Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: DrugBank:APRD00691 (EE2)
 7,802 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ortho,para,dichlorodiphenyl dichloroethane (o,p'DDD, Mitotane (Roussell)) is used as an adrenolytic drug to reduce adrenocortical mass and circulating cortisol levels in Cushing's syndrome but has the unwanted side-effect of inducing hypercholesterolaemia. This paper examined the mechanism of that effect in 30 patients with Cushing's syndrome treated with o,p'DDD during the past 10 years. o,p'DDD increased serum cholesterol by 68 per cent, mainly by increasing LDL-cholesterol. The latter effect was not due to impaired binding of LDL to its receptor, as shown in vitro using cultured fibroblasts. Increases in plasma mevalonic acid during o,p'DDD administration were suggestive of increased cholesterol synthesis, this effect being reversed by simvastatin. These findings suggest that o,p'DDD causes hypercholesterolaemia by increasing cholesterol synthesis. It is proposed that this effect is due to the drug's known ability to block cytochrome P450-mediated reactions, thus impairing the formation of oxysterols responsible for down-regulating hepatic cholesterol synthesis. Treatment with simvastatin, an inhibitor of cholesterol synthesis, reverses the hyperlipidaemia and enables o,p'DDD therapy to be maintained without increasing cardiovascular risk.
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PMID:Possible mechanism and treatment of o,p'DDD-induced hypercholesterolaemia. 148 Jul 41

FSH is the primary hormonal inducer of ovarian follicle maturation and a critically important regulator of steroidogenesis in granulosa cells. We examined possible molecular mechanisms subserving FSH action by assessing concentrations of cytochrome P450 cholesterol side-chain cleavage (P450scc) mRNA in porcine granulosa cells maintained in serum-free culture. Cellular concentrations of specific P450scc mRNA were measured by Northern blot hybridization using a 32P-labeled 1-kilobase porcine cDNA clone. Specificity was tested by estimating the granulosa cell mRNA content of the constitutively expressed enzyme, glyceraldehyde-3-phosphate dehydrogenase. Steroidogenesis was evaluated by measuring concomitant progesterone accumulation in the culture medium. Treatment with ovine FSH (100 ng/ml) increased P450scc mRNA concentrations in a time-dependent fashion, with significant effects on both P450scc mRNA concentrations and progesterone accumulation by 4 h and a maximal increase (8- to 10-fold) at 48 h. FSH dose-response studies at 48 h revealed a significant stimulatory effect of 30 ng/ml FSH on P450scc mRNA accumulation and progesterone production, with a maximal effect at 100 ng/ml FSH. To examine the role of cAMP in mediating granulosa cell P450scc mRNA accumulation, granulosa cells were treated with forskolin, cholera toxin, 8-bromo-cAMP, 8-bromo-cGMP, 5'AMP, or cAMP analogs that differentially stimulate the two isoenzymes of protein kinase-A. Increased specific P450scc mRNA accumulation and progesterone production occurred in response to each agent except 5'AMP and 8-bromo-cGMP. No effects of these agents were observed on glyceraldehyde-3-phosphate dehydrogenase mRNA. To assess possible feedback effects of steroid or sterol on FSH-stimulated P450scc mRNA concentrations, granulosa cells were treated with aminoglutethimide to block or with low density lipoprotein to stimulate steroid production. Inhibition of sterol utilization by the cholesterol side-chain cleavage enzyme had no effect on basal or FSH-stimulated concentrations of P450scc mRNA, but markedly suppressed progesterone production. Low density lipoprotein, which increases intracellular sterol, also did not alter basal or FSH-stimulated P450scc mRNA accumulation, suggesting that neither the utilization nor the availability of sterol regulates specific P450scc mRNA levels. Estradiol alone did not increase P450scc mRNA accumulation, but did augment progesterone production. Treatment of granulosa cells with estradiol and FSH produced a synergistic increase in progesterone concentrations, but did not affect FSH-stimulated P450scc mRNA accumulation.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Follicle-stimulating hormone increases concentrations of messenger ribonucleic acid encoding cytochrome P450 cholesterol side-chain cleavage enzyme in primary cultures of porcine granulosa cells. 184 8

The regulation of mRNA levels for delta 5-3 beta-hydroxysteroid dehydrogenase/delta 5----delta 4-isomerase (3 beta HSD), 17 alpha-hydroxylase/C17-20 lyase cytochrome P450 (P450(17 alpha] and cholesterol side-chain cleavage cytochrome P450 (P450scc) was studied in primary cultures of mouse Leydig cells. Treatment of Leydig cells with 8-bromo-cAMP (cAMP) was essential for expression of P450(17 alpha) mRNA, but not for 3 beta HSD. Treatment with cAMP caused a decrease in basal levels of 3 beta HSD mRNA. The addition of aminoglutethimide (AG), an inhibitor of cholesterol metabolism, to the cAMP-treated cultures resulted in increased expression of both 3 beta HSD and P450(17 alpha) mRNA levels. The addition of testosterone or the androgen agonist mibolerone to cAMP- plus AG-treated cultures reduced 3 beta HSD and P450(17 alpha) mRNA to levels comparable to those observed when cells were treated with cAMP only. The glucocorticoid dexamethasone reduced both basal and cAMP- plus AG-induced increases in 3 beta HSD mRNA, but not in P450(17 alpha) mRNA. Estradiol at a concentration of 1 microM had no effect on cAMP- plus AG-induced 3 beta HSD or P450(17 alpha) mRNA levels. The role of protein synthesis in mediating the cAMP induction of 3 beta HSD, P450(17 alpha), and P450scc was investigated. The addition of cycloheximide (10 micrograms/ml) to cAMP-treated cultures for 24 h completely suppressed both constitutive and cAMP-induced 3 beta HSD mRNA levels. Cycloheximide also repressed cAMP-induced levels of P450(17 alpha) to 12% of levels observed in the absence of cycloheximide. In sharp contrast, 24-h treatment with cycloheximide did not suppress cAMP induction of P450scc mRNA, but reduced basal levels by approximately 50%. A time course of induction by cAMP (50 microM) of P450(17 alpha) and P450scc mRNA showed very similar rates of increase in P450(17 alpha) and P450scc mRNA, with the greatest increase occurring between 12 and 24 h of treatment. The results of the study demonstrate that in normal mouse Leydig cells steady state levels of mRNA for 3 beta HSD, P450(17 alpha), and P450scc are differentially regulated. cAMP is required for maximal levels of all three mRNAs. There is high constitutive expression of 3 beta HSD and P450scc mRNA, while expression of P450(17 alpha) mRNA is absolutely dependent on cAMP stimulation. Endogenously produced testosterone negatively regulates the expression of cAMP-induced P450(17 alpha) and 3 beta HSD, while the glucocorticoid dexamethasone negatively regulates 3 beta HSD and P450scc.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Multiple mechanisms for regulation of 3 beta-hydroxysteroid dehydrogenase/delta 5----delta 4-isomerase, 17 alpha-hydroxylase/C17-20 lyase cytochrome P450, and cholesterol side-chain cleavage cytochrome P450 messenger ribonucleic acid levels in primary cultures of mouse Leydig cells. 187 81

Details concerning the endogenous regulation of hepatic cytochrome P450 monooxygenases in teleosts, and the features of this regulation common among fish species, are poorly known. Gonadally mature female winter flounder (Pseudopleuronectes americanus) have been reported to have severalfold lower levels of microsomal cytochromes P450 and b5 and NADPH-cytochrome c reductase than do males (Stegeman and Woodin ('84) Mar. Environ. Res., 14:422-425). These strong sex differences prompted more detailed study of P450 regulation in winter flounder liver, and a comparison with sex differences in another marine teleost, scup (Stenotomus chrysops). Ethoxyresorufin O-deethylase (EROD) activity/nmol P450 was less in gonadally mature females than in males of both species. Immunoblot analysis with MAb 1-12-3 to P450E (the EROD catalyst) showed that the content of P450E counterpart was also much less in females of both species. Aminopyrine N-demethylase (APND) and testosterone 6 beta-hydroxylase (6 beta-OHase) activities per nmol P450 were higher in gonadally mature female than in mature male flounder, differences not seen in scup. Polyclonal antibodies to scup P450A were shown to detect proteins in a number of teleosts. The levels of anti-P450A cross-reacting protein were greater in mature female than in male flounder, but as with 6 beta-OHase activity, the content of this protein was not sexually differentiated in scup. Estradiol treatment of winter flounder depressed the rates of EROD, APND, 6 beta-OHase, and estradiol 2-OHase activities per mg protein, but APND and 6 beta-OHase activities per nmol P450 were unchanged. Thus, E2 promotes general decreases in some hepatic P450-catalyzed activities, but in achieving sex differences there is also specific regulation of the P450E counterpart, and possibly of the 6 beta-OHase (P450A?). Other factors, temporal or hormonal, can modify the effect of E2 treatment, and may contribute to the specific regulation of P450 forms in naturally maturing fish, and to species differences in this regulation.
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PMID:Sex differences in hepatic monooxygenases in winter flounder (Pseudopleuronectes americanus) and scup (Stenotomus chrysops) and regulation of P450 forms by estradiol. 191 63

Monooxygenases in the cytochrome P450 IIIA subfamily are induced by a number of their xenobiotic substrates and by testosterone, an endobiotic substrate of importance in their regulation. 17 alpha-Ethinylestradiol (EE) is also metabolized by these enzymes and in this study Dark Agouti rats were used to examine the effects of subcutaneous implantation of controlled release silastic capsules containing EE to determine if this steroid also induces these enzymes. Data were compared with results obtained from equivalent groups of animals implanted with capsules containing testosterone propionate (TP). Liver microsomes prepared from male and female rats were used to identify intrinsic gender differences in the monooxygenases studied and gender differences in the responses to the implanted steroids were also determined. Effects due to imprinting of growth hormone secretion patterns were controlled by using male and female birth gonadectomized animals. Results obtained from groups with blank implants showed there were no effects due to the silastic implant material itself on the monooxygenases studied. The specific activities of erythromycin N-demethylation in liver microsomes of both EE and TP implanted male and female birth gonadectomized animals were enhanced relative to corresponding blank implanted controls consistent with both steroids having an effect to induce activity attributable to cytochrome P450 IIIA isoforms. Immunoinhibition studies using microsomes from EE treated female rats with erythromycin as substrate provided further evidence for this steroid having this induction effect. The specific activity of ethylmorphine N-demethylation was however not increased in microsomes prepared from the EE implanted female animals and was decreased in the corresponding male preparations. These findings distinguished the response to this steroid from that to TP and suggested induction by this estrogen of an isoform(s) having a more limited range of substrates than has characteristically been found in this subfamily. EE treatment also caused an increase in diazepam C3 hydroxylase consistent with an effect to induce P450 IIIA activity but this was found only in microsomes from birth gonadectomized female animals. This was in contrast to the effect of TP treatment which produced increases in this monooxygenase in both male and female animals. Another gender specific effect of EE was a striking decrease in morphine N-demethylase activity seen only in birth gonadectomized male rats. This again contrasted with the effect of TP which caused a marked increase in this activity in liver microsomes of both male and female birth gonadectomized animals consistent with the proposal that testosterone is important in the regulation of this activity.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Effects of ethinylestradiol and testosterone implants on hepatic microsomal cytochrome P450 monooxygenases of birth gonadectomized male and female Dark Agouti rats. 195 10

Estradiol-2/4-hydroxylase (E-2/4-H) activity was determined in the mouse uterus during early pregnancy as well as in ovarian steroid hormone-treated ovariectomized uterus. Under the assay conditions used, E-4-H was the predominant catechol estrogen-forming monooxygenase enzyme. The inhibition of E-4-H activity by SKF-525A, metyrapone and alpha-naphthoflavone suggested involvement of cytochrome P450-dependent monooxygenases. A haloestrogen, 2-fluoroestradiol (2-FL-E2), also inhibited this activity. During the peri-implantation period, no change in uterine E-4-H activity was noted on the morning of days 2 through 5, but the activity significantly (P less than 0.01) increased in the afternoon of day 4 of pregnancy. A single injection of estradiol-17 beta (E2, 100 ng/mouse) to ovariectomized mice significantly (P less than 0.01) elevated the level of E-4-H activity at 24 h as did injections of progesterone (P4, 2 mg/mouse) for 2 days. When 2 days of P4 (2 mg/mouse) treatment was combined with a single injection of E2 (20 ng/mouse), E-4-H activity increased 1.3-fold (P less than 0.05) by 24 h above that of P4 treatment alone. Dexamethasone (200 micrograms/mouse) and cholesterol (2 mg/mouse) treatment for 2 days had no effect on E-4-H activity. Thus, the stimulatory effect of P4 and E2 on E-4-H activity appeared to be specific. The increased activity of uterine E-4-H prior to implantation on day 4 evening and the modulation of its activity by P4 and/or E2 suggest an involvement of 4-hydroxyestradiol in embryo implantation.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Catechol estrogen formation in the mouse uterus and its role in implantation. 215 14

Insulin-like growth factor type I (IGF-I) is an important intraovarian peptide that stimulates granulosa cell steroidogenesis during follicular development. The cytochrome P450 cholesterol side-chain cleavage enzyme (P450scc) that converts cholesterol to pregnenolone is the rate-limiting step in progesterone biosynthesis. Since treatment of primary cultures of immature porcine granulosa cells with IGF-I will increase progesterone production as well as the synthesis of immunoprecipitable P450scc enzyme, we examined possible molecular mechanisms subserving these inductive effects of IGF-I. To this end, cultures of porcine granulosa cells were maintained in serum-free medium with or without IGF-I under various treatment paradigms. Cellular concentrations of specific P450scc mRNA were measured by Northern blot hybridization using a 32P-labeled 1-kilobase porcine cDNA clone. Northern blot autoradiogram densitometry data were normalized with a constitutively expressed 1.2-kilobase chicken glyceraldehyde-3-phosphate dehydrogenase cDNA clone. Steroidogenesis was monitored by measuring concomitant progesterone accumulation in the culture medium. Treatment with pure recombinant human IGF-I (100 ng/ml) significantly increased P450scc mRNA concentrations after 18 h, and maximal stimulation (10- to 20-fold) occurred by 48 h for both P450scc mRNA and progesterone accumulation. The IGF-I dose-response curve studied at 48 h showed a significant increase in P450scc mRNA levels at a minimal IGF-I concentration of 1 ng/ml (although progesterone production was not increased). Treatment with equimolar concentrations of epidermal growth factor, IGF-I, or insulin significantly increased P450scc mRNA concentrations, whereas fibroblast growth factor did not. To examine possible mechanisms underlying stimulation of P450scc by IGF-I, immature granulosa cells were treated with aminoglutethimide (a P450scc enzyme inhibitor), low density lipoprotein (to increase cholesterol delivery to granulosa cells), or estradiol in the presence or absence of IGF-I. Aminoglutethimide had no effect, alone or with IGF-I, on P450scc mRNA concentrations, but suppressed progesterone production. Low density lipoprotein alone also did not stimulate P450scc mRNA levels and only slightly increased progesterone accumulation, but acted synergistically with IGF-I to augment P450scc mRNA concentrations and progesterone accumulation. Estradiol alone did not stimulate P450scc mRNA concentrations, but did significantly increase progesterone production. Estradiol cotreatment with IGF-I synergistically enhanced progesterone production, but did not alter IGF-I-stimulated P450scc mRNA concentrations.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Insulin-like growth factor type I increases concentrations of messenger ribonucleic acid encoding cytochrome P450 cholesterol side-chain cleavage enzyme in primary cultures of porcine granulosa cells. 222 29

Estradiol is converted to catechol estrogens via 2- and 4-hydroxylation by cytochrome P450 enzymes. 4-Hydroxyestradiol elicits biological activities distinct from estradiol, most notably an oxidant stress response induced by free radicals generated by metabolic redox cycling reactions. In this study, we have examined 2- and 4-hydroxylation of estradiol by microsomes of human uterine myometrium and of associated myomata. In all eight cases studied, estradiol 4-hydroxylation by myoma has been substantially elevated relative to surrounding myometrial tissue (minimum, 2-fold; mean, 5-fold). Estradiol 2-hydroxylation in myomata occurs at much lower rates than 4-hydroxylation (ratio of 4-hydroxyestradiol/2-hydroxyestradiol, 7.9 +/- 1.4) and does not significantly differ from rates in surrounding myometrial tissue. Rates of myometrial 2-hydroxylation of estradiol were also not significantly different from values in patients without myomata. We have used various inhibitors to establish that 4-hydroxylation is catalyzed by a completely different cytochrome P450 than 2-hydroxylation. In myoma, alpha-naphthoflavone and a set of ethynyl polycyclic hydrocarbon inhibitors (5 microM) each inhibited 4-hydroxylation more efficiently (up to 90%) than 2-hydroxylation (up to 40%), indicating > 10-fold differences in Ki (<0.5 microM vs. > 5 microM). These activities were clearly distinguished from the selective 2-hydroxylation of estradiol in placenta by aromatase reported previously (low Km, inhibition by Fadrozole hydrochloride or ICI D1033). 4-Hydroxylation was also selectively inhibited relative to 2-hydroxylation by antibodies raised against cytochrome P450 IB1 (rat) (53 vs. 17%). These data indicate that specific 4-hydroxylation of estradiol in human uterine tissues is catalyzed by a form(s) of cytochrome P450 related to P450 IB1, which contribute(s) little to 2-hydroxylation. This enzyme(s) is therefore a marker for uterine myomata and may play a role in the etiology of the tumor.
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PMID:4-Hydroxylation of estradiol by human uterine myometrium and myoma microsomes: implications for the mechanism of uterine tumorigenesis. 756 5

The metabolism of praziquantel (PZQ) was studied in microsomes isolated from livers of differently pretreated rats and in the presence of various inhibitors of cytochrome P450 (P450) isoforms. Microsomes from phenobarbitone (PB)-pretreated rats metabolised PZQ to its major metabolite 4OH-praziquantel (4OH-PZQ) at a greater rate than those from 20-methylcholanthrene (MC) and saline (SA) pretreated rats. The Vmax for the PB microsomes was 600 nmol 4OH-PZQ formed/mg/min x 10(-3) compared to 91.4 nmol/mg/min x 10(-3) for MC and 238 nmol/mg/min x 10(-3) for SA microsomes. These results indicate that PZQ is metabolised by PB-inducible isoforms of P450. Inhibitor studies were conducted with microsomes from SA-pretreated animals. In these studies, caffeine, disulfuram, and tolbutamide were poor inhibitors of the metabolism of PZQ to 4OH-PZQ, with I50 values not determinable. Quinidine and quinine inhibited the hydroxylation of PZQ but with high Ki values. 17 alpha-Ethynylestradiol, cimetidine and diphenylhydramine were effective inhibitors of the formation of 4OH-PZQ, with 17 alpha-ethynylestradiol being the most potent with a Ki of 0.5 +/- 0.05 microM. From the known specificities of these P450 inhibitors, it is therefore concluded that cytochromes P450 1A2, 2E1, 2C9-10, and 2D6 probably do not contribute significantly to the metabolism of PZQ to its major metabolite in rats. It is likely that cytochromes P450 2B1 and 3A, both inducible by PB, are predominantly responsible for the formation of 4OH-PZQ.
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PMID:Characterisation of praziquantel metabolism by rat liver microsomes using cytochrome P450 inhibitors. 798 Jun 47

Understanding the effects of environmental contaminants on cetaceans and other marine mammals will require information on the biochemistry of xenobiotic metabolism in these species. We characterized the hepatic microsomal cytochrome P450 system in beluga whales (Delphinapterus leucas) from the Canadian Arctic. The content of native P450 averaged 0.203 and 0.319 nmol/mg microsomal protein, cytochrome b5 content averaged 0.199 and 0.236 nmol/mg, and rates of NADPH-cytochrome c reductase were 79 and 76 nmol/min/mg, for females and males respectively. Ethoxyresorufin O-deethylase (EROD), pentoxyresorufin O-depentylase (PROD), and benzo[a]pyrene (BP) hydroxylase (AHH) activities were significantly greater in males than in females, and were highly correlated with one another (r2 between 0.853 and 0.912). HPLC analysis of in vitro BP metabolites revealed benzo-ring (7,8- and 9,10-) dihydrodiols, consistent with activation of this compound, as well as 4,5-dihydrodiol,3-OH-, 7-OH-, and 9-OH-BP and 1,6- and 3,6-quinones. Estradiol 2-hydroxylase activity did not differ between sexes, and rates did not correlate with those of the other activities. Antibodies against scup P450B (an apparent teleost CYP2B) and rat CYP2B1 did not recognize proteins in beluga liver microsomes, but there was a protein detected by antibodies to PB-inducible rabbit CYP2B4. Antibodies to ethanol and ketone-inducible rat CYP2E1 reacted with two proteins in beluga liver microsomes. Antibodies specific to hydrocarbon-inducible CYP1A1 and/or CYP1A2 forms showed a single protein band, apparently more closely related to CYP1A1. The content of CYP1A was fivefold greater in male than in female beluga. CYP1A content was highly correlated with EROD, PROD, and AHH activities, suggesting that this P450 form is a primary catalyst for these reactions in beluga. CYP1A content and activity were highly correlated with the concentrations in blubber of non-ortho and mono-ortho PCB congeners, compounds that induce CYP1A in other mammals. These results indicate that a CYP1A is a catalyst for the metabolism of aromatic hydrocarbon pollutants in the beluga whale, and strongly suggest that this protein is induced in these organisms by environmental contaminants, including PCBs. The results support the measurement of CYP1A expression as a biomarker of exposure to inducers in marine mammals. The full functional and evolutionary relationships of beluga CYP1A and of beluga proteins immunologically related to other P450 forms are uncertain.
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PMID:Catalytic and immunochemical characterization of hepatic microsomal cytochromes P450 in beluga whale (Delphinapterus leucas). 818 32


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