Expression of Transient Receptor Potential Ankyrin 1 and Transient Receptor Potential Vanilloid 1 in the Gut of the Peri-Weaning Pig Is Strongly Dependent on Age and Intestinal Site

SIMPLE SUMMARY: Weaning is a critical event for the piglet, contributing to aberrant gut function and resulting in reduced barrier function and retarded protein digestion. The gut is able to “sense” nutrients and release gut hormones to regulate digestive processes. To that end, various gastrointestinal cell types possess transient receptor potential channels that are involved in regulating gastric motility and secretion. Herbal compounds, currently used in pig nutrition as antibiotic alternatives, are able to activate these channels and could potentially aid digestion. However, these channels have not been characterized in the gut of the pig and their ability to release gut hormones has never been explored. This study’s objective was to characterize TRPA1 and TRPV1 in the pig’s gut and explore their potential to modulate gastric function. A gene expression study was performed on tissues obtained from different locations in the guts of piglets of varying age. Moreover, the ability to secrete peptide hormones was investigated by characterizing them on enteroendocrine cells. Both channels were found to be expressed in the mucosa of the porcine gut, strongly dependent on age and location. Moreover, the endocrine nature of both channels was confirmed, indicating their possible role in gut hormone release and the regulation of gastric emptying. ABSTRACT: Transient receptor potential (TRP) channels contribute to sensory transduction in the body, agonized by a variety of stimuli, such as phytochemicals, and they are predominantly distributed in afferent neurons. Evidence indicates their expression in non-neuronal cells, demonstrating their ability to modulate gastrointestinal function. Targeting TRP channels could potentially be used to regulate gastrointestinal secretion and motility, yet their expression in the pig is unknown. This study investigated TRPA1 and TRPV1 expression in different gut locations of piglets of varying age. Colocalization with enteroendocrine cells was established by immunohistochemistry. Both channels were expressed in the gut mucosa. TRPV1 mRNA abundance increased gradually in the stomach and small intestine with age, most notably in the distal small intestine. In contrast, TRPA1 exhibited sustained expression across ages and locations, with the exception of higher expression in the pylorus at weaning. Immunohistochemistry confirmed the endocrine nature of both channels, showing the highest frequency of colocalization in enteroendocrine cells for TRPA1. Specific co-localization on GLP-1 immunoreactive cells indicated their possible role in GLP-1 release and the concomitant intestinal feedback mechanism. Our results indicate that TRPA1 and TRPV1 could play a role in gut enteroendocrine activity. Moreover, age and location in the gut significantly affected gene expression.