Effect of DL-alpha-lipoic acid on the status of lipid peroxidation and antioxidant enzymes in various brain regions of aged rats

Fulminant Hepatic Failure in Rats Induces Oxidative Stress Differentially in Cerebral Cortex, Cerebellum and Pons Medulla

Hepatic Encephalopathy (HE) is one of the most common complications of acute liver diseases and is known to have profound influence on the brain. Most of the studies, available from the literature are pertaining to whole brain homogenates or mitochondria. Since brain is highly heterogeneous with functions localized in specific areas, the present study was aimed to assess the oxidative stress in different regions of brain-cerebral cortex, cerebellum and pons medulla during acute HE. Acute liver failure was induced in 3-month old adult male Wistar rats by intraperitoneal injection of thioacetamide (300 mg/kg body weight for two days), a well known hepatotoxin. Oxidative stress conditions were assessed by free radical production, lipid peroxidation, nitric oxide levels, GSH/GSSG ratio and antioxidant enzyme machinery in three distinct structures of rat braincerebral cortex, cerebellum and pons medulla. Results of the present study indicate a significant increase in malondialdehyde (MDA) levels, reactive oxygen species (ROS), total nitric oxide levels [(NO) estimated by measuring (nitrites + nitrates)] and a decrease in GSH/GSSG ratio in all the regions of brain. There was also a marked decrease in the activity of the antioxidant enzymes-glutathione peroxidase, glutathione reductase and catalase while the super oxide dismutase activity (SOD) increased. However, the present study also revealed that pons medulla and cerebral cortex were more susceptible to oxidative stress than cerebellum. The increased vulnerability to oxidative stress in pons medulla could be due to the increased NO levels and increased activity of SOD and decreased glutathione peroxidase and glutathione reductase activities. In summary, the present study revealed that oxidative stress prevails in different cerebral regions analyzed during thioacetamide-induced acute liver failure with more pronounced effects on pons medulla and cerebral cortex.

PCB (Aroclor 1254) enhances oxidative damage in rat brain regions: protective role of ascorbic acid

PCBs are one of the environmental toxicants and neurotoxic compounds which induce the production of free radicals leading to oxidative stress. Oxidative stress is a contributing factor to alteration caused in neurodegenerative processes. The ability of Vitamin C to retard oxidative processes has been recognized for many years. Therefore, the present experiment was carried out to determine the antioxidant role of ascorbate on Aroclor 1254 induced oxidative stress in brain regions of albino rats. One group of rats received corn oil as vehicle for 30 days as control. The other group of rats were administered Aroclor 1254 at a dose of 2 mg/kg bw/day intraperitoneally for 30 days. One group of rats received Vitamin C (100 mg/kg bw/day) orally simultaneously with Aroclor 1254 for 30 days. The brain was dissected to cerebral cortex (Cc), cerebellum (C) and hippocampus (H). Enzymatic and non-enzymatic antioxidants such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST), reduced glutathione (GSH) and Vitamin C were estimated. Hydrogen peroxide (H(2)O(2)), lipid peroxidation (LPO) and acetylcholine esterase activity (AchE) were determined. Activities of SOD, CAT, GPx, GST, AchE and the concentration of GSH, Vitamin C were decreased while an increase in H(2)O(2) and LPO were observed in brain regions of PCB treated animals. Vitamin C administration retrieved all the parameters except GST, significantly. These results suggest that PCB induces oxidative stress in rat brain by decreasing the activities of antioxidant enzymes, which can be protected by Vitamin C treatment.

L-Carnitine and -Lipoic Acid Improve Age-Associated Decline in Mitochondrial Respiratory Chain Activity of Rat Heart Muscle

The aging process is characterized by a general decline in physiological functions that affects many tissues and increases the risk of death. In the present investigation using various substrates, the respiration rate was observed in young, middle-aged, and aged rats upon administration of carnitine (300 mg/kg body weight) and lipoic acid (100 mg/kg body weight). We observed that the rate of respiration, both State 3 and respiratory control ratio, decreased significantly in aged rats after using various substrates (except succinate). An increase in the State 4 respiration was observed in aged rats when beta-hydroxybutyrate as well as pyruvate and malate were used as substrates, whereas no change in the adenosine diphosphate/oxygen ratio ratio was observed. These changes were brought to normal levels upon cosupplementation of carnitine and lipoic acid. Thus, this study provides evidence for the role of carnitine and lipoic acid in alleviating the age-related decline in mitochondrial respiratory activity.

Protective Efficacy of α-Lipoic Acid on Acetylcholinesterase Activity in Aged Rat Brain Regions

The purpose of the present investigation was to measure the activity of acetylcholinesterase in discrete regions of young and aged rat brain before and after DL-alpha-lipoic acid supplementation. Two groups of male albino rats were used in this study (4 and 24 months of age). DL-alpha-lipoic acid was administered intraperitoneally with a regimen of 100 mg/kg body weight per day using alkaline saline as a vehicle for 7 and 14 days. The activity was measured in the cerebral cortex, cerebellum, striatum, hippocampus and hypothalamus, and found to be significantly decreased in some of the brain regions in aged rats. Administration of lipoic acid into aged rats reversed the decrease in the activity in the discrete brain regions. These results suggest that lipoic acid is effective in restoration of the activity of acetylcholinesterase in aged rats.

Antioxidant effect of ascorbic acid on PCB (Aroclor 1254) induced oxidative stress in hypothalamus of albino rats

BACKGROUND

PCBs are one of the environmental toxicants and neurotoxic compounds which induce the production of free radicals leading to oxidative stress. Vitamin C is well known as an outstanding antioxidant. We determined the protective role of ascorbate on hypothalamic antioxidant system of Aroclor 1254 exposed rats.

METHODS

The rats were injected Aroclor 1254 at a dose of 2 mg/kg bw/day intraperitoneally for 30 days. One group of rats received vitamin C (100 mg/kg bw/day) orally simultaneously with Aroclor 1254 for 30 days. Twenty-four hours after last treatment, the animals were killed and hypothalamic region was separated from brain tissue. Enzymatic and non-enzymatic antioxidants such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR) and vitamin C were estimated. Hydrogen peroxide (H(2)O(2)), lipid peroxidation (LPO) and acetylcholine esterase (AchE) activity were determined. Serum gonadotropins such as luteinizing hormone (LH) and follicle stimulating hormone (FSH) were also assayed.

RESULTS

Activities of SOD, CAT, GPx, GR, AchE and the concentration of vitamin C were decreased while an increase in H(2)O(2) and LPO were observed in hypothalamus of PCB treated animals. LH and FSH concentrations were also decreased in serum of PCB exposed animals. Vitamin C administration retrieved all the parameters significantly except serum hormonal profiles.

CONCLUSION

PCB induces oxidative stress in hypothalamus by decreasing the activities of antioxidant enzymes, which can be protected by vitamin C treatment.

Menopause: a review on the role of oxygen stress and favorable effects of dietary antioxidants

Menopause is often accompanied by hot flashes and degenerative processes such as arteriosclerosis and atrophic changes of the skin that suggest an acceleration of aging triggered by estrogen lack. Therefore, hormone replacement therapy (HRT) has been considered the most suitable treatment for the above symptoms and processes. However, because of the possible serious side effects of HRT (especially the increased risk of thrombo-embolic accidents and breast cancer) there is a growing demand for alternative treatments of the symptoms and pathological processes associated with menopause. In agreement with the above, we review research that supports the concept that oxygen stress contributes to menopause and that some of its physiopathological effects may be prevented and/or treated improving the antioxidant defense of menopausic and postmenopausic women. Accordingly, a selection of micronutrients may be useful as a dietary supplement for protection against the decline of physiological functions caused by age-related oxygen stress. Since aging is accompanied by a progressive oxidation of the physiological sulfur pool, we emphasize the role of the vitamins B that help to maintain the GSH/GSSG ratio in its normal reduced state. Nutritional supplements should also include the key antioxidant vitamins C and E, as well as beta-carotene and the mineral micronutrients found in the oxygen radical-detoxifying enzymes glutathione peroxidase and superoxide dismutase. Moreover, the reviewed data suport the concept that other antioxidants such as lipoic acid and the precursors of glutathione thioproline (TP) and l-2-oxothiazolidine-4-carboxylic acid (OTC), as well as the soy isoflavones and the "coantioxidants" of an hydroalcoholic extract of Curcuma longa may help to prevent antioxidant deficiency with resulting protection of mitochondria against premature oxidative damage with loss of ATP synthesis and especialized cellular functions. Therefore, the administration under medical advice of synergistic combinations of some of the above mentioned antioxidants in the diet as well as topically (for skin protection) may have favorable effects on the health and quality of life of women, especially of those who cannot be treated with HR, suffer high levels of oxygen stress, and do not consume a healthy diet that includes five daily rations of fresh fruit and vegetables.

Seizure-induced changes in mitochondrial redox status

The aim of this study was to determine seizure-induced oxidative stress by measuring hippocampal glutathione (GSH) and glutathione disulfide (GSSG) levels in tissue and mitochondria. Kainate-induced status epilepticus (SE) in rats resulted in a time-dependent decrease of GSH/GSSG ratios in both hippocampal tissue and mitochondria. However, changes in GSH/GSSG ratios were more dramatic in the mitochondrial fractions compared to hippocampal tissue. This was accompanied by a mild increase in glutathione peroxidase activity and a decrease in glutathione reductase activity in hippocampal tissue and mitochondria, respectively. Since coenzyme A (CoASH) and its disulfide with GSH (CoASSG) are primarily compartmentalized within mitochondria, their measurement in tissue was undertaken to overcome problems associated with GSH/GSSG measurement following subcellular fractionation. Hippocampal tissue CoASH/CoASSG ratios were decreased following kainate-induced SE, the time course and magnitude of change paralleling mitochondrial GSH/GSSG levels. Cysteine, a rate-limiting precursor of glutathione was decreased following kainate administration in both hippocampal tissue and mitochondrial fractions. Together these changes in altered redox status provide further evidence for seizure-induced mitochondrial oxidative stress.

Effect of bacoside A on brain antioxidant status in cigarette smoke exposed rats

Free radicals mediated oxidative stress has been implicated in the pathogenesis of smoking-related diseases and antioxidant nutrients are reported to prevent the oxidative damage induced by smoking. Therefore, the present study was conducted to evaluate the antioxidant role of bacoside A (triterpenoid saponin isolated from Bacopa monniera) against chronic cigarette smoking induced oxidative damage in rat brain. Adult male albino rats were exposed to cigarette smoke for a period of 12 weeks and simultaneously administered with bacoside A (10 mg/kg b.w./day, p.o.). Antioxidant status of the brain was assessed from the levels of reduced glutathione, vitamin C, vitamin E, and vitamin A and the activities of superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase. The levels of copper, iron, zinc and selenium in brain and serum ceruloplasmin activity were also measured. Oxidative stress was evident from the diminished levels of both enzymatic and non-enzymatic antioxidants. Alterations in the levels of trace elements with accumulation of copper and iron, and depletion of zinc and selenium were also observed. Bacoside A administration improved the antioxidant status and maintained the levels of trace elements. These results suggest that chronic cigarette smoke exposure enhances oxidative stress, thereby disturbing the tissue defense system and bacoside A protects the brain from the oxidative damage through its antioxidant potential.

Emerging role of Centella asiatica in improving age-related neurological antioxidant status

Free radicals have been hypothesized to play an important role in ageing process. There exists an imbalance between free radical production and antioxidant defense mechanism, which may lead to cell death during ageing. Our study was designed to determine whether extract of Centella asiatica, an antioxidant, when administered orally (300 mg/kg body weight/day) for 60 days would prevent age-related changes in antioxidant defense system, lipid peroxidation (LPO) and protein carbonyl (PCO) content in rat brain regions such as cortex, hypothalamus, striatum, cerebellum and hippocampus. Aged rats elicited a significant decline in the antioxidant status and increased the LPO and PCO as compared to control rats in all five regions studied. The increase in LPO and PCO contents were (64%, 34%) in cortex, (86%, 30%) in cerebellum, (51%, 47%) in striatum, (77%, 27%) in hypothalamus and (58%, 45%) in hippocampus, respectively, in aged rats as compared to young rats. Supplementation of C. asiatica was effective in reducing brain regional LPO and PCO levels and in increasing the antioxidant status. Thus, C. asiatica by acting as a potent antioxidant exerted significant neuroprotective effect and proved efficacious in protecting rat brain against age related oxidative damage.

Increased oxidative protein and DNA damage but decreased stress response in the aged brain following experimental stroke

Aged individuals experience the highest rate of stroke and have less functional recovery, but do not have larger infarcts. We hypothesized that aged individuals experience greater sublethal damage in peri-infarct cortex. Focal cortical stroke was produced in aged and young adult animals. After 30 min, 1, 3 and 5 days brain sections and Western blot were used to analyze markers of apoptotic cell death, oxidative DNA and protein damage, heat shock protein (HSP) 70 induction, total neuronal number and infarct size. Focal stroke produces significantly more oxidative DNA and protein damage and fewer cells with HSP70 induction in peri-infarct cortex of aged animals. There is no difference in infarct size or the number of cells undergoing apoptosis between aged and young adults. Stroke in the aged brain is associated with a greater degree of DNA and protein damage and a reduced stress response in intact, surviving tissue that surrounds the infarct.

Oxidative stress on mitochondrial antioxidant defense system in the aging process: Role of dl-α-lipoic acid and l-carnitine

BACKGROUND

Oxidative damage is hypothesized to accumulate throughout the lifetime of an organism, eventually giving rise to aging. The mitochondria may be the primary cellular source and target of endogenous ROS as they are produced as a normal byproduct of the electron transport system.

METHODS

Male albino Wistar rats were used in this study. The animals were divided into 6 groups, each group consisting of 6 animals. Groups I, III, and V were young, middle-aged and aged control rats and Groups II, IV, and VI were treated with carnitine (300 mg/kg bw) and dl-alpha-lipoic acid (150 mg/kg bw), respectively. After the treatment period, the animals were sacrificed and the heart and skeletal muscle were removed for analysis.

RESULT

There was a significant reduction in the levels of antioxidants in both middle-aged and aged rats whereas the thiobarbituric acid reactive substances were found to be increased. Co-supplementation of carnitine and lipoic acid improved the antioxidant status and brought down the levels of TBARS.

CONCLUSION

Co-supplementation of lipoic acid with carnitine has a beneficial effect in reversing the age-related abnormalities seen in aging. This effect was associated with the decrease in free radical production and rise in antioxidant levels by carnitine and lipoic acid, thereby lowering oxidative stress.

Alpha-Lipoic Acid Increases Na+K+ATPase Activity and Reduces Lipofuscin Accumulation in Discrete Brain Regions of Aged Rats

A convincing link between oxidative stress and neurodegenerative diseases has been found with the knowledge that it actually damages neuronal cells in culture. We analyzed the effect of DL-alpha-lipoic acid on lipofuscin and Na(+)K(+) ATPase in discrete brain regions of young and aged rats. In aged rats, the level of lipofuscin was increased, and the activity of Na(+)K(+)ATPase was decreased. Intraperitoneal administration of lipoic acid to aged rats led to a duration-dependent reduction and elevation in lipofuscin and enzyme activity, respectively, in the cortex, cerebellum, striatum, hippocampus, and hypothalamus of the brain. These results suggest that lipoic acid, a natural metabolic antioxidant, should be useful as a therapeutic tool in preventing neuronal dysfunction in aged individuals.

The impact of alpha-lipoic acid, coenzyme Q10 and caloric restriction on life span and gene expression patterns in mice

We evaluated the efficacy of three dietary interventions started at middle age (14 months) to retard the aging process in mice. These were supplemental alpha-lipoic acid (LA) or coenzyme Q(10) (CQ) and caloric restriction (CR, a positive control). LA and CQ had no impact on longevity or tumor patterns compared with control mice fed the same number of calories, whereas CR increased maximum life span by 13% (p <.0001) and reduced tumor incidence. To evaluate these interventions at the molecular level, we used microarrays to monitor the expression of 9977 genes in hearts from young (5 months) and old (30 months) mice. LA, CQ, and CR inhibited age-related alterations in the expression of genes involved in the extracellular matrix, cellular structure, and protein turnover. However, unlike CR, LA and CQ did not prevent age-related transcriptional alterations associated with energy metabolism. LA supplementation lowered the expression of genes encoding major histocompatibility complex components and of genes involved in protein turnover and folding. CQ increased expression of genes involved in oxidative phosphorylation and reduced expression of genes involved in the complement pathway and several aspects of protein function. Our observations suggest that supplementation with LA or CQ results in transcriptional alterations consistent with a state of reduced oxidative stress in the heart, but that these dietary interventions are not as effective as CR in inhibiting the aging process in the heart.

Changes in glucose-6-phosphate dehydrogenase, copper, zinc-superoxide dismutase and catalase activities, glutathione and its metabolizing enzymes, and lipid peroxidation in rat erythrocytes with age

We have studied the activities of enzymes (glucose-6-phosphate dehydrogenase (G-6-PD), copper, zinc-superoxide dismutase (Cu,Zn-SOD), catalase (CAT), selenium-dependent glutathione peroxidase (Se-GSH-Px) and glutathione-S-transferase (GST)), and the levels of reduced glutathione (GSH), oxidized glutathione (GSSG) and thiobarbituric acid-reactive substances (TBARS) in rat erythrocytes and estimated the ratio of GSH/GSSG and the redox index. Male Wistar rats at ages of 1, 6 and 12 months were used. The activities of G-6-PD and Cu,Zn-SOD, the levels of GSSG and TBARS were increased, while the activity of Se-GSH-Px and the level of GSH were decreased with age. GSH/GSSG ratio was significantly decreased with age. We found a positive correlation between age and G-6-PD (r=0.476, p<0.01), Cu,Zn-SOD (r=0.291, p<0.01), CAT (r=0.254, p<0.01) and GST activities (r=0.250, p<0.05), and GSSG (r=0.708, p<0.05) and TBARS levels (r=0.802, p<0.01), whereas the correlation between age and Se-GSH-Px activity (r=-0.376, p<0.05), GSH level (r=-0.603, p<0.01) and GSH/GSSG ratio (r=-0.685, p<0.05) were negative. We found age-related differences in erythrocyte antioxidant enzyme activities, GSH, GSSG, total GSH and TBARS levels, GSH/GSSG ratio and the redox index.

Effect of DL- -Lipoic Acid on the Status of Lipid Peroxidation and Lipids in Aged Rats

The effect of dextro and levo (DL)-alpha-lipoic acid on lipid peroxidation and lipids has been evaluated in plasma, liver, and kidney of young and aged rats. The levels of thiobarbituric acid reactive substances (TBARS) and lipids were considerably higher in aged rats compared with younger controls. DL-alpha-lipoic acid (100 mg/kg body wt/day) was administered intraperitoneally for 7 and 14 days. Supplementation of lipoic acid in aged rats prevents the elevated levels of TBARS and lipids. From our observations, we conclude that lipoic acid is very effective in normalizing age-related alterations in lipids, and it can be implemented in the aged to minimize age-associated disorders where free radicals are the major cause.

Neurochemical changes related to ageing in the rat brain and the effect of DL-alpha-lipoic acid

Age-related impairments of cognitive and motor function have been linked to a number of deleterious morphological and functional changes involving different areas of the brain. Loss of neurotransmitters, their receptors and responsiveness to neurotransmitters are key manifestations of neurological ageing and age-related disorders. In the present investigation we have evaluated the effect of DL-alpha-lipoic acid on neurotransmitters in discrete brain regions of young and aged rats. The levels of neurotransmitters were found to be lowered in aged rats. Moreover, DL-alpha-lipoic acid treated aged rats showed a increase in the status of dopamine, serotonin and norepinephrine. The results of this study provide evidence that DL-alpha-lipoic acid (a potent antioxidant) treatment can improve neurotransmitters during ageing. Hence, it can be concluded that DL-alpha-lipoic acid act as a potent neuromodulator in the brain of aged rats.