title: Effects of hypoxia and reoxygenation on the antioxidant defense system of the locomotor muscle of the crab Neohelice granulata (Decapoda, Varunidae).
abstract: Crustaceans often occur in areas with variations in oxygen and experience situations known as hypoxia and reoxygenation. Consequences of such situations are increased levels of reactive oxygen species. To avoid oxidative damage intertidal crabs appear to possess an efficient antioxidant defense system (ADS). However, to date, studies have not addressed the strategies that are adopted by the crabs when exposed to hypoxia/reoxygenation cycles. Towards this end we evaluated the ADS and the role of melatonin as an antioxidant in the locomotor muscle of the crab Neohelice granulata under conditions of severe hypoxia and reoxygenation. Total antioxidant capacity against peroxyl radicals and the enzymes superoxide dismutase, catalase, glutathione peroxidase (GPx), and glutathione-S-transferase as well as the key enzyme of glutathione synthesis, glutamate cysteine ligase (GCL), were evaluated. Furthermore, GSH, GSH/GSSG index as well as hemolymph and cellular melatonin levels were evaluated. During hypoxia, increased GPx and GCL activity and decreased GSH and mitochondrial melatonin levels were observed, but during reoxygenation catalase activity increased and cytosolic melatonin levels decreased. It appears that the ADS in the locomotor muscle of N. granulata exert a modulating effect when being confronted with hypoxia and reoxygenation to avoid oxidative stress. During hypoxia, the ADS appear to target GPX activity as well as GSH and mitochondrial melatonin. During reoxygenation, however, evidence suggests that catalase and cytosolic melatonin are involved in the recovery of the locomotor muscle from oxidative damage and the suppression of further damage.
authors.affiliation: Programa de Pós-Graduação em Ciências Fisiológicas, Fisiologia Animal Comparada, Instituto de Ciências Biológicas, Universidade Federal do Rio Grande, FURG, Av. Itália, Km 8, Rio Grande, RS, CEP 96203-900, Brazil.
authors.forename: Márcio Alberto
authors.initials: MA
authors.lastname: Geihs
authors.affiliation: Programa de Pós-Graduação em Ciências Fisiológicas, Fisiologia Animal Comparada, Instituto de Ciências Biológicas, Universidade Federal do Rio Grande, FURG, Av. Itália, Km 8, Rio Grande, RS, CEP 96203-900, Brazil.
authors.forename: Marcelo Alves
authors.initials: MA
authors.lastname: Vargas
authors.affiliation: Programa de Pós-Graduação em Ciências Fisiológicas, Fisiologia Animal Comparada, Instituto de Ciências Biológicas, Universidade Federal do Rio Grande, FURG, Av. Itália, Km 8, Rio Grande, RS, CEP 96203-900, Brazil.
authors.forename: Fábio Everton
authors.initials: FE
authors.lastname: Maciel
authors.affiliation: Department of Physiology, Oulu University, P.O. Box 3000, 50014, Oulu, Finland.
authors.forename: Olli
authors.initials: O
authors.lastname: Vakkuri
authors.affiliation: Department of Biology, Oulu University, P.O. Box 3000, 50014, Oulu, Finland.|Research Institute of Luminescent Organisms, Tokyo, Hachijojima, 100-1623, Japan.
authors.forename: Victor Benno
authors.initials: VB
authors.lastname: Meyer-Rochow
authors.affiliation: Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, UFRJ, Av. Carlos Chagas Filho 373 CCS, Bloco G2-001, Ilha do Fundão, Rio de Janeiro, RJ, 21449-902, Brazil.
authors.forename: Silvana
authors.initials: S
authors.lastname: Allodi
authors.affiliation: Programa de Pós-Graduação em Ciências Fisiológicas, Fisiologia Animal Comparada, Instituto de Ciências Biológicas, Universidade Federal do Rio Grande, FURG, Av. Itália, Km 8, Rio Grande, RS, CEP 96203-900, Brazil. famnery@terra.com.br.
authors.forename: Luiz Eduardo Maia
authors.initials: LE
authors.lastname: Nery
mesh_terms: D000818:Animals; D060829:Arthropod Proteins / Q000378:metabolism; D003386:Brachyura / Q000378:metabolism*; D002374:Catalase / Q000378:metabolism*; D005721:Glutamate-Cysteine Ligase / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000378:metabolism; D000860:Hypoxia / Q000378:metabolism*; D008297:Male; D008550:Melatonin / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism; D009132:Muscles / Q000378:metabolism*; D018384:Oxidative Stress; D010100:Oxygen / Q000378:metabolism*
chemical_list: D060829:Arthropod Proteins; D002374:Catalase; D005979:Glutathione Peroxidase; D005721:Glutamate-Cysteine Ligase; D005978:Glutathione; D008550:Melatonin; D010100:Oxygen
keywords: Antioxidant defense system; Crabs; Hypoxia; Melatonin; Muscle; Oxidative stress