EFFECTS OF SODIUM CHOLATE ON GROWTH AND GLUCOSE METABOLISM OF LARGEMOUTH BASS (MICROPTERUS SALMOIDES)

Cholic acid (CA) is the main bile acid (BAs) in fish. To explore the effects of cholic acid on the growth and glucose metabolism of largemouth bass (Micropterus salmoides), we formulated an experimental diet by adding 300 mg/kg sodium cholate (CAS) in the control diet for an 8-week trial before analyzing the effects of CAS on the growth, intestinal microbiota, gene expression of glucose metabolism and bile acid receptor Farnesoid X receptor (FXR) of largemouth bass. The results showed that CAS had no significant effects in the growth index, including weight gain rate (WGR), condition factor (CF), carcass ratio (CR), viscerosomatic index (VSI), hepatosomatic index (HSI) and mesenteric fat index (MFI). CAS also did not affect the body composition including moisture, crude protein, crude lipid and crude ash of the largemouth bass, and it did not regulate the intestinal microbiota of the largemouth bass. Sodium cholate promoted glycogen synthesis and activity of glycogen synthase (GCS) in liver but not in the muscle without impacting the activity of glycogen phosphorylase a (GPa) in the liver. Sodium cholate significantly promoted the expression of fructose-1,6-bisphosphatase (FBPase), glucose-6-phosphatase (G6Pase), and pyruvate kinase (PK) in liver, and it significantly decreased hexokinase (HK) genes in muscle. Moreover, sodium cholate significantly inhibited the expression of the bile acid receptor Farnesoid X receptor (FXR) in the liver, without changing the expression of intestinal FXR. These results suggest that 300 mg/kg CAS did not affect growth and body index of largemouth bass, and that CAS may regulate glucose metabolism via liver FXR expression.