Nitidine Chloride Alleviates Hypoxic Stress via PINK1-Parkin-Mediated Mitophagy in the Mammary Epithelial Cells of Milk Buffalo.

Simple Summary: Under heat stress, the aerobic metabolic activity of the body is significantly accelerated, which easily leads to hypoxia of high-oxygen consumption tissues, such as the mammary gland. In dairy cattle growing in the high-temperature and high-humidity environment in Guangxi, especially those in the peak period of lactation with strong metabolism, the lack of oxygen in the mammary cells is more obvious, and the milk volume and composition are greatly affected, and even lead to metabolic disorders. Nitidine chloride (NC) is a natural alkaloid with antioxidant properties that can remove excess reactive oxygen species (ROS). However, there is limited information on the effect of NC on BMECs hypoxic injury and its molecular mechanism. In this study, molecular biological methods combined with non-targeted metabolomics were used to study the protective effect of NC on BMECs induced by hypoxic stress. Based on the results obtained, we found that NC has a protective effect on hypoxic mitochondria and regulates amino acid metabolism in response to hypoxic stress. Hypoxia in the mammary gland epithelial cells of milk buffalo (BMECs) can affect milk yield and composition, and it can even cause metabolic diseases. Nitidine chloride (NC) is a natural alkaloid with antioxidant properties that can scavenge excessive reactive oxygen species (ROS). However, the effect of NC on the hypoxic injury of BMECs and its molecular mechanisms are still unknown. Here, an immunofluorescence assay, transmission electron microscopy (TEM), and flow cytometry, combined with untargeted metabolomics, were used to investigate the protective effect of NC on hypoxic stress injury in BMECs. It was found that NC can significantly reduce cell activity (p < 0.05) and inhibit cellular oxidative stress (p < 0.05) and cell apoptosis (p < 0.05). A significant decrease in mitophagy mediated by the PINK1-Parkin pathway was observed after NC pretreatment (p < 0.05). In addition, a metabolic pathway enrichment analysis demonstrated that the mechanisms of NC against hypoxic stress may be related to the downregulation of pathways involving aminoacyl tRNA biosynthesis; arginine and proline metabolism; glycine, serine, and threonine metabolism; phenylalanine, tyrosine, and tryptophan biosynthesis; and phenylalanine metabolism. Thus, NC has a protective effect on hypoxic mitochondria, and it can regulate amino acid metabolism in response to hypoxic stress. The present study provides a reference for the application of nitidine chloride to regulate the mammary lactation function of milk buffalo. [ABSTRACT FROM AUTHOR]