The effect of ascorbic acid supplementation on brain oxidative events in experimental diabetes (original) (raw)
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Beneficial effects of vitamins C and E against oxidative stress in diabetic rats
Nutrition Research, 2005
This study was designed to investigate the effects of vitamins C and E combinations on oxidative stress in erythrocytes from streptozotocin-induced diabetic rats. Concentrations of malondialdehyde and reduced glutathione and activities of superoxide dismutase and glutathione peroxidase were compared in 3 groups of 10 rats each (control nondiabetic rats [group I], untreated diabetic rats [group II], and diabetic rats treated with vitamins C and E [group III]). Diabetes developed 3 days after intraperitoneal administration of a single 60 mg/kg dose of streptozotocin in groups II and III. Thereafter, the rats in group III began to receive a combination of vitamins C and E. Six weeks later, the rats in groups II and III had significantly lower body weights and higher blood glucose levels than the rats in group I (all P b .001). Malondialdehyde levels in erythrocytes from group II rats were higher and glutathione, superoxide dismutase, and glutathione peroxidase levels were lower than those from rats in groups I and III (P b .01, P b .01, P b .001, and P b .01, respectively). The treatment with vitamins C and E lowered malondialdehyde levels and increased the antioxidant levels to near control values. The results verify the presence of oxidative stress in diabetes and suggest beneficial effects of vitamins C and E combinations in combating the oxidative stress in this disease.
Research in Experimental Medicine Zeitschrift Fur Die Gesamte Experimentelle Medizin Einschliesslich Experimenteller Chirurgie, 2001
We determined the effects of intraperitoneally administered vitamin C on the lipid peroxidation (as thiobarbituric acid-reactive substances, TBARS) and vitamin C and E levels and reduced glutathione (GSH) and glutathione peroxidase (GSH-Px) activity in the plasma, red blood cells (RBC), liver, and muscle of rats in relation to oxidative damage associated with diabetes induced by streptozotocin (STZ). One group was used as control and a second as diabetic. A third group received 30 mg vitamin C i.p. every other day. On day 4 after the injection of vitamin C, animals in the second and third groups were made diabetic by i.p. injection of STZ and administered vitamin C for 21 consecutive days, and we determined TBARS, vitamin E, and GSH levels and GSH-Px activities in plasma, RBC, liver, and muscle samples. Vitamin E levels in the plasma and liver were significantly higher (P<0.05) in the control group than in the diabetic group. Also, TBARS levels in the plasma, RBC, liver, and muscle samples were significantly lower (P<0.05) in controls than in the diabetic group. The TBARS levels in the RBC, liver, and muscle samples of the vitamin C group were significantly lower (P<0.05, P<0.01, and P<0.001, respectively). However, GSH-Px and GSH activities in RBC, liver, and muscle and vitamin C levels in liver were not significantly different between control and diabetic groups. Vitamin E levels in plasma (P<0.05, P<0.01) and liver (P<0.001), vitamin C levels in liver (P<0.001), and GSH (P<0.01) and GSH-Px activities in RBC (P<0.05, P<0.01) were significantly higher in the vitamin C group than both the control and diabetic groups. These results indicate that vitamin C has significant protective effects on the blood, liver, and muscle of rats against oxidative damage in diabetes.
Effect of Vitamin C and/or Vitamin E on Oxidative Stress and Lipid Profile in Diabetic Rats
2020
Diabetes Mellitus is one of the main threats to human health in the 21 st century. The present study was planned to evaluate the effect of vitamin C and/or vitamin E as hypocholesterolemic, antioxidant agent on oxidative stress and serum lipid profile in streptozoticin induced-diabetic rats using glibenclamide as reference drug for treatment of type II diabetes. 120 male adult Sprague Dawley rats were divided into 6 groups, normal control (C), diabetic control (D), diabetic treated with: glibenclamide (D G ), vitamin C (D C ), vitamin E (D E ); vitamin C and E (D C+E ). Diabetic group (D) revealed a significant increase in glucose, HbA 1C (258.1 vs 88.9 gm/dl; 8.09 vs 5.55 gm/dl respectively), liver and plasma MDA (124.03, 134.24 vs 60.44,
Acıbadem üniversitesi sağlık bilimleri dergisi, 2022
It is known that exogenous antioxidant supplementation may be beneficial against micro and macrovascular complications of diabetes. This study aimed to investigate the effect of vitamin C supplementation on insulin secretion, hyperlipidemia, oxidative stress and paraoxonase-1 enzyme (PON1) activity which are impaired due to chronic hyperglycemia in diabetic rats. For this purpose, twenty-four Wistar albino rats were divided into 3 groups as group C, DC and DCC. The rats in DC and DCC groups were induced diabetes by single dose streptozotocin injection (45 mg/kg). C and DC groups fed with standard rat diet (vitamin C free), DCC group fed with experimental diet supplemented with vitamin C at a dose of 200 mg/kg. According to the findings, rats in group C consumed less feed and water compared to diabetic rats during 8-weeks experimental period (p<0.001). In addition, total cholesterol and triglyceride levels of group C were lower than diabetic groups while PON1 activity and insulin values were higher (p<0.05). On the other hand, there were no significant differences between DC and DCC groups in terms of insulin, triglyceride, HDL, LDL and total cholesterol levels but TAS and PON1 activity levels of group DCC were significantly higher than group DC (p<0.05). As a conclusion, vitamin C supplementation may be helpful in increasing PON1 activity and antioxidant capacity in the presence of diabetes.
The effect of ascorbate supplementation on oxidative stress in the streptozotocin diabetic rat
Free Radical Biology and Medicine, 1992
An increase in oxidative stress may contribute to the development of diabetic complications. The key aqueousphase chain-breaking antioxidant ascorbate is known to be deficient in diabetes, and we have therefore investigated the effects of ascorbate supplementation on oxidative stress in the streptozotocin diabetic rat. Markers of lipid peroxidation (malondialdehyde [MDA] and diene conjugates) were increased in plasma and erythrocytes of untreated diabetic animals, and levels of the antioxidants ascorbate and retinol were reduced. Plasma tocopherol was unchanged. Insulin treatment normalized MDA and ascorbate levels, although ascorbate metabolism remained disturbed, as indicated by increased levels of dehydroascorbate. High-dose ascorbate supplementation in the absence of insulin treatment restored plasma ascorbate to normal and increased plasma retinol and tocopherol levels. However, MDA and diene conjugate levels remained unchanged, possibly as a result of increased iron availability. High-dose ascorbate supplementation should be approached with caution in diabetes, as ascorbate may exert both antioxidant and prooxidant effects in vivo.
Vitamin C in Health and Disease: Its Role in the Metabolism of Cells and Redox State in the Brain
Ever since Linus Pauling published his studies, the effects of vitamin C have been surrounded by contradictory results. This may be because its effects depend on a number of factors such as the redox state of the body, the dose used, and also on the tissue metabolism. This review deals with vitamin C pharmacokinetics and its participation in neurophysiological processes, as well as its role in the maintenance of redox balance. The distribution and the concentration of vitamin C in the organs depend on the ascorbate requirements of each and on the tissue distribution of sodium-dependent vitamin C transporter 1 and 2 (SVCT1 and SVCT2). This determines the specific distribution pattern of vitamin C in the body. Vitamin C is involved in the physiology of the nervous system, including the support and the structure of the neurons, the processes of differentiation, maturation, and neuronal survival; the synthesis of catecholamine, and the modulation of neurotransmission. This antioxidant interacts with self-recycling mechanisms, including its participation in the endogenous antioxidant system. We conclude that the pharmacokinetic properties of ascorbate are related to the redox state and its functions and effects in tissues.
The Effect of Vitamin C on the Metabolic Parameters of Experimental Diabetes Mellitus
American Journal of Pharmacology and Toxicology, 2007
The role of vitamin C on diabetes mellitus is unknown. The purpose of this study was to examine the effect of oral administration of vitamin C on some of the metabolic parameters of diabetic rats. Diabetes was induced by intraperitoneal injection of STZ (60 mg kg¯1 body weight at 12 weeks of age). Vitamin C (10, 50, 100 mg kg¯1 body weight) was administered orally for a period of four weeks to normal and diabetic male Wistar rats. In some experiments vitamin C was given either before or after the induction of diabetes mellitus. Glucose tolerance test (GTT) was performed on fasted normal, diabetic and vitamin C-treated rats at the end of the experimental period. Blood sugar level and weight were also recorded on a weekly basis for each rat in different groups. Vitamin C significantly (p<0.05) reduced blood glucose level and decreased weight gain in experimental diabetes mellitus at all doses when compared to untreated rats. This beneficial effect of vitamin C on the hyperglycemia of diabetic rats was dose-dependent. Moreover, vitamin C also improved GTT in diabetic rats compared to untreated diabetic rats. In conclusion, vitamin C may play a role in insulin metabolism and thus be a useful adjuvant therapy in diabetes mellitus.
Diabetologia, 1995
Increased generation of reactive oxygen species, coupled with impaired endogenous scavenging mechanisms, plays a prominent role in the aetiology of neurovascular abnormalities in experimental diabetes mellitus. We examined the efficacy of the natural anti-oxidants vitamins C, E and B-carotene in preventing nerve conduction and nutritive blood flow deficits in streptozotocin-diabetic rats. One month of diabetes caused a 19.1% reduction in sciatic motor conduction velocity (p < 0.001). This was approximately prevented 80-90% by high-dose (1000 mg. kg -1' day -1) vitamin E and B-carotene treatments (p < 0.001). Vitamin C had lesser effects; the maximum protection found for motor conduction velocity was 36 % using a dose of 150 mg. kg -1-day -1 (p <0.001). High dose (500 mg. kg -1 9 day -1) vitamin C had a lesser effect on conduction than intermediate doses. Joint vitamin C and lower dose (500 mg. kg -1. day -1) vitamin E treatment had a predominantly additive preventive effect against nerve dysfunction. Resistance to hypoxic conduction failure for sciatic nerve in vitro was markedly increased by diabetes and this remained relatively unaffected by treatment. Sciatic nutritive endoneurial blood flow, measured using microelectrode polarography and hydrogen clearance, was reduced 46.1% by 1 month of diabetes (p < 0.001). This was prevented to the extent of 87 %, 36 % and 98 % by vitamins E, C and [3-carotene, respectively (p < 0.01). These data emphasize the role of oxidative stress in the development of early neurovascular changes in experimental diabetes and show that naturally available scavengers have a neuroprotective action. [Diabetologia (1995[Diabetologia ( ) 38: 1285[Diabetologia ( -1294
Protective effects of vitamin E on central nervous system in streptozotocin-induced diabetic rats
Clinical and investigative medicine. Médecine clinique et experimentale, 2009
To evaluate the histopathological and antioxidant effects of vitamin E (VE) treatment on brain tissue in streptozotocin (STZ)-induced diabetic rats. Thirty two male Wistar albino rats were used. The study comprised four groups of 8 rats: Group A - untreated group, group B - diabetic group, group C - VE and group D - diabetic plus VE. In the diabetic groups, diabetes was induced by a single intraperitoneal injection of 65 mg/kg STZ. Vitamin E was given 50 mg/kg/day i.p. for three weeks. Concentrations of glucose, malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) were detected in the haemolysate. Glucose concentrations were increased in the blood of the STZ-treated rats compared with those in the diabetic groups (group B and D). The MDA concentrations in the brain from diabetic rats increased, whereas the GPx, SOD, CAT concentrations decreased. Treatment with VE returned concentrations of MDA, GPx, SOD and CAT toward control values. Th...
Alterations in free radical scavenger system profile of type I diabetic rat brain
Molecular and Chemical Neuropathology, 1998
The activities of the enzymes related to glutathione synthesis, degradation, and functions as well as reactive oxygen scavenging enzymes were analyzed in different brain regions, such as cerebral hemisphere, cerebellum, brainstem, thalamus, and hypothalamus after 1 and 3 mo of streptozotocin-induced diabetes in rats. Parallel studies were also made in age-matched control rats and insulin-treated diabetic rats. The content of glutathione (GSH) and its synthesizing enzyme γ-glutamylcystein synthetase and also superoxide dismutase (SOD) and catalase activities (reactive oxygen scavenging enzymes) were significantly decreased from almost all the brain regions studied. However, glutathione peroxidase (GPx), glutathione reductase (GR), glutathione S-transferase (GST), γ-glutamyl transpeptidase (γ-GTP), and glutamine synthetase (GS) activities were increased in the diabetic rat brain. Insulin treatment to the diabetic rats resulted in partial to full recovery in these enzymes activities. The present results emphasize the potentially serious alterations of brain free radical scavenger system in uncontrolled Type I diabetes.