Influence of short-term fasting on oxidative stress, antioxidant-related signaling molecules and autophagy in the intestine of adult Siniperca chuatsi

Starvation is a challenging issue in fish growth. In this study, we assessed the effect of short-term fasting on reactive oxygen species (ROS) content, antioxidant activity, the mRNA level of antioxidant and autophagyrelated signaling genes and autophagosome formation in the adult Siniperca chuatsi intestine. The results revealed that the ROS and MDA content increased during short-term starvation. Furthermore, GSH content and the activity of SOD, CAT, GST, and GPX increased significantly after a three-day fast, whereas glutathione reductase (GR) activity did not change. Meanwhile, the expression of antioxidant-related signaling genes such as NRF2 was upregulated. As for autophagy-related genes, the expression of Atg4b, BECLIN1 and LC3b did not change after three days of fasting, but significantly upregulated after seven days of fasting, while S6K1 exhibited a decreasing trend. The expression of mTOR decreased significantly after seven days of fasting. Both the mRNA and protein levels of LC3b increased significantly. The results of transmission electron microscopy indicated that the autophagosomes did not changed significantly in the three-day fasting group, but after seven days of starvation and resumed feeding for three days, autophagosomes in the intestine increased significantly. The results indicate that short-term fasting causes a range of physiological and molecular responses in the adult S. chuatsi intestine, which includes alterations in antioxidant signaling genes, antioxidant capacity and subsequently autophagy. Our findings provide a potential insight in the molecular regulatory mechanism of short-term fasting in the intestine of adult S. chuatsi.