Essential oil from Artemisia argyi alleviated liver disease in zebrafish (Danio rerio) via the gut-liver axis

The popularity of intensive fish farming has led to the emergence of fish diseases characterized by hepatobiliary syndrome. Artemisia argyi (A. argyi) essential oils have anti-inflammatory and anti-oxidant effects. However, their alleviating effects and mechanism on liver disease in fish are still unclear. Thus, adult zebrafish were used to construct an animal model to observe histopathological damages, determine biochemical parameters and expression of inflammatory cytokines and mRNAs in the PPAR-γ/NF-κB pathway, and conduct 16 S sequencing of intestinal microbiota. The results found that after treatment with A. argyi essential oil, the histopathological damage caused by ethanol was relieved; the CAT, SOD, and GSH levels were remarkably elevated, while the MDA level was obviously lowered (P < 0.05); the expression levels of IL-10 and IFN-γ mRNAs were enhanced, but the levels of IL-1β, IL-6, PPAR-γ, NF-κB, and TNF-α mRNAs were reduced (P < 0.05) relative to the EtOH group. A. argyi essential oil remarkably attenuated the damage to intestinal tissue structure, and elevated the levels of Muc2, ZO-1, Claudin-1, and Occludin mRNA (P < 0.05). Sequencing of the gut flora showed that A. argyi essential oil significantly altered the composition of gut microbes compared with the EtOH group. In addition, KEGG and COG analyses also showed significant (P < 0.05) changes in acetate cycling metabolism in the EtOH group, catechol 2, 3-dioxygenase and nitroreductase were significantly increased (P < 0.001), and lipid metabolism and terpenoid synthesis were significantly elevated (P < 0.001) in A. argyi essential oil group. The results indicate that A. argyi essential oil could effectively relieve ethanol-caused histopathological damage of livers by modulating the composition of gut microbiota, thus inhibiting the level of IL-1β and mRNAs in the PPAR-γ/NF-κB pathway, increasing the IL-10 level, reducing the oxidative stress. This may offer a rationale for further research on the rationality of A. argyi as a substitute for feed antibiotics in aquaculture.