Recent evidence for toxic effects of NH3 exposure on lung injury: Protective effects of L-selenomethionine

Ammonia (NH3) is a common air pollutant, which poses a serious threat to farm animals. L-selenomethionine is organic selenium (Se), which can inhibit intracellular ROS generation, block ROS-dependent autophagy, promote mitochondrial energy metabolism, and enhance the body's immunity. Lung, as an important organ of the respiratory system, is highly susceptible to the toxic effects of NH3. However, there were few studies on the mechanism of toxic effects of NH3 on lung tissues. The aim of this study was to investigate the effect of NH3 on the lungs in pigs and the alleviating effect of L-selenomethionine. Twenty-four Large White*Duroc*Min pigs were randomly assigned to 4 groups: control group, NH3 group, Se group, and NH3 +Se group. The results showed that exposure to NH3 caused damage and inflammation in lung tissues and significantly increased blood NH3 concentration. NH3 induced changes of oxidative stress indexes (GSH, GSH-Px, SOD, MDA, Keap1, Nrf2, and HO-1) and expressions of energy metabolism related genes (HK1, HK2, PFK, PK, LDHA, and HIF-1 alpha). Ultrastructure showed that mitochondrial damage and autophagosome increased significantly, and the expression levels of autophagy related genes (Beclin1, ATG5, ATG7, ATG10, and p62) changed. However, the addition of L-selenomethionine alleviated the above changes, but there was still a significant difference compared with the control group (P < 0.05). This finding can provide a new evidence for mitigation of NH3 toxicity.