Abstract
The effects of feeding and starvation have been studied with respect to oxidative stress and enzymatic antioxidant activities in the whole body of 4 cm rainbow trout fry Oncorhynchus mykiss (Walbaum 1792). The experiment was conducted for 28 days. The selected biomarkers for the study were determined, including non-enzymic scavengers glutathione (GSH), oxidized glutathione (GSSG) and malondialdehyde (MDA) contents and a number of enzymes are known to have major antioxidant activity, such as activities of süperoksit dismutaz (SOD), catalase (CAT), glutatyon peroksidaz (GSHpx), glutatyon Redüktaz (GR) and Glutatyon-S-Transferaz (GST). There is an endogenous cellular glutathione pool which consists of two forms of glutathione, i.e. the GSH and the GSSG. Oxidative damage was measured by the formation of MDA as an indication of lipid peroxidation. The activities of SOD in 14th and 28th day and the activity of CAT in 14th day were increased significantly during the 28 days of starvation. GSHpx and GR activities in starved fry decreased significantly in 28th day. GST activity in all starved fry showed the most significant increases the period of 28 days starving. The highest ΣSFA (Total Saturated Fatty Acid) content was obtained from 28 day starved fry. In starved fry, there was an apparent preference in utilization of C18:1n-9 than in the fed fry. In both starved and fed fry, C16:1n-7 was preferentially kept during the same period. Fry kept 28 days under starvation conditions exhausted C15:0, C17:0, C18:3n-6, C22:0, C24:0. They utilized less C20:5n-3 acid and conserved strongly C22:6n-3 acid. Concentrations of C20:5n-3, C22:5n-3, C22:6n-3 and total n-3 fatty acids significantly increased and C18:3n-3 significantly decreased in the whole body of starved fry during starvation period. A significant increase in the concentrations of C22:5n-3 and C22:6n-3 was determined in the fed fries in the last 2 weeks. Fat-soluble vitamins, cholesterol, stigmasterol and β-sitosterol levels were also determined in the same period of O. mykiss fry.
Highlights
As it is in mammals, antioxidant defense mechanisms of fish is composed of enzyme systems and antioxidant substances with a low molecular weight[1]
The increased süperoksit dismutaz (SOD) activity could be linked to the increased H2O2 production reactive oxygen species (ROS) may result in oxidative damage to key biological molecules, such as lipids The superoxide anion radical (O2−·), hydrogen peroxide (H2O2) and the highly reactive hydroxyl radical, HO
Most parameters evaluated in this study, followed an increasing tendency during starvation; this increase is statistically significant from the first days of experiment at the end of both feeding and starving periods
Summary
Fish and experimental set up for the feeding and starving experiment. The O. mykiss were obtained from local and commercial fish farm Yeşilova in Zara (Sivas–Turkey). The quartz assay cuvette containing the reaction mixture which consisted of 50 Mm potassium phosphate buffer (pH 7.1), 1 mM EDTA, 3.6 mM GSH, 3.6 mM sodium azide, 1 IU/mL glutathione reductase, 0.2 mM NADPH and 0.05 mM H 2O2. Reaction mixture in quartz assay cuvette consisted of 0.1 M potassium phosphate buffer (pH 7.2), 2 mM EDTA, 0.63 mM NADPH and 0.15 mM GSSG. According to the test results, the significance level of the data was found to be greater than 0.05 (P > 0.05) All stages of this fish experiment has been approved by Animal Experiments Local Ethics Committee (HADYEK) at Sivas Cumhuriyet University. All experimental procedures were conducted in accordance with the guidelines of the ethics committee and the regulations in the manusript
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