Effects of niacin on intestinal immunity, microbial community and intestinal barrier in weaned piglets during starvation

The objective was to evaluate the effects of niacin on intestinal immunity, microbial community and intestinal barrier in weaned piglets during starvation. In this study, twelve weaned piglets with similar body weight were randomly divided into two groups, six for each group. These piglets were treated with starvation, one group was treated with10 ml normal saline (Control), and the other group was perfused with 10 ml niacin solution (Niacin, 40 mg niacin was dissolved in equal volume of normal saline) once daily for three consecutive days. The results showed that niacin effectively attenuated the weight loss and diarrhea index (P < 0.05) in weaned piglets; Niacin improved jejunal villous height and intestinal morphological score (P < 0.05); Additionally, niacin significantly increased the mRNA expression of antimicrobial peptide (pBD2 and PR39) in the jejunum (P < 0.05); Meanwhile, niacin significantly increased ZO-1 and Occludin expression in the jejunum (P < 0.05). Furthermore, niacin improved the microbiota and the concentrations of acetate (P < 0.05). Conversely, niacin decreased the ratios of propionate/acetate and butyrate/acetate in the colonic contents of weaned piglets (P < 0.05); Interestingly, niacin increased the protein expression of SIRT1 (P < 0.05) and inhibited the protein expression of HDAC7 (P < 0.05). In conclusion, niacin attenuated the weight loss and diarrhea, and improved the expression of antimicrobial peptides, and enhanced intestinal epithelial barrier function, and improved the microbiota in the colonic contents of weaned piglets, suggesting that niacin may be an effective way for weaned piglets to maintain the gut and overall health.