotoxic metabolites.

Effects of streptolysin O, picibanil (OK 432) and interferon alpha 2A on cytochrome P-450-dependent monooxygenases and arylamine N-acetyltransferase in rat liver.

Streptolysin O, a thiol-activated exotoxin from group A beta-haemolytic streptococci, caused a dose-dependent depression of aniline hydroxylase, aminopyrine N-demethylase and ethylmorphine N-demethylase activities when added into the hepatic microsomal mixtures from male rats at concentrations 0.02-0.4 HU/mL in vitro. The activities of 7-ethoxycoumarin O-deethylase, 7-ethylresorufin O-deethylase and 7-pentylresorufin O-depentylase were not altered with the used concentrations of the toxin. Specific antibody against haemolytic action of streptolysin O added to incubation mixtures in vitro was not able to protect streptolysin-sensitive monooxygenases from the inhibition. The addition of streptolysin O (0.01-0.8 HU/mL) into the cytosol-containing medium did not significantly influence the activity of procainamide N-acetyltransferase. Immunomodulators picibanil (OK 432) and human recombinant interferon alpha 2A which are known to suppress oxidative metabolism in vivo in humans and animals, were without effect either on the cytochrome P-450-dependent monooxygenases or on the N-acetyltransferase activity when administered in vitro at the doses real in their clinical application (0.001-0.1 KE/mL of picibanil and 10-500 U/mL of alpha-interferon).

Age related effects of di(2-ethylhexyl)phthalate on hepatic cytochrome P450 monooxygenases in Wistar rats.

Age related response of di(2-ethylhexyl)phthalate (DEHP) was studied by administering the plasticizer (2000 mg/kg, orally) to 3, 6 and 10 week old wistar rats for 1, 7 or 15 days and determining the activity of hepatic P450 monooxygenases. Single administration of DEHP decreased the cytochrome P450 contents and activity of arylhydrocarbon hydroxylase, aniline hydroxylase and ethylmorphine N-demethylase at all the age groups while repeated exposure induced them with maximum alterations occurring in 3 week old rats. Repeated administration for 15 days, on the other hand, caused a decrease in the cytochrome P450 content and the activity of arylhydrocarbon hydroxylase, aniline hydroxylase and ethylmorphine N-demethylase only in the 3 week old rats. The 6 and 10 week old rats exposed to the same schedule of DEHP showed an inhibition in the activity of arylhydrocarbon hydroxylase and an increase in the activity of aniline hydroxylase and ethylmorphine N-demethylase, which was however lower than that seen after 7 days of exposure to DEHP in the respective age group of animals. Our data have indicated the differences in the sensitivity of the P450 monooxygenases towards DEHP and its metabolites amongst 3, 6 and 10 week old animals.

Estrogen, not testosterone, creates male predominance of a P4501-related cytochrome in adult guinea pig adrenals.

Guinea pig adrenal microsomes possess a distinctive cytochrome P450 that is immunochemically related to P4501 and correlates with microsomal capacity for xenobiotic metabolism. This 52K protein and the capacity for metabolizing compounds such as ethylmorphine are located in the zona reticularis, are suppressed by ACTH, and are predominant in adult males. The protein is undetectable and the enzyme activity is low in young prepubertal animals. In males, both increase with age. However, in females, the protein remains undetectable, and ethylmorphine demethylase activity remains low into adulthood. Despite this clear sex difference through puberty and into sexual maturity, we recently observed that in female retired breeders, both the 52K cytochrome P450 and the capacity for metabolism of ethylmorphine appear at levels equal to those in males of comparable age. As estrogen levels are low in female retired breeders, we decided to investigate whether estrogen plays a role in maintaining the low levels of this protein and of xenobiotic metabolism seen in younger females. In a series of gonadectomy and hormone replacement experiments, we demonstrated that estrogen suppressed the levels of both protein and enzyme activity in adult guinea pigs. Ovariectomy resulted in the appearance of the 52K cytochrome P450 and of ethylmorphine demethylase in female adrenal microsomes at levels comparable to those seen in adult males. Estrogen replacement suppressed the increase in both protein concentration and enzyme activity. In hemiovariectomized cycling females, compensatory hypertrophy of the remaining ovary occurred, and the characteristic low levels of the 52K P450 and enzyme activity were maintained. Furthermore, estrogen treatment of male guinea pigs suppressed levels of both the 52K P450 and ethylmorphine demethylase activity in male adrenals. These experiments demonstrate that estrogen plays a significant role in the regulation of this protein. Testosterone, on the other hand, was not required to maintain the higher levels of 52K P450 and correlated enzyme activity in adult males. The levels of both were the same in normal, castrated, and sham-operated males, treated with testosterone or vehicle alone or left untreated. In fact, castration of prepubertal males resulted in a rapid rise to adult male levels of both immunodetectable protein and enzyme activity, implying that some suppressive agent of testicular origin effects the gradual increase that normally occurs with age in males.(ABSTRACT TRUNCATED AT 400 WORDS)

Modulation of the rat hepatic cytochrome P450 composition by long-term streptozotocin-induced insulin-dependent diabetes.

The effects of long-term insulin-dependent diabetes on the enzymatic activities of hepatic cytochrome P450 isozymes were determined in rats rendered diabetic by the administration of streptozotocin and killed 4, 8, and 12 weeks following treatment. The O-dealkylations of ethoxyresorufin and pentoxyresorufin were elevated in the diabetic animals throughout the study, the extent of increase being similar at all three time points. p-Nitrophenol hydroxylase activity was induced in the diabetic animals 4 weeks following treatment with streptozotocin, but the extent of increase became less pronounced with the progress of the disease. A modest increase in ethylmorphine N-demethylase activity was also observed but only in the diabetic animals killed 4 weeks after the induction of diabetes. Finally, lauric acid hydroxylase activity was elevated in the diabetic animals 4 weeks following streptozotocin administration but then declined rapidly with the duration of the disease. It is concluded that the duration of diabetes modulates the hepatic cytochrome P450 profile, with the effect being isoenzyme specific. Mechanisms that may account for these changes are discussed.

In vivo effects of the anesthetic, benzocaine, on liver microsomal cytochrome P450 and mixed-function oxidase activities of gilthead seabream ( Sparus aurata)

Gilthead seabreams were exposed to benzocaine, 4-aminobenzoic acid ethyl ester, 57 mg/l in sea water for 3 min, daily, for 2 or 3 consecutive days. The fish were killed 20 hr after the last treatment. Benzocaine treatment for 2 or 3 days resulted in 57% and 67% inhibition of liver microsomal aniline 4-hydroxylase and ethylmorphine N-demethylase activities,respectively. The total cytochrome P450 content of fish liver microsomes was unaltered following the 2-day benzocaine treatment. However, additional 3 min benzocaine treatment on day 3 reduced cytochrome P450 level by 50%. Benzocaine produced type II difference spectra with rabbit liver microsomes. Difference spectra of fish liver microsomes elicited by benzocaine were complex. The position of peak and intensity were greatly influenced by the concentration of benzocaine.

Sex differences in the diabetes-induced modulation of rat hepatic cytochrome p450 proteins

Sex differences in the diabetes-induced changes in hepatic cytochrome P450 proteins were investigated in rats treated with streptozotocin. Changes in specific cytochrome P450 proteins were monitored using diagnostic substrates and immunologically utilizing specific polyclonal antibodies. When expressed in terms of nmoles of total cytochrome P450, ethoxyresorufin O-deethylase activity was increased by treatment with streptozotocin, the extent of induction being the same in the two sexes. In contrast, lauric acid hydroxylase and ethylmorphine N-demethylase activities were induced only in the male rat. Finally, p-nitrophenol hydroxylase and pentoxyresorufin O-dealkylase were enhanced by the same treatment in both sexes, the effect being more pronounced in the male. These findings indicate that sex-specific changes in certain cytochrome P450 proteins exist in response to insulin-dependent diabetes but these cannot, however, be ascribed to sex differences in the severity of diabetes induced by streptozotocin since the degrees of hyperketonaemia and hyperglycaemia were the same in the two sexes. These are likely to reflect sex-specific differences in growth hormone and triglyceride levels in the diabetic animals.

Characterization of cytochrome P450 dependent mixed-function oxidase system of gilthead seabream ( sparus aurata; sparidae) liver

1. 1. The average cytochrome P450 content of gilthead seabeam liver microsomes was found to be 0.078 ± 0.012 ( n = 4) nmol/mg protein, which was about 50%, 24% and 13% of that measured in trout, sturgeon and scup liver microsomes, respectively. 2. 2. Gilthead seabream liver microsomes contained a relatively higher amount of cytochrome b5, as 0.32 ± 0.05 ( n = 4) nmol/mg protein. 3. 3. Effects of microsomal protein amount and temperature ranging from 15 to 30°C on aniline 4-hydroxylation and ethylmorphine N-demethylation activities were examined. No significant differences were observed between the enzyme activities at these temperatures. 4. 4. The liver microsomal aniline 4-hydroxylase activity of gilthead seabream in the 1990 fall (0.016–0.021 nmol p-aminophenol/min/mg protein) was 4.5–6 times higher than that in the 1991 spring (0.003–0.004 nmol p-aminophenol/min/mg protein). 5. 5. Liver microsomal ethylmorphine N-demethylase activity measured in 1991 spring (0/371) nm ol formaldehyde/min/mig protein) was 41% higher than that in 1990 fall (0.263 nmol formaldehyde/min/mg protein).

Comparison of human fetal hepatic and adrenal cytochrome P450 activities with some major gestational steroids and ethylmorphine as substrates

The immunoidentified human fetal liver and adrenal microsomal contents of cytochromes P450IIIA and P450VIIA1 were compared to the metabolism of steroids and ethylmorphine. In fetal liver microsomes, 16α-hydroxylation of dehydroepiandrosterone (DHA) was catalyzed at a high rate in almost all investigated specimens and accompanied by a high ethylmorphine N-demethylase activity. Progesterone 16α- and 17α-hydroxylation was found only in the livers with the highest DHA 16α-hydroxylation activities, while 21-hydroxylation of progesterone was catalyzed only occasionally in these samples. In fetal adrenal microsomes, 21-hydroxylation of progesterone to 11-desoxycorticosterone (DOC) and 11-desoxycortisol (DOCOL) was catalyzed. In contrast to fetal liver, the adrenals also catalyzed the 17α-hydroxylation of pregnenolone and the formation of DHA from 17α-OH-pregnenolone. 16α-hydroxylation of DHA and ethylmorphine N-demethylation were modest in the adrenals. P450IIIA/HLp was immunoidentified in all investigated liver specimens except two ( 18 20 ) in which no ethylmorphine N-demethylation or 16α-hydroxylation of DHA was found. P450XVIIA1 bands were observed in 8 20 blots of liver specimens, but there was no correlation between the density of these bands and the 17α-hydroxylation of progesterone. All 11 fetal adrenal samples catalyzed DHA 16α-hydroxylation, although only 8 were positive for P450IIIA/HLp. All investigated adrenals were positive in regard of the P450XVIIA1 band, except one ( 8 9 ) with a low 17α-hydroxylation of progesterone. All adrenal specimens catalyzed 21-hydroxylation of progesterone and contained P450C21 bands in immunoblots and all samples catalyzed the formation of DOC and DOCOL from progesterone. Our findings in the fetal livers show a correlation between the DHA 16α-hydroxylation and immunoidentified P450IIIA/HLp bands. In adrenals, there was a correlation between the immunoidentified P450XVIIIA1 bands and the 17α-hydroxylation of progesterone.

Combined effect of cadmium and nickel on rat hepatic monooxygenases: possible stimulation of certain cytochrome P-450 isozymes

When male rats were given either a single dose of cadmium (3.58 mg CdCl 2·6H 2O kg , i.p.) 72 h prior to sacrifice or a single dose of nickel (59.5 mg NiCl 2·6H 2O kg , s.c.) 16 h prior to sacrifice, the activities of ethylmorphine N-demethylase, aminopyrine N-demethylase and aniline 4-hydroxylase, and the levels of cytochrome P-450 and microsomal heme were significantly decreased. Cadmium decreased the cytochrome b 5 level significantly, whereas it did not alter the NADPH-cytochrome c reductase activity significantly. In contrast, Ni did not alter the cytochrome b 5 level significantly but decreased the NADPH-cytochrome c reductase activity significantly. For the combined treatment, animals received the single dose of nickel 56 h after the single dose of cadmium and then they were killed 16 h later. In these animals ethylmorphine N-demethylase, aminopyrine N-demethylase and NADPH-cytochrome c reductase activities and cytochromes P-450 and b 5 levels increased significantly as compared to those of controls, whereas aniline 4-hydroxylase activity and microsomal heme level remained unaltered. In concordance with the increase in the enzyme activities, certain P-450 protein bands were observed to be elevated when studied on SDS-polyacrylamide gel electrophoresis. Furthermore, when the monooxygenase activities and SDS-polyacrylamide gel electrophoresis profiles of combined metal-treated animals were compared with those of the animals treated with classic inducers such as phenobarbital (75 mg kg i.p., 72, 48 and 24 h prior to sacrifice) and 3-methylcholanthrene (20 mg kg i.p., 72, 48 and 24 h prior to sacrifice), the combination of metals seemed to have tendency to stimulate certain phenobarbital and 3-methylcholanthrene inducible cytochrome P-450 isozymes.

Intralobular localization of different cytochrome p-450 form dependent monooxygenase activities in the liver of normal and inducer-treated rats

1. 1. Isolated periportal (PP) and perivenous (PV) hepatocytes from normal and inducer-treated rat livers were used to examine the following; intralobular localization of cytochrome P-450IA, P-450IIB, P-450IIE and P-450IIIA dependent monooxygenase activities and effects of phenobarbital (PB), beta-naphthoflavone (BNF) and pregnenolone-16 alpha-carbonitrile (PCN) on the zonal induction of these monooxygenases. 2. 2. 7-Ethoxyresorufin O-deethylase (7EROD), 7-pentoxyresorufin O-dealkylase (7PROD) and N-nitrosodimethylamine N-demethylase (NAND) activities of PP hepatocytes were not significantly different from those of PV hepatocytes. 3. 3. Ethylmorphine N-demethylase (EMND) activity was significantly higher in PV hepatocytes than in PP hepatocytes of normal rats. 4. 4. EMND activity was induced by PCN and PB treatments. The response of EMND activity to PCN treatment was higher in PP hepatocytes than that in PV hepatocytes, and as a result the PV dominance disappeared following PCN treatment. 5. 5. Extents of the response of this activity to PB treatment were similar in PP and PV hepatocytes, and PV dominance remained unchanged even after induction.