Xanthine oxidase activity exerts pro-oxidative and pro-inflammatory effects in serum of silver catfish fed with a diet contaminated with aflatoxin B1

Several studies have associated the involvement of xanthine oxidase (XO) activity, a source of uric acid and reactive oxygen species (ROS), to pro-oxidative and pro-inflammatory effects during pathological conditions. Considering this, the aim of this study was to evaluate whether upregulation on seric XO activity may be a pathway involved in the oxidative stress in fish exposed to a diet contaminated with aflatoxin B₁ (AFB₁ ), as well as whether it may be considered a pathway involved in ROS and NOx production. Xanthine oxidase activity, as well as the uric acid, ROS and NOx levels increased in serum of fish fed with a AFB₁ -contaminated diet on days 14 and 21 post-feeding compared to fish fed with a basal diet. Based on these evidences, upregulation of seric XO activity induces pro-oxidant and pro-inflammatory profiles in serum of fish fed with a AFB₁ -contaminated diet due to excessive formation on uric acid. Also, the excessive uric acid induces the release of pro-oxidant and pro-inflammatory mediators, as ROS and NOx, also contributing to oxidative and inflammatory profiles. In summary, the upregulation on seric XO activity may be considered a pathway involved in the oxidative stress of fish exposed to a diet contaminated with AFB₁ .

Biochemical parameters of silver catfish (Rhamdia quelen) after transport with eugenol or essential oil of Lippia alba added to the water

The transport of live fish is a routine practice in aquaculture and constitutes a considerable source of stress to the animals. The addition of anesthetic to the water used for fish transport can prevent or mitigate the deleterious effects of transport stress. This study investigated the effects of the addition of eugenol (EUG) (1.5 or 3.0 µL L-1) and essential oil of Lippia alba (EOL) (10 or 20 µL L-1) on metabolic parameters (glycogen, lactate and total protein levels) in liver and muscle, acetylcholinesterase activity (AChE) in muscle and brain, and the levels of protein carbonyl (PC), thiobarbituric acid reactive substances (TBARS) and nonprotein thiol groups (NPSH) and activity of glutathione-S-transferase in the liver of silver catfish (Rhamdia quelen; Quoy and Gaimard, 1824) transported for four hours in plastic bags (loading density of 169.2 g L-1). The addition of various concentrations of EUG (1.5 or 3.0 µL L-1) and EOL (10 or 20 µL L-1) to the transport water is advisable for the transportation of silver catfish, since both concentrations of these substances increased the levels of NPSH antioxidant and decreased the TBARS levels in the liver. In addition, the lower liver levels of glycogen and lactate in these groups and lower AChE activity in the brain (EOL 10 or 20 µL L-1) compared to the control group indicate that the energetic metabolism and neurotransmission were lower after administration of anesthetics, contributing to the maintenance of homeostasis and sedation status.