L-Arginine Alleviates Hydrogen Peroxide-Induced Oxidative Damage in Ovine Intestinal Epithelial Cells by Regulating Apoptosis, Mitochondrial Function, and Autophagy

Background: Previous studies demonstrated that dietary L-arginine (Arg) alters the equilibrium between reactive oxygen species (ROS) generation and biological defenses to resist oxidant-induced toxicity. Whether supplying Arg can protect ovine intestinal epithelial cells (OIECs) from hydrogen peroxide (H2O2)-induced oxidative damage is unclear. Objectives: The current study aimed to examine the effect of Arg on mitophagy, mitochondrial dysfunction, and apoptosis induced by H2O2 in OIECs. Methods: The OIECs were incubated in Arg-free DMEM supplemented with 100 AM Arg (CON) or 350 AM Arg (ARG) alone or with 150 mu M H2O2 (CON + H2O2, ARG + H2O2) for 24 h. Cellular apoptosis, mitochondrial function, autophagy, and the related categories of genes and proteins were determined. All data were analyzed by ANOVA using the general linear model procedures of SAS (SAS Institute) for a 2 x 2 factorial design. Results: Relative to the CON and ARG groups, H2O2 administration resulted in 44.9% and 26.5% lower (P < 0.05) cell viability but 34.7% and 61.8% greater (P < 0.05) ROS concentration in OIECs, respectively. Compared with the CON and CON + H2O2 groups, Arg supplementation led to 40.7% and 28.8% lower (P < 0.05) ROS concentration but 14.9%-49.0% and 29.3%-64.1% greater (P < 0.05) mitochondrial membrane potential, relative mitochondrial DNA content, and complex (I-IV) activity in OIECs, respectively. Compared with the CON and CON + H2O2 groups, Arg supplementation led to 33.9%-53.1% and 22.4%-49.1 % lower (P < 0.05) mRNA abundance of proapoptotic genes, respectively. Relative to the CON and CON + H2O2 groups, Arg supplementation resulted in 33.0%-59.2% and 14.6%-37.7% lower (P< 0.05) abundance of proapoptotic, mitophagy, and cytoplasmic cytochrome c protein, respectively. Conclusions: Supply of Arg protects OIECs against H2O2-induced damage partly by improving mitochondrial function and alleviating cellular apoptosis and autophagy.