Responses of growth performance and tryptophan metabolism to oxidative stress induced by diquat in weaned pigs

Abstract

During many pathological conditions, the tryptophan concentration in blood may be reduced. However, the effects of oxidative stress on tryptophan metabolism remain unknown. In this study, we investigated the effects of oxidative stress on growth performance and tryptophan metabolism in weaned pigs. A total of 24 weaned pigs were assigned to one of three treatments that included pigs fed ad libitum (control), pigs challenged with diquat at a dose of 10 mg/kg BW and fed ad libitum (oxidative stress) or pigs pair-fed to receive the same amount of feed as the diquat-challenged pigs. The trial lasted for 7 days. The growth performance and activities of antioxidant enzymes were declined in diquat-challenged pigs. The diquat challenge decreased the tryptophan concentration in serum and the 5-hydroxytryptamine concentration in the hypothalamus, and increased large neutral amino acids, kynurenine (Kyn) and malondialdehyde in serum. The 544-bp porcine partial mRNA sequence of the tryptophan 2,3-dioxygenase (TDO) gene was obtained according to the conserved region in the human gene sequence. In addition, the oxidative stress induced by the diquat challenge stimulated TDO-relative mRNA abundance in the liver and g-glutamyl transpeptidase activity in intestinal mucosa, but did not affect the mRNA levels of Na 1 -neutral amino acid transporter B0. These results suggested that oxidative stress induced by diquat depressed growth performance and increased metabolism of tryptophan via Kyn pathway that upregulated TDO mRNA expression in weaned pigs.

The Evaluation of Antioxidant and Anti‐Inflammatory Effects of Eucommia ulmoides Flavones Using Diquat‐Challenged Piglet Models

“…Diquat has been reported to impair growth performance and nutrient utilization [18, 19]. The reduced gut morphology and growth performance by diquat challenge in the present are in agreement with published report [28].…”

“…This is mainly due the disruption in the oxidative balance [18], which is evidenced by the decrease in serum concentrations of SOD, GSH-Px, CAT, T-AOC, and GSH after exposure to diquat injection in piglets of basal diet treatments. In the previous studies, diquat has been demonstrated to increase serum MDA concentration but also to inhibit the activities of SOD and GSH-Px [18, 19]. In addition, the present results of serum cytokine concentrations, intestinal histopathological grading, and MPO activity indicated that diquat evaluates the inflammatory response of weaned pigs, which is consistent with previous research [9, 28, 29].…”

“…In the current experiment, oxidative stress piglet model induced by diquat was used and has been widely used in vivo [18, 19]. Diquat has been reported to impair growth performance and nutrient utilization [18, 19].…”

“…Diquat could stimulate cellular production of ROS and inhibit the activities of antioxidant enzymes such as SOD and GSH-Px [18, 19, 34]. Antioxidant enzymes including SOD, CAT, and GSH-Px can neutralize toxic oxygen products, thereby normalizing the body homeostasis [2].…”

“…Therefore, the objectives of this experiment were to investigate the antioxidant activities and anti-inflammatory effects of the flavones extracted from the leaves of EU using an oxidative stress piglet model induced by diquat that is a bipyridyl herbicide exerts ability to produce free radicals by redox-cycling metabolism and widely accepted in vivo model of oxidative stress [17–19]. …”