Integration of Metabolomics and Transcriptomicsto Comprehensively Evaluate the Metabolic Effects of Gelsemium elegans on Pigs

SIMPLY SUMMARY: Some natural phytogenic feed additives, which contain several active compounds, have been shown to be effective alternatives to traditional antibiotics. Gelsemium elegans (G. elegans) has been used as a traditional Chinese herbal medicine for many years, and it has an obvious growth-promoting effect on animals such as pigs. To our knowledge, the internal mechanism of the influence of G. elegans on the animal body is still unclear. Here, the plasma metabolomics and liver transcriptional profile of crude extract of G. elegans in pigs were reported for the first time and the metabolic consequences of feeding piglets G. elegans for 45 days were evaluated. The results showed that the addition of 2% G. elegans powder to feed is nontoxic to pigs. In addition, G. elegans could be used as a phytogenic feed additive, which could improve the immune function of piglets, and the latent mechanism of G. elegans may be related to various signaling pathways, including the MAPK signaling pathway and PPAR signaling pathway. Collectively, results of the current provide a clearer understanding of the molecular mechanism of the pharmacological effects of G. elegans, which is of great significance for a safer and more rational application of this phytogenic feed additives. ABSTRACT: Some naturalphytogenic feed additives, which contain several active compounds, have been shown to be effective alternatives to traditional antibiotics. Gelsemium elegans (G. elegans) is a whole grass in the family Loganiaceae. It is a known toxic plant widely distributed in China and has been used as a traditional Chinese herbal medicine for many years to treat neuropathic pain, rheumatoid pain, inflammation, skin ulcers, and cancer. However, G. elegans not only is nontoxic to animals such as pigs and sheep but also has an obvious growth-promoting effect. To our knowledge, the internal mechanism of the influence of G. elegans on the animal body is still unclear. The goal of this work is to evaluate the metabolic consequences of feeding piglets G. elegans for 45 days based on the combination of transcriptomics and metabolomics. According to growth measurement and evaluation, compared with piglets fed a complete diet, adding 20 g/kg G. elegans powder to the basal diet of piglets significantly reduced the feed conversion ratio. Results of the liver transcriptome suggest that glycine and cysteine-related regulatory pathways, including the MAPK signaling pathway and the mTOR signaling pathway, were extensively altered in G. elegans-induced piglets. Plasma metabolomics identified 21 and 18 differential metabolites (p < 0.05) in the plasma of piglets in the positive and negative ion modes, respectively, between G. elegans exposure and complete diet groups. The concentrations of glycine and its derivatives and N-acetylcysteine were higher in the G. elegans exposure group than in the complete diet group.This study demonstrated that G. elegans could be an alternative to antibiotics that improves the immune function of piglets, and the latent mechanism of G. elegans may be related to various signaling pathways, including the MAPK signaling pathway and the PPAR signaling pathway.