Exploring the Differential Expression of a Set of Key Genes Involved in the Regulation and Functioning of the Stomach in the Post-Weaned Pig

SIMPLE SUMMARY: On commercial pig farms, weaning occurs prematurely at approximately four weeks of age, when the pig’s digestive and immune systems have not yet matured. The post-weaning period is often associated with poor performance, diarrhoea and even mortality. One area which has been somewhat overlooked, in terms of improving the health and performance of the post-weaned pig, is the stomach. The stomach’s acidic environment acts as one of the first lines of defence against ingested pathogens and plays a key role in ensuring optimal activity of certain digestive enzymes. The post-weaned pig’s poorly developed enzyme and acid secretory capacity leaves the pig more susceptible to pathogens and reduces its protein digestion capabilities. Improving the stomach’s functioning has the potential to enhance the health and performance of the post-weaned pig. However, to date, there have been minimal studies characterizing the different regions of the pig’s stomach, and more precisely the gene expression patterns in these regions. An advancement in the knowledge and understanding of the regions of the pig’s stomach would allow future researchers to more effectively target improved stomach functioning. The present study characterizes the gene expression patterns in the glandular regions (cardiac, fundic and pyloric) of the stomach, enhancing the understanding of the functions of each of these regions. ABSTRACT: Despite playing a key role in digestion, there is only a broad characterization of the spatiotemporal development of the three glandular regions of the stomach (cardiac, fundic and pyloric) in the weaned pig. Hence, the objective of this experiment was to explore the differential expression (DE) of a panel of key genes within the three glandular regions of the stomach. Eight pigs were sacrificed at d 8 post-weaning, and three mucosal samples were collected from each stomach’s glandular regions. The expression of a panel of genes were measured using QPCR. The true cardiac gland region was characterized by increased expression of PIGR, OLFM4, CXCL8 and MUC2 relative to the two other regions (p < 0.05). The fundic gland region was characterized by increased expression of ATP4A, CLIC6, KCNQ1, HRH2, AQP4, HDC, CCKBR, CHIA, PGA5, GHRL and MBOAT4 compared to the two other regions (p < 0.05). The pyloric gland region was characterized by exclusive expression of GAST (p < 0.05). A transition region between the cardiac and fundic region (cardiac-to-oxyntic transition) was observed with a gene expression signature that resembles a cross of the signatures found in the two regions. In conclusion, unique gene expression signatures were identifiable in each of the glandular regions, with a cardiac-to-oxyntic transition region clearly identifiable in the post-weaned pigs’ stomachs.