Effects of dietary supplementation with laminarin derived from Laminaria hyperborea and Laminaria digitata on colonic mucin gene expression in pigs

Abstract

Mucins, the main components of the mucus gel layer, are large multifunctional glycoproteins, with a protective gut barrier function. Cereal-derived β-glucans have been shown to directly affect mucosal architecture, mucin synthesis and secretion in the porcine intestine. Therefore, the aim of this study was to investigate the effects of seaweed-derived β-glucans (laminarin) extracted from Laminaria digitata and Laminaria hyperborea on mucin gene expression in the colon of the grower pig (liveweight 18 kg). Quantitative real-time PCR (qPCR) was carried out using primers specific for 7 mucin genes ( MUC 1, 2, 4, 5AC, 12, 13 and 20) with cDNA that was extracted from pigs (n = 7 animals per group) offered one of five dietary treatments; T1 — basal (control) diet, T2 and T3 — basal diets with laminarin from L. hyperborea at 300 ppm or 600 ppm, respectively, T4 and T5 — basal diets with laminarin from L. digitata at 300 ppm or 600 ppm, respectively. All 7 mucin gene transcripts were reliably detected in the porcine colon. Dietary supplementation with L. digitata derived laminarin at 600 ppm had a significant quadratic effect on MUC2 (P < 0.05) and MUC4 (P < 0.05) expression relative to the control cohort, whilst supplementation with laminarin derived from L. hyperborea had no effect on the expression of any of the mucin genes investigated. In conclusion, dietary supplementation with L. digitata derived laminarin had significant effects on the expression of the secreted mucin MUC2 and the membrane bound mucin MUC4, in the colon of grower pigs. In contrast, dietary supplementation with L. hyperborea derived laminarin had no effect on the expression of any of the mucin genes examined in this study.