title: Hydrogen peroxide detoxification in the midgut of the blood-sucking insect, Rhodnius prolixus.
abstract: 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.
authors.affiliation: 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. medicina@estacio.br
authors.forename: M C
authors.initials: MC
authors.lastname: Paes
authors.forename: M B
authors.initials: MB
authors.lastname: Oliveira
authors.forename: P L
authors.initials: PL
authors.lastname: Oliveira
mesh_terms: D000640:Amitrole / Q000494:pharmacology; D000818:Animals; D019328:Buthionine Sulfoximine / Q000494:pharmacology; D002374:Catalase / Q000037:antagonists & inhibitors / Q000378:metabolism; D004064:Digestive System / Q000187:drug effects / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005978:Glutathione / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism*; D017665:Hydroxyl Radical / Q000378:metabolism; D020064:Reduviidae / Q000187:drug effects / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D017665:Hydroxyl Radical; D019328:Buthionine Sulfoximine; D006861:Hydrogen Peroxide; D002374:Catalase; D013482:Superoxide Dismutase; D005978:Glutathione; D000640:Amitrole