Oxidant/antioxidant status in liver tissue of vitamin B6 deficient rats

BACKGROUND AND AIMS: The aim of this study was to evaluate the lipid peroxidation and antioxidant function in liver tissue of vitamin B6 deficient rats and investigate relationship among these parameters in either group. METHODS: Twenty-four male rats with a weight of 48-59 g were used for the experiment. The rats were divided into control (n=12) and vitamin B6 deficient groups. After 4 weeks of feeding, the rats were killed by cervical dislocation and liver tissues were removed. Biochemical measurements in liver tissue were carried out using a spectrophotometer. RESULTS: Liver tissue antioxidant potential, superoxide dismutase, glutathione peroxidase, glutathione-S-transferase, total (enzymatic plus non-enzymatic) superoxide scavenger activity, non-enzymatic superoxide scavenger activity, glutathione levels were significantly lower in vitamin B6 deficient rats than in control group. However, liver tissue glutathione reductase activity, and MDA values were significantly higher in vitamin B6 deficient rats than in control group. CONCLUSIONS: These results explicitly indicate that vitamin B6 deficiency causes a decrease in antioxidant defense system and an increase in oxidant stress in liver tissue in rats.     

The influence of dietary vitamin E and calcium status on intestinal tumors in rats.

Male Sprague-Dawley rats were fed from weaning low (1-5 ppm) and normal (26-50 ppm) vitamin E diets for 30-34 weeks. Dietary fat was also varied from 5% (Experiment 1) to 20% (Experiments 2 and 3). Intestinal tumors were induced by 1,2-dimethylhydrazine given subcutaneously as 10 weekly doses at 20 mg/kg body wt. Tumor incidence was lower by 30% and burden was 25%-50% lower for low vitamin E rats than for vitamin E-replete rats. This result was independent of the fat content of the diet. In Experiment 3, vitamin E and calcium were assessed for their influence on intestinal tumors at two levels, with dietary vitamin E at 5 and 50 ppm and calcium at 0.2% and 1.0% in a 2 x 2 factorial experiment. The high calcium-low vitamin E diet produced the greatest fall in tumor incidence and burden relative to the other treatments. In this experiment, vitamin E deficiency reduced tumor incidence and calcium supplementation reduced tumor burden, with a significant interaction of the two. However, this group also showed evidence of reduced food intake and kidney change (calcification), which may have confounded the result. This points to a risk associated with this combination of nutrients at these levels in long-term experiments.     

Effects of high level of vitamin C on tissue antioxidant status of guinea pigs.

Two groups of weanling male Hartley guinea pigs maintained on vitamin E deficient diet were supplemented with 0.4 I.U./100 g body weight/day of vitamin E and either 2 (Group A) or 10 (Group B) mg/100 g body weight/day of vitamin C for 5 weeks. As compared to Group A, the degree of erythrocyte hemolysis and liver TBAR level of Group B were significantly increased while plasma vitamin E and erythrocyte GSH levels were significantly decreased. In another experiment, two groups of guinea pigs were given 0.8 I.U./100 g body weight/day of vitamin E and 2 (Group C) or 30 mg/100 g body weight/day (Group D) of vitamin C. Levels of plasma vitamin E and erythrocyte GSH of Group D were significantly lower than those of Group C: however, erythrocyte hemolysis and liver TBAR were not affected by the level of vitamin C supplementation. The results suggest that the high levels of vitamin C supplementation lowered tissue antioxidant potential of animal when vitamin E was marginally adequate, and the hemolytic and peroxidizing effect of high level of vitamin C may be counteracted by increasing the level of vitamin E.     

Influence of Piper betle on hepatic marker enzymes and tissue antioxidant status in ethanol-treated Wistar rats

Piper betle L. is a commonly used masticatory in Asia. This study was carried out to investigate the hepatoprotective and antioxidant properties of P. betle, using ethanol intoxication as a model of hepatotoxic and oxidative damage. Ethanol-treated rats exhibited elevation of hepatic marker enzymes and disturbances in antioxidant defense when compared with normal rats. Oral administration of P. betle extract (100, 200, or 300 mg/kg body weight) for 30 days significantly (P <.05) decreased aspartate aminotransferase (AST), alanine aminotransferase (ALT), thiobarbituric acid reactive substances (TBARS), and lipid hydroperoxides in ethanol treated rats. The extract also improved the tissue antioxidant status by increasing the levels of nonenzymatic antioxidants (reduced glutathione, vitamin C, and vitamin E) and the activities of free radical-detoxifying enzymes such as superoxide dismutase, catalase, and glutathione peroxidase in liver and kidney of ethanol-treated rats. The highest dose of P. betle extract (300 mg/kg body weight) was most effective. The results were comparable with the known hepatoprotective drug, silymarin. These results indicate that P. betle could afford a significant hepatoprotective and antioxidant effect.     

Maternal aerobic exercise and vitamin B-6 status

Effects of an aerobic walking program during gestational weeks 22-30 on vitamin B-6 status and birth outcome were studied in 28 healthy pregnant women, aged 21-36 y, receiving vitamin-mineral supplements. Mean daily vitamin B-6 intake, excluding a 10-mg supplement, was 1.81 mg. Subjects in the walking (n = 18) and nonwalking (n = 10) groups had similar microbiologically assessed plasma total vitamin B-6 levels and radioenzymatically assessed plasma pyridoxal phosphate concentrations. One walker at 22 wk and at 30 wk and a second walker at 30 wk had plasma total vitamin B-6 concentrations in the low-normal range; the same was true for plasma pyridoxal phosphate levels except that the 30-wk value for the walker who was low at 22 wk was missing. Birth-outcome measurements were similar for both groups. Participation in the walking program slightly improved aerobic fitness without affecting vitamin B-6 status or birth outcome in pregnant women taking vitamin-mineral supplements.     

Changes in vitamin status in plasma during dieting and exercise

The micronutrient status of 12 obese male subjects was evaluated before and after a 14-week period of a low energy diet (3.0-3.9 MJ) with or without an exercise (5 h p/w) treatment. The subjects were matched on the basis of their body mass index (BMI kg/m2) into a diet group (D; average BMI 32.2) and a diet-exercise group (DE; average BMI 32.9). After 14 weeks both groups showed similar results in term of weight loss (D 15.1; DE 16.4 kg), fat loss (D 11.7; DE 13.6 kg) and loss of fat free mass (FFM) (D 3.4; DE 2.8 kg). With respect to changes of the micronutrients in blood plasma only the decrease in ferritin was significantly different between D and DE (P less than 0.05), with a larger decrease for DE. In both groups significant decreases of about 20% in fat soluble vitamins were observed. Water soluble vitamins demonstrated a large variation between individuals and decreases were not significant.     

Selenium and antioxidant vitamin status of elderly German women

OBJECTIVE: Low antioxidant intake and status have been shown to be associated with an elevated risk for various diseases. Data on the status of antioxidant vitamins, selenium and coenzyme Q10 of younger female seniors are scarce. The aim of this study was to assess the status of these antioxidants, as well as influencing factors such as dietary intake, anthropometric data and educational level in female seniors (60-70 years) in Germany. DESIGN: Dietary intake of alpha-tocopherol, beta-carotene and ascorbic acid was determined by a 3-day diet record. Serum concentrations of alpha-tocopherol, beta-carotene, ascorbic acid, selenium and coenzyme Q10 were measured. Anthropometric measures, socioeconomic and educational status were assessed. SETTING: In total, 178 elderly women without severe diseases in the region of Hannover, Germany, were included in the study. The mean (+/- s.d.) age and BMI of the women was 63.2 (2.73) years and 25.6 (3.77) kg/m2, respectively. The study participants were generally better educated than the overall German female population. RESULTS: Dietary intake of the ascorbic acid and alpha-tocopherol was below RDA in six and 75% of the women, respectively. In comparison to estimated desirable serum concentrations of alpha-tocopherol, ascorbic acid, beta-carotene and selenium, lower concentrations were found in 23, 1, 6, and 39% of the women, respectively. Ascorbic acid (r = 0.205, P = 0.009) and beta-carotene (r = 0.173, P = 0.025) intake were significantly associated with serum concentrations. Beta-carotene concentrations were influenced by the type of diet, BMI, and school education (R2 = 0.128, P < 0.001). Serum selenium was positively associated with alcohol intake (r = 0.229, P = 0.003). Neither employment nor vocational training was predictive for the serum concentrations of antioxidant vitamins, selenium or coenzyme Q10. CONCLUSIONS: Poor status of selenium and alpha-tocopherol is highly prevalent even among younger, well-educated female seniors, whereas ascorbic acid and beta-carotene status seems sufficient in most women.     

Effect of exercise on vitamin A utilization by rats

The effect of exercise was studies on vitamin A utilization by rat organism. The biological experiment was done using 64 growing Wistar rats with initial vitamin A levels in the liver 380 and 790 i.u. The rats were subjected during 12 days to 30, 60 and 90 minute exercise on moving track at 20 m/min speed. The rats were exercised in groups. During the experiment they were given water and food ad libitum but without vitamin A, for controlling its intake. The measure of vitamin A utilization by rat organism after its addition to the diet was determination of its level in plasma, liver and kidneys. No evident differences were found in diet intake and body mass and in vitamin A levels in plasma and kidneys in the groups of rats differing in exercise duration. Increased duration of the exercise reduced vitamin A content in the liver, and this reduction was significant in the group subjected to exercise during 90 minutes daily.     

Effects of megadoses of dietary vitamin E on the antioxidant status of rats fed lard or salmon oil

This study was undertaken to investigate whether megadoses of vitamin E in the diet of rats can have pro-oxidative activity. Two experiments with rats were conducted in which both the dietary vitamin E concentration (Experiment 1: 100; 500; 3000; 10,000 mg all-rac-alpha-tocopheryl acetate/kg, and Experiment 2: 100; 1000; 10,000 mg all-rac-alpha-tocopheryl acetate/kg) and the type of dietary fat (lard vs. salmon oil) were varied. Experimental parameters were the concentrations of thiobarbituric acid-reactive substances, 7 beta-hydroxycholesterol, the activities of several antioxidative enzymes, the concentration of glutathione in the liver, and the lag time during copper-induced low-density lipoprotein (LDL) oxidation. Increasing the dietary vitamin E concentration to 10,000 mg all-rac-alpha-tocopheryl acetate/kg led to a significant reduction of thiobarbituric acid-reactive substances in the liver after feeding salmon oil, and also to a significant reduction in 7 beta-hydroxycholesterol after feeding both dietary fats. Megadoses of vitamin E (3000 and 10,000 mg all-rac-alpha-tocopheryl acetate/kg) also led to a reduction in the activity of superoxide dismutase and the concentration of glutathione in the liver of rats fed salmon oil. The lag time during LDL oxidation was independent of the dietary vitamin E concentration. The study shows that megadoses of vitamin E, far from having pro-oxidative activity, actually increase the anti-oxidative capacity of the liver, especially after ingestion of salmon oil.     

Blood cells as functional markers of antioxidant vitamin status

Antioxidants have shown beneficial effects in several biological systems, in which they were able to prevent oxidative stress-associated damage. Vitamins C and E are key antioxidants in man. Dietary intake cannot accurately reflect plasma vitamin levels. However, the plasma levels of antioxidant vitamins could also reflect the acute assimilation of these vitamins. It has been pointed out that antioxidant vitamin blood contents reach a saturation level by intake of dietary supplements. Antioxidant vitamin plasma levels are the parameter most used to determine antioxidant status. However, the vitamin plasma levels may not reflect the nutritional status of vitamins. It has been pointed out that the vitamin E in adipose tissue can be used as a measure of vitamin E status. To determinate antioxidant vitamin contents in lymphocytes and neutrophils after exercise is a useful tool to assess the functional status of antioxidant vitamins.     

Effect of exercise on riboflavin status of rats

The effect of exercise on the riboflavin status of male rats was studied after 6 or 8 wk of treadmill running. Sedentary and exercised rats were pair fed diets marginal in riboflavin (2.0 or 2.5 mg/kg), and their tissue riboflavin concentrations and erythrocyte glutathione reductase activity coefficients (EGRAC) were compared. The rats exercised for 8 wk had similar body weights but significantly greater weights for heart, gastrocnemius and soleus muscles, less epididymal fat and more total muscle nitrogen and riboflavin than their sedentary controls. Similar changes were evident after 6 wk of exercise, but some were not statistically significant. The EGRAC values of both exercised and sedentary rats responded to changes in dietary riboflavin but were not different from each other. The specific activity of mitochondrial acyl-CoA dehydrogenase (per milligram protein) of the soleus muscle was unaffected by exercise; however, when expressed per gram of tissue or per muscle, the activities in exercised rats were 25% (P less than 0.05) and 60% (P less than 0.01) higher, respectively, than in sedentary rats. On the basis of the riboflavin-dependent parameters measured in this study, exercise did not increase the dietary riboflavin requirement of growing rats but did increase total riboflavin retention in gastrocnemius and soleus muscles.     

Effects of acute starvation on vitamin A status in rats

Maintenance of vitamin A stores in the body is dependent on a number of basic metabolic processes. These processes, such as protein and carbohydrate metabolism, are disrupted in acute starvation, and, as a result, alterations in vitamin A status may result. We investigated this possibility in 8-week-old Sprague-Dawley male rats. The rats were starved for 24, 48, and 72 hr but had free access to water. At 24 hours of starvation, the plasma retinol concentration was depressed, but not significantly so. After 48 and 72 hours of starvation, however, the plasma retinol concentration decreased to less than half of the control values (61 +/- 4 vs 124 +/- 12 nmol/dl at 72 hours, mean +/- SEM, (p less than 0.005). The hepatic retinoid (retinyl esters + retinol) concentration (nmol/g liver) was increased at 24 and 48 hours of starvation compared to controls (p less than 0.05), and by 72 hours the concentration was 56% greater in starved rats than in fed controls (p less than 0.001). The total hepatic retinoid content (mumol/total liver) was decreased moderately at all periods of starvation compared to controls (p less than 0.05). In both starved and fed animals, the total hepatic content per 100 g body weight, a measure of total vitamin A reserves, was statistically the same. These results demonstrate that acute starvation in rats alters the vitamin A equilibrium between the plasma and hepatic stores without affecting the overall vitamin A reserves.(ABSTRACT TRUNCATED AT 250 WORDS)     

Metabolic utilization of pyridoxine-beta-glucoside in rats: influence of vitamin B-6 status and route of administration

[3H]5'-O-(beta-D-glucopyranosyl) pyridoxine (PN-glucoside) and [14C]pyridoxine (PN) were administered orally or intraperitoneally to vitamin B-6-adequate or -deficient rats. Analysis of intestinal contents and feces indicated effective intestinal absorption of PN-glucoside relative to PN. There was greater retention of 14C than 3H in the liver and carcass regardless of the route of administration of the radiolabeled vitamins. There was no major difference in the relative distribution of 3H and 14C among the vitamin B-6 metabolites in the liver between the treatment groups, and no [3H]PN-glucoside was detected in any of the livers. For all groups, the majority of the 3H administered was detected in the urine within 24 h. Less excretion of both 3H and 14C in the urine was observed for the deficient rats. There was no major difference in the relative proportion of urinary [3H]PN-glucoside or [3H]4-PA between rats fed or injected with the radiolabeled vitamins. These results indicate that vitamin B-6 status influences the clearance of metabolites derived from PN and PN-glucoside, as well as the clearance of intact PN-glucoside. Vitamin B-6 status, however, has little or no effect on the utilization of PN-glucoside. This study also suggests that the intestine is the primary site of the limited conversion of PN-glucoside to biologically active PN in the rat.     

The influence of smoking on vitamin C status in adults.

To further define the relation between smoking and vitamin C status, the dietary and serum vitamin C levels of 11,592 respondents in the second National Health and Nutrition Examination Survey (NHANES II) were analyzed. Smokers of 20 cigarettes daily had the lowest vitamin C dietary intake (79 mg, 95% CI:73, 84) and serum levels (0.82 mg/dl, 95% CI: 0.77, 0.86; 46.6 mumol/L, 95% CI: 43.7, 48.8), while smokers of 1-19 cigarettes daily had decreased vitamin C intake (97 mg; 95% CI: 90, 104 mg) and serum levels (0.97 mg/dl, 95% CI: 0.92, 1.03; 55.1 mumol/L, 95% CI: 52.2, 58.5) compared to respondents who had never smoked (109 mg, 95% CI: 105, 113 and 1.15 mg/dl, 95% CI: 1.11, 1.18; 65.3 mumol/L, 95% CI: 63.0, 67.0, respectively). This inverse association between both intake and serum levels of vitamin C and smoking was independent of age, sex, body weight, race, and alcoholic beverage consumption. Following further adjustment for dietary vitamin C intake, the negative correlation between cigarette smoking and serum vitamin C levels persisted. The risk of severe hypovitaminosis C (serum levels less than or equal to 0.2 mg/dl; 11.4 mumol/L) was increased in smokers, particularly when not accompanied by vitamin supplementation (odds ratio 3.0, 95% CI: 2.5, 3.6). These data suggest that even though smoking adversely affects preferences for vitamin C rich foods, the inverse association between smoking and serum vitamin C levels occurs independently of dietary intake.     

The influence of smoking on vitamin D status and calcium metabolism

OBJECTIVE: To assess the influence of smoking on serum parathyroid hormone (PTH), serum vitamin D metabolites, serum ionized calcium, serum phosphate, and biochemical markers of bone turnover in a cohort of 510 healthy Danish perimenopausal women. DESIGN: A cross-sectional study. SETTING: Copenhagen, Denmark. SUBJECTS: Five-hundred-and-ten healthy women aged 45-58 y, included 3-24 months after last menstrual bleeding. None were using hormone replacement therapy. METHODS: The women were grouped according to their current smoking status. The two groups were compared with regard to serum levels of 25-hydroxyvitamin D (25OHD) and 1, 25-dihydroxyvitamin D (1,25-(OH)2D), intact PTH, ionized calcium and phosphate, osteocalcin, as well as urine pyridinolines. Bone mineral density (BMD) was measured with DEXA-scans. Multiple regression analyses were performed to detect the effect of potentially confounding lifestyle factors, such as calcium and vitamin D intakes, alcohol and coffee consumption, sunbathing, and physical exercise. RESULTS: Fifty percent were current smokers. Smokers had significantly reduced levels of serum 25OHD (P=0.02), 1,25(OH)2D (P=0.001), and PTH (P<0.001). There was no difference in serum ionized calcium between smokers and non-smokers. We found a negative effect of smoking on serum osteocalcin (P=0.01), while urinary pyridinolines were similar in the two groups. The small differences in lifestyle between the two groups could not explain these findings. Smokers had small but significant reductions in bone mineral density. CONCLUSIONS: Smoking has a significant effect on calcium and vitamin D metabolism, which is not likely to be explained by other confounding lifestyle factors. The depression of the vitamin D-PTH system seen among smokers may represent another potential mechanism for the deleterious effects of smoking on the skeleton, and may contribute to the reported risk of osteoporosis among smokers. Sponsorship: Grants from the Karen Elise Jensens Foundation.     

The influence of different durations of aerobic exercise on fuel utilization,lactate level and antioxidant defense system in trained rats

This study investigated the influence of different durations of aerobic exercise on fuel utilization, lactate levels and antioxidative status in trained rats. Forty rats underwent physical training (T, n = 20) or non- training (NT, n = 20) for 6 weeks. For physical training, animals exercised on a treadmill for 30 min 5 days per week. At the end of week 6, the animals in each group were subdivided into BE, DE-0.5, DE-1 and DE-2, which were sacrificed at the end of week 6 without having performed exercise or after exercise on a treadmill for 0.5h, 1h and 2h, respectively, immediately before being sacrificed. The plasma glucose level in DE-2 of the NT group was significantly lower than in the other groups. Muscle and liver glycogen levels were significantly lower in DE-1 and DE-2, but there were no significant differences between DE-1 and DE-2 in the T group. Liver protein in DE-2 of the NT group was significantly lower. Muscle TG levels were decreased in DE-0.5 of the T group, while those of the NT group were decreased in DE-1. FFA levels were increased in DE-0.5 of the T group and in DE-1 of the NT group. Lactate levels were increased in DE-0.5 of the NT group, while they were increased in DE-1 of the T group. Catalase activity of the T group was lower in BE but higher in DE-0.5, DE-1 and DE-2. SOD activities were higher in trained rats, while the GSH/GSSG ratios were higher in BE, DE-0.5 and DE-1 in the T group, and there was no difference in that of DE-2. There were no differences in MDA levels in BE and DE-0.5, but they were significantly lower in DE-1 and DE-2 of the T group. Overall, the results of this study, suggest that training may improve exercise performance by facilitating the mobilization and oxidation of fat and conserving limited carbohydrate storage, and that it may delay the onset of fatigue and enhance the antioxidative defense system, but cannot support two hours of vigorous exercise.     

VE、BR对糖尿病大鼠胰组织抗氧化影响

目的　探讨维生素E(VitaminE ,VE)和胆红素 (bilirubin ,BR)对糖尿病大鼠胰组织抗氧化的影响。方法　对用链佐霉素 (streptozotocin,STZ)诱发的糖尿病大鼠持续 4周给予BR、VE或BR VE后 ,测定胰组织中的丙二醛(MDA)、一氧化氮 (NO)、超氧化物歧化酶 (SOD)和一氧化氮合酶 (NOS)的水平。结果　与正常对照组比较 ,糖尿病组大鼠的MDA含量显著增加 (P <0 0 1) ,SOD活性显著降低 (P <0 0 1)。糖尿病组、给药组 (BR组、VE组和BR VE组 )大鼠的NO含量、NOS活性均显著升高 (P <0 0 1)。与糖尿病组比较 ,给药组除SOD活性显著升高 (P <0 0 1)外 ,其它 3项指标都显著降低 (P <0 0 5 ,P <0 0 1)。结论　BR和VE通过保护胰组织的SOD活性 ,降低胰组织中的MDA、NO和NOS水平 ,从而减轻自由基对糖尿病大鼠的氧化损伤。     

Induction of ceruloplasmin synthesis by retinoic acid in rats: influence of dietary copper and vitamin A status

Ceruloplasmin, a copper-containing acute phase plasma protein, has been shown to be regulated by 13-cis retinoic acid in rats. Ceruloplasmin activity was significantly increased within 24 h and remained elevated for at least 72 h after a single injection of 13-cis retinoic acid. With daily injections of retinoic acid, the ceruloplasmin activity continued to increase for at least 4 d. After 4 d, the activity was four times control levels. In copper-deficient rats, the ceruloplasmin activity did not increase in response to retinoic acid unless copper was also given to these rats 8 h after retinoic acid. Actinomycin D blocked the retinoic acid-induced stimulation of ceruloplasmin activity in copper-sufficient rats, but in copper-deficient rats only about half of the increase was blocked when the rats were given copper or copper and retinoic acid. By use of pulse-labeling techniques, ceruloplasmin synthesis was shown to increase 1.5-fold after retinoic acid and this increase was blocked by actinomycin D. When vitamin A-deficient rats were repleted with 13-cis retinoic acid for 3 or 5 d, both the ceruloplasmin activity and synthesis were significantly stimulated when compared to the nonrepleted, deficient rats. Therefore, the dietary components, copper and vitamin A, play an important role in the regulation of plasma ceruloplasmin levels.     

Effects of acute starvation on vitamin A status in rats.

Maintenance of vitamin A stores in the body is dependent on a number of basic metabolic processes. These processes, such as protein and carbohydrate metabolism, are disrupted in acute starvation, and, as a result, alterations in vitamin A status may result. We investigated this possibility in 8-week-old Sprague-Dawley male rats. The rats were starved for 24, 48, and 72 hr but had free access to water. At 24 hours of starvation, the plasma retinol concentration was depressed, but not significantly so. After 48 and 72 hours of starvation, however, the plasma retinol concentration decreased to less than half of the control values (61 +/? 4 vs 124 +/? 12 nmol/dl at 72 hours, mean +/? SEM, (p less than 0.005). The hepatic retinoid (retinyl esters + retinol) concentration (nmol/g liver) was increased at 24 and 48 hours of starvation compared to controls (p less than 0.05), and by 72 hours the concentration was 56% greater in starved rats than in fed controls (p less than 0.001). The total hepatic retinoid content (mumol/total liver) was decreased moderately at all periods of starvation compared to controls (p less than 0.05). In both starved and fed animals, the total hepatic content per 100 g body weight, a measure of total vitamin A reserves, was statistically the same. These results demonstrate that acute starvation in rats alters the vitamin A equilibrium between the plasma and hepatic stores without affecting the overall vitamin A reserves.(ABSTRACT TRUNCATED AT 250 WORDS)     

维生素A缺乏对大鼠铁营养状况的影响

目的 研究维生素A(VA)缺乏对大鼠铁营养状况的影响及其可能的机制。方法 雄性Wistar大鼠40只．按体重随机分为IVA和铁缺乏组，ⅡVA完全缺乏组，ⅢVA轻度缺乏组，Ⅳ VA正常对照组。实验动物喂饲8周后处死，测定血清VA、血清铁、铁蛋白、血红蛋白、肝内总铁含量，并用逆转录一聚合酶链反应(RT-PCR)法检测各组大鼠肝脏转铁蛋白mRNA的表达情况。结果 维生素A缺乏显地降低血清铁蛋白、血红蛋白和肝内总铁含量。抑制肝脏转铁蛋白mRNA的表达。结论 维生素A缺乏可能通过降低肝脏转铁蛋白mRNA的表达水平从而抑制了铁的吸收和转运。