The catalase inhibitor aminotriazole alleviates acute alcoholic liver injury / 生理学报

In this study, the effects of catalase (CAT) inhibitor aminotriazole (ATZ) on alcohol-induced acute liver injury were investigated to explore the potential roles of CAT in alcoholic liver injury. Acute liver injury was induced by intraperitoneal injection of alcohol in Sprague Dawley (SD) rats, and various doses of ATZ (100-400 mg/kg) or vehicle were administered intraperitoneally at 30 min before alcohol exposure. After 24 h of alcohol exposure, the levels of aspartate transaminase (AST), alanine transaminase (ALT) and lactate dehydrogenase (LDH) in plasma were determined. The degree of hepatic histopathological abnormality was observed by HE staining. The activity of hepatic CAT, hydrogen peroxide (H₂O₂) level and malondialdehyde (MDA) content in liver tissue were measured by corresponding kits. The levels of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in plasma were determined by ELISA method. The results showed that treatment with ATZ dose-dependently suppressed the elevation of ALT, AST and LDH levels induced by alcohol exposure, and that ATZ alleviated alcohol-induced histopathological alterations. Furthermore, ATZ inhibited the activity of CAT, reduced hepatic levels of H₂O₂and MDA in alcohol exposed rats. ATZ also decreased the levels of plasma TNF-α and IL-6 in rats with alcohol exposure. These results indicated that ATZ attenuated alcohol-induced acute liver injury in rats, suggesting that CAT might play important pathological roles in the pathogenesis of alcoholic liver injury.

The Effect of Simvastatin on the Expression of Catalase in Human Retinal Pigment Epithelial Cells

PURPOSE: To evaluate the effects of simvastatin on the catalase expression in human retinal pigment epithelium. METHODS: Retinal pigment epithelial (RPE) cells were incubated for 6 hours and 24 hours with various concentrations of simvastatin. In addition, RPE cells were incubated with 200 microM of H2O2 and various concentrations of simvastatin. After incubation, real-time polymerase chain reaction (PCR) was performed to examine the catalase messenger ribonucleic acid (mRNA) expression and a catalase assay was performed to examine the catalase activity in RPE. Intracellular reactive oxygen species (ROS) was measured using a fluorescence activated cell sorter (FACS). RESULTS: Simvastatin increased the amount of catalase mRNA and catalase activity at 10 microM in RPE cells. Under oxidative stress (200 microM of H2O2), 2.5 microM of simvastatin increased the catalase mRNA expression and 5 microM of simvastatin increased catalase activity in RPE cells. In addition, simvastatin reduced free radical formation but this effect was diminished in the presence of an irreversible catalase inhibitor, 3-amino-1,2,4-triazole (3-AT). CONCLUSIONS: Simvastatin exhibits anti-oxidative effects by inducing the catalase expression in human RPE cells. This anti-oxidative effect may be beneficial for preventing age-related macular degeneration induced by oxidative stress.

Effects of the administration of a catalase inhibitor into the fourth cerebral ventricle on cardiovascular responses in spontaneously hypertensive rats exposed to sidestream cigarette smoke

OBJECTIVE: Previous studies have demonstrated a relationship between brain oxidative stress and cardiovascular regulation. We evaluated the effects of central catalase inhibition on cardiovascular responses in spontaneously hypertensive rats exposed to sidestream cigarette smoke. METHODS: Male Wistar Kyoto (WKY) rats and spontaneously hypertensive rats (SH) (16 weeks old) were implanted with a stainless steel guide cannula leading into the fourth cerebral ventricle (4th V). The femoral artery and vein were cannulated for arterial pressure and heart rate measurement and drug infusion, respectively. The rats were exposed to sidestream cigarette smoke for 180 minutes/day, 5 days/week for 3 weeks (CO: 100-300 ppm). The baroreflex was tested using a pressor dose of phenylephrine (8 μg/kg, bolus) and a depressor dose of sodium nitroprusside (50 μg/kg, bolus). Cardiovascular responses were evaluated before and 5, 15, 30 and 60 minutes after injection of a catalase inhibitor (3-amino-1,2,4-triazole, 0.001 g/100 μL) into the 4th V. RESULTS: Vehicle administration into the 4th V did not affect the cardiovascular response, whereas administration of the central catalase inhibitor increased the basal HR and attenuated the bradycardic peak (p<0.05) to a greater extent in WKY rats exposed to sidestream cigarette smoke than in WKY rats exposed to fresh air. However, in spontaneously hypertensive rats, the effect of the catalase inhibitor treatment was stronger in the fresh air condition (p<0.05). CONCLUSION: Administration of a catalase inhibitor into the 4th V combined with exposure to sidestream cigarette smoke has a stronger effect in WKY rats than in SH rats. .

Antioxidant effects of methylprednisolone and hydrocortisone on the impairment of endothelium dependent relaxation induced by reactive oxygen species in rabbit abdominal aorta / 대한마취과학회지

BACKGROUND: The reperfusion following ischemia produces reactive oxygen species (ROS). We studied the influences of methylprednisolone (MPD) and hydrocortisone (CRT) on ROS effects using the endothelium of rabbit abdominal aorta. METHODS: Isolated rabbit aortic rings were suspended in an organ bath filled with Krebs-Henseleit (K-H) solution. After precontraction with norepinephrine, changes in arterial tension were recorded following the cumulative administration of acetylcholine (ACh). The percentages of ACh-induced relaxation of aortic rings before and after exposure to ROS, generated by electrolysis of K-H solution, were used as the control and experimental values, respectively. The aortic rings were pretreated with MPD or CRT at the same concentrations, and the effects of these agents were compared with the effects of ROS scavenger inhibitors: superoxide dismutase inhibitor, diethylthiocarbamate (DETCA), and the catalase inhibitor, 3-amino-1,2,4-triazole (3AT). RESULTS: Both MPD and CRT maintained endothelium-dependent relaxation induced by ACh in a dose-related manner in spite of ROS attack. The restored ACh-induced relaxation of MPD and CRT group was not attenuated by pretreatment of 3AT and DETCA. CONCLUSIONS: MPD and CRT preserve the endothelium-dependent vasorelaxation against the attack of ROS, in a dose-related manner. Endothelial protection mechanisms of MPD and CRT may be not associated with hydrogen peroxide and superoxide scavenging.

Antioxidant Effect of Captopril and Enalapril on Reactive Oxygen Species-Induced Endothelial Dysfunction in the Rabbit Abdominal Aorta

BACKGROUND: Reactive oxygen species (ROS) are known to be related to cardiovascular diseases. Many studies have demonstrated that angiotensin-converting enzyme inhibitors have beneficial effects against ROS. We investigated the antioxidant effect of captopril and enalapril in nitric oxide mediated vascular endothelium-dependent relaxations. MATERIALS AND METHODS: Isolated rabbit abdominal aorta ring segments were exposed to ROS by electrolysis of the organ bath medium (Krebs-Henseleit solution) after pretreatment with various concentrations (range, 10-5 to 3x10-4 M) of captopril and enalapril. Before and after electrolysis, the endothelial function was measured by preconstricting the vessels with norepinephrine (10-6 M) followed by the cumulative addition of acetylcholine (range, 3x10-8 to 10-6 M). The relevance of the superoxide anion and hydrogen peroxide scavenging effect of captopril and enalapril was investigated using additional pretreatments of diethyldithiocarbamate (DETCA, 0.5 mM), an inhibitor of Cu/Zn superoxide dismutase, and 3-amino-1,2,4-triazole (3AT, 50 mM), an inhibitor of catalase. RESULTS: Both captopril and enalapril preserved vascular endothelium-dependent relaxation after exposure to ROS in a dose-dependent manner (p<0.0001). Pretreatment with DETCA attenuated the antioxidant effect of captopril and enalapril (p<0.0001), but pretreatment with 3AT did not have an effect. CONCLUSION: Both captopril and enalapril protect endothelium against ROS in a dose-dependent fashion in isolated rabbit abdominal aortas. This protective effect is related to superoxide anion scavenging.

Catalase Induced by All-Trans Retinoic Acid Is Involved in Antiproliferation of 36B10 Cells / 대한방사선종양학회지

PURPOSE: All-trans retinoic acid (ATRA) has antiproliferative effects against brain tumor cells. Recently, ATRA has been reported to induce catalase. We investigated whether catalase induction by ATRA is associated with its antiproliferative effects. MATERIALS AND METHODS: 36B10 cells were exposed to 0~50microM ATRA for 24 or 48 hours and mRNA, protein, and activity of catalase were measured. Reactive oxygen species (ROS) were measured using 2',7'-dichlorofluorescin diacetate. A clonogenic assay was used to confirm the cytotoxic effect. RESULTS: The mRNA, protein, and activity of catalase were found to increase in a concentration- and incubation-time-dependent manner. The increase in catalase activity induced by ATRA was decreased by the addition of 3-amino-1,2,4-triazole (ATZ). ROS was also increased with ATRA and decreased by the addition of ATZ. The decrease in cell survival induced by ATRA was partly rescued by ATZ. CONCLUSION: Catalase induction by ATRA is involved in ROS overproduction and thus inhibits the proliferation of 36B10 cells.

Effect of ketorolac and diclofenac on the impairment of endothelium-dependent relaxation induced by reactive oxygen species in rabbit abdominal aorta / 대한마취과학회지

BACKGROUND: Reactive oxygen species (ROS) induce lipid peroxidation and tissue damage in endothelium. We studied the influences of ketorolac and diclofenac on ROS effects using the endothelium of rabbit abdominal aorta. METHODS: Isolated rabbit aortic rings were suspended in an organ bath filled with Krebs-Henseleit (K-H) solution bubbled with 5% CO2 and 95% O2 at 37.5degrees C. After being stimulated to contract with phenylephrine (PE, 10(-6) M), changes in arterial tension were recorded following the cumulative administration of acetylcholine (ACh, 3 x 10(-8) to 10(-6) M). The percentages of ACh-induced relaxation of aortic rings before and after exposure to ROS, generated by electrolysis of K-H solution, were used as the control and experimental values, respectively. The aortic rings were pretreated with ketorolac or diclofenac at the same concentrations (10(-5) M to 3 x 10(-4) M), and the effects of these agents were compared with the effects of ROS scavengers: catalase, mannitol, sodium salicylate and deferoxamine and the catalase inhibitor, 3-amino-1,2,4-triazole (3AT). RESULTS: Both ketorolac and diclofenac maintained endothlium-dependent relaxation induced by ACh in a dose-related manner inspite of ROS attack (P < 0.05 vs. control value). The 3AT pretreated ketorolac (3 x 10(-3) M) group was decreased more significantly than un-pretreated ketorolac (P < 0.05). CONCLUSIONS: These findings suggest that ketorlac and diclofenac preserve the endothelium-dependent vasorelaxation against the attack of ROS, in a concentration-related manner. One of the endothelial protection mechanisms of ketorolac may be hydrogen peroxide scavenging.

Antioxidant effect of lidocaine and procaine on reactive oxygen species-induced endothelial dysfunction in the rabbit abdominal aorta / 대한마취과학회지

BACKGROUND: Reactive oxygen species (ROS) induce lipid peroxidation and tissue damage in the endothelium. We tested the antioxidant effect of lidocaine and procaine on ROS-induced endothelial damage in the rabbit aorta. METHODS: Aortic rings isolated from rabbits were suspended in an organ bath filled with Krebs-Henseleit (K-H) solution bubbled with 5% CO2 and 95% O2 at 37.5degrees C. After precontraction with phenylephrine (PE, 10(-6) M), changes in tension were recorded following a cumulative administration of acetylcholine (ACh 3 x 10(-8) to 10(-6) M). Differences were measured as percentages of ACh-induced relaxation of aortic rings before and after exposure to ROS as generated by electrolysis of the K-H solution. The aortic rings were pretreated with lidocaine or procaine (10(-5) M to 3 x 10(-3) M) to compare their effects, as well as ROS scavengers, catalase, mannitol, sodium salicylate, and deferoxamine, and a catalase inhibitor, 3-amino-1,2,4-triazole (3AT). RESULTS: Lidocaine and procaine dose-dependently maintained endothelium-dependent relaxation induced by ACh despite ROS activity (P < 0.05 vs control value). The 3AT pretreated procaine (3 x 10(-3) M) group decreased more significantly than the un-pretreated procaine group (P < 0.05). CONCLUSIONS: These findings suggest that lidocaine and procaine dose-dependently preserve endothelium-dependent vasorelaxation against ROS attack, potentially via hydrogen peroxide scavenging.

ATZ (3-amino-1,2,4-triazole) injected into the fourth cerebral ventricle influences the Bezold-Jarisch reflex in conscious rats

OBJECTIVES: Many studies have investigated the importance of oxidative stress on the cardiovascular system. In this study we evaluated the effects of central catalase inhibition on cardiopulmonary reflex in conscious Wistar rats. METHODS: Male Wistar rats were implanted with a stainless steel guide cannula in the fourth cerebral ventricle. The femoral artery and vein were cannulated for mean arterial pressure and heart rate measurement and for drug infusion, respectively. After basal mean arterial pressure and heart rate recordings, the cardiopulmonary reflex was tested with a dose of phenylbiguanide (PBG, 8 μg/kg, bolus). Cardiopulmonary reflex was evaluated before and μl15 minutes after 1.0 μl 3-amino-1,2,4-triazole (ATZ, 0.01g/100μl)0.01 g/100 μl) injection into the fourth cerebral ventricle. Vehicle treatment did not change cardiopulmonary reflex responses. RESULTS: Central ATZ significantly increased hypotensive responses without influencing the bradycardic reflex. CONCLUSION: ATZ injected into the fourth cerebral ventricle increases sympathetic inhibition but does not change the parasympathetic component of the cardiopulmonary reflex in conscious Wistar rats.

Effects of amitrole on thyroid hormone-associated gene transcription in FRTL-5 cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To observe the effects of amitrole on the transcription of thyroglobulin (tg), thyroid peroxidase (tpo), Na(+)/I- symporter (nis), Na(+)/I- symporter (nis), thyroid-stimulating hormone receptor (tshr), thyroid transcription factor 1 (ttf-1) and paired-domain protein-8 (pax-8) genes in FRTL-5 cells and investigate the mechanism of amitrole for intervening in thyroid hormone activity.</p><p><b>METHODS</b>FRTL-5 cells were treated with amitrole at 0.001, 0.01 and 0.1 mg/ml for 24 h, respectively, after which the cells were collected for extraction of the total RNA. RT-PCR was used to examine the effects of amitrole on the transcription of tg, tpo, nis, tshr, pax-8 and ttf-1 genes in FRTL-5 cells.</p><p><b>RESULTS</b>Amitrole significantly induced tg gene transcription at all the doses, but produced no obvious effects on tpo and nis gene transcription. At the concentration of 0.1 mg/ml, amitrole significantly reduced pax-8 and tshr gene transcription but increased ttf-1 gene transcription.</p><p><b>CONCLUSION</b>The effects of amitrole on thyroid hormone activity may be related with its actions on tg, ttf-1, tshr and pax-8 gene transcription.</p>

Effects of amitraz on the arterial blood pressure and body rectal temperature of conscious rats

O presente trabalho estuda os efeitos da administraçäo única de amitraz (100 mg/kg) sobre a pressäo sanguínea arterial e a temperatura corporal de ratos Wistar. A administraçäo de amitraz diminuiu a pressäo sanguínea arterial e também produziu hipotermia. A administraçäo de tiramina (100,0 mg/kg) induziu um aumento significativo (p<0,05) na pressäo sanguínea arterial de ratos que receberam previamente amitraz, näo alterando a dos ratos controle. Metade dos ratos que receberam amitraz e tiramina morreram entre 3 e 10 horas após a administraçäo, fato este näo ocorrido com os animais que receberam soluçäo fisiológica e posteriormente tiramina. Os sinais de intoxicaçäo dos animais experimentais incluíram sedaçäo, falta de coordenaçäo motora e coma. A posterior administraçäo de ioimbina (10,0 mg/kg) näo alterou a hipotermia produzida pela administraçäo de amitraz (p<0,05). Apesar de näo poder ser excluída uma possível açäo do amitraz sobre alfa2-noradrenoceptores cerebrais, os resultados indicam uma provável açäo deste praguicida inibindo a enzima monoaminoxidase

Effects of Aminotriazole on Lung Toxicity of Paraquat Intoxicated Mice / 결핵

BACKGROUND: Paraquat, a widely used herbicide, is extremely toxic, causing multiple organ failure in humans. Paraquat especially leads to irreversible progressive pulmonary fibrosis, which is related to oxygen free radicals. However, its biochemical mechanism is not clear. Natural mechanisms that prevent damage from oxygen free radicals include changes in glutathione level, G6PDH, superoxide dismutase(SOD), catalase, and glutathione peroxidase. The authors think catalase is closely related to paraquat toxicity in the lungs METHOD: The effects of 3-amino-1,2,4-triazole(aminotriazole), a catalase inhibitor, on mice administered with paraquat were investigated. We studied the effects of aminotriazole on the survival of mice administered with paraquat, by comparing life spans between the group to which paraquat had been administered and the group to which a combination of paraquat and aminotriazole had been administered. We measured glutathion level, glucose 6-phosphate dehydrogenase(G6PDH), superoxide dismutase(SOD), catalase, and glutathione peroxidase(GPx) in the lung tissue of 4 groups of mice: the control grouts, group A(aminouiazole injected), group B(paraquat administered), group C(Paraquat and aminotriazole administered). RESULTS: The mortality of mice administered with paraquat which were treated with aminotriazole was significantly increased compared with those of mice not treated with aminotriazole. Glutathione level in group B was decreased by 20%, a significant decrease compared with the control group. However, this level was not changed by the administration of aminotriazole(group C). The activity of G6PDH in all groups was not significantly changed compared with the control group. The activities of SOD, catalase, and glutathione peroxidase(GPx) in the lung tissue were significantly decreased by paraquat administration(group B); catalase showed the largest decrease. Catalase and GPX were significantly decreased by aminotriazole treatment in mice administered with paraquat but change in SOD activity was not significant.(group C). CONCLUSION: Decrease in catalase activity by paraquat suggests that paraquat toxicity in the lungs is closely related to catalase activity. Paraquat toxicity in mice is enhanced by aminotriazole administration, and its result is related to the decrease of catalase activity rather than glutathione level in the lungs. Production of hydroxyl radicals, the most reactive oxygen metabolite, is accelerated due to increased hydrogen peroxide by catalase inhibition and the lung damage probably results from nonspecific tissue injury of hydroxyl radicals.

Brain biogenic amine levels after methanol administration: possible mechanism of action on central monoaminergic neurons in discrete areas of brain in Wistar rat.

Alterations in the steady state level of rat brain biogenic amines - dopamine, nor-epinephrine, epinephrine, serotonin and 5-hydroxy indole acetic acid, in response to intraperitoneal administration of methanol (3g/kg b.w.) were studied in discrete areas of the rat brain. The monoamine changes induced by methanol were quite different from those induced by ethanol consumption. They were also region-specific; hypothalamus being more vulnerable for methanol-induced monoamine changes. The effects produced by methanol were correlated with the blood and brain level of methanol at the given time, suggesting that the effects were dependent upon the local concentration of methanol in different brain regions. Acidosis induced by ammonium chloride and sodium formate administration did not alter the monoamine levels and therefore, the effects of methanol were not possibly due to acidosis. Blocking or delaying the metabolism of methanol either by 4-Methyl Pyrazole and 3-Amino 1,2,4-Triazole or by simultaneous administration of ethanol resulted in the potentiation of methanol effect. Therefore, it was concluded that methanol induced changes in brain biogenic amines were due to methanol per se and not due to metabolic end products viz. formaldehyde or formic acid.