Effects of high and low doses of vitamins A and E on the excitability of frog cardiomyocytes

The effects of complex vitamins A and E on electrophysiological characteristics was investigated on frog cardiomyocytes. Large doses of vitamins A and E decreased the steepness of the action potential (AP) front, decreased the spike amplitude, shortened the plateau, decreased the steepness in the last phase of AP-repolarization, and decreased the rest potential level but considerably increased overshoot. The Ap-duration decreased noticeably. Small doses of vitamins decreased the spike amplitude, shortened the plateau, decreased the Ap-duration. We assume that complex of vitamins A and E can affect the cardiomyocyte membrane transport function, mainly due to the suppression of the slow membrane channels. The AP-front increase is less steep under the influence of vitamins. It is shown that the 0-phase depolarization speed decreases due to the inhibition of sodium channels.     

Effect of gamma-radiation on the content of vitamin E in rats

The dynamics of vitamin E dose-dependence in the blood serum of Vistar line male rats after the total single irradiation with 60Co gamma-quantums in 0.2; 0.5; 1.0; 3.0 and 5.0 Gy doses (during 120 days); 7.0 Gy (during 20 days); 9.0 Gy (during 15 days) were studied. The vitamin E content values both in the norm and in 0.5, 1, 2, 4, 6, 8, 10, 15, 20, 30, 45, 65, 90 and 120 days after irradiation are given. The experiment data show that the dose dependence of vitamin E products has wavelike character. The possible causes of the vitamin E level decrease under intake of small and high doses of gamma-irradiation are discussed.     

Regulation of ovarian antioxidant vitamins, reduced glutathione, and lipid peroxidation by luteinizing hormone and prostaglandin F2 alpha.

Reactive oxygen species are generated by the rat ovary, and they evoke marked antigonadotropic responses in ovarian cells. Protection against reactive oxygen species is provided by antioxidants such as vitamins C, E, and A, and reduced glutathione (GSH). Our objectives were to establish the ovarian levels of these antioxidants during development and regression of the corpus luteum of the pseudopregnant rat and to determine whether these levels were changed by an acute treatment with either a luteotropic (LH) or luteolytic (prostaglandin [PG] F2 alpha) agent. In addition, we evaluated the extent of oxidative activity in the ovary by determining the level of lipid peroxidation. Follicular development was associated with a significant increase in ovarian levels of vitamin A and GSH, whereas levels of vitamins E and C were unchanged. During the luteal phase, vitamin E levels tended to increase, whereas vitamin A and GSH levels decreased. Luteal regression was associated with a marked increase in ovarian levels of vitamins E and A, whereas GSH levels increased only transiently. Acute treatment with LH in the midluteal phase produced a transient decrease in vitamin C levels that was maximal at 4 h. Luteal vitamin E levels were markedly increased 24 h after LH treatment, whereas vitamin A levels were unchanged, and no evidence of lipid peroxidation was seen. Acute treatment with PGF2 alpha produced a transient decrease in luteal vitamin C levels coincident with transient lipid peroxidation and a sustained fall in serum progesterone levels. Ovarian vitamin A levels were elevated 24 h after PGF2 alpha treatment.(ABSTRACT TRUNCATED AT 250 WORDS)     

Potency of peroral and parenteral administration of Zinc-DTPA for decorporation of 241Am from the gastrointestinal tract

An effect of cincacine at three doses (25, 150 and 300 mumol/kg) has been studied in rats receiving 241Am citrate intragastrically. The radionuclide was introduced every other day for 2 weeks. The total content was 925 kBq/kg. A cincacine administration leads to limitation of radionuclide accumulation in the major organs of deposition independent of the modes of intake. At gastrointestinal 241Am intake peroral cincacine administration is more effective in limiting this radionuclide accumulation in skeleton but less effective in reduction of its accumulation in liver compared to parenteral cincacine. No reliable dependence of cincacine efficacy on dosage has been revealed. A morphology study of organs has shown that cincacine ingestion at a dose of 150 mumol/kg for 4 weeks and at a dose of 300 mumol/kg for 2 weeks produces a toxic effect on the small intestine mucosa. 25 mumol/kg is the optimum dose and per os administration of higher doses is not expedient.     

Dietary supplementation of vitamin A, C and E prevents p-dimethylaminoazobenzene induced hepatic DNA damage in rats

The preventive effect of antioxidant vitamins A, C, E and their analogues against DNA damage induced by a hepatocarcinogen p-dimethylaminoazobenzene (DAB) was assessed by comet assay. For genotoxicity (DNA damage) study, male albino rats were divided into 11 groups, consisting of four rats each. Group I served as control. Group II to VII received 1, 10, 100, 200, 300 and 400 mg per kg body wt of DAB respectively; group VIII to XI received 500 mg/kg body wt of DAB. They were sacrificed by cervical decapitation 3, 6, 12 and 24 h after treatment; livers were excised immediately and subjected to comet assay to measure DNA damage. To study the effect of vitamins, experiments were conducted on a group of 275 rats divided into 3 sets of 25 rats each. First set served as control; second set received 0.06% DAB and third set received 0.06% DAB, along with analogues of vitamins A, C and E. Rats fed with 0.06% DAB were provided water ad libitum for a period of 4 months, followed by a normal (basal) diet for further 2 months. Vitamins A (10,000-50,000 IU), C (75-1000 mg) and E (50-500 mg) and their analogues were given (per kg body wt) to the third set of rats by gavage route once in a week for a period of 6 months. The DAB induced DNA damage only at the highest tested dose of 500 mg/kg body wt. Administration of high doses of vitamin A acid, L-ascorbic acid and vit. E succinate individually prevented the DNA damage. However, administration of a mixture of these vitamins at low doses prevented the DAB-induced DNA damage, which may be due to their synergistic effect. The results indicate that there is a significant advantage in mixed vitamins therapy at low dose over the treatment with individual vitamins.     

Normal adaptations to exercise despite protection against oxidative stress

It has been reported that supplementation with the antioxidant vitamins C and E prevents the adaptive increases in mitochondrial biogenesis and GLUT4 expression induced by endurance exercise. We reevaluated the effects of these antioxidants on the adaptive responses of rat skeletal muscle to swimming in a short-term study consisting of 9 days of vitamins C and E with exercise during the last 3 days and a longer-term study consisting of 8 wk of antioxidant vitamins with exercise during the last 3 wk. The rats in the antioxidant groups were given 750 mg·kg body wt(-1)·day(-1) vitamin C and 150 mg·kg body wt(-1)·day(-1) vitamin E. In rats euthanized immediately after exercise, plasma TBARs were elevated in the control rats but not in the antioxidant-supplemented rats, providing evidence for an antioxidant effect. In rats euthanized 18 h after exercise there were large increases in insulin responsiveness of glucose transport in epitrochlearis muscles mediated by an approximately twofold increase in GLUT4 expression in both the short- and long-term treatment groups. The protein levels of a number of mitochondrial marker enzymes were also increased about twofold. Superoxide dismutases (SOD) 1 and 2 were increased about twofold in triceps muscle after 3 days of exercise, but only SOD2 was increased after 3 wk of exercise. There were no differences in the magnitudes of any of these adaptive responses between the control and antioxidant groups. These results show that very large doses of antioxidant vitamins do not prevent the exercise-induced adaptive responses of muscle mitochondria, GLUT4, and insulin action to exercise and have no effect on the level of these proteins in sedentary rats.     

Vitamin Intake Reduce the Risk of Gastric Cancer: Meta-Analysis and Systematic Review of Randomized and Observational Studies

Aim

The association between vitamin intake and gastric cancer (GC) has been widely debated due to the relatively weak evidence. In this study, a meta-analysis of prospective and well designed observational studies were performed to explore this association.

Methods

MEDLINE, Cochrane Library, and Sciencedirect were searched for studies of vitamin consumption and gastric cancer. This produced 47 relevant studies covering 1,221,392 human subjects. Random effects models were used to estimate summary relative risk (RR). Dose-response, subgroup, sensitivity, meta-regression, and publication bias analyses were conducted.

Results

The RR of gastric cancer in the group with the highest vitamin intake was compared to that of the lowest intake group. Total vitamin intake was 0.78 (95% CI, 0.71−0.83). In 9 studies that individuals were given doses at least 4 times above the tolerable upper intake (UL) vitamins, the RR was 1.20 (95% CI, 0.99−1.44). However, in 17 studies that individuals received doses below the UL, the RR was 0.76 (95% CI, 0.68−0.86). Dose-response analysis was conducted on different increments in different types of vitamins (vitamin A: 1.5 mg/day, vitamin C: 100 mg/day, vitamin E: 10 mg/day) intake with a significant reduction in the risk of gastric cancer, respectively, 29% in vitamin A, 26% in vitamin C, and 24% in vitamin E.

Conclusion

This meta-analysis clearly demonstrated that low doses of vitamins can significantly reduce the risk of GC, especially vitamin A, vitamin C, vitamin E.     

Dietary regulation of ornithine transcarbamylase mRNA in liver and small intestine

In the rat, changes in dietary protein intake give rise to changes in the levels of ornithine transcarbamylase (OTC) in liver and small intestine--an increase in liver and decrease in small intestine. The changes in enzyme level are accompanied by similar changes in levels of specific mRNA. Thus in liver, there is an increase in the level of specific mRNA when protein intake is increased, whereas in small intestine there is a small decrease. Comparison of changes in specific mRNA with total poly-A-containing RNA showed that the change in OTC mRNA in liver paralleled the change in total RNA levels. In contrast, in small intestine the small decrease in OTC mRNA levels when protein intake was increased was in the face of an increase in the level of total mRNA. Whereas the level of OTC is 20-fold higher in liver than in small intestine, the mRNA level for the enzyme differs by only 2.5-fold.     

Thermogenesis, energy intake and serum leptin in Apodemus chevrieri in Hengduan Mountains region during cold acclimation

Environmental factors play an important role in the seasonal adaptation of body mass and thermogenesis in small, wild mammals. The purpose of the present study was to test the hypothesis that ambient temperature was a cue to trigger the adjustments in body mass, energy intake, and serum leptin level in Apodemus chevrieri during 42 days of cold exposure. Our data demonstrated that cold acclimation induced a decrease in body mass and a significant increase in energy intake in A. chevrieri. Serum leptin levels were positively correlated with body mass and fat mass. These data suggest that A. chevrieri reduced the body mass and increased energy intake and thermogenic capacity under cold acclimation. Further, serum leptin appears to be involved in the energy intake regulation and thermoregulation.     

Modulation of restraint stress induced oxidative changes in rats by antioxidant vitamins

In the present study we examined immobilization stress-induced antioxidant defense changes in rat plasma and also observed the antioxidant effects of pre and post vitamins A, E and C administration (15 mg/Kg of body weight) individually and in combination (vit E + C) on these alterations.Following immobilization stress the circulating activities of superoxide dismutase, catalase and glutathione-S-transferase were decreased, while the level of thiobarbituric acid reactive substances (TBARS) was increased as compared to non-stressed control rats.Post treatment with individual vitamins A, E and C (after exposure to stress) resulted in a less marked alteration of plasma TBARS levels and activities of SOD, GST and catalase as compared to pre vitamin stress or stress alone treatments. Both pre and post vitamin treatments were effective in preventing stress induced derangement of free radical metabolism with a relative dominance by latter. The combined treatment with vitamin E and C did not show any additive antioxidant effect on restraint stress induced altered free radical metabolism, rather a predominant effect similar to vitamin E alone was observed. The prevention of oxidative stress generated in response to restraint stress by the vitamins can be summarized as: vitamin (E + C) i.e. vit E > vit C > vit A, thus combined vitamin (E + C) treatment though showed maximum preventive effect, but was similar to vitamin E treatment alone, in terms of the circulating activities of SOD, GST, catalase and TBARS levels.     

AZT induces oxidative damage to cardiac mitochondria: protective effect of vitamins C and E

AZT (zidovudine) is a potent inhibitor of HIV replication and a major antiretroviral drug used for AIDS treatment. A major limitation in the use of AZT is the occurrence of severe side effects. The aim of this work was to test whether AZT causes oxidative damage to heart mitochondria and whether this can be prevented by supranutritional doses of antioxidant vitamins. An experimental animal model was used in which mice were treated with AZT for 35 days (10 mg/kg/day) in drinking water. Animals treated with antioxidant vitamins were fed the same diet as controls but supplemented with vitamins C (ascorbic acid, 10 g/ kg diet) and E (alpha-dl-tocopherol, 0.6 g/kg diet) for 65 days before sacrifice. This resulted in a daily intake of 1250 mg/kg/day (vitamin C) and 75 mg/kg/day (vitamin E). Cardiac mitochondrial DNA (mtDNA) of mice treated with AZT had over 120% more oxo-dG (8-oxo-7,8-dihydro-2'-deoxyguanosine, which is a biomarker of oxidative damage to DNA) in their mitochondrial DNA than untreated controls. AZT treatment also caused an increase in mitochondrial lipid peroxidation and an oxidation of mitochondrial glutathione. Dietary supplementation with supranutritional doses of the antioxidant vitamins C and E protected against these signs of mitochondrial oxidative stress. The oxidative effects of AZT are probably due to an increase in production of reactive oxygen species by mitochondria of AZT-treated animals, raising the possibility that oxidative stress may play an important role in the cardiotoxicity of AZT.     

Endotoxin-challenges precocial neonates and iron changes

In adult mammals fever is associated with the reduction of blood plasma iron level. Immature mammals, however, show either a decrease (precocial animals such as guinea pig neonates) or a lack of reduction (altricial animals such as human neonates) of plasma iron in response to endotoxin. In order to determine whether this difference is connected with maturity just after delivery, plasma iron concentration, hematocrit, body temperature and body mass were measured in rat pups injected with E. coli endotoxin in doses of 50 or 200 μg kg⁻¹. Rat pups, like human neonates, are altricial animals. In 7-day-old rats injection of LPS led to a dose-dependent decrease in plasma iron level. The fall in plasma iron was accompanied by changes in body temperature and body mass. The results showed that plasma iron response to endotoxin in altricial rat neonates is similar to that observed in precocial guinea pig pups. Accepted: 4 October 1996     

Protective action of vitamins on the spermatogenesis in lead-treated Swiss mice

The protective action of vitamins C and E against lead acetate-induced reduced sperm count and sperm abnormalities in Swiss mice has been studied. Intraperitoneal injection of lead acetate (10mg/kg body weight) in the present study stimulates lipid peroxidation in the testicular tissue, indicated by a significant increase in malondialdehyde content in the experimental mice group. This is associated with an increased generation of noxious reactive oxygen species (ROS). Significantly reduced sperm count associated with increased sperm abnormality percentage in the lead-injected mice group compared to controls substantially proves the ongoing damaging effects of lead-induced ROS on developing germ cells. However, intraperitoneal administration of vitamin C (Vit C) at a concentration equivalent to the human therapeutic dose (10 mg/kg body weight) was able to minimize significantly the testicular malondialdehyde content with a concomitant increase in sperm count and significant decrease in the percentage of abnormal sperm population. Vitamin E (Vit E) (100 mg/kg body weight) treatment of a batch of lead-injected mice had a similar effect as Vit C but with a comparatively lower efficacy. On the other hand, coadministration of both vitamins (Vit C + Vit E) at the above mentioned doses to lead-treated mice led to the most significant decline in malondialdehyde content along with elevated sperm count and reduction in the percentage of abnormal sperm population. The protective action and the synergistic action of both vitamins (C and E) against lead-induced genotoxicity are discussed.     

Effects of methionine containing paracetamol formulation on serum vitamins and trace elements in male rats

Methionine is an effective antidote in the treatment of paracetamol-induced toxicity but at large doses it has been reported to induce or aggravate a number of pathological conditions. It also alters plasma levels of many vital elements and molecules. This study was designed to identify if the alteration observed for antioxidant vitamins and minerals especially at sub-toxic and toxic levels of exposure in our earlier study of 24-hour exposure period may warrant trace elements supplementation. This was investigated by carrying out a 48-hour study to test the ability of a living organism to restore homeostasis of these vital molecules and elements. The levels of antioxidant minerals and vitamins were estimated in the serum samples obtained from adult male Wistar rats exposed to paracetamol tablets. At 100 mg\kg BW (body weight) vitamin A, niacin, riboflavin, selenium and manganese were not significantly different from the control group. Moreover at 350 mg\kg, all these indices except zinc were not significantly different in the exposed group compared with controls whereas at 1000 mg\kg level of exposure manganese, selenium and vitamin E were not significantly decreased at the end of 48 hours of exposure but copper, niacin and vitamin A were significantly increased in the exposed group compared with the controls. These results suggest that with time the body may be capable of bringing about restoration of the levels of some of these elements\vitamins. This was more evident at 350 mg\kg level of exposure than a higher dose of 1000 mg\kg level.Keywords: Paracetamol formulation, Vitamins, Trace elements.     

Adaptive character of metabolism in Eothenomys miletus in Hengduan Mountains region during cold acclimation

Environmental factors play an important role in the seasonal adaptation of body mass and thermogenesis in small, wild mammals. The purpose of the present study was to test the hypothesis that ambient temperature was a cue to trigger the seasonal adjustments in body mass, energy intake, uncoupling protein 1 (UCP1) in brown adipose tissue (BAT), and other biochemical characteristics of Eothenomys miletus during 49 days of cold exposure. Our data demonstrated that cold acclimation induced a remarkable decrease in body mass, a significant increase in energy intake and metabolic rate, and high expression of UCP1 in BAT of E. miletus. Biochemical characteristics of BAT and liver respiration were also increased following cold acclimation. These data suggest that E. miletus reduced the body mass and increased energy intake and expenditure under cold acclimation. Increased expression of UCP1 was potentially involved in the regulation of energy metabolism and thermogenic capacity following cold acclimation.     

The influence of B-group vitamins on monooxygenase activity of cytochrome P450 3A4: Pharmacokinetics and electro analysis of the catalytic properties

Simultaneous administration of loading doses of B-group vitamins and diclofenac allow to decrease the daily dose of this drug without reduction of its analgesic effect. In all three schemes of the diclofenac intake (diclofenac alone, diclofenac plus 2 tablets of Gitagamp (a mixture of B-group vitamins), and diclofenac plus 4 tablets of Gitagamp—maximal concentration of blood diclofenal (C_max) was observed 1 h after the treatment. In the case of diclofenac treatment alone, with 2 tablets of Gitagamp, and with 4 tablets of Gitagamp C_max values were 1137.2 ± 82.4, 1326.7 ± 122.5 and 2200.4 ± 111.3 ng/mL, respectively. Thus, loading doses of B-group vitamins caused a statistically significant effect on the C_max value of blood diclofenac concentration; they also reduced manifestations of the pain syndrome. Pharmacodynamics and pharmacokinetics data were confirmed in electrochemical studies of cytochrome P450 3A4 (CYP3A4) activity. This enzyme was immobilized onto screen printed graphite electrodes modified with gold nanoparticles and synthetic membrane-like compound didodecyldimethylammonium bromide (DDAB/Au). Electrochemical analysis revealed the influence of B-group vitamins on metabolism of the non-steroidal anti-inflammatory drug diclofenac catalyzed by cytochrome P450 3A4. Comparative analysis of the effect of 300 μM vitamins of the B-group (B₁, B₂, and B₆) demonstrated that riboflavin was the most effective inhibitor of diclofenac hydroxylation catalyzed by CYP3A4. These data support possibility of regulation of pharmacokinetic parameters and manifestation of pharmacodynamic effects by loading doses of B-group vitamins, which regulate the catalytic activity of drug metabolizing enzymes such as cytochrome P450 3A4.     

Phospholipid Hydroperoxides and Lipid Peroxidation in Liver and Plasma of ODS Rats Supplemented with α-Tocopherol and Ascorbic Acid

Forty-five mutant male ODs rats, unable to synthesize ascorbic acid, were fed nine diets containing 5, 50 or 250 mg of vitamin E/kg diet and 150,300 or 900 mg of vitamin C/kg diet for 21 days. The concentrations of vitamins C and E increased in liver and plasma in relation to the level of these vitamins in the diet. Vitamin C dietary supplementation increased the plasma vitamin E content at low levels of vitamin E intake, supporting the concept of an in vivo synergism between both antioxidant vitamins. Vitamin C, at the dietary levels studied, did not affect the lipid peroxidation. Vitamin E decreased liver and plasma endogenous levels of thiobarbituric acid-reactive substances and liver sensitivity to non-enzymatic lipid peroxidation. This was confirmed by a highly specific assay of lipid hydroperoxides using high performance liquid chromatography with chemiluminescence detection. The hepatic concentration of both phosphatidylcholine and phosphatidylethanolamine hydroperoxides decreased as the vitamin E content of the diet increased. The results show for the first time the capacity of vitamin E to protect against peroxidation of major phospho-lipids in vivo under basal unstressed conditions.     

Effect of naphthoquinones and tocopherols on the level of integral proteins in mitochondrial membranes and DNA levels in rat and rabbit tissue

Naphthoquinones and tocopherols are studied for their effect on the state of integral proteins of the mitochondrial liver and myocardium membranes in the experiments on the male rats and rabbits. It is established that deficiency of vitamins K and E in the organism (naphthoquinones and tocopherols) is followed by a decrease in the content of integral proteins and by disturbances in correlation of their fractions. These changes in K, E-avitaminosis are accompanied by a decrease of the DNA content in the tissues. Realization of K and E vitamins on the level of structural biomembrane organization is supposed to be possible.     

Fasting and lactation effect fat-soluble vitamin A and E levels in blood and their distribution in tissue of grey seals (Halichoerus grypus)

Grey seals among other phacoids represent a good model to study the mobilisation, transfer and deposition of fat-soluble components such as vitamins in lactating females and suckling pups because during the lactation period mothers may fast completely while secreting large quantities of high fat milks, and pups deposit large amounts of fat as blubber. The level of vitamins A and E in different tissues (liver, adipose tissue, kidney, heart, skeletal muscle, testis) and blood plasma of adult grey seal females and males changed as a result of fasting and lactation; changes were also observed in pups. The most obvious effects were a significant increase of retinol and a decrease of vitamin E levels in plasma of females with the onset of lactation as well as a substantial decrease in liver vitamin E. In suckling pups both retinol and vitamin E levels in plasma increased with the onset of suckling; after weaning no changes in retinol but a significant decrease in plasma vitamin E was observed. While liver vitamin A levels tended to be unaffected by suckling or post-weaning fast, liver vitamin E levels increased with the uptake of milk substantially (P<0.01) and returned at weaning to low levels similar to that in fetuses. Adipose tissue levels of vitamin A and E in both females and pups were only marginally affected by lactation, suckling or post-weaning fast. Results indicate that both plasma and liver levels of vitamin A and E are affected by the mobilisation, absorption and deposition of these components during lactation in seals to a much greater extent than adipose tissue, from which fat-soluble vitamins are mobilized at rates similar to that of lipids.     

Comparison of the effects of neuropeptide Y and adrenergic transmitters on LH release and food intake in male rats

In view of the recent demonstrations that Neuropeptide Y (NPY) and adrenergic transmitters coexist in neurons of the rat brain, we have compared the effects of intraventricular (Ivt) injections of NPY and catecholamines on LH release and food intake in intact male rats. Of the three catecholamines, dopamine (DA), norepinephrine (NE) and epinephrine (E), only E (5.3 micrograms or 15.9 micrograms/rat) significantly stimulated LH release, although NE and E (5.3 micrograms/rat) were equally effective in eliciting food intake in satiated rats. Ivt administration of 10 micrograms NPY significantly stimulated LH release, whereas either lower (0.5 or 2 micrograms/rat) or higher (25 micrograms/rat) doses were ineffective. In contrast, NPY at doses of 0.5 - 10 micrograms/rat increased cumulative food intake in a dose-related fashion. These findings present preliminary evidence of the physiological correlates of the neuronal coexistence of adrenergic transmitters and NPY in the brain and raise the possibility that NPY may normally act either independently, in concert with or via adrenergic systems to evoke LH release and feeding responses in the rat.