Diet Composition Modulates Intestinal Hydrolytic Enzymes in White‐Footed Mice (Peromyscus leucopus)

Abstract

Animals can digestively accommodate to diets with varying substrate levels by routinely possessing plenty of spare digestive capacity or by modulating digestive capacity to match changes in dietary substrate level. There are few studies of this in wild mammals, though in laboratory mice and rats levels of intestinal disaccharidases and peptidases are known to change in correlation with dietary carbohydrate and protein levels, respectively. We maintained white‐footed mice for 12–81 days on diets enriched in either starch (diet C), protein (diet P) or lipid (diet L). There was no effect of either diet, or time on the diet, on their body mass when tissues were harvested. There were no significant effects of body mass on small intestinal mass or length, and no significant effects of diet on small intestinal mass or length. Diet treatment affected the summed activities of maltase, sucrase and aminopeptidase‐N. Post‐hoc Tukey comparisons showed that in all cases summed activity was lowest for diet L, with no differences between diets C and P. Activities of all three enzymes tended to be highest most often in midintestine, and whatever factor(s) reduced enzyme activities on the L diet apparently did so in all intestinal positions. This is only the second study in a wild small mammal, to our knowledge, testing for digestive modulation to diet composition. Like the other study, we found evidence of modulation, but the pattern differed from that observed in laboratory mice and rats in that the expected correlations with dietary carbohydrate and protein were not apparent. Maltasisc activity was relatively high in white‐footed mice, which suggests that they may routinely possess plenty of spare digestive capacity.Support or Funding InformationSupported by NSF 1354893 to WHK.