GENE CLONING OF GPR43 AND ITS DISTRIBUTION IN THE TISSUE OF BLUNT SNOUT BREAM AND THE EFFECT OF BERBERINE ON ITS MRNA EXPRESSION

This study was conducted to explore the effects of berberine on the mRNA expression of G protein coupled receptors 43 (GPR43) and the lipid metabolism performance of blunt snout bream fed with high-fat diet. GPR43 in blunt snout bream was cloned and sequenced with a RACE assays. The effects of berberine on GPR43 mRNA expression in tissues were also investigated. The obtained full-length nucleotide sequence covers 2026 bp, which has an open reading frame of 981 bp, and translates a total of 326 amino acids. Moreover, GPR43 mRNAs were detected in different tissues of blunt snout bream. In blunt snout bream, the expression of GPR43 in intestine, hepatopancreas, gill and white muscle were the highest. 320 fish (80.00±0.90) g were randomly divided into four trial groups (each has four replicates) and fed with 4 diets (normal diet, normal diet with 50 mg/kg berberine, high-fat diet, and high-fat diet with 50 mg/kg berberine, among which normal diet has 5% lipid and high-fat diet has 10% lipid), respectively. The expression of GPR43 mRNA in the high-fat diet group decreased compared with control group, while it significantly increased (P<0.05) after adding in berberine. Compared with the control group, the contents of free fatty acids (FFA), triglycerides (TG), cholesterol (CHO), and mRNA expressions of Cytokinins protein kinase (p38), and Peroxidase value-added factor (PPARγ) all increased (P<0.05) in the high-fat group, but a dramatic decrease (P<0.05) happened after adding in berberine. The same result was found on the composition of Polyunsaturated fatty acids (PUFA) in hepatopancreas and muscle tissues. A completely inverse variation was presented on the mRNA expressions of Carnitine palm acyltransferaseⅠ (CPTⅠ), Peroxidase value-added factor (PPARα&β) and AMP dependent protein kinase (AMPK), as well as on the compositions of Saturated fatty acids (SFA) and Monounsaturated fatty acids (MUFA) in both tissues. Nevertheless, the difference between berberine supplemental normal diet group and control group was out of regular pattern. So further work is still needed to explore the role of berberine in normal circumstances. Overall, the results showed the supplement of berberine could slow down lipid deposition in hepatopancreas, and restore lipid homeostasis which has been damaged by continuous high-fat diet feeding.