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Altan F, Cizmeci SU, Kose AM, Corum O, Uney K. Determination of temporal changes in hepatic drug-oxidizing capacity using plasma metabolite/caffeine ratios in non-pregnant and pregnant goats. J Vet Pharmacol Ther 2024; 47:28-35. [PMID: 37435998 DOI: 10.1111/jvp.13401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 06/20/2023] [Accepted: 06/29/2023] [Indexed: 07/13/2023]
Abstract
Caffeine (CF) is a metabolic probe drug used in the determination of the hepatic drug-oxidizing capacity. The aim of this study was to investigate temporal changes in the hepatic drug-oxidizing capacity using plasma metabolite/CF ratios in non-pregnant goats (n = 11) and pregnant goats (n = 23). CF (5 mg/kg, intravenous) was administered in six periods (Period 1-6) with 45 days between two periods. The plasma levels of CF and its metabolites, theophylline (TP), theobromine (TB) and paraxanthine (PX), were determined by HPLC-UV. To evaluate hepatic drug-oxidizing capacity in terms of enzymes that play a role in CF metabolism, the plasma metabolic ratios including TB/CF, PX/CF, TP/CF and TB + PX + TP/CF were determined at 10 h following CF administration. Plasma metabolite/CF ratios were similar between non-pregnant and pregnant goats. However, plasma metabolite/CF ratios in Period 3 (45 days in pregnant goats) were significantly higher than those other periods in both pregnant and non-pregnant goats. The effect of pregnancy may not be observed on drugs that are substrates of enzymes involved in CF metabolism in goats.
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Affiliation(s)
- Feray Altan
- Department of Pharmacology and Toxicology, Faculty of Veterinary Medicine, Dokuz Eylul University, Izmir, Turkey
| | - Sakine Ulkum Cizmeci
- Department of Obstetrics and Gynecology, Faculty of Veterinary Medicine, Selcuk University, Konya, Turkey
| | - Ayse Merve Kose
- Department of Obstetrics and Gynecology, Faculty of Veterinary Medicine, Hatay Mustafa Kemal University, Hatay, Turkey
| | - Orhan Corum
- Department of Pharmacology and Toxicology, Faculty of Veterinary Medicine, Hatay Mustafa Kemal University, Hatay, Turkey
| | - Kamil Uney
- Department of Pharmacology and Toxicology, Faculty of Veterinary Medicine, Selcuk University, Konya, Turkey
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Dickmann LJ, Tay S, Senn TD, Zhang H, Visone A, Unadkat JD, Hebert MF, Isoherranen N. Changes in maternal liver Cyp2c and Cyp2d expression and activity during rat pregnancy. Biochem Pharmacol 2008; 75:1677-87. [PMID: 18342837 DOI: 10.1016/j.bcp.2008.01.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2007] [Revised: 01/20/2008] [Accepted: 01/25/2008] [Indexed: 11/25/2022]
Abstract
During human pregnancy, CYP2C9, CYP2C19, and CYP2D6 activities are altered. The aim of the current study was to determine if this phenomenon can be replicated in the rat, and to evaluate the mechanisms that contribute to the changes in Cyp2c and Cyp2d activity during pregnancy. The intrinsic clearance of dextromethorphan O-demethylation, a measure of Cyp2d2 activity, was decreased 80% at both days 9 and 19 of gestation when compared to non-pregnant controls. The decreased intrinsic clearance was a result of both decreased V(max) and increased K(m)-values at both days of gestation. Quantitative RT-PCR revealed that transcripts of Cyp2d2 and Cyp2d4 were significantly decreased at day 19 of pregnancy (p<0.05) when compared to day 9 and non-pregnant controls. The decrease in Cyp2d mRNA levels correlated with a decrease in several nuclear receptor mRNA levels (RARalpha, RXRalpha, HNF1 and HNF3beta) but not with the mRNA levels of nuclear receptors usually associated with regulation of P450 enzymes (PXR, CAR and HNF4alpha). In contrast, Cyp2c12 and Cyp2c6 transcription and protein expression were not significantly altered during rat pregnancy although the intrinsic clearance of Cyp2c6 mediated diclofenac 4'-hydroxylation was increased 2-fold on day 19 of gestation when compared to non-pregnant controls. The increase in intrinsic clearance was due to a decrease in the K(m)-value for 4'-hydroxydiclofenac formation. These data show that pregnancy significantly alters the expression and activity of drug metabolizing enzymes in an enzyme and gestational stage specific manner. These changes are likely to have toxicological and therapeutic implications.
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Affiliation(s)
- Leslie J Dickmann
- Department of Pharmaceutics, University of Washington, Seattle, WA 98195, USA
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Lesage MG, Keyler DE, Burroughs D, Pentel PR. Effects of pregnancy on nicotine self-administration and nicotine pharmacokinetics in rats. Psychopharmacology (Berl) 2007; 194:413-21. [PMID: 17619178 DOI: 10.1007/s00213-007-0830-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2006] [Accepted: 05/15/2007] [Indexed: 11/28/2022]
Abstract
RATIONALE Because of the adverse effects of smoking during pregnancy, understanding the factors that influence maternal smoking may help in developing better treatments to help women quit smoking during pregnancy. Animal models could be useful for this purpose. OBJECTIVE The purpose of the present study was to begin the development of an animal model of smoking during pregnancy by initially characterizing nicotine self-administration (NSA) in pregnant rats. Another purpose was to begin to explore the effects of pregnancy on nicotine pharmacokinetics in rats. MATERIALS AND METHODS In experiment 1, female rats self-administering nicotine during 23-h sessions were examined throughout gestation and lactation. In experiment 2, locomotor activity was measured during pregnancy to assess further potential motor effects of pregnancy. Experiments 3 and 4 compared the single-dose pharmacokinetics of nicotine in male, nonpregnant female, and pregnant females in the first and third trimester of pregnancy and the first week of lactation. RESULTS NSA decreased over the course of pregnancy with NSA significantly lower in the third trimester compared to nonpregnant controls. NSA remained suppressed for up to 10 days into lactation. Locomotor behavior was also significantly suppressed during the second and third trimesters and throughout lactation. Nicotine elimination was slower in pregnant females compared to nonpregnant females only in the third trimester. CONCLUSIONS NSA, locomotor behavior, and nicotine elimination in rats are decreased during late pregnancy. The present study is the first to characterize NSA during pregnancy in animals, providing a potential model of maternal smoking in humans.
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Affiliation(s)
- Mark G Lesage
- Minneapolis Medical Research Foundation, 914 South 8th Street, D3-860, Minneapolis, MN 55404, USA.
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He XJ, Ejiri N, Nakayama H, Doi K. Changes in cytochrome P450 isozymes (CYPs) protein levels during lactation in rat liver. Exp Mol Pathol 2005; 79:224-8. [PMID: 16226747 DOI: 10.1016/j.yexmp.2005.08.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2005] [Accepted: 08/25/2005] [Indexed: 11/17/2022]
Abstract
The effects of pregnancy on CYPs protein level in the liver have been investigated in our previous study. Since pregnancy was associated with a decrease in CYPs protein level, the objective of this study was to investigate whether CYPs protein can revert to the virgin control level after delivery. Western blot analysis was performed to investigate the changes of total nine CYPs protein (CYP1A1, CYP2B1/CYP2B2, CYP2C6, CYP2C12, CYP2D1, CYP2D4, CYP2E1, CYP3A1 and CYP4A1) at three distinct phases: delivery (postpartum day 0, PPD 0), peak lactation (PPD 14) and on weaning (PPD 28). By PPD 0, CYP1A1, 2B1, 2B2, 2C6, 2E1 and CYP4A1 were markedly down-regulated when compared with virgin controls. By PPD 14, however, CYP1A1, 2B1, 2B2 and CYP2C6 returned to the virgin control level. All the decreased CYPs during lactation were at the virgin control level at PPD 28. The expression of CYP2C12, CYP2D1 and CYP 3A1 did not differ between lactating, post-lactation and virgin control rats. CYP2D4 was not detectable in microsomal proteins obtained from virgin control rats at a protein loading of 20 mug total protein per lane.
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Affiliation(s)
- Xi Jun He
- Department of Veterinary Pathology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
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Kishi R, Sata F, Katakura Y, Wang RS, Nakajima T. Effects of pregnancy, age and sex in the metabolism of styrene in rat liver in relation to the regulation of cytochrome P450 enzymes. J Occup Health 2005; 47:49-55. [PMID: 15703451 DOI: 10.1539/joh.47.49] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
To elucidate the effect of maternal styrene exposure, which is due to various postnatal changes in the development and behavior of offspring, we investigated pregnancy-induced changes in the metabolism of styrene in rat liver in relation to the regulation of cytochrome P450 enzymes. We also examined age and sex-induced changes in the metabolism of styrene. Pregnancy appeared to exert a negative effect on cytochrome P450 content at the late stage, whereas microsomal protein content showed little change during pregnancy. Pregnancy significantly decreased the rate of formation of styrene glycol at the late stage. The percentage of remaining activity in microsomes exposed to anti-CYP2E1 was lower than that exposed to anti-CYP2C11/6 in pregnant and non-pregnant female rats and immature male rats, indicating that CYP2E1 contributes to the metabolism of styrene more than CYP2C11/6 in these rats. Although pregnancy seemed to decrease styrene metabolism, the contribution of CYP2E1 seemed to be slightly increasing. In conclusion, pregnancy clearly influences the metabolism of styrene as well as other characteristic factors such as age and sex. It is very important to elucidate the changes in specific P450 isozyme composition related to their characteristic modification and in their affinity for chemicals.
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Affiliation(s)
- Reiko Kishi
- Department of Public Health, Hokkaido University Graduate School of Medicine, Japan.
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6
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He XJ, Ejiri N, Nakayama H, Doi K. Effects of pregnancy on CYPs protein expression in rat liver. Exp Mol Pathol 2005; 78:64-70. [PMID: 15596063 DOI: 10.1016/j.yexmp.2004.08.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2004] [Indexed: 10/26/2022]
Abstract
A body of evidence suggests that pregnancy may be responsible for the depression in the microsomal enzyme activity and the reduction in the total content of cytochrome P450 (CYP) in the rat liver. However, changes in expression of individual CYP isozyme remain poorly known. The current study was designed to examine the changes in CYPs protein expression in the liver of F344 rats in midpregnancy and late pregnancy by Western blot analysis and immunohistochemistry. Total nine antirat CYPs antibodies (CYP1A1, CYP2B1/CYP2B2, CYP2C6, CYP2C12, CYP2D1, CYP2D4, CYP2E1, CYP3A1, and CYP4A1) were used. In comparison with age-matched nonpregnant control rats, there were significant decreases in hepatic levels of CYP2B2, CYP2C6, and CYP4A1 in midpregnancy (day 13) and CYP2B2, CYP2C6, CYP4A1, CYP1A1, CYP2B1, and CYP2E1 in late pregnancy (day 19). The expression of CYP2C12, CYP2D1, and CYP 3A1 did not differ between nonpregnant and pregnant rats, and CYP2D4 was not detectable in microsomal proteins obtained from nonpregnant and pregnant rats at a protein loading of 20 mug total protein per lane. Immunohistochemistry showed that there were no differences in the distribution and degree of immunostainability for the abovementioned antibodies to nine CYPs between pregnant and nonpregnant rats.
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Affiliation(s)
- Xi Jun He
- Department of Veterinary Pathology, Graduate School of Agricultural and Life Sciences, The University of Yayoi 1-1-1, Bunkyo-ku, Tokyo, Japan
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Dorman DC, Allen SL, Byczkowski JZ, Claudio L, Fisher JE, Fisher JW, Harry GJ, Li AA, Makris SL, Padilla S, Sultatos LG, Mileson BE. Methods to identify and characterize developmental neurotoxicity for human health risk assessment. III: pharmacokinetic and pharmacodynamic considerations. ENVIRONMENTAL HEALTH PERSPECTIVES 2001; 109 Suppl 1:101-11. [PMID: 11250810 PMCID: PMC1240547 DOI: 10.1289/ehp.01109s1101] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
We review pharmacokinetic and pharmacodynamic factors that should be considered in the design and interpretation of developmental neurotoxicity studies. Toxicologic effects on the developing nervous system depend on the delivered dose, exposure duration, and developmental stage at which exposure occurred. Several pharmacokinetic processes (absorption, distribution, metabolism, and excretion) govern chemical disposition within the dam and the nervous system of the offspring. In addition, unique physical features such as the presence or absence of a placental barrier and the gradual development of the blood--brain barrier influence chemical disposition and thus modulate developmental neurotoxicity. Neonatal exposure may depend on maternal pharmacokinetic processes and transfer of the xenobiotic through the milk, although direct exposure may occur through other routes (e.g., inhalation). Measurement of the xenobiotic in milk and evaluation of biomarkers of exposure or effect following exposure can confirm or characterize neonatal exposure. Physiologically based pharmacokinetic and pharmacodynamic models that incorporate these and other determinants can estimate tissue dose and biologic response following in utero or neonatal exposure. These models can characterize dose--response relationships and improve extrapolation of results from animal studies to humans. In addition, pharmacologic data allow an experimenter to determine whether exposure to the test chemical is adequate, whether exposure occurs during critical periods of nervous system development, whether route and duration of exposure are appropriate, and whether developmental neurotoxicity can be differentiated from direct actions of the xenobiotic.
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Affiliation(s)
- D C Dorman
- Chemical Industry Institute of Toxicology, Research Triangle Park, North Carolina, USA
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Abstract
Nicotine metabolism is exceedingly sensitive to perturbation by numerous host factors. To reduce the large variations and discrepancies in the literature pertaining to nicotine metabolism, investigators in future studies need to recognize and better control these host factors. Recent advances in the understanding of nicotine metabolism have suggested new approaches to elucidating underlying mechanisms of certain toxic effects associated with cigarette smoking.
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Affiliation(s)
- M J Seaton
- Department of Pharmacology, Pennsylvania State University College of Medicine, Hershey 17033
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Foster BC, Litster DL, Buttar HS, Dawson B, Zamecnik J. Biotransformation and urinary excretion of 4-substituted amphetamines in pregnant mice. Biopharm Drug Dispos 1993; 14:709-19. [PMID: 8305630 DOI: 10.1002/bdd.2510140807] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The urinary elimination of 4-hydroxyamphetamine (PHA) and a series of homologous 4-alkoxy-substituted amphetamines and their metabolites was examined after single and multiple oral administration to pregnant and non-pregnant mice. The metabolic profile and extent of biotransformation in a series of alkoxy analogues were affected by the size of the alkoxy side chain, multiple dosing and pregnancy. There were increased recoveries of both the substrate and the conjugated derivative of PHA during gestation. The major metabolic routes observed were O-dealkylation, conjugation, and aliphatic hydroxylation of the propoxy side chain. There was some evidence of oxidative deamination. Pregnancy did not alter the profile of the major metabolites detected by GLC and NMR spectroscopy.
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Affiliation(s)
- B C Foster
- Bureau of Drug Research, Sir Frederick Banting Research Centre, Ottawa, Ontario, Canada
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10
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Borlakoglu JT, Scott A, Henderson CJ, Wolf CR. Alterations in rat hepatic drug metabolism during pregnancy and lactation. Biochem Pharmacol 1993; 46:29-36. [PMID: 8347134 DOI: 10.1016/0006-2952(93)90344-v] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The hepatic microsomal drug metabolism during pregnancy and lactation was studied. Four days post partum, the concentrations of cytochrome P450 and cytochrome b5 were reduced by 50% when compared with pregnant rats, at day 10 of gestation. Within this time period the N-demethylation of aminopyrine, the rate of aldrin epoxidation and the N-demethylation of demethylnitrosamine was reduced by 53, 74 and 21%, respectively. However, the rates of ethoxyresorufin-O-deethylation did not differ amongst both groups and the deethylation of 4-nitroanisole and the 4-hydroxylation of aniline was increased by 71 and 31%, respectively in lactating rats. Furthermore, the activities of UDP-glucuronyltransferase and glutathione S-transferase were increased by 21 and 27%, but those of epoxide hydrolase were reduced by 85%. Western immunoblot analysis of microsomal proteins obtained from pregnant and lactating rats shows that only proteins encoded by the genes of CYP2C6 and CYP3A1 are expressed at detectable levels, whereas the expression of CYP1A1, CYP1A2, CYP2A1, CYP2B1, CYP2E1 and CYP4A1 was not detectable in pregnant and lactating rats at a protein loading of 3 micrograms total protein per well. In contrast, in northern blot hybridization experiments, detectable amounts of mRNA of the above named isoenzymes were measurable, but at varying intensities. Based on the northern blot hybridization analysis, an approximate 4-fold and 3-fold increase in CYP2A1 mRNA and CYP3A1 mRNA was found, when lactating rats were compared with female controls or pregnant rats, at day 10 of gestation.
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Affiliation(s)
- J T Borlakoglu
- University of Reading, Department of Biochemistry and Physiology, U.K
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11
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Gerdin E, Rane A. N-demethylation of ethylmorphine in pregnant and non-pregnant women and in men: an evaluation of the effects of sex steroids. Br J Clin Pharmacol 1992; 34:250-5. [PMID: 1389949 PMCID: PMC1381396 DOI: 10.1111/j.1365-2125.1992.tb04132.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
1. The effects of oestrogens, testosterone, progesterone and medroxyprogesterone acetate (MPA) on the rate of N-demethylation of ethylmorphine (EM) to norethylmorphine (NEM) were studied in human adult liver microsomes. 2. N-Demethylase activity was found to be inhibited by progesterone and MPA to a similar extent while oestrogens and testosterone had no or negligible effects. 3. These findings prompted us to measure the N-demethylation of EM in relation to serum progesterone concentration in vivo in three groups of volunteers with large physiological differences in their endogenous levels of progesterone, i.e. i) pregnant women, ii) non-pregnant ovulating women and iii) men. 4. The metabolic ratio (MRP) of EM to NEM in plasma 60 min after dosage and the corresponding ratio in urine sampled for 6 h (MRU,1), measured on two occasions 14 days apart were used to reflect intraindividual variation in the rate of N-demethylation. 5. The average difference in MRP and MRU,1 between the two occasions was similar in all groups. However, the variability in MRP between individuals within a group was significantly higher in ovulating women than in men, but this had no relation to the serum concentrations of progesterone or oestradiol. 6. The cumulative 12 h urinary excretion of EM, NEM and morphine (MO) after hydrolysis with beta-glucuronidase was about 46%. There was no difference in the metabolic ratio of EM to NEM and its conjugate(s) in the urine between the luteal and the follicular phases. Our findings suggest that the menstrual cycle does not influence the rate of N-demethylation of EM.
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Affiliation(s)
- E Gerdin
- Department of Obstetrics and Gynaecology, University Hospital, Uppsala, Sweden
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12
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Sikoki FD, Tubb RA, Curtis LR. Elevation of sex steroids and inhibition of UDP-glucuronyltransferase are out of phase during gonadal maturation in the common carp. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. C, COMPARATIVE PHARMACOLOGY AND TOXICOLOGY 1989; 92:267-72. [PMID: 2565184 DOI: 10.1016/0742-8413(89)90052-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
1. Plasma sex steroid concentrations, onset of gonadal maturation, and hepatic microsomal UDP-glucuronyltransferase (UDPGT) activities were followed under natural temperature and photoperiod in outdoor tanks, and under controlled laboratory temperature and photoperiod regimens in common carp (Cyprinus carpio). 2. Decreased activity of UDPGT was out of phase with elevations in plasma testosterone and 17 beta-estradiol during gonadal maturation. 3. Injection of pituitary extract induced final gonadal maturation and transient elevations (within 24 hr) of both plasma sex steroid concentrations and UDPGT activities. 4. There were no simple relationships between plasma sex steroid concentrations and activity of hepatic microsomal UDPGT in common carp.
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Affiliation(s)
- F D Sikoki
- Department of Fisheries and Wildlife, Oregon State University, Corvallis 97331
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13
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Abstract
In a study of caffeine and its metabolites in pregnant and non-pregnant women, on average 56.8% of the administered caffeine dose was recovered in the urine in both groups. However, compared to the controls, the pregnant subjects produced smaller amounts of 1-methylxanthine and 1-methyluric acid, whereas the excretion of most of the other metabolites, particularly 3,7-dimethylxanthine and 3-methylxanthine tended to be greater. It is suggested that hormonal influences on the hepatic caffeine metabolising enzymes might be implicated.
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Brown LP, Flint OP, Orton TC, Gibson GG. Chemical teratogenesis: testing methods and the role of metabolism. Drug Metab Rev 1986; 17:221-60. [PMID: 3552539 DOI: 10.3109/03602538608998291] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Sunouchi M, Takanaka A, Mizokami K, Inoue K, Fujimori K, Kasuya Y, Omori Y. Comparison of hepatic drug-metabolizing enzymes induced by 3-methylcholanthrene and phenobarbital between pre- and postnatal rats. Toxicol Appl Pharmacol 1984; 73:457-63. [PMID: 6326348 DOI: 10.1016/0041-008x(84)90098-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Effects of 3-methylcholanthrene (3MC) and phenobarbital (PB) on the hepatic drug-metabolizing enzyme system in fetal liver of rats were investigated. Intraperitoneal administration of 3MC (25 mg/kg, 72 and 48 hr before death) to pregnant rats significantly increased hexobarbital (HB) and aminopyrine (AM)-metabolizing activities in fetuses on the 21st day of gestation to 148.0 and 150.6% of control fetuses, respectively. In contrast, HB and AM-metabolizing activities in 4-day-old neonates and mothers were decreased by administration of 3MC on the 21st day of gestation. Benzo[a]pyrene (BP)-metabolizing activity, NADPH-cytochrome c reductase activity, and cytochrome P-450 content in 3MC-treated fetuses were significantly increased to 2143.6, 137.6, and 323.8% of the control, respectively. Following 3MC administration, the maximum absorption of the cytochrome P-450-CO difference spectra in liver microsomes of fetuses was observed at 449-450 nm. The induction profile following 3MC administration in the fetal livers was different from that in the neonatal and the maternal livers. On the other hand, intraperitoneal administration of PB (60 mg/kg, 72, 48, and 24 hr before death) significantly increased HB, AM, and BP-metabolizing activities in fetal livers to 263.7, 231.0, and 151.2% of the respective controls. The profile induced by PB in the fetal livers was similar to that in maternal livers. These results suggest that HB and AM-metabolizing enzymes in fetal livers treated with 3MC or PB possess the capacity to be induced, and the responsiveness of the drug-metabolizing enzyme system to 3MC during the prenatal stage may differ from the postnatal stage.
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Stock BH. Hepatic drug metabolism in pregnancy. QUARTERLY REVIEWS ON DRUG METABOLISM AND DRUG INTERACTIONS 1984; 5:53-81. [PMID: 6397784 DOI: 10.1515/dmdi.1984.5.1.53] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The results of both isolated tissue and whole animal experimentation, whilst showing some unexplored inconsistencies, suggest that late pregnancy is associated with a reduced ability of the liver to metabolise foreign compounds. The mechanism of this reduced capacity and the physiological reason for it are unclear but such change does have implication for therapeutic response in pregnancy. Available results from the limited and often poorly structured studies of drug levels in pregnant women neither prove nor disprove the existence of similar changes in hepatic monooxygenase activity during human pregnancy.
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Weitman SD, Vodicnik MJ, Lech JJ. Influence of pregnancy on parathion toxicity and disposition. Toxicol Appl Pharmacol 1983; 71:215-24. [PMID: 6636186 DOI: 10.1016/0041-008x(83)90338-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The effects of pregnancy and lactation on the toxicity and distribution of parathion and paraoxon were examined. Signs of cholinergic stimulation were more intense in pregnant mice when compared to virgin controls after administration of parathion or its active metabolite, paraoxon. Cholinesterase activity and tissue levels of parathion and paraoxon were determined in mice at 19 days of gestation or Day 19 postpartum after administration of a single dose of 5 mg/kg parathion or 0.58 mg/kg paraoxon. Plasma (pseudo) cholinesterase activity was consistently lower in treated pregnant mice. Total brain cholinesterase was also suppressed to a greater degree in pregnant mice after treatment with parathion or paraoxon when compared with virgin animals treated similarly. In addition, when equal quantities of paraoxon (32 micrograms) were administered to both pregnant and virgin animals, total brain cholinesterase was significantly less in pregnant mice. Administration of parathion to lactating mice on Day 19 postpartum did not result in any significant differences in plasma or brain cholinesterase activity when compared to that in virgin animals. Pregnant mice treated with 5 mg/kg parathion demonstrated higher concentrations of both parathion and paraoxon in blood and brain than similarly treated virgin controls which correlated with the enhanced cholinesterase inhibition. Decreased ability to detoxify paraoxon was also demonstrated by a significant reduction in serum paraoxonase activity during pregnancy.
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Abstract
The available evidence suggests that for most drugs, adverse effects in the fetus may vary with gestational state and among species due to: (i) changes in the fetal exposure to the drug (i.e. due to changes in the pharmacokinetics of the drug in the mother and/or the fetus), or to (ii) changes in the susceptibility of the fetus to the drug. The fetal exposure to a drug during gestation is influenced more by the varying capacity of mother and/or fetus to eliminate the drug than by any intrinsic 'barrier' phenomenon at the placenta. Although differential maternal/fetal protein binding, active transplacental transport processes and 'ion-trapping' effects may influence the fetal exposure of some drugs, the main mechanisms by which fetal exposure may be modulated during pregnancy are via the capacity for irreversible drug elimination--by the fetus or, less often, by the placenta. The susceptibility of a fetus to adverse drug reactions is determined by the ontogeny of vital processes and the nature of the interaction between the drug and the process. Hence 'gestational state' and 'species' dependent differences in adverse drug effects, in the presence of a constant level of exposure of drug, reflect the time dependent appearance of these processes and the differences in ontogeny of the processes among species. At present, no studies have attempted to relate the measured fetal drug exposure to the intensity of a drug response at different stages of gestation or among species. Although there is a dearth of information in this field, it is apparent that in all species the placentas of all species pose little obstruction to the passage of xenobiotics (including drugs), to the fetus. The consequence of this exposure will depend on a myriad of pharmacokinetic and pharmacodynamic considerations for a given substance in a given species. Hence the outcome cannot be predicted, but must be empirically determined. Extrapolation of findings among different drugs, species and gestational states must be undertaken with caution, recognizing the above considerations and limitations.
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