Dietary Glycyrrhetinic Acid Regulates Appetite and Improves Growth Performance of Piglets via Mediating Gut-Brain Axis

Compared with the Gal group, GA supplementation improved the average daily feed intake during 14-28 d and 0-28 d, and had a trend to increase the total weight gain and reduced the F/G in piglets during the whole period. GA supplementation increased the protein levels of hypothaslamus NPY, increased the AGRP and NPY positive cells and decreased POMC positive cells in hypothaslamus by immunohistochemistic staining when compared with Gal group. Compared to Gal group, GA supplementation increased the protein levels of jejunum T1R2 and T1R3, as well as markedly improved the immunofluorescence expression of T1R2 and T1R3 protein in jejunum. GA supplementation increased jejunum ghrelin level and the serum levels of ghrelin, AGRP, and NPY than those of the Gal group, as well as decreasing serum POMC level. GA supplementation increased the serum l-cystine level, as well as the jejunum AA transporter SLC6A19 mRNA expression. In addition, dietary GA increased the Romboutsia relative abundance than that of the Gal group.