title: Effect of melatonin in the antioxidant defense system in the locomotor muscles of the estuarine crab Neohelice granulata (Decapoda, Brachyura).
abstract: In vertebrates, many studies verified different effects of melatonin in the antioxidant defense system (ADS). In crustaceans, few studies have been conducted to verify this possibility. We verified the melatonin effects in the crab Neohelice granulata using low (0.002 and 0.02 pmol/crab) and high (2.0 and 20.0 pmol/crab) melatonin dosages in short-term (0.5h) and long-term (9.5h) experiments. We analyzed the antioxidant capacity against peroxyl radicals (ACAP), reactive oxygen species (ROS) concentration, levels of by products of lipid peroxidation (LPO), oxygen consumption (VO(2)), the activity of glutamate cysteine ligase (gamma-GCL) and catalase (CAT) and glutathione content (GSH). Finally, the effects of exogenous melatonin were verified in terms of melatonin and N(1)-acetyl-N(2)-formyl-5-methoxykynuramine (AFMK) content in the muscles of N. granulata. In short-term experiment and low dosages, melatonin increased the VO(2), gamma-GCL activity and GSH content (p<0.05) and decreased melatonin content (p<0.05) without effects in ROS, ACAP and LPO (p>0.05). Possibly, melatonin is acting in the ADS increasing its efficiency and/or acting in mitochondrial activity and/or through signaling muscles to increase its consumption. AFMK was only detected in the eyestalk and cerebroid ganglia. In high dosages melatonin effects decreased, possibly by the desensitization of their receptors. In long-term experiment, melatonin decreased ACAP (p<0.05), and CAT activity (p<0.05) in low dosages. In high dosages melatonin reduced VO(2) (p<0.05) and increased ACAP (p<0.05), possibly stimulating others components of the ADS. In conclusion, melatonin in the locomotor muscles of N. granulata affects the antioxidant/pro-oxidant balance in a time and dosage dependent manner.
authors.affiliation: Programa de Pós-Graduacão em Ciências Fisiológicas - Fisiologia Animal Comparada, Instituto de Ciências Biológicas, Universidade Federal do Rio Grande - FURG, Av. Itália, Km 8, Rio Grande, RS 96201-900, Brazil.
authors.forename: Márcio Alberto
authors.initials: MA
authors.lastname: Geihs
authors.forename: Marcelo Alves
authors.initials: MA
authors.lastname: Vargas
authors.forename: Fábio Everton
authors.initials: FE
authors.lastname: Maciel
authors.forename: Sergiane Souza
authors.initials: SS
authors.lastname: Caldas
authors.forename: Bruno Pinto
authors.initials: BP
authors.lastname: Cruz
authors.forename: Ednei Gilberto
authors.initials: EG
authors.lastname: Primel
authors.forename: José Maria
authors.initials: JM
authors.lastname: Monserrat
authors.forename: Luiz Eduardo Maia
authors.initials: LE
authors.lastname: Nery
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D003386:Brachyura / Q000187:drug effects*; D002374:Catalase / Q000378:metabolism*; D017952:Ganglia, Invertebrate / Q000187:drug effects / Q000378:metabolism; D005721:Glutamate-Cysteine Ligase / Q000378:metabolism*; D005978:Glutathione / Q000378:metabolism*; D007735:Kynuramine / Q000031:analogs & derivatives / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects*; D008550:Melatonin / Q000378:metabolism* / Q000494:pharmacology; D009132:Muscles / Q000187:drug effects / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology; D010101:Oxygen Consumption / Q000187:drug effects*; D017382:Reactive Oxygen Species / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D017382:Reactive Oxygen Species; D007735:Kynuramine; C041550:N-acetyl-N-formyl-5-methoxykynurenamine; D002374:Catalase; D005721:Glutamate-Cysteine Ligase; D005978:Glutathione; D008550:Melatonin