The aim of this present study was to identify the earliest point at which
riboflavin deficiency affects post-weaning bowel development in rats. After weaning, eighty Wistar rats were weight-matched as pairs, one animal being fed a normal synthetic diet and the other being fed the same diet but deficient in
riboflavin.
Body weight, feeding and rates of growth were monitored and eight pairs of animals were taken for analysis at 45, 69, 93, 117 and 141 h.
Riboflavin status was monitored by determining the erythrocyte
glutathione reductase activation coefficient (EGRAC), and hepatic
flavins were measured by a fluorescence assay. Changes to the number and dimensions of villi and crypts in the duodenum were determined, as well as crypt division (bifurcation) and the
DNA synthesis index of the crypt epithelium by
bromodeoxyuridine (
BrdU) labelling.
Riboflavin deficiency was established in the experimental rats, as demonstrated by a significant increase in EGRAC after 45 h (P<0.001) and decreased liver
flavins after 96 h (P<0.001). After 96 h a significant increase in the size and cellularity of the crypts (P<0.001 in both cases) was seen in these
riboflavin-deficient animals, with a decreased incidence of bifurcating crypts and of
BrdU-labelled cells. No changes to villus number or size were observed. The present study has demonstrated that developmental changes to the duodenal crypt arise shortly after circulating
riboflavin measurements show evidence of deficiency. These changes primarily affect cell proliferation and crypt bifurcation, and precede long-term changes such as the reduction of villus number.