Organ- and species-specific properties of glucose-6-phosphate dehydrogenase and the effect of molsidomine

Glucose-6-phosphate dehydrogenase (G-6-PDH) is the key enzyme of the pentose phosphate cycle and therefore regulates the synthesis of the nucleic acid constituent ribose-5-phosphate. At the same time the enzyme is coupled to the synthesis of reduced glutathione (GSH) which detoxifies electrophilic molecules (radicals) in the organism. Activity and stability of G-6-PDH and the influence of SIN 1--the active metabolite of molsidomine (Corvaton)--dithiothreitol (DTT) and NADP on these parameters were studied in enzyme preparations from different organs of the rat (liver, ethmoturbinates, blood) and from blood of mouse, guinea pig, rabbit, dog and man. The highest activity of G-6-PDH was measured in rat ethmoturbinates (69.26 +/- 5.91 mU/mg protein/min), the lowest in human blood (2.99 +/- 0.18 mU/mg protein/min). G-6-PDH of rat ethmoturbinates and of rat and dog blood was unstable and nearly completely inhibited by SIN 1. The enzyme of rat liver and of human, mouse, guinea pig and rabbit blood was stable and not influenced by SIN 1. These organ-and species-specific findings are discussed with respect to the toxicological actions of SIN 1.(ABSTRACT TRUNCATED AT 250 WORDS)     

Acinar distribution of glutathione-dependent detoxifying enzymes. Low glutathione peroxidase activity in perivenous hepatocytes

The acinar distribution of glutathione S-transferase (GST), glutathione peroxidase (GPx), glutathione reductase (GR), and glucose-6-phosphate dehydrogenase (G-6-PDH) was examined by analyzing periportal (p.p.) and perivenous (p.v.) rat hepatocytes selectively isolated by the digitonin-collagenase perfusion. The cytosolic GST activity was higher in p.v. cells, but the microsomal GST and cytosolic GR were found to be evenly distributed in the acinus. In contrast, the activity of both the Se-dependent GPx and the microsomal (Se-independent) GPx, as well as G-6-PDH, was much lower in the p.v. than in the p.p. cells. The heterogeneous distribution of GST, GPx and G-6-PDH was confirmed by analyzing liver perfusion effluents collected after ante- or retrograde digitonin infusion. The relatively low activities of GPx and G-6-PDH in the p.v. cells could partly explain the susceptibility of this region to chemical injury.     

Comparison of hypoxic cell radiosensitizers,KIN-804, KIN-844, KIN-806 and TX-1877, on brain and liver metabolizing capacities in mice bearing Ehrlich ascites carcinoma

The biochemical effects of the 2-nitroimidazole hypoxic cell radiosensitizers KIN-804, KIN-806, and their analogues KIN-844 and TX-1877 on brain acetylcholinesterase (AChE) and hepatic free radical scavenging systems, such as reduced glutathione (GSH) and glucose-6-phosphate dehydrogenase (G-6-PDH) levels, and hepatic antioxidants, such as superoxide dismutase (SOD) and catalase, were evaluated in Ehrlich ascites carcinoma (EAC)-bearing Swiss albino mice. The assay of brain AChE revealed nonsignificant changes with all drugs examined. To evaluate the hepatic metabolic capacity, groups of mice were divided into control, EAC-inoculated, 10-Gy local gamma-irradiated, and KIN-804, KIN-844, KIN-806, or TX-1877 (50 mg/kg body weight, i.p.) groups, and gamma-irradiation was combined with each drug. EAC inoculation markedly suppressed GSH, G-6-PDH, SOD, and catalase levels. On the other hand, treatment with gamma-irradiation significantly enhanced them. The treatment of EAC-bearing mice with each drug alone in the absence of gamma-irradiation revealed that KIN-806 and its derivative TX-1877 showed antitumor activity through their significant recovery of GSH and SOD levels, respectively, in the EAC-bearing mice group. Similarly, the combined treatment of EAC-bearing mice with gamma-irradiation with each of the drugs tested showed that KIN-806 and TX-1877 significantly increased GSH and SOD, and to a lesser extent G-6-PDH and catalase levels. On the other hand, KIN-804 and KIN-844 had only a nonsignificant effect on all parameters examined. In conclusion, these data reveal that the administration of KIN-806 and TX-1877 with or without subsequent gamma-irradiation, resulted in significant recovery of GSH and SOD activities that were inhibited by EAC inoculation.     

A comparative study of the efficacy of pharmacological agents in regulating the level of NADPH in the hepatocytes in an acute lesion]

Experiments on mice with acute toxic damage to the liver induced by thioacetamide (200 mg/kg) demonstrated inhibited activity of enzymes glucose-6-phosphate dehydrogenase (G-6-PDH), NADPH-dependent isocitrate dehydrogenase and malate dehydrogenase in the hepatocyte mitochondrial and microsomal-cytosol fractions. Pharmacotherapy with membranostabilizers and cytochrome P-450 inducers activated the enzymes under study, the degree of activation depended on agents used.     

蒿甲醚对小鼠体内日本血吸虫磷酸化酶,乳酸脱氢酶,三磷酸腺苷 …

目的：观察蒿甲醚（Ａｒｔ）对日本血吸早磷酸化酶（ＰＰ）、乳酶脱氢酶（ＬＤＨ）、６－磷酸工唿科（Ｇ－６－ＰＤＨ）和三磷酸腺苷酶（ＡＴＰａｓｅ）的影响。方法：感染３２－３８天的小鼠于灌服Ａｒｔ１００－３００ｍｇ．ｋｇ＾－１后２４－７２ｈ剖 杀，收集雌（♀）、雄虫（０１６５）、按ＮＡＤＨ和ＮＡＤＰＨ的形成和无机磷的释放量测定 上述４种酶。结果：感染小鼠用Ａｒｔ３００ｍｇ．ｋｇ＾－１治疗后２４－４８ｈ，♀     

Hexachlorocyclohexane-induced testicular dysfunction in rats

Weanling male albino rats were fed 100, 750 and 1500 p.p.m. of technical HCH for 90 days. There was marked testicular atrophy with reduced tubule size and spermatogenetic arrest at 1500 p.p.m. Histochemically, there was accumulation of cholesterol-positive lipids in the Sertoli cells and the Leydig cells of the atrophied testis and biochemical estimation revealed significant increase of total lipid and cholesterol contents. Activities of delta 5 3 beta hydroxysteroid dehydrogenase (delta 5 3 beta HSDH), 17 beta hydroxysteroid dehydrogenase (17 beta HSDH) and glucose-6-phosphate dehydrogenase (G-6-PDH) in the interstitial cells were markedly decreased suggesting steroidogenic inhibition in the Leydig cells of the atrophied testis due to HCH feeding.     

Effects of isoprenaline and phenylephrine on energy-rich phosphate compounds and glucose-6-phosphate in smooth and cardiac muscle

1. Tension changes produced by phenylephrine and isoprenaline have been examined in four tissues-the guinea-pig taenia coli, the longitudinal muscle strip of rabbit duodenum, the abdominal aorta of the rabbit and the rat heart.2. Changes in the amounts of adenosine triphosphate (ATP), creatine phosphate (CP) and glucose-6-phosphate (G-6-P) associated with the addition of phenylephrine and isoprenaline have been measured in the four tissues using enzymatic fluorimetric analysis.3. An alpha-adrenoceptor-mediated increase in tension (phenylephrine; rabbit aorta) was associated with no change in the amounts of ATP, CP or G-6-P.4. An alpha-adrenoceptor-mediated decrease in tension (phenylephrine; guineapig taenia coli and rabbit duodenum) was associated with no change in the amounts of ATP, CP or G-6-P.5. A beta-adrenoceptor-mediated increase in force of contraction (phenylephrine and isoprenaline; rat heart) was associated with a reduction in the amounts of ATP and CP and an increase in the amount of G-6-P.6. A beta-adrenoceptor-mediated decrease in tension (isoprenaline; guinea-pig taenia coli and rabbit duodenum) was associated with an increase in the amounts of ATP and CP and no change in the amount of G-6-P.7. beta-Adrenoceptor-mediated metabolic changes were antagonized by propranolol.     

Glucose-6-phosphate dehydrogenase and gama-glutamyltranspeptidase activities in the liver during chemically induced hepatocarcinogenesis in rats and mice

Glucose-6-phosphate dehydrogenase (G-6-PDH) and γ-glutamyltranspeptidase (γ-GTP) were studied in the liver of rats and mice receiving a diet which contained 3′-methyl-4-(dimethylamino)azobenzene (3′-Me-DAB), diethylnitrosamine (DEN), or o-aminoazotoluene (o-AT). Elevated G-6-PDH activity was first observed within 2 weeks after the start of 3′-Me-DAB feeding, reaching a maximum at 4 weeks. There was a decrease from the 4-week level at about 6 weeks, followed by a sustained increase. The maintained activity after 8 weeks was about 6 times higher than in control rat liver. γ-GTP activity in rat liver increased immediately after the start of 3′-Me-DAB feeding; it was about 12 times the control value after 3–4 weeks. At 5–6 weeks, the activity decreased somewhat from the 3 to 4-week level, but this was followed by a further sustained increase. In rats receiving the DEN-containing water, the liver G-6-PDH and γ-GTP activities changed in the same way as in the 3′-Me-DAB-fed rats. Both activities increased in the early stage, reaching a maximum by 6 weeks, subsided at 7 weeks, and rose again from 9 weeks. In mice receiving o-AT-containing diet, hepatic G-6-PDH activity also changed in a biphasic pattern and closely related with that of liver γ-GTP activity.     

Effects of cianidanol (KB-53) on experimental liver injury in mice--histopathological, histochemical and enzyme-histochemical studies

Protective effects of KB-53 on acute liver injury induced by carbon tetrachloride (CCl4) and 1-naphtylisothiocyanate (ANIT) in mice was investigated by means of histopathological, histochemical and enzymehistochemical examinations. Diffuse centrilobular necrosis, ballooning degeneration of hepatocytes and hemorrhage were markedly observed in the livers of the mice one to three days after a subcutaneous injection of CCl4. On the other hand, in the livers of KB-53 pretreated mice, forcal necrosis was observed and inflammatory cells had already infiltrated one day after CCl4-intoxication. Three days later, remarkable development of absorbent granulation tissues with syncytium and hepatocytic mitosis was observed. Furthermore, a number of PAS positive materials such as mucopolysaccharides and mucoproteins were detected in the livers of KB-53 pretreated mice. KB-53 inhibited the disappearance of glucose-6-phosphatase (G-6-Pase) in the liver after CCl4-intoxication and the rise of alkaline phosphatase (Al-Pase) in the liver after ANIT-intoxication. In addition, KB-53 inhibited the rise of Al-Pase and total bilirubin in the serum of mice after CCl4 and ANIT-intoxication. All these findings suggest that KB-53 protects liver against the morphological and functional changes, and it potentiates the proliferative and regenerative activity of the liver impaired with CCl4 and ANIT.     

新生儿红细胞G-6-PD缺陷症50例临床分析

目的:对新生儿红细胞葡萄糖-6-磷酸脱氢酶(G-6-PD)缺陷症进行临床分析.方法:用四氮唑蓝(NBT)定量法测定新生儿红细胞G-6-PD活性.结果:男女发病率有一定差异,男性明显多于女性;男女患者G-6-PD活性、黄疸程度和血红蛋白均值无显著性差异(P>0.05).结论:新生儿红细胞G-6-PD缺陷症的发病可以由感染、氧化性药物、缺氧等因素诱发,也可以没有任何诱因,男女患者在G-6-PD活性、病情程度上没有差异.     

醋酸棉酚长期给药的进一步观察

给成年雄性大鼠每日服醋酸棉酚10 mg/kg,每周服6天。服6个月后进行病理和组织化学观察。结果说明给醋酸棉酚大鼠各主要脏器(心、肝、脾、肺、肾、肾上腺)的形态都没有明显变化。组织化学观察说明,给棉酚大鼠的肝脏油红“O”染色、G-6-P酶、ATP酶、ALP酶、ACP酶、糖原、RNA和DNA肾脏G-6-PDH、油红“O”染色、ATP酶、ACP酶、ALP酶;肾上腺3β-甾体脱氢酶、油红“O”染色、苏丹黑染色等与对照组比较都没有明显差别。     

Bees wax polyphenols as suppressor of CC1--induced oxidative stress in rats

Bee's wax produced by honeybees is rich in polyphenols. As the polyphenols are thought to protect cell constituents against oxidative damage through scavenging of free radicals, the present work was undertaken to evaluate the effects of polyphenols extracted from bees wax on the oxidative stress induced by carbon tetrachloride (CCl4) in rats. The polyphenols extracted by 80% methanol from bee wax (PBW) were fed to Wistar rats at 100 mg/kg body weight and 200 mg/kg body weight for 14 days in order to study its antioxidative and antihepatotoxic effects against CCl4 (1.5 ml/kg body weight)-induced stress. On 15th day all the rats were sacrificed, blood was collected for serum and organs/tissues were excised for biochemical analysis. The results showed a significant decrease in hepatic antioxidant enzyme activities viz. catalase, glucose-6-phosphate dehydrogenase (G-6-PDH), glutathione peroxidase (GSH-Px), glutathione reductase, superoxide dismutase (SOD) and a significant increase in glutathione S-transferase (GST) and gamma-glutamyl transpeptidase (GGT) by CCl4, probably due to the peroxidative effects. The prophylactic use of PBW at 200 mg/kg level resulted in a significant increase in CCl4-induced reduction in catalase, G-6-PDH, GSSGR and SOD. The hepatic levels of lipid peroxides viz. malondialdehyde, conjugated dienes and lipid hydroperoxides, enhanced by the administration of CCl4 were brought down by the ingestion of PBW at a level of 200 mg/kg. The hepatotoxicity caused by the administration of CCl4 was reduced significantly. Hence, it is concluded that the polyphenols from bees wax exhibit hepatoprotective and antioxidative properties in     

Dithranol, glucose-6-phosphate dehydrogenase inhibition and active oxygen species.

Inhibition of glucose-6-phosphate dehydrogenase (G6-PDH) by dithranol (anthralin, CAS 480-22-8) has been studied in the presence of catalase, superoxide dismutase (SOD) and various scavengers of active oxygen species. Most scavengers were found to be either inhibitors of G6-PDH by themselves or simply without effect. The combined addition of catalase and SOD as well as the heat-denatured enzymes and the oxygen radical scavengers alpha-tocopherol and salicylic acid markedly reduced the inhibitory effect of dithranol. The direct exposure of G6-PDH to active oxygen species led to different results. When liberated from a water-soluble naphthalene endoperoxide, singlet oxygen was without effect whereas photosensitization with methylene blue resulted in a total loss of enzyme activity. Experiments under anaerobic conditions revealed that this inhibition was accomplished by the triplet state of the sensitizer. Superoxide anion radical was highly effective at concentrations corresponding to the amount of that produced by a 10 mumol/l dithranol solution. In contrast, hydroxyl, alkylperoxyl and alkoxyl radicals were all less efficient. H2O2 and alkylhydroperoxides did not alter the enzyme activity. The results suggest that .O2- is the potent species towards G6-PDH, if dithranol acts through formation of active oxygen species.     

Effect of praziquantel on some aspects of carbohydrate metabolism in mice infected with Schistosoma mansoni

Schistosoma mansoni infection in mice resulted in a marked decrease in blood glucose and liver glycogen accompanied by a significant increase in hepatic glucose-6-phosphatase (G-6-Pase) activity. Moreover, the results indicated that infection produced a significant increase in blood pyruvate and hepatic glucose-6-phosphate dehydrogenase (G-6-PD) activity with a significant decrease in blood lactate. Infected mice were treated with praziquantel which was given at two doses of 500 mg/kg body wt on two consecutive days. Seven and 14 days respectively after drug administration, such treatment caused a marked improvement in the previous aspects of carbohydrate metabolism. This is indicated by the tendency of the blood glucose of infected mice to be restored, the marked increase in their liver glycogen content, the normalization of their blood lactate and pyruvate as well as by the marked decrease of their hepatic G-6-Pase activity and the progressive increase in their hepatic G-6-PD activity. Praziquantel given to normal mice moderately affected the blood glucose and the previously mentioned hepatic enzymes. However, the drug markedly increased the liver glycogen content of normal mice and failed to elicit any change in their blood pyruvate and lactate. Possible explanations of these findings are discussed.     

Antioxidant status of erythrocytes and their response to oxidative challenge in humans with argemone oil poisoning

Oxidative damage of biomolecules and antioxidant status in erythrocytes of humans from an outbreak of argemone oil (AO) poisoning in Kannauj (India) and AO intoxicated experimental animals was investigated. Erythrocytes of the dropsy patients and AO treated rats were found to be more susceptible to 2,2'-azobis (2-amidinopropane) dihydrochloride (AAPH) induced peroxidative stress. Significant decrease in RBC glutathione (GSH) levels (46, 63%) with concomitant enhancement in oxidized glutathione (172, 154%) levels was noticed in patients and AO intoxicated animals. Further, depletion of glutathione reductase (GR), glucose-6-phosphate dehydrogenase (G-6-PDH) and glutathione-S-transferase (GST) (42-52%) was observed in dropsy patients. Oxidation of erythrocyte membrane lipids and proteins was increased (120-144%) in patients and AO treated animals (112-137%) along with 8-OHdG levels in whole blood (180%) of dropsy patients. A significant reduction in alpha-tocopherol content (68%) was noticed in erythrocytes of dropsy patients and hepatic, plasma and RBCs of AO treated rats (59-70%) thereby indicating the diminished antioxidant potential to scavenge free radicals or the limited transport of alpha-tocopherol from liver to RBCs leading to enhanced oxidation of lipids and proteins in erythrocytes. These studies implicate an important role of erythrocyte degradation in production of anemia and breathlessness in epidemic dropsy.     

Carbohydrate and lipid metabolism in rats after hypokinesia

Hypokinesia (diminished muscular activity) elicits several substantial alterations in carbohydrate and lipid metabolism of animals and man. The aim of this study was to examine certain parameters of carbohydrate and lipid metabolism in blood and tissues of 118 rats weighing 180-220 g, during a 90 days' exposure to hypokinesia (HK) and a 90-days' readaptation period (RP), that is, after the termination of HK. All of the rats were divided into experimental and control groups. The experimental group of rats were kept in small individual cages made of plexiglass and the control group of rats was placed under ordinary vivarium conditions. The rats were decapitated on the 90th day of HK and on the 15th, 30th, 60th and 90th days of the RP. Such indices were measured as glycogen (G), total lipid (TL), cholesterol (CH) and triglycerides (TG) in hepatic tissues and skeletal muscles, and glucose-6-phosphate-dehydrogenase (G-6-PDH) activity in the liver and fatty tissues. There were also assayed: blood serum, sugar, total cholesterol, alpha-cholesterol (alpha-CH), beta-cholesterol (beta-CH) lipoproteins, acetone bodies (AB) and free fatty acids (FFA). On the 90th day of HK the content of CH, FFA and AB increased, the value of sugar and TG decreased in blood, the amount of G decreased and the level of CH increased in the liver and skeletal muscles. On the 15th day of RP most of the parameters under study returned to normal. However, G-6-PDH in the liver and adipose tissue were elevated and remained higher till the 60th day of the RP.(ABSTRACT TRUNCATED AT 250 WORDS)     

栎精对葡萄糖-6-磷酸酶基因表达及活性的影响

目的：探讨栎精对葡萄糖-6-磷酸酶基因表达及活性的影响。方法：将原代培养的大鼠肝细胞在含有25mmol／L的葡萄糖和不同浓度的栎精培养16h后提取RNA，以半定量RT—PCR方法检测葡萄糖-6-磷酸酶的催化亚基（G6PC）和转运亚基（G6PT）的mRNA水平，并应用葡萄糖双脱氢酶偶联法测定葡萄糖-6-磷酸酶的活性。结果：25mmol／L葡萄糖能够使G6PC和G6PT的mRNA水平升高2倍左右（P〈0．05），不同浓度的栎精可抑制G6PC和G6PT的转录及酶的活性。结论：栎精能够抑制体外葡萄糖-6-磷酸酶基因的表达及其活性。     

Mechanism of anti-inflammatory action of 2-(2-fluoro-4-biphenylyl) propionic acid (flurbiprofen)]

Anti-inflammatory mechanism of 2-(2-fluoro-4-biphenylyl) propionic acid (Flurbiprofen, FP-70) was studied by various analysis in comparison with other drugs. It was found in the test of rat edema induced by various phlogists that carrageenin and yeast-induced edemas were markedly inhibited by FP-70, whereas dextran, formalin, serotonin and bradykinin-induced edemas were scarcely inhibited by FP-70. The action of FP-70 was similar to that of soy bean trypsin inhibitor. However, FP-70 showed no effects on kinin synthetase and kininase. FP-70 showed a marked inhibition on prostaglandin synthesis. The inhibitory effect of FP-70 was 10.1, 96.5 and 2280.6 times as large as indomethacin, ibuprofen and acetylsalicylic acid, respectively. FP-70 did not inhibit the permeability of dye induced by prostaglandin E2 in the rat skin. FP-70 inhibited the acid phosphatase and beta-glucuronidase activities of isolated lysosome of rat liver and also suppressed the release of acid phosphatase from the lysosome. These effects were similar to those of indomethacin. On the other hand, FP-70 suppressed markedly the heat-induced hemolysis of dog erythrocytes. The effect was similar to that of indomethacin and was 10 times stronger than those of ibuprofen, ibufenac and phenylbutazone. Activation of rat liver mitochondrial ATPase by FP-70 at a concentration of 10 muM was 74.7%, while indomethacin showed 37.8% activation at the same concentration. FP-70 as well as ibuprofen and phenylbutazone uncoupled the oxidative phosphorylation in rat liver mitochondria. From the above and previously reported results, it is suggested that the potent anti-inflammatory action of FP-70 is the result of the following effects; inhibition on the protein and leucocyte migration, inhibition on the prostaglandin synthesis, stabilization of the cell membrane and activation of ATPase.     

The effect of anti-inflammatory drugs on eicosanoid formation in a chronic model of inflammatory bowel disease in the rat.

1. The effects of anti-inflammatory drugs on eicosanoid formation and colonic damage in a chronic model of inflammatory bowel disease (IBD) in the rat were investigated. 2. A single colonic instillation of the hapten, trinitrobenzene sulphonic acid (TNB) resulted in ulceration and inflammation which persisted for 3 weeks. 3. The macroscopic colonic damage, present 3 weeks after TNB, was correlated with an increase in immunoreactive 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) and leukotriene B4 (LTB4) synthesis by the rat colon. 4. Anti-inflammatory drugs were administered 2 weeks after TNB, when there was substantial colonic damage, and continued for a week. The experimental drug BW755C inhibited the increased formation of 6-keto-PGF1 alpha and LTB4 by the inflamed colon. Indomethacin and aspirin markedly inhibited prostanoid formation in both inflamed and control colon. Sulphasalazine or prednisolone also inhibited the formation of 6-keto-PGF1 alpha but the effects were less marked. 5. None of the anti-inflammatory drugs significantly reduced the colonic damage induced by TNB. 6. The results suggest that eicosanoids, including LTB4, have only a minor role in maintaining the chronic macroscopic damage induced in the rat colon by TNB. The role of such eicosanoids in the underlying infiltration and activity of inflammatory cells in this model of IBD, however, is not known.