Antioxidant activity and duodenum transporter gene expression in quail fed citric acid

Abstract

The study aimed to evaluate the effects of citric acid supplementation on the performance and the gene expression in the duodenum of Japanese quail. Genes related to antioxidant activity: superoxide dismutase (SOD) and glutathione peroxidase 7 (GPX7); and genes related to nutrient uptake in the enterocytes’ apical membrane: sodium-glucose cotransporter 1 (SGLT1, responsible for the glucose absorption), glucose transporter 2 (GLUT2) and B⁰AT1 (responsible for the absorption of neutral amino acids in brush board membrane) were evaluated. For this, 270 laying quails (Coturnix japonica) were fed a diet supplemented with 0%, 0.6% or 1.2% of citric acid. Gene expression was evaluated by the quantitative reverse transcription-polymerase chain reaction (qRT-PCR) at 35 days old (n = 5). The highest expression of the SGLT1 gene was observed in quails fed the 1.2% citric acid supplemented diet (0.120 AU). Birds fed diets with both levels of citric acid supplementation showed a higher B⁰AT1 gene expression than quails fed no citric acid. Quails fed the 1.2% of citric acid supplemented diet had the lowest SOD gene expression (0.3455 AU). The birds receiving the diets supplemented with citric acid showed a lower GPX7 gene expression than the quails fed the 0% citric acid diet. These results suggests that the effect of citric acid on gene expression in the digestive tract may have contributed to the greater weight gain and lower feed intake observed in birds fed diets supplemented with citric acid.

Keywords: B⁰AT1, intestinal health, organic acid, pathogenic microorganisms, SGLT1