Paes M C, Oliveira M B, Oliveira P L
Departamento de Bioquímica Médica, Instituto de Ciências Biomédicas, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Ilha do Fundão, Rio de Janeiro, RJ, Brazil.
Arch Insect Biochem Physiol. 2001 Oct;48(2):63-71. doi: 10.1002/arch.1058.
Here we investigated H2O2 production and detoxification in the hematophagous hemiptera, Rhodnius prolixus. Superoxide dismutase (SOD) catalyzes the dismutation of superoxide radical (O2-). This reaction produces hydrogen peroxide, which is scavenged by antioxidant enzymes such as catalase (CAT). SOD and CAT activities were found in all tissues studied, being highest in the midgut. CAT was dose-dependently inhibited in vivo by injections of 3-amino-1,2,4-triazole (AT). Insects treated with AT showed a twofold increase in H2O2 levels. Injection of DL-buthionine-[S, R]-sulfoximine (BSO), an inhibitor of glutathione synthesis, also resulted in a fourfold increase in H2O2, together with stimulation of CAT activity. Simultaneous administration of both AT and BSO had a synergistic effect on midgut H2O2 content. Taken all together, our results suggest that CAT and glutathione-dependent mechanisms cooperate to control H2O2 concentration in the midgut cell and prevent hydroxyl radical generation by Fenton reaction in this tissue.
在此，我们研究了吸血半翅目昆虫——南美锥蝽（Rhodnius prolixus）中过氧化氢的产生及解毒过程。超氧化物歧化酶（SOD）催化超氧阴离子自由基（O2-）的歧化反应。该反应产生过氧化氢，而过氧化氢会被过氧化氢酶（CAT）等抗氧化酶清除。在所研究的所有组织中均发现了SOD和CAT活性，其中中肠中的活性最高。通过注射3-氨基-1,2,4-三唑（AT），CAT在体内受到剂量依赖性抑制。用AT处理的昆虫过氧化氢水平增加了两倍。注射谷胱甘肽合成抑制剂DL-丁硫氨酸-[S,R]-亚砜胺（BSO）也导致过氧化氢增加了四倍，同时刺激了CAT活性。同时给予AT和BSO对中肠过氧化氢含量具有协同作用。综上所述，我们的结果表明，CAT和谷胱甘肽依赖性机制协同控制中肠细胞中的过氧化氢浓度，并防止该组织中通过芬顿反应产生羟基自由基。
