Brain Catalase Activity Research Articles

Differences in ethanol-induced behaviors in normal and acatalasemic mice: Systematic examination using a biobehavioral approach

In studies designed to further examine the previously reported involvement of catalase in ethanol-induced effects, we attempted to confirm earlier observations by using normal (C3H-N) and acatalasemic (C3H-A) mice. These mice are identical in every respect and differ only in their catalase activity. Data suggested that the application of 3-amino-1,2,4-triazole (AT), a catalase inhibitor, to both substrains of mice resulted in a proportional decrease in motor activity, thus supporting our earlier observations. We also showed that this effect was specific to ethanol because AT did not have any effect on cocaine-induced motor activity in both substrains. Contrary to the effects of ethanol, these substrains did not differ activity in response to cocaine. In an additional study, we observed that acatalasemic mice differed from the normals in their pattern of voluntary ethanol consumption. Acatalasemic mice consumed more ethanol but only when it was presented in the range of concentrations between 12 and 18%. Finally, we also obtained data suggesting that suggesting that acatalasemic mice have longer duration of sleep time following ethanol administration compared to normals. Catalase activity was measured in both substrains. Results, once again, confirmed earlier data that the substrains differ in this activity and that AT further decreases brain catalase activity in both mice. Finally, when brain homogenates derived from both substrains were incubated with ethanol significant differences in the amount of generated acetaldehyde were found between the two mice strains. Together, these results provide strong support for the involvement of brain catalase in a variety of ethanol-induced behavioral effects.

Dose- and time-dependent effect of an acute 3-amino-1,2,4-triazole injection on rat brain catalase activity

The results presented in this study demonstrate a progressive inhibition of rat brain catalase activity by AT in vivo. Furthermore, the inhibition of brain catalase by AT demonstrates the presence of hydrogen peroxide in brain, since AT inhibits catalase in the presence of this compound. The rate of inhibition of catalase seems to be dependent upon the rate by which H2O2 is generated. A time course study showed slower onset of the inhibition of brain as compared to liver catalase, possibly reflecting tissue hydrogen peroxide levels or, alternatively, a rate-limiting penetration of AT into brain and into the catalase compartment. The presence of AT in brain was confirmed over the time period of the observed inhibition of brain catalase. Catalase inhibitors are of particular interest in the study of the physiological role of catalase. This study further supports the use of AT in investigations designed to further understand the role of brain catalase.

Effect of 3-amino-1,2,4-triazole on ethanol-induced narcosis, lethality and hypothermia in rats

It has been proposed that ethanol can be oxidized in brain via the peroxidatic activity of catalase and that centrally formed acetaldehyde may mediate several of the psychopharmacological actions of ethanol. The present study was designed to investigate the role of brain catalase in the mediation of ethanol-induced narcosis, hypothermia and lethality in rats. Rats were pretreated with the catalase inhibitor 3-amino-1,2,4-triazole (AT) or saline. Five hours later, animals in each pretreatment group received IP injections of ethanol (3 or 4 g/kg). Ethanol-induced narcosis was significantly attenuated in AT-pretreated rats compared to the saline control group. As well, AT pretreatments reduced significantly the lethal effect of these ethanol doses. However, AT-pretreated ethanol-injected animals significantly reduce their body temperature as compared to the saline-ethanol animals. Blood ethanol determinations revealed that AT did interfere with ethanol metabolism. AT inhibits significantly brain catalase activity at all doses used in this study. The results indicate a role for brain catalase in ethanol effects. Furthermore, they suggest that catalase may be involved in the oxidation of ethanol in brain and that centrally formed acetaldehyde may play a role in ethanol-induced narcosis and lethality, but not hypothermia.

Studies on Ethanol‐Brain Catalase Interaction: Evidence for Central Ethanol Oxidation

The purpose of the present investigation was to further study the relationship between ethanol and brain catalase in vivo. Rats were pretreated intraperitoneally (ip) with varying doses of ethanol or saline 30 min prior to administration of cyanamide (0.68 mmol/kg; ip), 4-hydroxypyrazole (1 mmol/kg; ip) or saline. Rat tissues were perfused in situ under ether anaesthesia. Brain catalase activity was measured using the Clark electrode. Results confirmed inhibition of brain catalase activity by cyanamide and 4-hydroxypyrazole. Ethanol protected catalase from cyanamide and 4-hydroxypyrazole inactivation in a dose-related manner. In a second study, homogenates from perfused brains were incubated in the presence of glucose and glucose oxidase with ethanol or saline and cyanamide or saline. Cyanamide was shown to inhibit the catalase activity in vitro in a dose-related manner. Ethanol prevented this inhibition of catalase when added to the incubation medium prior to cyanamide. These data suggest a competition between ethanol and inhibitors for the H2O2-catalase compound. They also confirm the presence and generation of H2O2 in the rat brain in vivo, and overall seem to support the notion that centrally formed acetaldehyde via brain catalase may be responsible for some of the psychopharmacological actions of ethanol.

Effects of Hypoxic Hypoxia and Reoxygenation on H2O2 Production in Rat Brain in vivo

The effects of hypoxic hypoxia and subsequent reoxygenation on hydrogen peroxide (H2O2) production was studied in the rat brain in vivo. Brain H2O2 production was measured by H2O2-dependent aminotriazole inactivation of endogenous brain catalase activity. Brain catalase activities of rats breathing air (0.2 ATA O2, control) were 168 +/- 5 (n = 10), 125 +/- 4 (n = 6), and 100 +/- 5 (n = 8) U/g brain (mean +/- SEM) at 0, 30, and 60 min after i.p. aminotriazole injection, respectively. Catalase activities after exposure to 5% O2 with N2 for 15 min, 10% O2 with N2 for 30 min, and 6% O2 with nitrous oxide (N2O) for 15 min were 131 +/- 4 (n = 7), 122 +/- 6 (n = 5), and 124 +/- 6 (n = 7) U/g brain, respectively, at 30 min after aminotriazole injection, and were not significantly different from each other or control. Reoxygenated on room air, 100% O2, and hyperbaric 3 ATA O2 for 30 min immediately after each period of hypoxia, brain catalase activity at 60 min after aminotriazole injection in the group of pre-exposure to 6% O2 with N2O was 67 +/- 3, 74 +/- 3, and 67 +/- 6 U/g brain with 0.2 ATA O2 (n = 6), 1.0 ATA O2 (n = 5), and 3.0 ATA O2 (n = 5), respectively. All of these were significantly different from control and other hypoxic pre-exposure groups with N2 (p <0.01) but not from each other. Reoxygenation of the brain after hypoxia with N2O could exacerbate cerebral damage by increasing oxygen free radical production.

Brain lipid peroxidation and antioxidant protectant mechanisms following acute cyanide intoxication

The status of brain antioxidant enzymes and glutathione levels in mice intoxicated with KCN were correlated with lipid peroxidation in brain membranes. KCN (7 mg/kg, s.c.) rapidly increased conjugated dienes in brain lipids, with peak levels observed 30 min after cyanide treatment. At 60 min post cyanide, conjugated diene levels were only slightly elevated above controls. Temporal changes in activity of most antioxidant enzymes corresponded with the observed time course of cyanide-induced membrane lipid peroxidation. Thirty minutes after KCN, brain catalase (CA), glutathione peroxidase (GP x) and glutathione reductase (GR) activities were significantly reduced (percent inhibition compared to control: CA 44%, GP x 30%, and GR 41%). At 60 min, CA and GP x enzyme activity returned to control levels, whereas GR was elevated 34% above control activity. Superoxide dismutase was not significantly inhibited 30 min after KCN, but declined to 71% of control activity at 60 min. Brain levels of reduced glutathione declined 42% below control 30 min after cyanide and returned to within 9.4% of control at 60 min. At 30 and 60 min after cyanide, oxidize glutathione levels were not significantly changed from control levels. These studies suggest that membrane lipid peroxidation and subsequent membrane dysfunction observed in cyanide intoxication is related in part to a compromised antioxidant defense.

Effects of 3-amino-1,2,4-triazole on ethanol-induced open-field activity: evidence for brain catalase mediation of ethanol's effects.

The role of brain catalase in the mediation of ethanol's effects on motor activity was investigated. Male Long-Evans rats were pretreated with i.p. injections of the catalase inhibitor, 3-amino-1,2,4-triazole (AT) (1 g/kg) or saline (S). Four hours later, animals in each group received i.p. injections of one of two doses of ethanol (ETOH) [1.0 g/kg (E1) or 2.0 g/kg (E2)] or one of two volumes of distilled water (W1 or W2). Ten minutes after the administration of these agents, animals were placed in open-field chambers and motor activity was recorded during a 10-min testing period. Results indicated that the motor depression produced by 2.0 g/kg of ETOH was significantly attenuated in AT pretreated rats (group AT-E2). AT pretreatment, however, had no effect on motor activity for subjects injected with 1.0 g/kg ethanol or water. Total brain catalase activity in AT-pretreated animals was 15% of control animals. No differences in blood ethanol levels were observed between AT- and S-pretreated animals. An interaction between ethanol and AT at the level of the central nervous system is suggested. The results of the present study suggest that brain catalase activity may be involved in ethanol's effects. They also provide further support for the notion that acetaldehyde may be produced directly in the brain via catalase and that it may be a factor mediating some of ethanol's central effects.

Catalase activity measured in rats naive to ethanol correlates with later voluntary ethanol consumption: possible evidence for a biological marker system of ethanol intake.

Catalase activity in blood collected from young rats naive to ethanol (65 days) was significantly and positively correlated with later voluntary consumption of ethanol. Catalase activity levels were also correlated with catalase activity in brain and blood sampled after exposure to ethanol. The results obtained in the present study extend and confirm earlier findings (Aragon et al. 1985c) that brain catalase activity and voluntary ethanol intake are unidirectionally and causally related. The results also suggest that brain catalase activity may be part of an enzymatic system controlling the production and elimination of acetaldehyde in brain. This system may be a biological marker system mediating the affinity of organisms to ingest ethanol.

Distribution of superoxide dismutase, glutathione peroxidase and catalase in developing rat brain

This study was carried out to assess the developmental pattern of copper- and zinc-containing superoxide dismutase (CuZnSOD), manganese-containing superoxide dismutase (MnSOD), glutathione peroxidase (GSH-Px) and catalase (CAT) activity in rat brain. The enzymes studied were assayed in different brain regions (cerebral cortex, striatum, cerebellum and brainstem) and enzyme values were corrected for erythrocyte contamination. The cerebral ontogenetic pattern of these enzymes is characterized by increasing CuZnSOD activity, a progressive decrease in CAT activity and, after an initial 10-day fall, increasing GSH-Px activity. The activity of MnSOD appeared to be quite stable up to 40 weeks of age. Similar and comparable changes were seen in all brain regions studied.

Hyperoxia increases H2O2 production by brain in vivo.

Hyperoxia and hyperbaric hyperoxia increased the rate of cerebral hydrogen peroxide (H2O2) production in unanesthetized rats in vivo, as measured by the H2O2-mediated inactivation of endogenous catalase activity following injection of 3-amino-1,2,4-triazole. Brain catalase activity in rats breathing air (0.2 ATA O2) decreased to 75, 61, and 40% of controls due to endogenous H2O2 production at 30, 60, and 120 min, respectively, after intraperitoneal injection of 3-amino-1,2,4-triazole. The rate of catalase inactivation increased linearly in rats exposed to 0.6 ATA O2 (3 ATA air), 1.0 ATA O2 (normobaric 100% O2) and 3.0 ATA O2 (3 ATA 100% O2) compared with 0.2 ATA O2 (room air). Catalase inactivation was prevented by pretreatment of rats with ethanol (4 g/kg), a competitive substrate for the reactive catalase-H2O2 intermediate, compound I. This confirmed that catalase inactivation by 3-amino-1,2,4-triazole was due to formation of the catalase-H2O2 intermediate, compound I. The linear rate of catalase inactivation allows estimates of the average steady-state H2O2 concentration within brain peroxisomes to be calculated from the formula: [H2O2] = 6.6 pM + 5.6 ATA-1 X pM X [O2], where [O2] is the concentration of oxygen in ATA that the rats are breathing. Thus the H2O2 concentration in brains of rats exposed to room air is calculated to be about 7.7 pM, rises 60% when O2 tension is increased to 100% O2, and increases 300% at 3 ATA 100% O2, where symptoms of central nervous system toxicity first become apparent. These studies support the concept that H2O2 is an important mediator of O2-induced injury to the central nervous system.

Genetic Variation in Ethanol Sensitivity in C57BL/6 and DBA/2 Mice: A Further Investigation of the Differences in Brain Catalase Activity

Genetic Variation in Ethanol Sensitivity in C57BL/6 and DBA/2 Mice: A Further Investigation of the Differences in Brain Catalase Activity

A correlation between voluntary ethanol consumption and brain catalase activity in the rat

The relationship between voluntary ethanol consumption and brain catalase activity was investigated in male Long Evans rats. In the first study, rats which were voluntarily consuming alcohol or water for 25 days were sacrificed by decapitation immediately (group A) or 15 days (group B) following withdrawal of alcohol and their brains analysed for catalase activity. Mean brain catalase activity did not differ among the two groups of rats exposed to ethanol and the ones exposed to water only. Furthermore, there were significant positive correlations between individual voluntary ethanol intake and catalase activity in both groups, (group A:r=.69, p≤0.05; group B:r=.54, p≤0.05). In a second study, rats were forced to drink high levels of ethanol presented as the only source of fluid for 25 days. Rats were sacrificed and brain, liver, muscle and heart tissue were extracted and analysed for catalase activity. There were no differences in mean brain catalase activity between water and forced ethanol drinking rats indicating that the enzyme was not inducible by high volume ethanol consumption. The results suggest that inherent differences in brain catalase activity may be one of the factors in determining an animal's propensity to voluntarily consume ethanol.

Relationship between catalase activity and uptake of elemental mercury by rat brain

Uptake of mercury by brain after intravenous injection of elemental mercury was investigated in the rat. Catalase activity was inhibited by aminotriazole either by intraperitoneal injections affecting catalase in most tissues of the animal or by intraventricular injections affecting catalase in the brain selectively. Uptake of elemental mercury by rat brain was not influenced by intraperitoneal administration of aminotriazole resulting in 50% inhibition of brain catalase. However, when the inhibitor was injected intraventricularly in concentrations to give a 50% inhibition of brain catalase, it was shown that the mercury uptake by the brain was significantly decreased. In the latter case when only brain catalase was inhibited and the supply of elemental mercury to brain was maintained, mercury uptake by brain was proportional to the activity of catalase in brain tissue and to the injected amount of elemental mercury. Contrary to the intraventricular injection of aminotriazole, in animals receiving aminotriazole intraperitoneally prior to elemental mercury injection, we suggest that the lower activity of brain catalase is compensated by an increased supply of elemental mercury caused by the generally lower oxidation rate in the animal. This view is supported by the finding that mercury uptake by liver increased due to aminotriazole intraperitoneally although activity of catalase was depressed.

Relationship between catalase activity and uptake of elemental mercury by rat brain.

Uptake of mercury by brain after intravenous injection of elemental mercury was investigated in the rat. Catalase activity was inhibited by aminotriazole either by intraperitoneal injections affecting catalase in most tissues of the animal or by intraventricular injections affecting catalase in the brain selectively. Uptake of elemental mercury by rat brain was not influenced by intraperitoneal administration of aminotriazole resulting in 50% inhibition of brain catalase. However, when the inhibitor was injected intraventricularly in concentrations to give a 50% inhibition of brain catalase, it was shown that the mercury uptake by the brain was significantly decreased. In the latter case when only brain catalase was inhibited and the supply of elemental mercury to brain was maintained, mercury uptake by brain was proportional to the activity of catalase in brain tissue and to the injected amount of elemental mercury. Contrary to the intraventricular injection of aminotriazole, in animals receiving aminotriazole intraperitoneally prior to elemental mercury injection, we suggest that the lower activity of brain catalase is compensated by an increased supply of elemental mercury caused by the generally lower oxidation rate in the animal. This view is supported by the finding that mercury uptake by liver increased due to aminotriazole intraperitoneally although activity of catalase was depressed.

Uptake of elemental mercury and activity of catalase in rat, hamster, guinea-pig, normal and acatalasemic mice.

Uptake of elemental mercury after inhalation (3.5 mg/m3) and the activity of catalase in brain, liver, kidney and blood were investigated in rat, hamster, guinea-pig, and normal and acatalasemic mice. The uptake of mercury in the species investigated varied considerably, being highest in the two strains of mice, followed by rat and hamster, and lowest in the guinea-pig. The uptake seemed to be more dependent on pulmonary ventilation than on the activity of catalase. The two strains of mice were exposed to a wide range of mercury concentrations in air (0.002-3.5 mg/m3). The content of mercury in brain, liver and kidney was linearly dependent on the mercury concentration in the air, whereas in blood this relationship was exponential. At the lower concentrations of mercury in the inhaled air, the mercury level in blood was significantly lower, and in kidney higher in the acatalasemic mice compared to the normal ones. In acatalasemic mice the mercury content in liver was higher at all concentrations investigated, whereas in brain no difference between the two strains was found.

Pharmacological and toxicological properties of 4-hydroxypyrazole, a metabolite of pyrazole.

The effects of 4-hydroxypyrazole (4-HP), a principal metabolite of pyrazole, were studied in mice. The compound was toxic, much more so than pyrazole with an LD50 of 1.1 mmol/kg (92 mg/Kg) and doses greater than 1.5 mmol/kg (126 mg/kg) were almost invariably fatal. Toxicity seemed to be centered on the liver with microscopic evidence of centrolobular necrosis apparent. Mouse liver catalase was almost totally inhibited 1 hour after administration of 1 mmol/kg of 4-HP. Tryptophan pyrrolase was also inhibited 4-HP seemed to penetrate into the brain as judged by inhibition of brain catalase activity. A slight increase in brain serotonin concentration was found but 4-HP had no effect in the doses used (1.5 mmol/kg or 4 x 1.0 mmol/kg) in brain or heart noradrenaline. We conclude that the pyrazole-induced decrease in brain noradrenaline is not mediated via 4-HP. Furthermore, simultaneous treatment with methanol and pyrazole, which prevents the formation of 4-HP, did not prevent the decrease in brain noradrenaline levels. Since methanol prevented the pyrazole-induced decrease in brain catalase activity, we can also rule out the possibility that the decrease in brain noradrenaline is secondary to pyrazole-induced inhibition of brain catalase. It is concluded that though 4-HP is an active metabolite of pyrazole, causing, in particular, the hepatotoxicity of the parent molecule, it is not responsible for all the varied biological of pyrazole.

Hydrogen Peroxide Production by Rat Brain In Vivo

Abstract: H2 O2 production by rat brain in vivo was observed with a method based on the measurement of brain catalase. The administration to the rat of 3‐amino‐1, 2, 4‐triazole, an H2 O2‐ dependent inhibitor of catalase, caused progressive inhibition of brain catalase activity in both the supernatant and pellet fractions of homogenates of the striatum and prefrontal cortex. The prevention of catalase inhibition by prior administration of ethanol confirmed that catalase inhibition in vivo was dependent upon H2 O2. A significant portion of the catalase (30‐33%) appeared in the supernatant fraction from a slow‐speed homogenization procedure and was not significantly contaminated by either erythrocytes or capillaries. In the whole homogenate, less than 6% of the catalase activity was attributed to erythrocytes. Modification of intracellular monoamine oxidase activity by either pargyline or reserpine did not change the rate of inhibition of catalase by aminotriazole. A probable interpretation of these data is that H2 O2 generated by mitochondrial monoamine oxidase does not reach the catalase compartment; the catalase is contained in particles described by other investigators as the microperoxisomes of brain. In studies in vitro, the production of H2 O2 by rat brain mitochondria with either dopamine or serotonin as substrate was confirmed.

On the Seasonal Flactuations of Liver, Blood and Brain Catalase Activity in Normal Mice

On the Seasonal Flactuations of Liver, Blood and Brain Catalase Activity in Normal Mice