NO modulates the molecular basis of rat interscapular brown adipose tissue thermogenesis

Molecular mechanisms underlying interscapular brown adipose tissue (IBAT) thermogenesis were elucidated. Namely, gene and/or protein expression of uncoupling protein 1 (UCP1), peroxisome proliferator-activated receptor gamma (PPARgamma), PPARgamma-coactivator-1alpha (PGC-1alpha), vascular endothelial growth factor (VEGF) and proliferating cell nuclear antigen (PCNA) - key molecules that regulate thermogenesis-related processes - mitochondriogenesis, angiogenesis and IBAT hyperplasia, in rats subjected to cold (4+/-1 degrees C) for 1, 3, 7, 12, 21 and 45days were investigated. Particularly, to examine influence of nitric oxide (NO) on IBAT thermogenic-program, cold-exposed animals were treated by l-arginine or N(omega)-nitro-l-arginine-methyl ester (L-NAME). Related to control (22+/-1 degrees C), cold induced time-coordinated UCP1, PPARgamma and PGC-1alpha transcriptional activation accompanied by PCNA activation and increased VEGF immunolabeling that correlate with endothelial NO synthase (eNOS) transcriptional activation suggesting NO involvement in these thermogenic-factors activation. Observed molecular changes were translated into increased mitochondrial-remodeling, angiogenesis, and IBAT hyperplasia. l-Arginine augmented and prolonged cold-induced increase of eNOS, inducible NOS and thermogenic-molecules expression, IBAT nerve supply, vascularity, hyperplasia and mitochondrial-remodeling, while L-NAME had an opposite effects. Results show that NO improves thermogenesis-related mitochondriogenesis, angiogenesis and tissue hyperplasia, positively affecting molecular basis of these processes, suggesting that NO is an essential regulator of IBAT thermogenic-program operating, at genes, proteins and tissue structure levels.

Interrelationship of antioxidative status, lipid peroxidation, and lipid profile in insulin-dependent and non-insulin-dependent diabetic patients

This study aimed to investigate the interrelationship of plasma lipid profile, lipid peroxidation, and erythrocyte antioxidative defense in patients with insulin-dependent (IDDM) and non-insulin-dependent (NIDDM) diabetes mellitus. Plasma levels of total cholesterol, triglycerides, and lipid peroxides and the activities of copper, zinc superoxide dismutase (CuZnSOD), catalase, glutathione peroxidase (GSH-Px), as well as the amount of glutathione in erythrocytes, were determined in IDDM, NIDDM, and nondiabetic control subjects. Additionally, morphology of erythrocytes in all subjects was examined. Plasma levels of total cholesterol and triglycerides were significantly increased in NIDDM compared with controls. Also, the lipid peroxide level was higher in NIDDM than in either control or IDDM subjects. CuZnSOD activity in erythrocytes was elevated in NIDDM patients compared with the control. In NIDDM patients, more extensive erythrocyte spherocytosis and echinocytosis compared with both control and IDDM subjects were observed. In contrast with the IDDM group, the observed abnormality in lipid metabolism in NIDDM patients is closely associated with increased lipid peroxidation, changes in antioxidative defense, and erythrocyte morphology.

The effects of cold acclimation and nitric oxide on antioxidative enzymes in rat pancreas

Alterations of pancreatic antioxidative defense (AD) and possible nitric oxide (NO) role in AD organization of adult rats receiving l-arginine.HCl (2.25%) or N(omega)-nitro-l-arginine methyl ester (L-NAME.HCl, 0.01%) as drinking liquids and maintained at room (22+/-1 degrees C) or low (4+/-1 degrees C) temperature for 45 days were studied. For that purpose, copper, zinc- and manganese superoxide dismutase (CuZnSOD, MnSOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione S-transferase (GST) and glutathione reductase (GR) activities were determined. Cold-induced decrease of CuZnSOD was inhibited with L-NAME, while l-arginine produced the same effect as cold in both supplemented groups. Cold acclimation elevated GSH-Px activity. l-Arginine and L-NAME expressed no effect on GSH-Px in rats kept at room temperature. L-NAME additionally elevated cold-induced GSH-Px activity, l-arginine expressing a similar trend. Cold-induced increase in GST activity was inhibited by L-NAME, while l-arginine inhibited this enzyme in both supplemented groups. Cold acclimation increased GR activity in control and L-NAME-treated group and l-arginine expressed a similar trend. Neither of the treatments affected MnSOD and CAT activities. Cold-induced changes of pancreatic AD were additionally affected by the alterations in l-arginine-NO-producing pathway. Some AD changes in the same direction with l-arginine or L-NAME point to the complexity of nitrogen compounds metabolism and function, accompanied by tissue-specific response.

Free radical equilibrium in interscapular brown adipose tissue: relationship between metabolic profile and antioxidative defense

Interscapular brown adipose tissue (IBAT) hyperplasia involves a new metabolic and structural profile, resulting from acclimation of animals to a cold environment. Cold-induced changes of several antioxidative defense (AD) components in IBAT and their interrelationship with uncoupling protein 1 (UCP1), sympathetic innervation and apoptosis were studied using cold-acclimated adult rat males (4 +/- 1 degrees C, 45 days). Their age-matches were maintained at 22 +/- 1 degrees C serving as the controls. In cold-adapted rats, activities of CuZn- and Mn-superoxide dismutase (SOD) and apoptosis were reduced, while catalase (CAT), glutathione peroxidase (GSH-Px), glutathione S-transferase (GST) activities and glutathione (GSH) content were increased compared to the control. IBAT mass, protein content, plasma free fatty acid (FFA) concentration, sympathetic innervation and UCP1 level were significantly increased in cold-acclimated group compared to the corresponding control. These results suggest that decreased CuZn and MnSOD activities in IBAT represent an adaptive response due to UCP1-induced mitochondrial uncoupling. Additionally, intensive fatty acid oxidation led to an increased H(2)O(2) production which resulted in increased CAT, GSH-Px and GST activities and GSH level. Generally speaking, cold-induced changes of AD in the IBAT are closely connected with newly established metabolic profile in this tissue, thus making an important part of the entire tissue homeostasis including cell survival.

The effects of l-arginine and l-NAME supplementation on redox-regulation and thermogenesis in interscapular brown adipose tissue

Changes in inducible nitric oxide synthase (iNOS) protein levels and its relationship with the hyperplasia and uncoupling protein 1 (UCP1) levels were examined in interscapular brown adipose tissue (IBAT) of adult rat males receiving l-arginine (l-Arg; 2.25%) or N-nitro-l-arginine methyl ester (l-NAME; 0.01%)as a drinking liquid and maintained at low (4±1°C) or room(22±1°C) temperature for 45 days.

Cold generally diminished both iNOS immunopositivity and protein level in IBAT, as well as the rate of apoptosis. Among groups acclimated to cold,higher iNOS immunopositivity and protein levels were detected only in the l-Arg-treated group. Furthermore, chronic l-Arg treatment increased IBAT mass and UCP1 protein content, while l-NAME had an opposite effect, decreasing both IBAT mass and UCP1 protein level, as compared to the control maintained at 4±1°C.

These data suggest that nitric oxide (NO) produced by iNOS could also contribute to overall NO-associated regulation of thermogenesis in IBAT. Namely, that iNOS, i.e. NO, in correlation with enhanced thermogenesis,additionally induced IBAT hyperplasia and UCP1 level compared to that induced by low temperature. Cooperative action of decreased apoptosis accompanied by increased tissue hyperplasia and UCP1 level, observed in IBAT of cold-acclimated rats, would be a way of meeting the metabolic requirements for increased thermogenesis.

Doxorubicin toxicity to the skin: possibility of protection with antioxidants enriched yeast

The possibility of skin protection against doxorubicin toxicity was examined after oral antioxidative pretreatment of the rats with yeast supplemented with selenium and vitamins E, C and A for 15 days. The activity and level of antioxidative defense components were monitored in the skin and blood 48 h after i.v. applied doxorubicin. In the blood, increased glutathione peroxidase activity in the erythrocytes, and amounts of vitamin E and glutathione in the plasma were found after the antioxidative treatment. It also led to an increase of the reductive capacity in the skin (increased thioredoxin reductase activity and reduced glutathione level). Doxorubicin alone, depleted reductive capacity, i.e. decreased the activity of thioredoxin reductase in the skin, as well as the content of reduced glutathione both in the skin and blood plasma. Depletion of reductive capacity represents one of the first harmful doxorubicin effects to the skin at the time when the changes of other antioxidative enzyme activities were not detectable. Reductive capacity in the skin of animals given antioxidative pretreatment was maintained elevated upon doxorubicin application in comparison with the corresponding control. Oral supplementation with antioxidants thus prevents toxic effects of doxorubicin in the skin and may contribute to the alleviation of its secondary cytotoxicity during the chemotherapy.

Seasonal changes in the antioxidative defense in ground squirrels (Citellus citellus): possible role of GSH-Px

As seasonal hibernators, ground squirrels decrease their body temperature to 7 degrees C and hibernate during the winter. Maintenance at 30 degrees C prevents seasonal changes of body temperature and animals remain euthermic and active. We measured selenium (Se)-dependent glutathione peroxidase (GSH-Px), as well as the activity of other antioxidative components such as superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), and glutathione-S-transferase (GST) and the amount of low-molecular-weight antioxidants glutathione (GSH), ascorbic acid (AsA), and vitamin E (vit E) in spring, summer, and winter in ground squirrels continuously kept at a temperature of 30 degrees C. We examined liver and interscapular brown adipose tissue (IBAT) as thermogenic tissues, as well as the brain and the kidneys. During the winter, we found a decrease in enzymatic activity and an increase in the level of low molecular antioxidants in all tissues. Correlation analysis revealed a similarity in the composition of antioxidative defense (AD) among the tissues examined. The results obtained clearly demonstrated numerous correlative expressions of antioxidative components in this experimental model, especially of GSH-Px, suggesting the complexity of the system responsible for the maintenance of physiological homeostasis.

Effect of selenium-enriched yeast pretreatment on the antioxidative defense in the skin of rats exposed to heat shock

Skin protection against heat shock and the specificity in the organization of antioxidative defenses were examined in rats given oral antioxidative pretreatment with selenium (Se)-enriched yeast and vitamins E, C, and A for 15 days and then exposed to hyperthermia. The activity of antioxidative enzymes in the skin and the liver was monitored 1 hour and 3 hours after heat shock. Glutathione peroxidase (GSH-Px) activity was increased in the skin after heat shock in the groups supplemented with antioxidants, but not in the controls. In contrast, the activity of liver GSH-Px was increased only in the controls receiving antioxidants. Heat shock led to a decrease in liver superoxide dismutase (SOD) activity at 1 hour in the antioxidant-supplemented group, but this was unchanged in the liver of all other groups and in the skin. The activity of thioredoxin reductase (TR) in the skin was increased in the antioxidant supplemented group 1 hour after heat shock, whereas the hepatic thioredoxin reductase activity was decreased. The activities of catalase (CAT), glutathione reductase (GR), and glutathione-S-transferase (GST) were unaffected by either treatment. These results suggest that supplementation with antioxidants protects the skin against heat shock, especially with respect to the GSH-Px and TR activity. The different response of the skin in comparison with the liver probably reflects differences in organization and regulation of antioxidative defenses.

Seasonal changes in the activity of antioxidative defense in the kidneys of the euthermic ground squirrel (Citellus citellus)

The aim of this work was to determine the activity of the antioxidant enzymes: superoxide dismutase (EC 1.15.1.1; SOD), catalase (EC 1.11.1.6; CAT), glutathione peroxidase (EC 1.11.1.9; GSH-Px), glutathione-S-transferase (EC 2.5.1.18; GST), glutathione reductase (EC 1.6.4.2; GR) and the low molecular mass antioxidants: ascorbic acid (ASA) and vitamin E (vit E) in the kidney of ground squirrels during circannual changes. Keeping the ground squirrel at the temperature of thermic neutrality (30 degrees C) provides a stable euthermic state during the whole year and thus any change is due to the circannual rhythm. The highest specific activity of all examined antioxidative defense enzymes in the kidney was found in the spring, when ground squirrels are seasonally the most active. In the summer, lower specific activity of GSH-Px as well as of SOD and CAT were noted and, when expressed per g wet mass, only a decrease in GSH-Px activity was recorded. In the kidney of ground squirrels kept at 30 degrees C, the lowest specific activity of all examined enzymes was found during the winter and, when expressed per g wet mass, only the SOD activity was lower than in the spring and summer. Higher amounts of vitamins C and E were found in the ground squirrel kidneys in the summer. The results obtained in this work demonstrate that circannual regulation of metabolic activity, which is inherent to seasonal hibernators, is also expressed at the level of antioxidative defense in the kidneys.

Seasonal variation in the antioxidant defense system of the brain of the ground squirrel (Citellus citellus) and response to low temperature compared with rat

Seasonal variation in the activity of antioxidant enzymes (superoxide dismutase (EC 1.15.1.1.; SOD), catalase (EC 1.11.1.6; CAT), glutathione peroxidase (EC 1.11.1.9; GSH-Px), glutathione reductase (EC 1.6.4.2; GR), glutathione-S-transferase (EC 2.5.1.18; GST) and low-molecular-weight antioxidants: ascorbic acid (AsA), vitamin E (VIT E) and glutathione (CSH+GSSG) were examined in the brain of the ground squirrels (Citellus citellus) maintained at 30 degrees C during the whole year. The highest activity (per mg protein) of antioxidant defense (AD) enzymes was found in the spring and was much lower in the summer. A further decrease in activity of CAT, GSH-Px and GST was observed in the winter. The highest levels of AsA and glutathione were recorded in winter in comparison with spring and summer. AD system in the brain of the ground squirrel and rates (maintained at thermoneutrality) exposed to low temperature (4 degrees C) for 3, 6 or 24 hr during the summer was studied as well. Summer was chosen as a period of stable euthermia for ground squirrels and in thermoregulation similar to rats. Consumption of free fatty acid and glucose during the acute exposure to low temperature was found to be species specific. In the ground squirrel, an increase in the specific activities of SOD, after 3, 6 and 24 hr, CAT after 3 and 6 hr and GR after 6 hr of exposure to low temperature was detected. When activities were expressed in U/g wet mass, an increase of SOD after 3, 6 and 24 hr (P < 0.02, P < 0.02, P < 0.005) and CAT and GSH-Px 3 hr (P < 0.01) upon exposure to low temperature was observed. In the rats, no changes in the specific activities of these enzymes after exposure to low temperature were recorded and only an increase in GST activity (U/g wet mass) after 6 hr exposure was registered. Low-molecular-weight AD components in both animal species were unchanged upon short-term exposure to low temperature. The species-specific differences in brain AD between the rats and the ground squirrels after short exposure to low temperature may be ascribed to seasonal changes of the brain activity in the latter.

Activity of antioxidant defense enzymes and glutathione content in some tissues of the Belgrade (b/b) laboratory rat

The activity of antioxidant defense (AD) enzymes--superoxide dismutase (SOD, EC 1.15.1.1.), catalase (CAT, EC 1.11.1.6.), glutathione peroxidase (GSH-Px, EC 1.11.1.9.), glutathione-S-transferase (GST, EC 2.5.1.18), glutathione reductase (GR, EC 1.6.4.2) and glutathione (GSH) content of the anemic Belgrade (b/b) laboratory rats--were measured and analyzed in liver, spleen, lung, heart, brain and testes in comparison with nonanemic controls. The activities of hepatic Mn SOD, CAT, GSH-Px and GST (P < 0.02, P < 0.01 and P < 0.005) were decreased in anemic, comparing with nonanemic animals, whereas the spleen CuZn SOD, Mn SOD, CAT and GSH-Px (P < 0.005, P < 0.02, P < 0.005 and P < 0.01) activities were increased. In the lung of anemic rats, Mn SOD, GSH-Px and GR (P < 0.005, P < 0.01, P < 0.05) activities were higher, whereas GST (P < 0.01) activity was lower in relation to nonanemic ones. In anemic rats, heart Mn SOD (P < 0.05) activity was increased, brain GSH-Px (P < 0.005) activity was lower, whereas GR (P < 0.02) activity was higher compared with nonanemic controls. CuZn SOD (P < 0.05) activity in the testes was elevated and GSH-Px (P < 0.05) reduced in anemic animals. GSH content was decreased in the liver (P < 0.01), lung and brain (P < 0.005) and increased in the spleen (P < 0.02) of anemic rats in relation to the controls. Our data suggest phenotype specific differences in the AD system of the Belgrade (b/b) rat tissues in comparison with nonanemic controls.

Activities of antioxidant enzymes and formation of the glutathione adduct of hemoglobin (Hb ASSG) in epileptic patients with long-term antiepileptic therapy

The activities of antioxidant enzymes (AOE) and amounts of glutathione adduct of Hb (Hb ASSG) in erythrocytes of chronic epileptic patients treated with mono or mixed therapy of phenobarbital (PB), carbamazepin (CBZ) and valproic acid (VPA), were evaluated and the results were compared with those for normal individuals. The activity of superoxide dismutase (SOD) was lowered for 40% to 60% in epileptic patients relative to normal controls. The lowest activity of SOD was found in patients treated with CBZ and PB. Activity of glutathione peroxidase (GSH-Px) was lowered comparing to the control from cca 15% in patients treated with PB to 50% in those treated with either CBZ alone or with CBZ in combination with PB. For the later two sub-groups of patients significantly lowered activities of catalase and glutathione reductase (cca 20% and 30-40%, respectively) were also characteristic. The highest amounts of Hb ASSG (cca 4% of the tota lHb) were found in hemolysates of patients with the lowest AOE levels i.e., in those treated with CBZ alone or with CBZ in combination with PB. In hemolysates of patients treated with PB, Hb ASSG represented 2.4% of the total Hb, while it was totally absent in those treated with VPA, although SOD and GSH-Px levels in erythrocytes of both of these sub-groups of patients were lowered to the same extent.

Effect of long-term exposure to cold on the antioxidant defense system in the rat

Catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GR), and glutathione-S-transferase (GST) activities as well as glutathione (GSH), ascorbic acid (AsA), and vitamin E concentrations were analyzed in the blood, liver, brain, interscapular brown adipose tissue (IBAT), and small intestine of rats exposed to low environmental temperature (4 degrees C; 35, 75, and 105 d of exposure) and in controls of the same age exposed to an environmental temperature of 22 +/- 2 degrees C. Prolonged cold exposure resulted in an increase in GSH-Px in IBAT and in small intestine after 35, 75, and 105 d of exposure. Catalase activity in cold-exposed animals was higher in IBAT after 75 and 105 d of cold exposure. Glutathione reductase activity was greater in brain after 35 d, in liver after 75 d, and in IBAT after 105 d of exposure to low temperatures as compared to the controls. In contrast, GST activity was lower in liver and IBAT after 35 and 75 d of cold exposure. AsA and GSH (determined only 105 d after cold exposure) were markedly higher in IBAT, whereas plasma GSH was lower and plasma AsA was higher in cold-exposed animals. The observed changes in analysed components of the antioxidant defense system under conditions of prolonged exposure to low temperature suggest that a reorganization the activity of this system at the molecular level occurred. Although other studies indicate that a 21-d cold exposure is sufficient for adaptation of thermogenesis, the present study shows that in general, longer periods are required for the registration of the changes in the antioxidant defense system.

Seasonal dependence of the activity of antioxidant defence enzymes in the ground squirrel (Citellus citellus): the effect of cold

1. The activity of antioxidant defense enzymes (SOD, CAT, GSH-Px and GST) was analysed during the autumn and winter in the ground squirrel adapted to 30 degrees C and subsequently exposed to cold for 6 and 24 hr. 2. The liver CAT activity as well as the IBAT CAT and GSH-Px activities differed between animals adapted to 30 degrees C, studied in autumn, and those studied in winter. 3. MnSOD activity in the liver was increased in autumn but decreased in winter after 6 hr cold exposure reaching the control level 24 hr later. Cold exposure induced a decrease in CAT activity (except after 24 hr cold exposure in winter) and an increase in GSH-Px activity. Lower GST activity was found after 24 hr exposure to cold in winter. 4. The IBAT SOD activity decreased under the influence of cold during both seasons with a tendency to return to the control level only in winter. Cold exposure produced a decrease in GST in both seasons and CAT activity in autumn. GSH-Px activity was increased in winter only. 5. The results indicate a seasonal dependence of the activity of antioxidant defence enzymes in the ground squirrel. Seasonal influence was evidenced in animals exposed to cold as well.

Antioxidant defenses in the ground squirrel Citellus citellus. 2. The effect of hibernation

In spring and autumn, the ground squirrel Citellus citellus is awake and active but in winter it usually hibernates. Reawakening from hibernation involves intense metabolic activity in the interscapular brown adipose tissue (IBAT). The IBAT of hibernation animals showed significant increases in the activities of superoxide dismutase (both copper-zinc and manganese-containing enzymes), glutathione peroxidase, and in the amount of ascorbate present. Glutathione peroxidase also increased in the liver, as did ascorbate in the plasma. These changes were not merely a consequence of exposure to low environmental temperatures. It is proposed that antioxidant defenses are increased in the IBAT of ground squirrels at the onset of hibernation in order to protect the tissue from reactive oxygen species generated as a result of the intense metabolic activity sustained by this tissue during reawakening.

Antioxidant defenses in the ground squirrel Citellus citellus. 1. A comparison with the rat

The antioxidant defenses of the liver, erythrocytes, blood plasma, and interscapular brown adipose tissue (IBAT) of male ground squirrels were compared with those of male rats kept under identical conditions and fed the same diet. Superoxide dismutase (SOD), ascorbate, vitamin E, catalase, glutathione, and enzymes of glutathione metabolism were measured. In general, antioxidant defenses in erythrocytes were lower in ground squirrels than in rats. The same was true in liver, except that catalase-specific activity was higher. In IBAT, ascorbate, vitamin E, catalase, and glutathione reductase were higher than in rat and more of the SOD activity present was cyanide-insensitive (MnSOD). It is suggested that IBAT in ground squirrels may need a relatively greater antioxidant defense because of its important role in thermogenesis, especially in reawakening from hibernation. No major differences in antioxidant defenses between male and female ground squirrels were observed, except that the SOD activity of IBAT was higher in females.