Structural patterns of swine ileal mucosa following L-glutamine and nucleotide administration during the weaning period. An histochemical and histometrical study

Dietary supplementations with L-glutamine and/or nucleotides were screened for their effects on intestinal mucosa in 16 female weaning piglets. The animals were transported to the university's facilities 24 hours after weaning. They were grouped four to a pen in controlled environmental conditions and fed one of the following four diets for 28 days: control diet (C); C+0.5% L-glutamine (G); C+0.05% "nucleotides" (N); and C+0.5 % L-glutamine+0.05% "nucleotides" (GN). Individual body weights and feed intake per group were recorded at the beginning and the end of the study as well as weekly during it. There were no significant performance differences among the groups. After 28 days the animals were slaughtered and the distal ileum and liver were examined histologically. Anti-proliferating cell nuclear antigen (PCNA) as well as anti-human macrophage immunostaining, and a modified TdT-mediated dUTP nick-end labeling technique (TUNEL) were performed, and intraepithelial lymphocyte percentage was evaluated to assess morpho-functional aspects of the ileum. Histometry was performed by assessing cell indices and counts of immuno-reactive structures. Feeding G and/or N resulted in an increase in villi (V) height, crypt (C) depth, and a decrease in V:C ratio (P<0.01). In addition, feeding G and/or N resulted in an increase in mitotic mucosal cells (M), and a decrease in apoptotic mucosal cells (A), thus decreasing the A:M index (P<0.01). The percentages of mucosal macrophages were greater in G and/or N groups (P<0.001) than in control piglets, and similarly among the groups the percentages of intraepithelial lymphocytes varied (P<0.01). Our data showed that the diet supplementation with G and/or N had positive effects on some morpho-functional characteristics of piglet ileal mucosa. These ameliorative effects may potentially be linked to a good responsiveness of piglets to a stressful period, like a precocious weaning is in this species.