Journal of Functional Foods (Nov 2019)
Dietary taurine regulates free amino acid profiles and taurine metabolism in piglets with diquat-induced oxidative stress
Abstract
Background: Amino acids, especially taurine, are considered as biomarkers of various pathological conditions. Under oxidative stress, taurine is associated with the modulation of free amino acids (FAAs) and taurine metabolism. Objectives: To study the effects of taurine on FAAs and taurine metabolism in main fluids and organs during oxidative stress in a piglet model. Methods: Diquat was injected intraperitoneally to induce oxidative stress. Thirty-five piglets were treated with taurine (0, 0.15%, 0.30%, and 0.60%) for 28 days. FAA, taurine, taurine transporter (TauT), and taurine biosynthesis enzyme levels were determined using HPLC, RT-PCR, and western blot analyses in body fluid and tissues. Results: Taurine alleviated hepatic injury by significantly reducing the inflammatory response and alanine transaminase (ALT) levels (P < 0.05) and by restoring histological morphology. It also remolded the disrupted FAAs in fluid and tissues in piglets with diquat-induced oxidative stress. Serum, longissimus dorsi muscle, soleus threonine, and urinary taurine might be biomarkers of oxidative stress. Taurine supplementation significantly increased taurine content in the serum, skeletal muscle, and liver in a dose-dependent manner (P < 0.05). The mRNA expression level of TauT was remarkably up-regulated in the duodenum and jejunum and significantly down-regulated in skeletal muscle (P < 0.05) compared to that in the control. Taurine treatment significantly up-regulated the liver mRNA expression of cysteine dioxygenase (P < 0.05). TauT protein expression during oxidative stress was significantly down-regulated in the skeletal muscle (P < 0.05) and significantly up-regulated in the small intestine (P < 0.05) and the expression levels of cysteine dioxygenase and cysteine sulfinate decarboxylase were significantly increased and decreased, respectively (P < 0.05) compared to the corresponding levels in the control group. Conclusions: Dietary taurine has a protective effect in piglets with diquat-induced oxidative stress. FAAs and taurine homeostasis are regulated by taurine supplementation in a complex interplay between TauT and taurine biosynthesis enzymes in the liver, intestine, and skeletal muscle.
