Influences of different stress models on the antioxidant status and lipid peroxidation in rat erythrocytes

Effects of age and circadian rhythm on vital parameters and erythrocyte osmotic fragility of donkeys during seasonal changes

This study investigates the effects of seasonal variations on the erythrocyte osmotic fragility and vital parameters of donkeys Equus africanus asinus at the National Animal Production Research Institute (NAPRI) in Shika, Kaduna State, Nigeria. The research focused on two key periods: the hot-dry season (April) and the rainy season (July). Twelve donkeys were classified into three age groups: young (1-3 years), adult (4-6 years), and old (7-9 years). Blood samples were collected at six-hour intervals over a 24-hour period, while dry-bulb and wet-bulb temperatures were measured to compute the temperature-humidity index (THI). Vital parameters including rectal temperature, respiratory rate, and heart rate were also recorded. Results showed higher dry-bulb temperatures (DBT) during the hot-dry season, with the lowest DBT of 12°C at 00:00 h and the highest of 25.5°C at 18:00 h. Young donkeys exhibited the highest erythrocyte osmotic fragility during the hot-dry season, while old donkeys showed elevated fragility during the rainy season. Results also demonstrated that erythrocyte osmotic fragility varied significantly with age and season, with young donkeys exhibiting the highest fragility during the hot-dry season at a 0.3% NaCl concentration. However, old donkeys showed increased fragility during the rainy season, which shows the influence of both age and environmental conditions on erythrocyte stability. Also, rectal temperatures were higher in young donkeys during the hot-dry season compared to adults, while heart rates showed significant elevation across all age groups during the rainy season. Overall, this study elucidates the physiological adaptations of donkeys to seasonal thermal stress, providing critical insights into their health management and welfare in varying climatic conditions. Understanding these dynamics is essential for optimizing donkey husbandry practices, especially in regions facing climate variability. These findings contribute valuable knowledge to the field of veterinary physiology and highlight the necessity of tailored management strategies to mitigate the impact of seasonal stressors on animal health.

A reflexion on the oxidative stress and animal welfare: a review

A wide range of studies have documented the role of oxidative stress in the development of chronic pathological disorders and even in the aging itself. However, its significance to modern animal health and welfare remains neglected. Oxidative stress in biological systems refers to a disturbance in the balance between pro-oxidants and antioxidants in favour of the former, leading to potential damage of biomolecules. In farm animals, oxidative stress may be involved in several pathological conditions, including those that are relevant for animal production and the general welfare of the individuals, resulting in some cases in irreversible losses. The oxidative stress concept and how it may result in disease or be prevented are complex questions with no simple answers and therefore, call professionals for deep reflection, to maintain a high standard of animal welfare and production. The aim of this review was to gather relevant information on the characteristics of pro-oxidants and antioxidant as well as their significance in animal production systems.

Effects of Housing and Management Systems on the Growth, Immunity, Antioxidation, and Related Physiological and Biochemical Indicators of Donkeys in Cold Weather

The study was designed with a 2 × 2 factorial experiment to evaluate the effects of growth performance, immune function, antioxidant status, blood biochemical indexes, and hormone levels of donkeys in different housing and management systems in cold weather. Twenty-four male donkeys with similar body weight and age were randomly allocated into four treatment groups that were as follows: a cold-water-drinking group without a windproof facility, a lukewarm-water-drinking group without windproof facilities, a cold-water-drinking group with a windproof facility, and a lukewarm-water-drinking group with a windproof facility. The experiment lasted for 42 days. The results showed that windproof facilities increased average daily gain (ADG) and decreased average daily feed intake (ADFI) and feed-to-gain ratio (F:G) at all time periods (p < 0.01) of the experiment. Windproof facilities increased the digestibility of dry matter (DM), crude fat (CF), crude protein (CP), ash, calcium (Ca), and phosphate (P) on day 21 (p < 0.01), and increased the digestibility of DM, CF, ash, and P on day 42 (p < 0.01). The respiration rate and the skin temperature of the abdomen and legs increased (p < 0.05) and rectal temperature tended to increase (p = 0.083) by adopting windproof facilities at 07:00; the windproof facilities tended to increase the skin temperature of the ears and abdomen (p = 0.081, p = 0.091) at 14:00. For the blood parameters, with windproof facilities, the concentrations of total protein (TP), blood urea nitrogen (BUN), triglyceride (TG) and high-density lipoprotein cholesterol (HDL-C) increased (p < 0.05) and glucose (GLU) concentration decreased (p < 0.05) at 07:00 on day 21; the concentrations of TG and cholesterol (CHO) increased and the concentrations of TP, BUN, and GLU decreased at 07:00 on day 42 (p < 0.05). The concentrations of adrenocorticotropic hormone (ACTH), cortisol (COR), triiodothyronine (T3), and thyroxine (T4) decreased (p < 0.05) at 07:00 on day 21, and T4 concentration decreased (p < 0.05) at 07:00 on day 42. The concentrations of interleukin-4 (IL-4), immunoglobulin A (IgA), immunoglobulin G (IgG), and immunoglobulin M (IgM) increased (p < 0.01) and the concentrations of interleukin-1β (IL-1β) and tumor necrosis factor-alpha (TNF-α) decreased (p < 0.01) on days 21 and 42. The activities of total superoxide dismutase (T-SOD) and glutathione peroxidase (GPx) increased (p < 0.05), and malondialdehyde (MDA) concentration decreased (p < 0.01) on day 21; the activities of T-SOD and catalase (CAT) increased (p < 0.05), and MDA concentration decreased (p < 0.01) on day 42. However, under the conditions of this experiment, water temperature did not affect the above indexes on days 21 and 42. These results indicated that adopting windproof facilities in a cold climate can mitigate the effects of atrocious weather on the production performance of donkeys.

Effect of season on slaughter performance, meat quality, muscle amino acid and fatty acid composition, and metabolism of pheasants (Phasianus colchicus)

This study aimed to investigate the effect of summer and winter on slaughter performance, muscle quality, flavor-related substance content, and gene expression levels related to the fat metabolism of pheasants. One-hundred 1-day-old pheasants were fed for 5 months starting in March and July and then, respectively, slaughtered in summer (August) and winter (December). The results revealed that compared with summer, winter not only increased pheasant live weight, dressed percentage, full-eviscerated yield, and muscle yield (p < 0.05) but also enhanced the activities of SOD and CAT in serum (p < 0.05). Winter significantly increased meat color, the contents of inosinic acid, and flavor amino acid in muscle. Amino acid contents in leg muscles of pheasants in winter were significantly higher than in summer except for histidine (p < 0.05). Winter increased the contents of muscle mono-unsaturated fatty acid, reducing saturated fatty acid. Summer improved fat synthesis in liver, promoted the deposition of triglycerides and cholesterol, and reduced the expression levels of fat metabolism-related genes in muscle, while winter increased the expression levels of genes related to muscle fat metabolism to provide energy for body and affect muscle fatty acid profile. Overall, pheasants fed in winter had better sensory quality and flavor than summer.

Deoiled sunflower seeds ameliorate depression by promoting the production of monoamine neurotransmitters and inhibiting oxidative stress

We aimed to evaluate the antidepressant activity of deoiled sunflower seeds (SFS), which are rich in tryptophan, in our mouse model and explored a possible mechanism of action. Male C57BL/6J mice were subjected to chronic unpredictable mild stress (CUMS) and were administered a diet containing SFS as the main protein source. SFS alleviated CUMS-induced depression-like behaviors, compared to the effects of a whey protein-based diet. This effect was related to increases in the levels of serotonin, dopamine, norepinephrine, acetylcholine, and brain-derived neurotrophic factor in SFS-fed mice. These changes accompanied the amelioration of inflammatory abnormalities and oxidative stress. SFS increased the aromatic amino acid levels, and the ratio of tryptophan to neutral amino acids. Furthermore, the antidepressant-like effects of SFS were involved in lipid, nucleotide, and amino acid metabolism. In summary, SFS was found to attenuate depression-like symptoms in mice. These antidepressant effects may be related to the increase in the levels of aromatic amino acids and neurotransmitters, amelioration of oxidative stress and inflammation, and the regulation of the levels of abnormal metabolites to the normal levels.

Rest-Phase Hypothermia Reveals a Link Between Aging and Oxidative Stress: A Novel Hypothesis

In endotherms, growth, reproduction, and survival are highly depended on energy metabolism. Maintenance of constant body temperature can be challenging for endotherms under continuously changing environmental conditions, such as low or high ambient temperatures or limited food. Thus, many birds may drop body temperature below normothermic values during the night, known as rest-phase hypothermia, presumably to decrease energy metabolism. Under the assumption of the positive link between aerobic metabolism and reactive oxygen species, it is reasonable to suggest that low body temperature, a proxy of energy metabolism, will affect oxidative stress of the birds. Aging may considerably affect behavior, performance and physiology in birds and still requires further investigation to understand age-specific changes along the lifespan of the organism. Until today, age-specific rest-phase hypothermic responses and their effect on oxidant-antioxidant status have never been investigated. We exposed 25 zebra finches (Taeniopygia guttata) of three age classes, 12 young birds (1.1–1.3 years old), 8 middle-aged (2.4–2.8 years old), and 5 old birds (4.2–7.5 years old) to day-long food deprivation or provided them normal access to food under thermoneutral conditions. We compared night-time body temperature, measured through implanted data loggers, and quantified plasma oxidative status (uric acid, antioxidant capacity, and d-ROM assay) the following morning. We found age-related differences in night-time body temperature following a day-long food deprivation while all three age groups remained normothermic in the night following a day with access to food. The lowest minimum body temperature (LSM ± SE: 36.6 ± 0.2°C) was observed in old individuals during rest-phase hypothermia. Surprisingly, these old birds also revealed the highest levels of plasma oxidative damage, while young and middle-aged birds maintained higher night-time body temperature and showed lower values of oxidative damage. These results lead us to propose a novel hypothesis on how aging may lead to an accumulation of oxidative damage; the impaired physiological capacity to thermoregulate with advancing age does increase the risk of oxidative stress under challenging conditions. When energy is limited, the risk to encounter oxidative stress is increasing via a compensation to defend normothermic body temperatures.

Healthful aging mediated by inhibition of oxidative stress

The progressive increase in lifespan over the past century carries with it some adversity related to the accompanying burden of debilitating diseases prevalent in the older population. This review focuses on oxidative stress as a major mechanism limiting longevity in general, and healthful aging, in particular. Accordingly, the first goal of this review is to discuss the role of oxidative stress in limiting longevity, and compare healthful aging and its mechanisms in different longevity models. Secondly, we discuss common signaling pathways involved in protection against oxidative stress in aging and in the associated diseases of aging, e.g., neurological, cardiovascular and metabolic diseases, and cancer. Much of the literature has focused on murine models of longevity, which will be discussed first, followed by a comparison with human models of longevity and their relationship to oxidative stress protection. Finally, we discuss the extent to which the different longevity models exhibit the healthful aging features through physiological protective mechanisms related to exercise tolerance and increased β-adrenergic signaling and also protection against diabetes and other metabolic diseases, obesity, cancer, neurological diseases, aging-induced cardiomyopathy, cardiac stress and osteoporosis.

Genetic parameter estimates for plasma oxidative status traits in slaughter pigs

The aim of the present study was to assess the effect of sex and to estimate genetic parameters for several traits related to plasma oxidative status in slaughter pigs, i.e., ferric reducing ability of plasma (FRAP), concentrations of α-tocopherol and malondialdehyde (MDA), and glutathione peroxidase (GPx) activity. Blood samples were collected at slaughter from 477 Piétrain × (Landrace × Large White intercross) pigs of 2 performance test stations. Heritabilities (±SE) of plasma oxidative status traits as well as their phenotypic and additive genetic correlations with animal performance traits were estimated with multiple-trait REML animal models using VCE software. Results displayed no significant difference between barrows and gilts for FRAP and α-tocopherol in plasma. However, gilts had a significantly higher concentration of MDA and lower GPx activity compared with barrows. Heritability estimates were high for GPx (0.55 ± 0.05), and medium to low for α-tocopherol (0.30 ± 0.06), FRAP (0.22 ± 0.05), and MDA (0.15 ± 0.04). Estimated additive genetic and phenotypic correlations between these four traits were generally low, except for a negative additive genetic correlation between FRAP and GPx of -0.45 (±0.23). Additive genetic correlations between plasma oxidative status traits and animal performance traits were also generally absent or low with maximum values of ~0.3. Parameter estimates in this study have to be interpreted with caution because of the small size of the dataset. Nevertheless, it may be concluded that there is considerable additive genetic variance for plasma oxidative status traits in slaughter pigs. More research is warranted on the genetic determination of oxidative stress in farm animals and its relevance in breeding programs.

Protective action of alkylglycerols under stress

The adaptogenic properties of alkylglycerols (AGs) after 1 month's treatment were investigated in a rat model of acute immobilization stress (AIS). The animals receiving AGs 157 mg/kg showed a body weight (BW) decrease in addition to a more pronounced increase in the adrenal glands index under stress conditions. Also, AGs at this dose prevented AIS-induced catalase inhibition. In addition, antiulcerative AG effects were already detected at a dose of 15 mg/kg. The data indicate that AGs promote adrenal gland activation in AIS. At the same time, AGs neutralize some of negative effects of stressful conditions, which include restoration of the oxidation-reduction balance, reduction of gastric mucosal stress lesion formation.LAY SUMMARYThe effect of alkylglycerols, ether lipids from marine organisms, was studied in stressed animals. AGs have antioxidant activity and can be useful in the complex therapy of stomach lesions.

Chronic restraint stress induces esophageal fibrosis with enhanced oxidative stress in a murine model

Although the underlying mechanism of stress remains unknown, it has been associated with the pathophysiology of gastroesophageal reflux diseases, the development of which appear to be accelerated by oxidative stress and fibrosis. The aim of the current study was to investigate the effect of chronic restraint stress on esophageal oxidative stress and fibrosis, as well as the impact of oxidative stress in a murine model whereby 8-week old C57BL/6J male mice were subjected to intermittent chronic restraint stress for a two-week period. The current study demonstrated that chronic restraint stress significantly reduced the body weight of mice compared with the control group. Although chronic restraint stress did not significantly alter the levels of triglycerides or cholesterol, free fatty acid concentration was significantly increased compared with the control group. Furthermore, chronic restraint stress significantly upregulated the expression levels of several fibrotic biomarkers including collagen type I, transforming growth factor β-1, α-smooth muscle actin and SMAD-3 compared with the control group. In addition, the expression levels of the reactive oxygen species (ROS) NADPH oxidase-4 and malondialdehyde were significantly increased, while the expression levels of nuclear factor erythroid 2-related factor 2 and heme oxygenase-1 were significantly decreased in esophageal tissue from mice in the chronic restraint stress group compared with the control group. In conclusion, chronic restraint stress may induce esophageal fibrosis by accumulating ROS and increasing fibrotic gene expression in a murine model.

Dysregulation of stress systems and nitric oxide signaling underlies neuronal dysfunction in Alzheimer's disease

Stress is a multimodal response involving the coordination of numerous body systems in order to maximize the chance of survival. However, long term activation of the stress response results in neuronal oxidative stress via reactive oxygen and nitrogen species generation, contributing to the development of depression. Stress-induced depression shares a high comorbidity with other neurological conditions including Alzheimer's disease (AD) and dementia, often appearing as one of the earliest observable symptoms in these diseases. Furthermore, stress and/or depression appear to exacerbate cognitive impairment in the context of AD associated with dysfunctional catecholaminergic signaling. Given there are a number of homologous pathways involved in the pathophysiology of depression and AD, this article will highlight the mechanisms by which stress-induced perturbations in oxidative stress, and particularly NO signaling, contribute to neurodegeneration.

Quercetin protects against stress-induced anxiety- and depression-like behavior and improves memory in male mice

The present study evaluates the protective role of Quercetin (Quer), against immobilization stress- induced anxiety, depression and cognition alteration in mice using behavioral and biochemical parameters. 24 adult Albino mice were distributed into 2 groups vehicle (n=12; 1 ml/kg) and Quer injected (n=12; 20 mg/kg/ml). The animals received their respective treatment for 14 days. On day 15, after the drug administration, animals were sub-divided into 4 groups (n=6); (i) unstressed + vehicle; (ii) stressed + vehicle; (iii) unstressed + Quer; (iv) stressed + Quer. On day 16, 24 h after the immobilization stress behavioral activities (light-dark activity, elevated plus maze, Morris water maze, and forced swim test) monitored and then animals were decapitated 1 h after the drug administration. Brain samples were collected for biochemical (antioxidant enzymes, AChE, ACh, 5-HT and its metabolite) analysis. The present study indicates the Quer reversed the stress-induced anxiety and depression, in addition, memory performance was more enhanced in stressed group. Following the treatment of Quer, stress-induced elevation of lipid peroxidation and suppression of antioxidant enzymes were also reversed. Administration of Quer decreased AChE in unstressed, while levels of acetylcholine were increased in vehicle and Quer treated stressed animals. The metabolism of 5-HT was increased in Quer treated stressed than unstressed animals. In conclusion, the present finding showed that Quer could prevent the impairment of antioxidant enzymes and also regulate the serotonergic and cholinergic neurotransmission and produce antianxiety, antidepressant effect and enhance memory following 2 h immobilization stress in mice.

Effects of Crocin on Learning and Memory in Rats Under Chronic Restraint Stress with Special Focus on the Hippocampal and Frontal Cortex Corticosterone Levels

Background:

Chronic stress adversely influences brain functions while crocin, as an effective component of saffron, exhibits positive effects on memory processes. This study investigated the effects of different doses of crocin on the improvement of learning and memory as well as corticosterone (CORT) levels in the hippocampus and frontal cortex of rats subjected to chronic stress.

Materials and Methods:

Forty male rats were randomly allocated to five different groups (n = 8): Control, sham; stress (6 h/day for 21 days) groups, and two groups receiving daily intraperitoneal injections of one of two doses (30 and 60 mg/kg) of crocin accompanied by 21 days of restraint stress. Latency was evaluated as a brain function using the passive avoidance test before and one-day after a foot shock. CORT levels were measured in the homogenized hippocampus and frontal cortex.

Results:

Results revealed that chronic stress had a significantly (P < 0.01) negative effect on memory. Crocin (30 and 60 mg/kg), however, gave increase to significantly (P < 0.01 and P < 0.05; respectively) improved memory functions in the stressed rats. Furthermore, the CORT levels in the hippocampus and frontal cortex declined significantly (P < 0.05) in the stress group compared to the control. Only a crocin dose of 30 mg/kg was observed modulate significantly (P < 0.05) the CORT levels in the hippocampus and frontal cortex in the stressed group.

Conclusions:

It was found that the lower crocin dose (30 mg/kg) had more beneficial effects than its higher (60 mg/kg) dose on learning and memory under chronic stress conditions. Moreover, it was speculated that different doses of crocin act on different neurotransmitters and biochemical factors in the brain.

The effect of sulfite and chronic restraint stress on brain lipid peroxidation and anti-oxidant enzyme activities

Sulfites are used as anti-microbial and anti-oxidant agents in a variety of drugs, and function as a preservative in many food preparations. In addition to these effects, sulfites oxidize to sulfite radicals initiating lipid peroxidation. The objective of our study was to investigate the effect of restraint stress and sulfite on brain lipid peroxidation and anti-oxidant enzyme activities. Forty male Wistar rats, aged three months, were randomized to one of the following groups: control, restraint stress, sulfite-treated and restraint stress-/sulfite-treated. Chronic restraint stress was applied for 21 days (1 h/day) and sodium metabisulfite (520 mg/kg per day) was given by gavage for the same period. Lipid peroxidation was measured using the thiobarbituric acid (TBA) fluorometric assay. TBA-reactive substances (TBARS) were found increased in all treatment groups when compared to the control group. Spectrophotometric measurement of copper/zinc superoxide dismutase (Cu/Zn SOD) and catalase (CAT) revealed decreased enzyme activities in rats exposed to restraint stress compared to control and sulfite-treated rats. GSH-Px activities were significantly decreased in the restraint stress and sulfite-treated rats compared with the control rats. GSH-Px activity measured in restraint stress-/sulfite-treated rats was significantly lower than in the other groups. The presented data confirms the pro-oxidant activity of restraint stress and establishes that decreased anti-oxidant enzyme activities in restraint stress-treated rats enhances brain lipid peroxidation caused via the ingestion of sulfites.

Bird Integumentary Melanins: Biosynthesis, Forms, Function and Evolution

Melanins are the ubiquitous pigments distributed in nature. They are one of the main pigments responsible for colors in living cells. Birds are among the most diverse animals regarding melanin-based coloration, especially in the plumage, although they also pigment bare parts of the integument. This review is devoted to the main characteristics of bird melanins, including updated views of the formation and nature of melanin granules, whose interest has been raised in the last years for inferring the color of extinct birds and non-avian theropod dinosaurs using resistant fossil feathers. The molecular structure of the two main types of melanin, eumelanin and pheomelanin, and the environmental and genetic factors that regulate avian melanogenesis are also presented, establishing the main relationship between them. Finally, the special functions of melanin in bird feathers are also discussed, emphasizing the aspects more closely related to these animals, such as honest signaling, and the factors that may drive the evolution of pheomelanin and pheomelanin-based color traits, an issue for which birds have been pioneer study models.

Chronic unpredictable mild stress generates oxidative stress and systemic inflammation in rats

Stress is considered to be a causal agent of chronic degenerative diseases, such as cardiovascular disease, diabetes mellitus, arthritis and Alzheimer's. Chronic glucocorticoid and catecholamine release into the circulation during the stress response has been suggested to activate damage mechanisms, which in the long term produce metabolic alterations associated with oxidative stress and inflammation. However, the consequences of stress in animal models for periods longer than 40days have not been explored. The goal of this work was to determine whether chronic unpredictable mild stress (CUMS) produced alterations in the redox state and the inflammatory profile of rats after 20, 40, and 60days. CUMS consisted of random exposure of the animals to different stressors. The following activities were measured in the liver and pancreas: reduced glutathione (GSH), lipid peroxidation (LPO), superoxide dismutase (SOD), catalase (CAT), total antioxidant capacity (TAC), and protein oxidation. Similarly, serum cytokine levels (IL-6, TNF-α, IL-1β, and IL-10) were determined. CUMS activated the stress response from day 20 until day 60. In the liver and pancreas, GHS levels were decreased from day 40, whereas protein lipid peroxidation and protein oxidation were increased. This is the first work to report that the pancreas redox state is subject to chronic stress conditions. The TAC was constant in the liver and reduced in the pancreas. An increase in the TNF-α, IL-1β, and IL-6 inflammatory markers and a decrease in the IL-10 level due to CUMS was shown, thereby resulting in the generation of a systemic inflammation state after 60days of treatment. Together, the CUMS consequences on day 60 suggest that both processes can contribute to the development of chronic degenerative diseases, such as cardiovascular disease and diabetes mellitus. CUMS is an animal model that in addition to avoiding habituation activates damage mechanisms such as oxidative stress and low-grade chronic inflammation, which allows the study of physio-pathological stress aspects over prolonged time periods of at least 60days.

Protective Effects of Crocus Sativus L. Extract and Crocin against Chronic-Stress Induced Oxidative Damage of Brain, Liver and Kidneys in Rats

PURPOSE

Chronic stress has been reported to induce oxidative damage of the brain. A few studies have shown that Crocus Sativus L., commonly known as saffron and its active constituent crocin may have a protective effect against oxidative stress. The present work was designed to study the protective effects of saffron extract and crocin on chronic - stress induced oxidative stress damage of the brain, liver and kidneys.

METHODS

Rats were injected with a daily dose of saffron extract (30 mg/kg, IP) or crocin (30 mg/kg, IP) during a period of 21 days following chronic restraint stress (6 h/day). In order to determine the changes of the oxidative stress parameters following chronic stress, the levels of the lipid peroxidation product, malondialdehyde (MDA), the total antioxidant reactivity (TAR), as well as antioxidant enzyme activities glutathione peroxidase (GPx), glutathione reductase (GR) and superoxide dismutase (SOD) were measured in the brain, liver and kidneys tissues after the end of chronic stress.

RESULTS

In the stressed animals that receiving of saline, levels of MDA, and the activities of GPx, GR, and SOD were significantly higher (P<0.0001) and the TAR capacity were significantly lower than those of the non-stressed animals (P<0.0001). Both saffron extract and crocin were able to reverse these changes in the stressed animals as compared with the control groups (P<0.05).

CONCLUSION

These observations indicate that saffron and its active constituent crocin can prevent chronic stress-induced oxidative stress damage of the brain, liver and kidneys and suggest that these substances may be useful against oxidative stress.

Oxidative stress and antioxidant activity in hypothermia and rewarming: can RONS modulate the beneficial effects of therapeutic hypothermia?

Hypothermia is a condition in which core temperature drops below the level necessary to maintain bodily functions. The decrease in temperature may disrupt some physiological systems of the body, including alterations in microcirculation and reduction of oxygen supply to tissues. The lack of oxygen can induce the generation of reactive oxygen and nitrogen free radicals (RONS), followed by oxidative stress, and finally, apoptosis and/or necrosis. Furthermore, since the hypothermia is inevitably followed by a rewarming process, we should also consider its effects. Despite hypothermia and rewarming inducing injury, many benefits of hypothermia have been demonstrated when used to preserve brain, cardiac, hepatic, and intestinal function against ischemic injury. This review gives an overview of the effects of hypothermia and rewarming on the oxidant/antioxidant balance and provides hypothesis for the role of reactive oxygen species in therapeutic hypothermia.

Evaluation of sesamol and buspirone in stress induced anxiety in mice

Objectives:

The present study was designed to elucidate the effects of sesamol, buspirone and their combination in immobilization stress induced behavioral and biochemical alterations in mice.

Materials and Methods:

Male Laca mice (divided into 10 groups with 6 animals each) were pre-treated with sesamol (5 and 10 mg/kg; p.o.), buspirone (5 and 10 mg/kg; p.o.) and combination of sesamol (5 and 10 mg/kg; p.o.) with buspirone (5 mg/kg; p.o.) for consecutive five days. On the 6^th day, animals were immobilized for 6 h and various behavioral tests such as body weight, locomotor activity, mirror chamber test and elevated plus maze were carried out. Biochemical estimations such as lipid peroxidation and nitrite concentration, glutathione and catalase levels were done. Data was analyzed using One way ANOVA followed by Tukey's test (P < 0.05) was considered statistical significant.

Results:

Immobilization stress significantly (P < 0.05) impaired body weight, locomotor activity, induced anxiety like behavioral and oxidative damage as compared to naοve animal. Pretreatment with sesamol (5 and 10 mg/kg; p.o.) and buspirone (5 and 10 mg/ kg; p.o.) significantly (P < 0.05) improved body weight, locomotor activity, and anxiety like behavior in mirror chamber as well as plus maze performance tasks and anti-oxidant like effect as evidenced by reduced lipid peroxidation, nitrite concentration and restoration of reduced glutathione and catalase activity as compared to control animals. Further, co- administration of sesamol (5 and 10 mg/kg) with buspirone (5 mg/kg) significantly (P < .05) potentiated the anti anxiety effects as compared to their effects alone.

Conclusions:

The present study suggests that combination of sesamol and buspirone potentiated the antianxiety effects against anxiety induced by immobilization stress and oxidative damage in mice.

Plasma reactive oxygen metabolites and non-enzymatic antioxidant capacity are not affected by an acute increase of metabolic rate in zebra finches

Understanding the sources of variation in oxidative stress level is a challenging issue due to the implications of oxidative stress for late age diseases, longevity and life-history trade-offs. Reactive oxygen species that cause oxidative stress are mostly a by-product of energy metabolism and it is therefore often assumed that oxidative stress is proportional to energy consumption. In mammals, an increased metabolic rate induced by cold exposure generally increases oxidative stress. However, compared to mammals, birds generate fewer free radicals per ATP produced and hence it is not obvious that, in birds, a cold-induced increase of metabolic rate increase oxidative stress. We tested whether cold-induced increase in metabolic rate increased oxidative stress in zebra finches by exposing individuals to cold and warm overnight temperatures. We registered metabolic rate and plasma levels of non-enzymatic antioxidants and reactive oxygen metabolites (ROMs), a measure of oxidative damage. Metabolic rate was on average 88 % higher in cold compared to warm temperature, with females being stronger affected than males. However, temperature had no effect on plasma antioxidants or our measure of oxidative damage. Middle-age birds had higher levels of plasma antioxidants than younger and older birds, but age was unrelated to ROMs. Birds showed repeatability of plasma ROMs across temperatures but not of non-enzymatic antioxidants. In contrast to similar studies in mammals, our results do not show evidence of increased oxidative stress in plasma after an acute cold-induced increase of metabolic rate but research in more bird species is needed to assess the generality of this pattern.

Effect of peppermint oil on serum lipid peroxidation and hepatic enzymes after immobility stress in mice

This study was undertaken to determine the influences of various doses of peppermint oil on the hepatic en-zymes, alanine transaminase, apartate tranaminase, alkaline phosphotase and gamma glutamyl transferase and the level of malondialdehyde in the serum of mice with and without immobility stress. The mice exposed to drink water, 0.9, 27 and 60 mg/kg peppermint oil from the days 1 to 5 for a period of 4 h before and after immobility stress. Serum MDA in-creased in treatment group II, III and IV after immobility stress. There was a significant decrease in ALT in treatment group III and IV after immobility stress. There were also significant decreases in ALP and GGT in treatment group IV af-ter immobility stress. This result may suggest that, MDA level is higher in immobilization stress group than in the un-immobilized animals in serum and this results show that enzyme activities decreased after immobilization stress.

Interplay between plasma oxidative status, cortisol and coping styles in wild alpine marmots, Marmota marmota

Variation in how individuals cope behaviourally and physiologically with stressors is widespread and can have a significant impact on life-history traits and fitness. Individual coping styles are characterised by differential behavioural and adrenocortical reactivity to various challenges. As stress hormones can affect the production of reactive chemical species and the antioxidant status, individuals with different coping styles may differ also in oxidative status. Field studies on wild mammalian populations are few in number and none so far has simultaneously tested the relationship between coping style, adrenocortical reactivity and oxidative status in the same individuals. We measured individual variation in coping styles along a proactive-reactive continuum together with variation in baseline and stress-induced plasma oxidative damage, plasma non-enzymatic antioxidant capacity and cortisol in wild alpine marmots, Marmota marmota. Confirmatory path analysis revealed that different coping styles are accompanied by different baseline and stress-induced plasma oxidative statuses. Our findings also highlight the potential role of cortisol as a mediator of such differences.

The effects of in vivo and ex vivo various degrees of cold exposure on erythrocyte deformability and aggregation

BACKGROUND

This study aimed to investigate alterations in hemorheology by cold exposure, in vivo and ex vivo, and to determine their relationship to oxidative stress.

MATERIAL/METHODS

Rats were divided into 2 in vivo and ex vivo cold exposure groups. The in vivo group was further divided into control (AR), AC (4°C, 2 hours) and ALTC (4°C, 6 hours) subgroups; and the ex vivo group was divided into control (BR) and BC (4°C, 2 hours) subgroups. Blood samples were used for the determination of erythrocyte deformability, aggregation, and oxidative stress parameters.

RESULTS

Erythrocyte deformability and aggregation were not affected by 2-hour ex vivo cold exposure. While 2 hour in vivo cold exposure reduced erythrocyte deformability, it returned to normal after 6 hours, possibly due the compensation by acute neuroendocrine response. Six hours of cold exposure decreased aggregation index, and might be an adaptive mechanism allowing the continuation of circulation. Aggregation of ex vivo groups was lower compared to in vivo groups. Cold exposure at various temperatures did not cause alterations in plasma total oxidant antioxidant status and oxidative stress index (TOS, TAS, OSI) when considered together.

CONCLUSIONS

Results of this study indicate that the alterations observed in hemorheological parameters due to cold exposure are far from being explained by the oxidative stress parameters determined herein.

Restorative biological processes and health

Research on psychological influences on physiology primarily focuses on biological responses during stressful challenges, and how those responses can become dysregulated with prolonged or repeated exposure to stressful circumstances. At the same time, humans spend considerable time recovering from those challenges, and a host of biological processes involved in restoration and repair take place during normal, non-stressed activities. We review restorative biological processes and evidence for links between psychosocial factors and several restorative processes including sleep, wound healing, antioxidant production, DNA repair, and telomerase function. Across these biological processes, a growing body of evidence suggests that experiencing negative emotional states, including acute and chronic stress, depressive symptoms, and individual differences in negative affectivity and hostility, can influence these restorative processes. This review calls attention to restorative processes as fruitful mechanisms and outcomes for future biobehavioral research.

Antioxidant enzymes are differently changed in experimental ischemic hippocampal CA1 region following repeated restraint stress

Restraint stress induces physiological changes in the brain. In the present study, we observed the effects of repeated stress on ischemic damage associated with oxidative stress in gerbils. Animals were placed into restrainers for 5h (between 09:30 h and 14:30 h) for 21 consecutive days prior to 5 min of transient cerebral ischemia. Experimental groups were divided into 4 groups; 1) sham-operated control-group (sham-group), 2) ischemia-operated control-group (ischemia-group), 3) sham-operated stress-group (stressed-sham-group), and 4) ischemia-operated stress-group (stressed-ischemia-group). Serum corticosterone level in the ischemia-group was highest (330% vs the sham-group) at 12h post-ischemia, and serum corticosterone levels in the stressed-ischemia-group were significantly lower than the ischemia-group. Locomotor activity in the ischemia-group was significantly increased (300% vs the sham-group) at 1 day post-ischemia; however, locomotor activity in the stressed-ischemia-group was less increased compared to the ischemia-group. A few NeuN (neuron-specific soluble nuclear antigen)-positive ((+)) cells were found in the stratum pyramidale (SP) of the hippocampal CA1 region (CA1) 4 days post-ischemia in the ischemia-group; however, in the stressed-ischemia-group at 4 days post-ischemia, 83.8% of NeuN(+) neurons were found. In addition, we found a few Fluro-Jade B (a marker for neuronal degeneration)(+) and TUNEL(+) cells in the stressed-ischemia-group at 4 days post-ischemia. In gliosis, glial fibrillary acidic protein(+) astrocytes in the stressed-ischemia-groups was similar to the ischemia-groups; however, ionized calcium-binding adapter molecule 1(+) microglia in the stressed-ischemia-groups were much less activated than the ischemia-groups. Among antioxidants, Cu,Zn-superoxide dismutase (SOD1) immunoreactivity in the SP was higher in the stressed-ischemia-groups than the ischemia-groups. Catalase immunoreactivity in the SP of the stressed-ischemia-groups was similar to the ischemia-groups. However, Mn-superoxide dismutase and glutathione peroxidase immunoreactivity were lower than the ischemia-groups. In brief, our results indicate that repeated restraint stress significantly attenuates ischemic neuronal damage and locomotor activity following ischemia. In addition, SOD1 among antioxidants significantly increases in the stressed-ischemia-groups.

Antioxidant flavonoid glycosides from Evolvulus alsinoides

Oxidative damage is an established outcome of chronic stress. Thus, the present study was designed to investigate the modulatory role of ethanolic extract of Evolvulus alsinoides (EA) in terms of oxidative alterations at peripheral and central level in rats subjected to chronic unpredictable stress (CUS). CUS exposure for 7 days reduced Cu, Zn superoxide dismutase and catalase activity with increase in glutathione peroxidase activity and lipid peroxidation, while decrease in reduced glutathione level in blood plasma, frontal cortex and hippocampus regions of brain. Oral administration of EA extract at 200mg/kg p.o. normalized these stress induced oxidative alterations with an efficacy similar to that of melatonin. Further, EA extract was taken up for detailed chemical investigation. Two new flavonol-4'-glycoside, kaempferol 4'-O-beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranoside (3) and kaempferol 4'-O-alpha-L-rhamnopyranosyl-(1-->6)-beta-D-glucopyranoside (5) were isolated, along with eight known compounds (1, 2, 4 and 6-10). The structures of new compounds were established by detailed spectroscopic studies, while known compounds were characterized by direct comparison of their reported NMR data. All these compounds were evaluated for their in vitro antioxidant activity. Compounds 3, 5, 9 and 10 at 100 and 200 microg/ml showed significant in vitro antioxidant activity. Therefore, EA may hold great potential in preventing clinical deterioration in stress induced oxidative load and related disorders.

Hypolipidemic and hepatoprotective effects of flax and pumpkin seed mixture rich in omega-3 and omega-6 fatty acids in hypercholesterolemic rats

Flax and pumpkin seeds are a rich source of unsaturated fatty acids, antioxidants and fibers, known to have anti-atherogenic and hepatoprotective activities. These effects were evaluated in Wistar rats fed with 1% cholesterol diet. The study was performed on 30 male rats divided into three groups: a control group (CD), CD-chol group fed diet with 1% cholesterol and MS-chol group fed diet enriched with flax and pumpkin seed mixture. In CD-chol group, total cholesterol TC, triacylglycerol TG in plasma and liver, plasma LDL-C, atherogenic index AI and LDL/HDL ratio significantly increased. In MS-chol group lipid parameters decreased significantly, plasma and liver fatty acid composition showed an increase of PUFAs (ALA and LA), and MUFAs (oleic and eicosaenoic acid) and a decrease of SFA (palmitic and stearic acid). In plasma and liver of MS-chol group, malondialdehyde levels decreased and the efficiency of antioxidant defense system was improved compared to CD-chol group. Liver histological sections showed lipid storage in hepatocytes of CD-chol group and an improvement was noted in MS-chol group. Our results suggested that flax and pumpkin seed mixture had anti-atherogenic and hepatoprotective effects which were probably mediated by unsaturated fatty acids present in seed mixture.

Psychosocial factors, biological mediators, and cancer prognosis: a new look at an old story

PURPOSE OF REVIEW

The present article briefly reviews the prognostic role of psychosocial factors in cancer and concentrates on biological markers that may mediate such relationships. We focus on specific markers that show promising mediating roles.

RECENT FINDINGS

The article reviews the prognostic role of psychosocial factors as shown in longitudinal studies and in previous reviews. We present the general stress response and its relevance to cancer progression. The main focus of the article is on the prognostic roles of specific biomarkers that had to meet three criteria for being accepted as biomarkers - being related to a psychosocial factor at the level of the brain, the circulation, and the tissue/cellular level. We review studies supporting the mediating roles of neurohormones and neurotransmitters (e.g., cortisol, norepinephrine), the vagal nerve and inflammation, interleukin-1, DNA damage, and the hormone oxytocin.

SUMMARY

These biomarkers may mediate the relationships between certain psychosocial factors (e.g., hopelessness, social support) and cancer progression. Future studies should test the effects of altering such biomarkers on the prognosis of patients scoring high/low on their associated psychosocial factors. Clinical implications that need to be tested are provided.

Changes in antioxidant defense status in hypercholesterolemic rats treated with Ajuga iva

The aim of the study was to investigate the effect of aqueous extract of Ajuga iva (Ai) on serum and tissues lipid peroxidation as well as antioxidant enzymes activities in red blood cells (RBC) and tissues, in high hypercholesterolemic rats (HC). Male Wistar rats (n=12) were fed on 1% cholesterol-enriched diet for 15d. After this adaptation phase, hypercholesterolemic rats (total cholesterol=6.5+/-0.6mol/l) were divided into two groups fed the same diet and treated or not with Ai for 15d. Thiobarbituric acid reactive substances (TBARS) concentrations in serum, LDL-HDL(1), HDL(2) and HDL(3) were respectively, 5-, 7.8-, 2.3- and 5-fold lower in Ai treated than untreated hypercholesterolemic groups. TBARS concentrations were 1.4-fold lower in heart and 2.8-fold higher in kidney in Ai-HC treated than untreated HC group. Superoxide dismutase activity was respectively, 1.2- and 1.4-fold higher in RBC and muscle in Ai treated than untreated group. In RBC, Ajuga iva treatment enhanced glutathione peroxidase (GSH-Px) (+9%) and glutathione reductase (GSSH-Red) (+12%) in Ai-HC treated than untreated HC group. GSSH-Red activity was 1.4- and 1.5-fold higher in adipose tissue and heart, respectively and 3.7-fold lower in kidney in Ai treated than untreated group. Liver catalase activity was 1.6-fold higher in Ai treated than untreated group. Adipose tissue and muscle total glutathione content represented in Ai treated group 35% and 36% of the value noted in untreated group. Nitric oxide values of liver, adipose tissue and heart were 3.3-, 2.5- and 3.4-fold higher in Ai-HC than HC group. Ajuga iva treatment enhanced alpha-tocopherol contents (+25%) in Ai treated than untreated group. In conclusion, Ajuga iva treatment is more effective to improve the antioxidant capacity of RBC than that of tissues. Indeed, Ai is able to reduce the oxidative stress in hypercholesterolemic rats by increasing the antioxidant enzymes activity.

Antioxidative and metabolic responses to extended cold exposure in rats

In this work, we investigated whether extended cold exposure increases oxidative damage and susceptibility to oxidants of rat liver, heart, kidney and lung which are metabolically active tissues. Moreover in this study the effect of cold stress on some of the lipid metabolic mediators were studied in rat experimental model. Male albino Sprague-Dawley rats were randomly divided into two groups: The control group (n=12) and the cold-stress group (n=12). Tissue superoxide dismutase (SOD), catalase (CAT), glutathion S-transferase (GST) and glutathion reductase (GR) activities and glutathion (GSH) were measured using standard protocols. The biochemical analyses for total lipid, cholesterol, trigliceride, HDL, VLDL and LDL were done on autoanalyzer. In cold-stress groups SOD activity was decreased in the lung whereas it increased in the heart and kidney. CAT activity was significantly decreased (except liver) in all the tissues in treated rats. GST activity of cold-induced rats increased in liver and heart while decreased in the lung. GR activity was significantly decreased (except in liver) in all the tissues in cold-stressed rats. GSH level was significantly increased in the heart but decreased in the lung of animals exposed to cold when compared to controls. It was found that among the groups trigliceride, total lipid, HDL and VLDL parameters varied significantly but cholesterol and LDL had no significant variance. In this study, we found that exposure of extended (48 h) cold (8 degrees C) caused changes both in the antioxidant defense system (as tissue and enzyme specific) and serum lipoprotein profiles in rats.

Possible mechanism of adaptogenic activity of seabuckthorn (Hippophae rhamnoides) during exposure to cold, hypoxia and restraint (C–H–R) stress induced hypothermia and post stress recovery in rats

The present study was carried out to investigate mechanism of adaptogenic activity of seabuckthorn dry leaves aqueous lyophilized extract, administered in rats at a dose of 100 mg/kg body weight prior to cold (5 degrees C)-hypoxia (428 mmHg)-restraint (C-H-R) exposure up to fall of T(rec) 23 degrees C and recovery (T(rec) 37 degrees C) from C-H-R induced hypothermia. The effect of extract treatment was studied on key metabolic regulatory enzymes in blood, liver and muscle and tissue glycogen in rats on attaining T(rec) 23 degrees C and post stress recovery of T(rec) 37 degrees C. In control rats during C-H-R exposure on attaining T(rec) 23 degrees C there was significant decrease in enzyme activities of blood hexokinase (HK), citrate synthase (CS) and glucose-6-phosphate dehydrogenase (G-6-PD); liver CS; and in muscle glycogen, and CS and G-6-PD activities. In control rats on recovery of T(rec) 37 degrees C there was also a significant decrease in liver and muscle glycogen levels along with decreased enzyme activities of blood G-6-PD; liver CS; and liver and muscle G-6-PD. This suggested that during severe stressful exposure to C-H-R and post stress recovery the aerobic metabolism as well as hexose monophosphate (HMP) pathway is suppressed. The single and five doses extract treatment restricted the decrease or better maintained tissue glycogen and enzyme activities, viz. HK, phosphofructokinase (PFK), CS and G-6-PD, in blood, liver and muscle, during C-H-R exposure (T(rec) 23 degrees C) and recovery of T(rec) 37 degrees C. The results suggest that seabuckthorn extract treatment caused a trend for shifting anaerobic metabolism to aerobic during C-H-R exposure and post stress recovery.

Stress-dependent induction of protein oxidation, lipid peroxidation and anti-oxidants in peripheral tissues of rats: comparison of three stress models (immobilization, cold and immobilization-cold)

1. It is known that stress causes disruption of homeostasis and an imbalanced anti-oxidant status in several organs. The aim of the present study was to determine the effects of three stress models on protein oxidation, lipid peroxidation and anti-oxidant enzyme activities in the liver, kidney and heart, and to investigate the relationship between corticosterone and some oxidative stress parameters. In addition, we investigated the most effective stress model for each parameter in each tissue. 2. Thirty-six male Wistar rats (aged 3 months old, weighing 220 +/- 20 g) were divided randomly into four groups of nine rats each: control (C), immobilization stress (IS), cold stress (CS), and immobilization-cold stress (ICS). 3. Results showed that corticosterone levels were increased in all stress groups. Levels of protein carbonyl (PC), conjugated dienes (CD) and thiobarbituric acid-reactive substances (TBARS) were increased, whereas reduced glutathione (GSH) levels were decreased in all tissues of all stress groups. Copper, zinc-superoxide dismutase (Cu,Zn-SOD) activities were increased in the liver and kidney of all stress groups, but were decreased in heart of the IS and CS groups. Catalase (CAT) activities were increased in liver of the CS group and in kidney and heart of all stress groups, but were decreased in liver of the IS and ICS groups. Selenium-dependent glutathione peroxidase (Se-GSH-Px) activities were increased in liver of the CS and ICS groups and in heart of all stress groups, but were decreased in kidney of the IS group. Also, Se-GSH-Px activity levels remained unchanged in liver of the IS group and in kidney of the CS and ICS groups. The increased CAT activity and unchanged Se-GSH-Px activity observed in kidney suggest that H2O2 may be primarily scavenged by CAT. 4. The strong correlations between corticosterone and oxidative damage markers (e.g. protein oxidation, lipid peroxidation and GSH levels) suggest a relationship between these parameters. Liver was affected most by the CS model, whereas kidney and heart were affected most by ICS model. Stress-induced changes in the activities of anti-oxidant enzymes and GSH levels were found to be tissue- and enzyme-specific. In conclusion, results of the present study suggest that each stress model affects the different organ tissues in different ways.

Measuring circulating antioxidants in wild birds

Antioxidants protect against free radical damage, which is associated with various age-related pathologies. Antioxidants are also an important buffer against the respiratory burst of the immune system. This protection presumably has costs and therefore might underlie important life-history trade-offs. Studying such trade-offs in a comparative context requires field-applicable methods for assessing antioxidant capacity in wild animals. Here, we present modifications to a simple spectrophotometric assay (the TEAC or TAS assay) that can be applied to miniscule amounts of blood plasma to determine circulating antioxidant capacity. Additionally, uric acid, the most abundant circulating antioxidant, should be measured independently. Uric acid in birds is derived from amino acid catabolism, perhaps incidentally to its antioxidant function. The assay was validated in experimental studies on chickens showing effects of diet on antioxidant capacity, and in field measurements on 92 species of birds, which demonstrate substantial species differences in constitutive antioxidant capacity. Furthermore, most wild birds demonstrate a dramatic change in antioxidant capacity due to stress. These results show that this technique detects variation appropriate for both interspecific and intraspecific studies, and that antioxidants and uric acid change in response to conditions of interest to field ecologists, such as diet and stress.

Immobilization stress in rat tissues: alterations in protein oxidation, lipid peroxidation and antioxidant defense system

We determined the effects of immobilization stress on antioxidant status, protein oxidation and lipid peroxidation in brain, liver, kidney, heart and stomach of rats. Sixteen male Wistar rats (3 months old) were divided into controls (C) and immobilization stress group (IS). IS rats were immobilized for 180 min/day for 15 days. Plasma corticosterone levels were increased in IS group. Copper,zinc-superoxide dismutase activities were increased in brain, liver and kidney, but decreased in the heart and stomach after immobilization. Catalase activities were increased in brain, kidney and heart, and decreased in liver and stomach. Selenium-dependent glutathione peroxidase activities were decreased in brain and kidney, but increased in heart and stomach. Reduced glutathione levels were decreased, while protein carbonyl, conjugated dienes and thiobarbituric acid-reactive substances levels were increased in all tissues. Our results showed that the response of antioxidant defense system to stress differs for each tissue, and protein oxidation and lipid peroxidation is induced by immobilization stress in peripheral tissues.

Immobilization stress causes extra-cellular oxidant-antioxidant imbalance in rats: restoration by L-NAME and vitamin E

Stress has been shown to be associated with altered homeostasis that may lead to oxidant-antioxidant imbalance. Non-enzymatic antioxidants are important regulators of reactive oxygen species produced in extra-cellular milieu and represent the first line of defense against them. Extra-cellular non-enzymatic antioxidants may be disturbed by the production of superoxide and nitric oxide and this has not been studied in stressful situation previously. In the present study, effects of immobilization stress (IS), both acute (IS x 1) and repeated (IS x 7) were assessed on extra-cellular total antioxidant capacity measured as plasma ferric reducing antioxidant power (FRAP) and protein sulfhydryls, and oxidative stress measured as leukocyte superoxide generation, plasma nitric oxide production (total nitrates and nitrites, NOx) and lipid peroxides in rats. Effects of pretreatment with nitric oxide synthase (NOS) inhibitors and vitamin E were also studied on these biochemical parameters. The results showed that both IS x 1 and IS x 7 resulted in extra-cellular oxidant-antioxidant imbalance as oxidant generation was increased and non-enzymatic antioxidants were depleted. Pretreatment either with NOS inhibitors or vitamin E restored stress-induced extracellular oxidant-antioxidant imbalance implying their potential role as antioxidants. Our data suggest that there is extra-cellular oxidant-antioxidant imbalance in the stressed rats, with greater magnitude of severity in repeated stress paradigm. Augmentation of antioxidant defenses might be beneficial in long-term stress.

Alterations in brain antioxidant status, protein oxidation and lipid peroxidation in response to different stress models

The aim of this study was to investigate the effects of different stress models on copper, zinc-superoxide dismutase (Cu,Zn-SOD), catalase (CAT) and selenium-dependent glutathione peroxidase (Se-GSH-Px) activities, and reduced glutathione (GSH), protein carbonyl (PC) and lipid peroxidation marker (conjugated diene (CD) and thiobarbituric acid-reactive substances (TBARS)) levels in brain of rats, and to determine the most effective stress model according to each parameter. Rats were divided into four groups as following: control group (C), immobilization stress group (IS), cold stress group (CS) and immobilization-cold stress group (ICS). All stress models increased brain Cu,Zn-SOD and CAT activities, PC, CD and TBARS levels, plasma corticosterone levels and decreased brain GSH concentrations. Se-GSH-Px activity was increased in CS and ICS groups. When all stress models were taken into consideration, the highest increases in Cu,Zn-SOD and Se-GSH-Px activities were found in CS group. The lowest GSH level was seen in IS group. The highest increases in PC and TBARS levels were found in ICS group. The highest increase of CD concentration was seen in IS and ICS groups. Our results suggest that different stress models have different degrees of influences on enzymatic and non-enzymatic antioxidant defense systems, protein oxidation and lipid peroxidation in the brain.