Effect of ascorbic acid and vitamin E on biochemical changes associated with vitamin E deficiency in rats

Weanling male Sprague Dawley rats were fed a vitamin E and C-free basal diet with or without supplementation of 100 IU vitamin E per kg diet. After 20 weeks, the vitamin E-deficient rats were divided into four groups, six in each group, and received supplemental ascorbic acid and/or vitamin E by tube feeding daily for 7 days: Group I, 30 mg ascorbic acid/100 g body wt.; Group II, 0.03 mg RRR-alpha-tocopheryl acetate/100 g body wt.; Group III, 30 mg ascorbic acid and 0.03 mg RRR-alpha-tocopheryl acetate/100 g body wt.; and Group IV, placebo. The six control rats (Group V) received placebo. The rats were sacrificed, blood and liver samples were collected for biochemical determinations. Vitamin E deficiency significantly increased erythrocyte (RBC) spontaneous hemolysis, liver thiobarbituric acid (TBA) value, activities of glutamateoxaloacetate transaminase (GOT), pyruvate kinase (PK), and creatine phosphokinase (CPK) in plasma, and significantly lowered plasma vitamin E levels and glutathione peroxidase (GPX) activities. Tube-feeding ascorbic acid for 7 days produced partial reversal effect on liver TBA values, activities of plasma PK, GOT, CPK, and plasma vitamin E levels but not on RBC hemolysis and plasma GPX activity. Tube feeding both ascorbic acid and vitamin E showed similar partial reversal effect as feeding vitamin E alone on all the parameters stated above. The results suggest that ascorbic acid may spare the metabolism of vitamin E and partially reverse the changes in some of the biochemical parameters characteristic of vitamin E deficiency.     

Effect of dietary ascorbic acid on levels of serum mineral nutrients in guinea pigs

The effect of dietary ascorbic acid on the serum mineral nutrients, Ca, Cu, Fe, K, Mg, Mn, Na and Zn in guinea pigs has been studied. Large amounts of ascorbic acid were administered to experimental animals in their drinking water. The daily ascorbic acid intake from the diet for the control animals was 10 mg/kg body weight. The mean ascorbic acid intakes for the two groups of experimental animals were 366 (37 times control) and 722 (72 times control) mg/kg body weight/day. In the ascorbic acid-treated animals, there was a significant increase in serum ascorbic acid levels in comparison with the controls. No substantial differences were observed in the body weights. The large quantities of dietary ascorbic acid did not influence serum levels of all eight minerals studied when the experimental and control values were compared using the two-tailed Student's t-test. However, serum level of copper in the guinea pigs ingesting a daily dose of 722 mg of ascorbic acid per kg body weight was slightly below control value when one-tailed Student's t-test was used.     

Effect of dietary ascorbic acid, cholesterol and PCB on cholesterol and bile acid metabolism in a rat mutant unable to synthesize ascorbic acid

The effect of acute or chronic ascorbic acid deficiency on the activity of hepatic cholesterol 7 alpha-hydroxylase and fecal excretion of bile acids was investigated in ODS-od/od (OD) rats (a rat mutant unable to synthesize ascorbic acid) fed a purified basal diet or purified diets containing either cholesterol (2%) or polychlorinated biphenyl (PCB) (200 mg/kg). In OD rats, the dietary requirement of ascorbic acid to maintain normal growth and normal levels of cholesterol in serum and liver is about 300 mg of ascorbic acid/kg diet. In OD rats fed the basal diet, acute or chronic ascorbic acid deficiency did not affect the activity of hepatic cholesterol 7 alpha-hydroxylase and fecal excretion of bile acids. However, in OD rats fed diets containing either cholesterol or PCB, acute ascorbic acid deficiency caused a higher level of serum cholesterol, a lower activity of hepatic cholesterol 7 alpha-hydroxylase and a lower excretion of fecal bile acids than in OD rats fed a basal diet containing an adequate level of ascrobic acid. It is concluded that acute ascorbic acid deficiency causes a hypercholesterolemia due to the depression of bile acid synthesis in OD rats fed a purified diet with cholesterol or PCB.     

Effect of dietary ascorbic acid intake on tissue vitamin C in mice

The effect of graded levels of dietary ascorbic acid on blood and tissue ascorbic acid levels in mice has been studied. Six levels of dietary ascorbic acid (0, 0.076, 0.5, 1, 5 and 8%) were used. Plasma ascorbic acid rose as dietary ascorbic acid intake increased from 1 to 8%. Mice fed a diet with 5 or 8% added ascorbic acid had significantly higher levels of ascorbic acid in the heart, kidney, lung, muscle and spleen than did control mice fed an ascorbic acid-free diet. Mice fed a diet with 1% added ascorbic acid had elevated ascorbic acid levels in the heart, kidney, lung and spleen. No significant change was observed in ascorbic acid level in the brain, adrenal gland or leukocytes in any of the experimental groups. Ascorbic acid level in the eyes was only slightly higher in mice fed a diet containing 8% added ascorbic acid than in control mice. The observation that the kidney had the greatest increase in ascorbic acid content suggests that the kidney may be a very important organ not only in elimination but also in catabolism of this vitamin. A diet containing 0.5 or 0.076% added ascorbic acid did not significantly increase ascorbic acid content in any of the organs studied. Mice fed a diet with 0.076% added ascorbic acid had slightly, but statistically significantly, lower levels of ascorbic acid in the liver, lung, muscle and spleen that control mice. Mice fed a diet with 0.5% added ascorbic acid had a lower ascorbic acid content in the liver and muscle than the controls.(ABSTRACT TRUNCATED AT 250 WORDS)     

Response of plasma retinol to dietary changes of ascorbic acid and selenium in the guinea pig

Ascorbic acid (AA) and retinol were measured in plasma and selenium (Se) was measured in erythrocytes of guinea pigs fed a Torula yeast based semipurified diets supplemented with either 0 (-AA), 200 (+AA), or 400 (++AA) mg of AA/kg of diet and either 0.05 (+Se) or 0.2 (++Se) ppm of Se for 24 days. After 24 days on the dietary regimen, plasma AA was shown to be dependent on dietary intake of AA and erythrocyte Se was shown to be dependent on dietary intake of Se. Two groups of guinea pigs, (-AA, +Se) and (-AA, ++Se) had mean body weights of 29.8±2.7 (P<0.001) and 21.2±4.0 (P<0.01)% respectively less than the group of guinea pigs fed AA/Se adequate diets. Plasma retinol was directly correlated with plasma AA (r=0.4322, P<0.001), and there was a trend for plasma retinol to be directly related to the erythrocyte Se levels. This work implies that AA and Se has some undefined “sparing” effect on retinol.     

Long-term effects of dietary polychlorinated biphenyl and high level of vitamin E on ascorbic acid and lipid metabolism in rats

Long-term feeding of purified diets containing (per kg diet) 100 mg of polychlorinated biphenyl (PCB) and 1000 mg of vitamin E (RRR-alpha-tocopheryl acetate) to male Wistar rats was carried out. Rats fed a diet containing PCB rapidly became hypercholesterolemic and maintained high cholesterol levels throughout the 240 d of the experiment. Rats fed a high dietary level of vitamin E plus PCB had higher serum cholesterol and lower liver cholesterol than rats fed a lower level of vitamin E plus PCB. In rats fed PCB, urinary excretion of ascorbic acid was higher than in rats not fed PCB. Urinary ascorbic acid was lower in rats fed high levels of vitamin E plus PCB than in those fed the normal levels of vitamin E plus PCB. Rats fed PCB had lower liver vitamin A storage and higher vitamin A in kidney than rats not fed PCB. This implies that a redistribution of vitamin A occurred in rats fed PCB. Histological observations revealed that central halves of the hepatic lobules of rats fed PCB showed distinct changes consisting of hypertrophy of hepatocytes in the perivenous region and accumulation of vacuoles (lipid droplets) in the cells in the remaining affected portion. Administration of a high dose of vitamin E could not ameliorate this lesion while the treatment depressed effectively the lipid peroxidation. This suggests that the lipid peroxidation was not responsible for the hepatic damage induced by PCB.     

Effect of ascorbic acid nutriture on blood histamine and neutrophil chemotaxis in guinea pigs

Histamine suppresses certain immune responses, including neutrophil chemotaxis. The present study examined whether the histamine-lowering effect of ascorbate was accompanied by enhanced chemotaxis in guinea pigs. Animals were fed low ascorbate, adequate or high ascorbate diets (0.5, 2.0 or 50 mg ascorbate.100 g body wt-1.d-1) for 4 wk. Mean liver ascorbate paralleled dietary intake, and these values differed significantly. Blood histamine was significantly depressed in the high ascorbate group compared to the adequate and low ascorbate groups, and liver ascorbate was inversely correlated to blood histamine levels (r = -0.64, P less than 0.001). The random migration of neutrophils was not significantly affected by vitamin dosage. Leukocyte chemotaxis was significantly impaired in low ascorbate animals compared to that of animals with adequate ascorbate nutriture. Leukocyte chemotaxis in high ascorbate animals did not differ significantly from that in the adequate or low ascorbate groups. Furthermore, chemotaxis was significantly lower when cells extracted from animals with adequate ascorbate nutriture were incubated in low ascorbate or high ascorbate serum rather than in autologous serum. These data suggest that the histamine-lowering effect of supplemental ascorbate does not appear to enhance leukocyte chemotaxis and that serum from guinea pigs fed low or high levels of ascorbate appears to contain factors that depress chemotaxis.     

Effect of dietary ascorbic acid, cholesterol and PCB on cholesterol concentrations in serum and liver in a rat mutant unable to synthesize ascorbic acid

The effect of ascorbic acid deficiency and excessive ascorbic acid intake on serum and liver levels of cholesterol and lipids was investigated in ODS-od/od (OD) rats fed a normal diet, a cholesterol-containing diet or a polychlorinated biphenyl (PCB)-containing diet. The OD rat is a rat mutant unable to synthesize ascorbic acid. In OD rats, the dietary requirement of ascorbic acid to maintain normal growth and normal levels of cholesterol in serum and liver is about 300 mg of ascorbic acid/kg diet. In control (ODS-+/+) rats that can synthesize ascorbic acid, dietary addition of 0.5% cholesterol and 0.25% cholic acid caused elevation of cholesterol concentrations in serum and liver, elevation of total lipids in liver and reduction of the ratio of high density lipoprotein (HDL) cholesterol to total cholesterol in serum. Dietary addition of PCB (200 mg/kg diet) caused elevation of serum concentration of cholesterol and of the ratio of HDL-cholesterol to total cholesterol in serum. In OD rats fed a normal diet, ascorbic acid deficiency slightly elevated serum concentration of cholesterol, elevated liver concentration of cholesterol and reduced the ratio of HDL-cholesterol to total cholesterol in serum; and ascorbic acid excess did not affect serum and liver concentrations of cholesterol and the ratio of HDL-cholesterol to total cholesterol in serum. In OD rats fed a cholesterol-containing diet, ascorbic acid deficiency elevated serum and liver concentrations of cholesterol, and did not affect the ratio of HDL-cholesterol to total cholesterol in serum; and ascorbic acid excess did not affect serum and liver concentrations of cholesterol and the ratio of HDL-cholesterol to total cholesterol in serum.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of erythorbic acid administration on activities of drug metabolic enzyme and phosphatases in guinea pigs administered an adequate amount of ascorbic acid

The effect of erythorbic acid (ErA) administration on activities of liver aniline hydroxylase, liver acid phosphatase, and serum alkaline phosphatase, and the content of liver cytochrome P-450 was studied to determine whether or not ErA would affect the availability of ascorbic acid (AsA) in normal and AsA-deficient guinea pigs. In experiment I, changes of the enzyme activities and liver cytochrome P-450 content in the guinea pigs administered AsA and/or ErA and sacrificed on days 4, 10, 16, and 30 were examined. Moreover, in experiment II, after 16 days of depletion of AsA, the guinea pigs were administered AsA and/or ErA. These animals were sacrificed on days 0, 4, and 20 of the repletion period, after which the activities of drug metabolic enzyme and phosphatases and content of cytochrome P-450 during recovery were observed. The enzyme activities and cytochrome P-450 content of AsA-supplemented guinea pigs were similar to those of ErA-supplemented animals and also similar to those of both AsA and ErA-supplemented guinea pigs throughout the experimental period. During the repletion of the AsA-depleted guinea pigs, there were no significant differences in these enzyme activities and cytochrome P-450 content among the animals administered AsA and/or ErA. These results suggested that ErA administration may not affect the AsA availability in the guinea pigs.     

Effect of estrogens on ascorbic acid in the plasma and blood vessels of guinea pigs

The administration of mestranol to guinea pigs resulted in a marked reduction of the ascorbic acid concentration in their blood plasma and an even greater reduction in the ascorbic acid concentration in their blood vessels. Theoretically, these changes could lower the negative potential of the blood vessel wall and might therefore predispose to intravascular thrombosis.     

Bile acid metabolism in ascorbic acid-deficient guinea pigs.

Sterol balance techniques have been used to determine the effect of short-term ascorbic acid (AA) deprivation on bile acid excretion in the guinea pig. The effects of a brief (2-week) AA deficiency on bile acid pool sizes and the activity of the rate controlling enzyme in bile acid biosynthesis have been determined. It was found that, while food intake and body weight were not affected by the short-term AA deficiency, liver AA levels had fallen to 25% of control levels. At the same time, the rate of excretion of bile acids and the size of the bile acid pool were both reduced by about 50% in guinea pigs deficient in AA. These results were supported by a decrease in the activity of cholesterol 7 alpha-hydroxylase in the deficient animals. It is concluded that an AA deficiency will significantly impair bile acid metabolism independent of any side effects of clinical scurvy.     

Effects of dietary vitamin E and high level of ascorbic acid on iron distribution in rat tissues

The effects of dietary vitamin E and high-level supplementation of ascorbic acid on iron distribution in rat tissues were studied. Weanling male Sprague-Dawley rats, fed ad libitum a vitamin E and ascorbic acid free basal diet, were divided into four groups. They were supplemented with 0 or 45 IU/kg diet of vitamin E, and O or 0.2% ascorbic acid in a 2 X 2 complete factorial design. After 12 weeks, rats were killed; blood, liver, spleen, heart and skeletal muscle were collected for analysis. Vitamin E deficiency resulted in significantly decreased plasma iron levels and total iron binding capacity. The total iron and nonheme iron contents of the liver and spleen were significantly higher in the vitamin E-deficient groups compared with control groups. Vitamin E or ascorbic acid supplementation had no effect on iron content of the heart. Non-heme iron levels on per gram tissue were highest in the skeletal muscle of the group to which no vitamin E or ascorbic acid were supplemented. It appears that vitamin E and ascorbic acid interactively affect the iron distribution in rat tissues.     

Effect of graded doses of erythorbic acid on ascorbic acid content of tissues of guinea pigs

The effect of graded doses of erythorbic acid (ErA) on the content of ascorbic acid (AsA) in the tissues of guinea pigs administered AsA was studied. The guinea pigs were administered 5 mg AsA and 1, 5, 20, and 100 mg ErA; or 1 mg AsA and 1 and 20 mg ErA; or 20 mg AsA and 20 mg ErA for 16 days. The animals were then sacrificed, and the liver, adrenal glands, spleen, and kidneys were removed to determine the contents of AsA and ErA by using HPLC. The content of AsA in the tissues of the animals administered less than 5 mg ErA together with 5 mg AsA was not significantly different from that of the animals administered 5 mg AsA. The administration of 100 mg ErA together with 5 mg AsA caused a decrease in the amount of AsA in the tissues. The content of AsA in the tissues of the animals administered ErA together with 1 mg AsA was not significantly different from that of the animals administered 1 mg AsA. In the case of animals administered an equal amount of both AsA and ErA, the AsA tissue content was consistently much higher than that of ErA. These results indicated that the administration of relatively small amounts of ErA did not appear to reduce the availability of AsA.     

Effect of single oral doses of ascorbic acid on body temperature in healthy guinea pigs

A series of experiments were conducted to examine the effect of single oral doses of ascorbic acid on body temperature in healthy guinea pigs. Fifteen male guinea pigs (approximately 200 g) were fed a nonpurified diet designed for rabbits (a scorbutogenic diet) ad libitum and received orally 2 mg L-ascorbic acid/100 g body wt daily. After acclimation, rectal temperatures were recorded hourly following five separate ascorbate dosage treatments: 0 (control dosage), 2, 10 or 50 mg ascorbic acid/100 g body wt, or 50 mg ascorbic acid and 0.07 mg indomethacin/100 g body wt. Mean body temperature was significantly elevated (P less than 0.05) after 1 h in animals receiving either the 10 or 50 mg dosage (+ 0.27 +/- 0.05 and + 0.41 +/- 0.07 degree C, respectively) compared to that in animals receiving the 2 mg dosage (-0.07 +/- 0.05 degree C), the recommended daily intake for guinea pigs. Changes in body temperature of animals receiving the 50 mg dosage plus indomethacin did not differ significantly from those reported with the 2 mg dosage. Thus, a single oral dose of ascorbic acid at levels 5-25 times the recommended intake, can elevate body temperature significantly in healthy guinea pigs, a phenomenon which is inhibited by indomethacin administration.