Short-term malnutrition in neonatal rabbits: Effect on gastrointestinal epithelial proliferation

We determined DNA synthesis, cell turnover and cell migration in 72-h fasted and control neonatal rabbits because acute neonatal malnutrition causes specific regional alterations in brush border structure and function. Decreased cell turnover and/or migration might partly explain these observations. We injected fed and fasted neonatal rabbits with [³H]thymidine. At 1 and 72 h after injection we assessed cell proliferation and migration. Villus height was less in proximal small bowel from fasted rabbits (PF) than in fed controls (PC). Villus height was lower in proximal than in distal small bowel from fasted rabbits (DF). DNA synthesis, as measured by incorporation of [³H]thymidine into DNA, was less in PF and DF than in PC and distal small bowel from fed rabbits (DC) whether expressed per μg DNA or per intestinal segment. Similarly, thymidine kinase activity ws lower in PF and DF than in PC and DC. For both fed and fasted rabbits, more cells were present in the proliferative zone from proximal small bowel than in that from distal. Small bowel labeling index was less in PC than in DC, and less in DF than in DC. The ratio of the number of cells in the proliferative zone to the number of cells in crypt was greater in PC than in DC and greater in DF than in DC. The migration zone was significantly greater in PC than in PF and greater in the fed group in the proximal small bowel than in the distal small bowel. Thus, a 72-h fast in neonatal animals resulted in decreased DNA synthesis and cell migration. Regional alterations in cell proliferation occurred. These results could explain, at least in part, previous observations of the altered structure and function induced in the small bowel of fasted neonatal rabbits.