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At least 343 records · Page 19Linked to original sources
PubMed1982

Interrelationship of carcinogen and glucocorticoid in perinatal enzyme induction.

Polycyclic aromatic hydrocarbons such as 3-methylcholanthrene can interrelate certain of their effects with those of glucocorticoid in the fetomaternal unit and the infant. We describe the induction by both classes of compounds in perinatal rat liver of enzymes that modify their biologic activity, and present further evidence for glucocorticoid-mimetic effects of 3-methylcholanthrene. We suggest that some degree of fetal teratogenicity and imprinting of postnatal events can arise from these mimetic effects, which should be taken into consideration along with the more direct perinatal toxicity of these mutagens.

Adrenalectomy↗
PubMed1982

Regulation of ovarian ornithine decarboxylase. Role of Calcium ions in enzyme induction in isolated swine granulosa cells in vitro.

When swine granulosa cells were cultured in chemically defined medium selectively deficient in Ca2+, the dose-dependent stimulation of ornithine decarboxylase (EC 4.1.1.17) activity in response to prostaglandin E2, L-epinephrine or the somatomedin, multiplication-stimulating activity, was attenuated markedly. Putative calcium influx blockers, verapamil and diltiazem, also inhibited hormone-stimulated enzymic activity. Similar inhibitory effects were exerted by divalent (cobalt) or trivalent (lanthanum) cations believed to compete with calcium for extracellular binding sites. The suppressive effects of extracellular calcium deprivation were time-dependent (suggesting gradual depletion of intracellular calcium stores), and could be mimicked by the intracellular antagonist of calcium action, trifluoperazine. The mechanism(s) subserving diminished hormonal induction of enzyme activity could not be accounted for by alterations in cell viability, general protein synthesis, half-life of decay of enzyme activity (measured in the presence of cycloheximide), or apparent Km of ornithine decarboxylase. Ca2+ and/or calcium antagonists did not modify enzyme activity in cell-free preparations. These observations implicate Ca2+ in the hormonal induction of a discrete cytosolic enzyme in isolated intact ovarian cells.

Animals↗
PubMed1990

Hepatic peroxisomal and microsomal enzyme induction by citral and linalool in rats.

The short-term effects of oral administration of citral and linalool to rats have been compared. Male Wistar rats were given, by gastric intubation, 1.5 g citral or linalool/kg body weight/day for 5 days. Citral caused peroxisome proliferation as indicated by induction of cyanide-insensitive palmitoyl-CoA oxidation and bifunctional enzyme; levels of microsomal cytochrome P-450 IVA1 were also raised. Linalool caused induction of the peroxisomal enzymes but not of cytochrome P-450 IVA1, indicating that it possesses activity somewhat different from that of citral. These results suggest that the mechanisms of peroxisome proliferation may be independent of induction of cytochrome P-450 IVA1.

Acyclic Monoterpenes↗
PubMed1994

Specific and dose-dependent enzyme induction by omeprazole in human beings.

Omeprazole induces hepatic cytochrome P-4501A2. In a previous study this effect was shown to be significant in vivo in 6 poor metabolizers, including 1 intermediate metabolizer, but not in 12 extensive metabolizers of S-mephenytoin after 7 days of treatment with 40 mg/day omeprazole. In this study, the specificity of the inducing potential of omeprazole was investigated in these volunteers. Furthermore, in eight of the extensive metabolizers the dose-dependence of cytochrome P-450 1A2 induction was evaluated. Cytochrome P-450 1A2 activity was monitored by means of the 13C-[N3-methyl]caffeine breath test and by means of plasma caffeine clearance before omeprazole treatment with 120 mg/day, on the seventh day of dosage and after a 7-day washout. Omeprazole plasma concentration was measured. Results were compared with those after 40 mg. gamma-Glutamyltransferase activity in serum, as well as urinary excretion of D-glucaric acid and 6 beta-hydroxycortisol, were measured on the same study days in all study groups (n = 26). In the eight extensive metabolizers the breath test indicated a dose-dependent increase of cytochrome P-450 1A2 activity of 8.5% +/- 15.0% (40 mg, mean +/- SD, NS) and 27.2% +/- 16.5% (120 mg, p = 0.002). Caffeine clearance was increased by 31.6% +/- 20.7% (p < 0.001) with the higher dose. None of the study groups exhibited a significant increase of gamma-glutamyltransferase activity or urinary excretion of D-glucaric acid or 6 beta-hydroxycortisol. This was in contrast to the phenobarbital-type induction observed after treatment with antiepileptic drugs. Induction by omeprazole seems to be restricted to cytochrome P-450 1A enzymes.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗