Calo Jessica, Blanco Ayelén M, Comesaña Sara, Conde-Sieira Marta, Morais Sofia, Soengas José L
Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía and Centro de Investigación Mariña, Universidade de Vigo, 36310, Vigo, Pontevedra, Spain.
Lucta S.A., Innovation Division, UAB Research Park, Bellaterra, Spain.
Sci Rep. 2021 Mar 2;11(1):4933. doi: 10.1038/s41598-021-84303-9.
This study aimed to characterize amino acid sensing systems in the gastrointestinal tract (GIT) of the carnivorous fish model species rainbow trout. We observed that the trout GIT expresses mRNAs encoding some amino acid receptors described in mammals [calcium-sensing receptor (CaSR), G protein-coupled receptor family C group 6 member A (GPRC6A), and taste receptors type 1 members 1 and 2 (T1r1, T1r2)], while others [taste receptor type 1 member 3 (T1r3) and metabotropic glutamate receptors 1 and 4 (mGlur1, mGlur4)] could not be found. Then, we characterized the response of such receptors, as well as that of intracellular signaling mechanisms, to the intragastric administration of L-leucine, L-valine, L-proline or L-glutamate. Results demonstrated that casr, gprc6a, tas1r1 and tas1r2 mRNAs are modulated by amino acids in the stomach and proximal intestine, with important differences with respect to mammals. Likewise, gut amino acid receptors triggered signaling pathways likely mediated, at least partly, by phospholipase C β3 and β4. Finally, the luminal presence of amino acids led to important changes in ghrelin, cholecystokinin, peptide YY and proglucagon mRNAs and/or protein levels. Present results offer the first set of evidence in favor of the existence of amino acid sensing mechanisms within the fish GIT.
本研究旨在表征肉食性鱼类模式物种虹鳟胃肠道（GIT）中的氨基酸传感系统。我们观察到，虹鳟胃肠道表达了一些在哺乳动物中描述的编码氨基酸受体的mRNA[钙敏感受体（CaSR）、G蛋白偶联受体C家族第6组成员A（GPRC6A）以及味觉受体1型成员1和2（T1r1、T1r2）]，而其他受体[味觉受体1型成员3（T1r3）以及代谢型谷氨酸受体1和4（mGlur1、mGlur4）]未被发现。然后，我们表征了这些受体以及细胞内信号传导机制对胃内给予L-亮氨酸、L-缬氨酸、L-脯氨酸或L-谷氨酸的反应。结果表明，casr、gprc6a、tas1r1和tas1r2 mRNA在胃和近端肠道中受氨基酸调节，与哺乳动物存在重要差异。同样，肠道氨基酸受体触发的信号通路可能至少部分由磷脂酶Cβ3和β4介导。最后，管腔中氨基酸的存在导致胃饥饿素、胆囊收缩素、肽YY和胰高血糖素原mRNA和/或蛋白质水平发生重要变化。目前的结果提供了第一组证据，支持鱼类胃肠道中存在氨基酸传感机制。
