VITAMIN-A-DEFICIENT RATS HAVE ONLY MILD CHANGES IN JEJUNAL STRUCTURE AND FUNCTION

This study investigated the effect of clinical and subclinical vitamin A deficiency on intestinal structure and function in rats. Weanling m ale rats fed a vitamin A-deficient diet (VA-) for 40-42 or 60-63 d wer e compared with rats either pair-fed (PF) or with free access to the s ame diet supplemented with vitamin A (VA+). A reference (REF) group wa s fed a standard rat diet. Weight began to plateau in VA- rats after 4 2 d, becoming significantly different from PF rats at 60-63 d (P < 0.0 2). Diarrhea did not develop in any study group. VA- rats had clinical signs of vitamin A deficiency in the 60-63 d study, but not in the 40 -42 d study. However, serum and liver retinol concentrations were negl igible in all VA- rats. VA- rats in the 60-63 d study had significantl y reduced villus height (P < 0.02), and sucrase and maltase activities (P < 0.02) compared with PF rats. There were no differences between V A- and PF rats in mucosal wet weights, protein and DNA concentrations, thymidine kinase activity and glucose transport. No differences were detected in the 40-42 d study for any variable measured. Because clini cal vitamin A deficiency in rats causes only mild changes in intestina l structure and function, it is unlikely that these alterations alone are responsible for the interactions observed in epidemiological studi es between vitamin A deficiency and diarrheal disease.