Oxidative stress and antioxidant responses in juvenile Brazilian flounder Paralichthys orbignyanus exposed to sublethal levels of nitrite

Abstract

This study evaluated the effects of short-term exposure to sublethal levels of nitrite on oxidative stress parameters and histology of juvenile Brazilian flounder Paralichthys orbignyanus. An assessment of fish recovery was also performed. Fish were exposed to 0.08 (control), 5.72, 10.43, and 15.27 NO-N mg L for 10 days followed by the same recovery time. Gill, liver, and muscle samples were collected after 1, 5, and 10 days of exposure and after recovery for the measurement of antioxidant capacity against peroxyl radicals (ACAP), glutathione-S-transferase (GST) activity, content of non-protein (NPSH) and protein thiols (PSH), and lipid peroxidation levels by thiobarbituric acid-reactive substances (TBARS) content. Nitrite exposure induced alterations which compromised the overall antioxidant system (reduced ACAP and GST activity) and enhanced oxidative damage in lipids and proteins. Increases in GST activity and NPSH and PSH contents were also demonstrated. The recovery period allowed for resumption of basal levels for all (treatment 5.72 NO-N mg L) or some of the evaluated parameters (other treatments). In conclusion, exposure to nitrite concentrations from 5.72 to 15.27 NO-N mg L induced oxidative stress and antioxidant responses in juvenile Brazilian flounder. The 10-day recovery period was sufficient for a complete resumption of basal physiological condition of fish exposed to concentrations of up to 5.72 NO-N mg L.

Water pH and hardness alter ATPases and oxidative stress in the gills and kidney of pacu ( Piaractus mesopotamicus )

“…Interestingly, in circumneutral pH, an elevation of water hardness reduced GST activity in the gills on these same days (1 and 5), which suggests that, in this tissue, HWH had no positive effect when pacus were exposed to circumneutral pH. The ACAP assessment sheds light on the overall antioxidant status of the fish against peroxyl radicals (Maltez et al, 2018), which was compromised in the kidney of pacus through alkaline pH exposure on day 5. In addition, a possible explanation for lower gills ACAP (higher relative area) in alkaline pH with HWH on day 1 was due to a compensatory effect, because an increase in GST activity and a reduction in TBARS levels were observed under these conditions.…”

“…The lipid peroxidation levels were measured according to Oakes, Van Der Kraak (2003) by thiobarbituric acid reactive substances (TBARS) content. The TBARS content was determined by the quantification of MDA (malondialdehyde) following the protocol described in detail by Maltez et al (2018). The data are expressed as nmol TMP (tetramethoxypropane (ACROS Organics)) mg wet tissue −1 .…”

“…Our results demonstrated that, even in acidic (mainly) or alkaline waters, oxidative stress in pacu gills and kidney is less intense after a longer exposure period (15 days), because, in acidic pH, fish were able to increase their antioxidant defences and, in alkaline pH (except to kidney TBARS at LWH), oxidative stress variables were stable independently of hardness on day 15. Maltez et al (2018) suggests that, in some cases, a recovery period (10 days or more) is necessary to complete restoration of homeostasis after the end of the stressful conditions. Thus, we believed that pacu requires 15 days or more to acclimate to waters with acidic or alkaline pH and to restore the activity of osmoregulatory and oxidative stress enzymes in gills and kidney.…”

Effects of chronic sub‐lethal nitrite exposure at high water chloride concentration on Atlantic salmon ( Salmo salar, Linnaeus 1758) parr

“…Accumulation of NO 2 − in tissues can result in mass mortality of fish as several functions such as gas transport, ion regulation, and cardiovascular, endocrine and excretory processes are affected (Jensen, ; Svobodová et al, ). In addition, exposure to nitrite can also induce oxidative stress and antioxidant responses in juvenile Brazilian flounder (Maltez et al, ). Nitrite has affinity for the branchial chloride uptake mechanism, that is, NO 2 − can replace Cl − in the chloride/bicarbonate (Cl − /HCO 3 − ) gill transporters (Jensen, ).…”

Acute toxicity and sublethal effects of nitrite on oxidative stress in early juvenile Brazilian flounder, Paralichthys orbignyanus

“…A condition of oxidative stress can be triggered by high production of ROS or due to the compromise of the antioxidant defence system, or by the combination of both situations (Halliwell & Gutteridge, 2015). Recent studies showed that fish exposure to nitrite can compromise the antioxidant system (Maltez et al, 2018) and also induced increased ROS (Sun et al, 2014) and RNS as nitric oxide (NO) production, which also have capacity to cause oxidative damage (Jensen et al, 2015; Jensen & Hansen, 2011).…”