Tannic Acid Induces Intestinal Dysfunction and Intestinal Microbial Dysregulation in Brandt’s Voles (Lasiopodomys brandtii)

SIMPLE SUMMARY: Long-term evolution has resulted in plants developing defense mechanisms against herbivores, including physical defenses (such as hard outer skin, needles, thorns, etc.) and chemical defenses (such as toxic plant secondary metabolites, etc.) that interfere with animal eating, digestion, and metabolism, thus restricting animals’ food choices. In this study, we investigated the effects of dietary tannic acid on the digestion and mucosal barrier function of Brandt’s voles. The results revealed that plant tannins are a very powerful deterrent for Brandt’s voles. This research advances our broad knowledge of interactions between plants and herbivores, as well as the ecological significance of plant secondary metabolites. ABSTRACT: Brandt’s vole (Lasiopodomys brandtii) is a small herbivorous mammal that feeds on plants rich in secondary metabolites (PSMs), including tannins. However, plant defense mechanisms against herbivory by Brandt’s voles are not clearly established. This study aimed to investigate the effects of dietary tannic acid (TA) on the growth performance, intestinal morphology, digestive enzyme activities, cecal fermentation, intestinal barrier function, and gut microbiota in Brandt’s voles. The results showed that TA significantly hindered body weight gain, reduced daily food intake, changed the intestinal morphology, reduced digestive enzyme activity, and increased the serum zonulin levels (p < 0.05). The number of intestinal goblet and mast cells and the levels of serum cytokines and immunoglobulins (IgA, IgG, TNF-α, IL-6, and duodenal SlgA) were all reduced by TA (p < 0.05). Moreover, TA altered β-diversity in the colonic microbial community (p < 0.05). In conclusion, the results indicate that TA could damage the intestinal function of Brandt’s voles by altering their intestinal morphology, decreasing digestive ability and intestinal barrier function, and altering microbiota composition. Our study investigated the effects of natural PSMs on the intestinal function of wildlife and improved our general understanding of plant–herbivore interactions and the ecological role of PSMs.