Calcium-sensing receptor and the regulation of nutrient absorption and barrier function in pigs

Abstract

This study is to explore the potential roles of the calcium-sensing receptor (CaSR) on gut health in pigs. Chapter one introduces the background of the whole study, which helps to elicit the thesis hypothesis and objectives outlined in Chapter three. A literature review is provided in Chapter two that reviews the structural features, physiological roles, and related underlying mechanisms of the CaSR. The distribution and localization of the pCaSR were explored in Chapter four, and our results found the wide expression of the pCaSR in the intestine. In Chapter five identifies the expression of the pCaSR in porcine enterocytes, while data revealed that the pCaSR is not expressed in porcine enterocytes. Chapter six describes the ligands screening of the pCaSR and related cell signaling, and we found that the activation of the pCaSR showed biased agonism through multiple signaling. Furthermore, α-casein (90-95) and L-Tryptophan (L-Trp) are type II agonists for the pCaSR. In Chapter seven, both the roles of CaSR ligands in gut hormone secretion and the mechanisms and effects of CaSR ligands in the gut barrier function were explored using an in vitro model challenged with peptidoglycan (PGN). Our results suggested that L-Trp and α-casein (90-95) attenuated the inflammation response and improved nutrient absorption and barrier function. In Chapter eight we provide a general discussion, and all references are included in Chapter nine. Collectively, the pCaSR is widely expressed in the porcine tissues, and the activation of the pCaSR has the potential to improve gut health and growth performance in swine production.