Carvacrol Protects IPEC-J2 Cells from Oxidative Stress by Suppressing Autophagy

Oxidative stress impairs intestinal function and causes poor growth performance in piglets. Carvacrol is a natural essential oil, and its anti-oxidative and anti-inflammatory activities in the intestines of piglets have been reported in many studies. However, the mechanisms underlying these protective effects against oxidative stress remain unclear. This study aimed to investigate the possible pathway of carvacrol in the porcine intestine under oxidative stress using an in vitro model. Porcine intestinal epithelial cells (IPEC-J2) were treated with carvacrol and hydrogen peroxide (H(2)O(2)), an oxidative stress inducer, to investigate the protective mechanisms of carvacrol under oxidative stress. We found that carvacrol ameliorated a H(2)O(2)-induced loss of cell viability, apoptosis, and reduced intracellular reactive oxygen species (ROS) and malondialdehyde (MDA) levels. Carvacrol reduced mitochondrial ROS generation and increased citrate synthase activity during oxidative stress. Furthermore, carvacrol attenuated an increase in the autophagy marker LC3II-to-I ratio and reduced the accumulation of lysosomes and autolysosomes induced by H(2)O(2). The increased protein expression of the mitophagy marker PINK1, induced by H(2)O(2), was also reduced by carvacrol treatment. Metformin-activated autophagy diminished the protective effects of carvacrol on cell viability and MDA levels under H(2)O(2) treatment, indicating that autophagy inhibition is necessary for carvacrol-induced protection in IPEC-J2 cells during oxidative stress. In conclusion, this study demonstrated the underlying mechanism that carvacrol exerted its anti-oxidative effects on porcine intestinal epithelial cells by relieving excessive autophagy during weaning stress.