Efeito da dieta contendo rutina sobre a inflamação, apoptose e a resposta antioxidante em jundiás (Rhamdia quelen) infectados com Aeromonas hydrophila

Abstract

Fish culture conditions lead fish as silver catfish (Rhamdia quelen) to stressful situations, making them more susceptible to diseases caused by bacteria, including Aeromonas hydrophila. Thus, there is a real need to improve the fish handling and welfare, since it represents a constant concern to fish farming. In this context, natural products appear as interesting options to be studied. Rutin-added diet can be an alternative to prevent diseases related to the stress inherent to the culture conditions, since it has been described as having antimicrobial, anti-inflammatory, antioxidative properties, among others. This work aimed to evaluate the possible protective effect of rutin-containing diet on muscle of silver catfish infected with A. hydrophila. For this, silver catfish were randomly divided into 4 groups: control; 0.15% rutin; A. hydrophila; and 0.15% rutin + A. hydrophila. After 2 weeks of feeding with the experimental diets, fish from groups A. hydrophila and 0.15% rutin + A. hydrophila were experimentally infected with A. hydrophila and those from groups 1 and 2 received vehicle (0.9% saline). The infected and uninfected animals were fed the control and rutin diets for a further week, totalizing 3 experimental weeks. After this period, silver catfish were euthanized, and the muscle was collected for the evaluation of markers of cell death, inflammation and oxidative stress. Rutin-added diet decreased the hemorrhage, inflammatory infiltration and myeloperoxidase activity in infected fish. This diet also reduced apoptosis induced by A. hydrophila through decreasing the expression of phosphorylated Akt and Bax in these animals. In addition, rutin-added diet reduced the levels of nitric oxide and superoxide anion as well as increased superoxide dismutase activity, which were altered in infected silver catfish. This diet was not able to recover neither the levels of reduced glutathione (GSH) and cysteine nor the expression of the catalytic subunit of glutamate cysteine ligase in silver catfish, decreased as a result of the infection. Despite this, rutin-added diet elevated the glutathione reductase activity and the levels of cysteine residues in proteins, as well as reduced the content of mixed disulfides, which were modified in infected fish. This diet also decreased the levels of oxidized glutathione (GSSG), thus reducing the GSSG to GSH ratio, which was increased in infected animals. Finally, rutin-added diet reduced levels of lipid peroxidation, increased ascorbic acid and total antioxidant capacity, which were altered in infected fish. Therefore, the addition of rutin in the diet protects the muscle of silver catfish in a challenging situation, as A. hydrophila infection.