Messenger RNA Gene Expression Screening of VIP and PACAP Neuropeptides and Their Endogenous Receptors in Ruminants

SIMPLE SUMMARY: This study aimed to measure the neuropeptides, vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase activating polypeptide (PACAP), and their receptors, termed VPAC1, VPAC2 and PAC1 in ruminants. To date, we are unaware of any reported quantitative polymerase chain reaction (qPCR) measurements for these genes in either sheep (weathers) or cows (steers). To this end, we isolated total RNA from 15 different tissues from both wethers and steers and performed qPCR measurements. These data revealed expression for VIP and PACAP in the brain and intestines of both ruminant species, while VPAC1 and PAC1 receptors were detected in the brain, throughout the intestines (e.g., duodenum, jejunum, ilium, and colon), metabolically relevant organs (e.g., liver, kidney, and fat), and spleen (a primary immune organ). In contrast, VPAC2 was not detected in wethers, and only detected in spleen and omasum (muscular third stomach) in steers. Collectively, these data reveal for the first-time tissue expression profiles for the VIP and PACAP ligands and their receptors in ruminants that will provide researchers a better understanding of their biological activities in these animals. ABSTRACT: Vasoactive Intestinal Peptide (VIP) and Pituitary Adenylate-Cyclase-Activating Peptide (PACAP) are anti-inflammatory neuropeptides that play important roles in human and rodent gut microbiota homeostasis and host immunity. Pharmacologically regulating these neuropeptides is expected to have significant health and feed efficiency benefits for agriculturally relevant animals. However, their expression profile in ruminant tissues is not well characterized. To this end, we screened for VIP and PACAP neuropeptides and their endogenous GPCRs using 15 different tissues from wethers and steers by RT-qPCR. Our results revealed relatively similar expression profiles for both VIP and PACAP neuropeptide ligands in the brain and intestinal tissue of both species. In contrast, the tissue expression profiles for VPAC1, VPAC2, and PAC1 were more widespread and disparate, with VPAC1 being the most diversely expressed receptor with mRNA detection in the brain and throughout the gastrointestinal tract. These data are an important first step to allow for future investigations regarding the VIP and PACAP signaling pathways in livestock ruminant species.