GENE EXPRESSION OF THE L-AMINO ACID–SENSING RECEPTOR T1R1/T1R3 CHANGES IN GUT TISSUES OF PIGS IN RESPONSE TO DIETARY PROTEIN.

We have shown that the porcine umami taste receptor T1R1/T1R3 is present in pig’s gut and its expression increases in the small intestine after weaning. The aim of this study was to determine if the expression of the pT1r1/pT1r3 genes in taste and gut tissues changes in response to variation in the content of dietary CP and essential AA (EAA). Forty-eight Pietrain x Landrance piglets were used from weaning (26 d of age) to 20 d after weaning. Piglets were allotted to 3 dietary treatments (16 piglets/treatment): high CP diet (HCP, 24%CP, 15 g/kg of Lys), low CP diet (LCP, 17%CP, 9 g/kg of Lys) and LCP diet supplemented with all EAA (SAA, 17%CP, 15 g/kg of Lys). Four animals per treatment were sacrificed on d 20 after weaning to collect tissue samples of fungiform and circumvallate papillae (TC), stomach (S), liver (L), duodenum (D) and ileum (I). The relative abundance of mRNA of the pT1r1 and pT1r3 genes was quantified via real-time PCR using the tata box biding protein as housekeeping gene. Real-time data were analyzed using the GEE model with an exchangeable correlation structure and the GENMOD procedure of SAS. Fold change estimations were performed for sex, diet, tissue and their interaction relative to the liver from the HCP group. The expression of the pT1r1 gene was upregulated in S, D and I (P<0.05) of the LCP group, whereas the expressionof the pT1r3 gene was upregulated in TC, S and D (P<0.05) of the SAA group and tended to increase in D and I (P<0.1) of the LCP group. In summary, the expression of the porcine umami taste receptor mainly responded to changes in CP intake. Interestingly, supplementing the LCP diet with essential AA to meet piglet’s requirement tended to prevent such a response in the pT1r1 gene. Taken together, these observations suggest that the porcine umami taste receptor plays a role in sensing the enteral supply of protein. tech.service.fad@lucta.com