[Effects of vitamins deficiency on the cytochrome P450 inducibility in rats].

The purpose of the study was to determine multi-vitamin deficiency effects on the inducibility of main isoforms of cytochrome P450 in the rat liver. The study was carried out on 4 groups of Wistar rats. Rats of the 1st and 3rd group received semi-synthetic diets containing adequate (100% of recommended vitamin level) level of vitamins, the 2nd and 4th--the semi-synthetic diet containing vitamins in the amount of 20% from adequate level. The duration of the experiment was 4 weeks. During the last week indole-3-carbinol (I-3-C) in dose of 20 mg/kg body weight was added to the diet of the 3rd and 4th group of rats. Vitamin E content in liver and blood serum declined by 59 and 34%, respectively in rats which were fed vitamin-deficient diet (2nd group); vitamin A level decreased by 5 times in the liver, but was not changed in blood serum. Multi-vitamin deficiency in the diet led to the increase in the liver ethoxyresorufin O-dealkylase (EROD) activity of CYP1A1, methoxyresorufin O-dealkylase (MROD) activity of CYP1A2 and testosteron 6beta-hydroxylase (6beta-TG) activity of CYP3A by 11, 80 and 53%, respectively, and gene expression of CYP1A1, CYP1A2, CYP3A and AhR by 8,5; 1,6; 2,4 and 3,6 fold. In rats fed diet with adequate levels of vitamins (3rd group) I-3-C increased activity of EROD and MROD by 4,4 and 5,5 fold, and the expression of CYP1A1, CYP1A2 and AhR genes by 148; 3 and 3,5 fold compared to the parameters of the 1st group (without I-3-C). Multi-vitamin deficiency increased I-3-C-related induction of EROD activity and expression of CYP1A1 and CYP1A2 genes, but decreased I-3-C-related induction of the MROD activity. Thus, 5-fold reducing of vitamin content in rat diet lead to significant changes in activity and inducibility of cytochrome P450 of CYP1A and 3A family, which play a key role in the detoxification and metabolism of drugs.

Activity of xenobiotic-metabolizing enzymes in the liver of rats with multi-vitamin deficiency.

The purpose of the study was to determine how multi-vitamin deficiency affects xenobiotic-metabolizing enzyme (XME) activities in the rat liver. Vitamin levels and XME activities were studied in the livers of male Wistar rats who were fed for 4 weeks with semi-synthetic diets containing either adequate (100 % of recommended vitamin intake) levels of vitamins (control), or decreased vitamin levels (50 % or 20 % of recommended vitamin intake). The study results have shown that moderate vitamin deficiency (50 %) leads to a decrease of vitamin A levels only, and to a slight increase, as compared with the control, in the following enzyme activities: methoxyresorufin O-dealkylase (MROD) activity of CYP1 A2 - by 34 % (p < 0.05), UDP-glucuronosyl transferase - by 26 % (p < 0.05), and quinone reductase - by 55 % (p < 0.05). Profound vitamin deficiency (20 %) led to a decrease of vitamins A, E, B1, B2, and C, and enzyme activities in the liver: MROD - to 78 % of the control level (p < 0.05), 4-nitrophenol hydroxylase - to 74 % (p < 0.05), heme oxygenase-1 - to 83 % (p < 0.05), and quinone reductase - to 60 % (p < 0.05). At the same time, the UDP-glucuronosyl transferase activity and ethoxyresorufin O-dealkylase activity of CYP1A1, pentoxyresorufin O-dealkylase activity of CYP2B1/2 and 6ß-testosterone hydroxylase, as well as the total activity of glutathione transferase did not differ from the control levels. The study has demonstrated that profound multi-vitamin deficiency is associated with a decrease in the expression of CYP1A2 and CYP3A1 mRNAs to 62 % and 79 %, respectively. These data indicated that a short-term but profound multi-vitamin deficiency in rats leads to a decrease in the activities and expression of the some XME that play an important role in detoxification of xenobiotics and metabolism of drugs and antioxidant protection.

[Effects of polyvitamin deficiency on the activity of xenobiotic-metabolizing enzymes in rat liver].

The activity of xenobiotic-metabolizing enzymes was studied in the liver of male Wistar rats, which were fed for 4 weeks diets, containing 100 (control), 50 and 20% of vitamin adequate level. Moderate (50%) polyvitamin deficiency increased activity of EROD (by 13%), MROD (by 34%; p<0,05), 4-nitrophenol hydroxylase (by 16%), 6beta-testosterone hydroxylase (by 17%), UDP-glucuronosyle transferase (by 26%, p<0,05) and quinone reductase (by 55%, p<0,05). Deep (20%) polyvitamin deficiency decreased in liver activity of MROD (to 78% of control level, p<0,05), 4-nitrophenol hydroxylase (to 74%, p<0,05), heme oxygenase-1 (to 83%, p<0,05) and quinone reductase (to 60%, p<0,05). At the same time a 22% increase in the UDP-glucuronosyle transferase activity compared to the control group was found; activities of EROD, PROD, 6beta-testosterone hydroxylase and the total activity of glutathione S-transferase were unchanged. Deep polyvitamin deficiency had no significant effect on CYP1A1 mRNA and AhR mRNA level, whereas the expression of CYP1A2 mRNA and CYP3A1 mRNA were decreased to 62 and 79%, respectively, as compared with control.

Influence of nutrients and other dietary materials on cytochrome P-450 enzymes.

The cytochrome P-450 (P-450) enzymes are collectively responsible for the bulk of oxidation of xenobiotic chemicals, including drugs, pesticides, and carcinogens. This biotransformation can result in either increased or decreased toxicity, depending on the situation. The regulation of individual P-450 enzymes is a complex subject, with examples of induction and direct inhibition and stimulation. Nutrients and food additives can modify P-450 activities and consequently influence toxicity. P-450s also influence the toxicity of potentially harmful materials found in foods, as well as some vitamins and natural products. Some of the foodstuffs and conditions that influence P-450 in experimental animals and in humans are protein, carbohydrate, lipid, obesity and fasting, water- and fat-soluble vitamins, minerals, sulfides, isothiocyanates, indoles, ellagic acid, capsaicin, terpenes, flavones, butylated hydroxytoluene and hydroxyanisole, charbroiled foods, ethanol, and (monosodium) glutamate and aspartate. Consideration is given, when possible, to differences in responses between animal models and humans.

[Induction of monooxygenase system and incorporation of radioactivity from 2-14C-lysine into proteins of rat liver microsomes under the action of phenobarbital and the background of lysine, methionine, threonine and vitamin A, C and E deficiencies]. / Induktsiia monooksigenaznoi sistemy i vkliuchenie radioaktivnoi metki iz 2-14C-lizina v belki mikrosom pecheni krys pri vozdeistvii fenobarbitala na fone defitsita lizina, metionina, treonina i vitaminov A, C i E

The effect of diet on induction of monooxygenases and distribution of radioactivity from 2-14-C-lysine in fractions of liver homogenate, muscle homogenate and blood of male rats treated with phenobarbital (80 mg/kg, three days) was studied. 2-14-C-lysine was injected intraperitoneally 24 h before the first injection of phenobarbital. It was demonstrated that monooxygenase induction, increase of relative liver weight and incorporation of radioactivity from 2-14-C-lysine into fractions of liver homogenate in phenobarbital-treated rats fed diet deficient in lysine, methionine, threonine and vitamins A, C and E were more pronounced as compared with the similarly treated rats which were fed a balanced diet. The possibility of mobilization of deficient essential components to liver from other organs and tissues for maintenance of monooxygenase induction is discussed.

[The induction of the monooxygenase system and the incorporation of the radioactive label from 2-14C-lysine into the liver microsome fraction of rats exposed to phenobarbital against a background of deficiencies in lysine, methionine, threonine and vitamins A, C and E]. / Induktsiia monooksigenaznoi sistemy i vkliuchenie radioaktivnoi metki iz 2-14C-lizina vo fraktsiiu mikrosom pecheni krys pri vozdeistvii fenobarbitala na fone defitsita lizina, metionina, treonina i vitaminov A, C i E.

The effect of diet on induction of monooxygenases and distribution of label from 2-14C-lysine in fractions of liver homogenate, muscle homogenate and blood of male rats treated with phenobarbital (80 mg/kg, three days) was studied. 2-14C-lysine was injected intraperitoneally 24 h before the first injection of phenobarbital. It was demonstrated that monoxygenase induction, increase of relative liver weight and incorporation of label from 2-14C-lysine into fractions of liver homogenate in phenobarbital-treated rats were more pronounced as compared with the similarly treated rats that were fed a balanced diet. The possibility of mobilization of deficient essential components to liver from other organs and tissues for maintenance of monoxygenase induction is discussed.

[Effect of protein-vitamin deficiency on the enzyme activity of lipolysis and the synthesis of cholesterol esters during hypokinesia]. / Vliianie belkovo-vitaminnoi nedostatochnosti na aktivnost' fermentov lipoliza i sinteza éfirov kholesterina v usloviiakh gipokinezii.

Balanced diet during 60-day hypokinesia leads to inhibition of lipoprotein lypase (LPLA) and liver triglyceride lypase (L-TGLA) activity of the rat blood serum. The level of very low density lipoproteins (VLDLP) grows, and suppression of lecithin-cholesteryl-acyltransferase (LCAT) activity is accompanied by reduction of the share of cholesterol derivatives with polyunsaturated fatty acids. Combined effects of protein-vitamin insufficiency and hypokinesia result in parversion of the lipolysis processes, that manifests in prevalence of L-TGLA over LPLA. The levels of VLDLP increase, and growth of LCAT activity is acompanied by the growth of cholesteryl linoleate share and level. Hypokinesia combined with the studied experimental diets was found to lead to increase of the free fatty acid level and to decrease of the blood serum levels of phospholipids and triglycerides.

[Effect of acute and chronic lindane poisoning on the function of the liver microsome mono-oxygenase system in rats maintained on a diet deficient in lysine, methionine, threonine and vitamins A, C and E]. / Vliianie ostrogo i khronicheskogo otravleniia lindanom na funktsiiu monooksigenaz mikrosom pecheni krys na fone nedostatochnogo postupleniia v organizm lizina, metionina, treonina i vitaminov A, C i E.

Polynutrient deficiency in essential amino acids and vitamins A, C and E led to induction of liver tissue microsomal monooxygenase system in male rats of WAG strain within first 2 hrs and to inhibition of the induction within the subsequent hours after a single dose administration of a pesticide lindane (18 mg/kg) as compared with control animals maintained on a normal diet. The deficiency in essential nutrients caused also a delay in the monooxygenase induction in rats treated daily within 3 months with lindane at a dose of 0.9 mg per kg of body mass. No distinct nutritionally-dependent differences in the rate of the monooxygenase induction were observed after 6 months of the chronic treatment with the pesticide. Activity of monooxygenases in nutritionally-deprived and lindane-treated rats was decreased as compared with the similarly treated rats which were maintained on a normal diet. The induction of monooxygenases in experimental rats was accompanied by an increase in relative mass of liver tissue. The increase in liver tissue mass appears to occur as an adaptive response to the polynutrient deficiency and the effect of xenobiotics in order to maintain the enzymatic system at an adequate functional level.

[Changes in the activity of antioxidant enzymes in an experimental peroxidation syndrome in the rabbit]. / Izmenenie aktivnosti antioksidantnykh fermentov pri éksperimental'nom sindrome peroksidatsii u krolikov.

Activity of the antioxidant enzymes under conditions of experimental syndrome of peroxidation was studied in rabbits maintained at a diet deprived of antioxidants. Peroxidation of lipids was increased in the animals; at the same time, content of the vitamin-antioxidants was decreased in their tissues. Activity of the antioxidant enzymes was distinctly increased within the first steps of the experiment after which it was decreased. The data obtained suggest that deficiency of the vitamin-antioxidants may be transitory compensated by an increase in activity of the antioxidant enzymes; long-term deprivation of bioantioxidants led, however, to inhibition of biosynthesis of the antioxidant enzymes.

The effect of certain vitamin deficiencies on hepatic drug metabolism.

There is increasing evidence that the liver microsomal drug metabolizing system is affected by various vitamins such as ascorbic acid, riboflavin, and alpha-tocopherol. In regard to ascorbic acid deficiency there is a decrease in the quantity of hepatic microsomal electron transport components such as cytochrome P-450 and NADPH-cytochrome P-450 reductase, as well as decreases in a variety of drug enzyme reactions such as N-demethylation, O-demethylation, and steroid hydroxylation. In addition, young animals given high supplements of vitamin C have increased quantities of electron transport components and overall drug metabolism activities. Kinetic studies indicate no change in the apparent Km of N-demethylase, O-demethylase or hydroxylase for drug substrates in animals depleted or given high amounts of the vitamin. However, there are qualitative changes in both type I and II substrate-cytochrome P-450 binding. Ascorbic acid is not involved in microsomal lipid peroxidation or in any qualitative or quantitative change in phosphatidylcholine. Replenishing vitamin C-deficient animals with ascorbic acid required 3 to 7 days for the electron transport components and drug metabolism activities to return to normal levels. Induction with phenobarbital and 3-methylcholanthrene is not impaired in the deficient animal since drug metabolism activities are induced to the same extent as normal controls; however, the administration of delta-aminolevulinic acid, a precursor of heme synthesis, to deficient animals caused an increase in the quantity of cytochrome P-450. The effects of riboflavin deficiency on electron transport components and drug metabolism activities have been noted only in adult animals after prolonged periods of deficiency. Decreases in drug metabolism activities occur with both type I (aminopyrine and ethylmorphine) and type II (aniline) substrates. As was found with ascorbic acid deficiency, drug enzyme induction occurred to the same extent with phenobarbital in deficient and normal animals. In addition, it required from 10 to 15 days for the drug metabolism activities to return to normal levels when deficient animals were replenished with riboflavin. The effect of vitamin E on drug metabolism is specific in N-demethylase activities decrease while O-demethylase activities are not affected in the deficient state. This vitamin differs from ascorbic acid and riboflavin in that several laboratories have reported no quantitative decrease in cytochrome P-450, although there are some reports that it and delta-aminolevulinic acid dehydratase are lowered quantity of cytochrome in E-deficient animals. The effect of vitamin E, if any, on the P-450 is unresolved; an important question that requires further clarification. As with ascorbic acid there is no difference in the apparent Km of N-demethylase enzymes for varous substrates and the protective effect of vitamin E does not appear to be one of an antioxidant inhibiting microsomal lipid peroxidation.