Starvation-Induced Proximal Gut Mucosal Atrophy Diminished With Aging

Background: Starvation induces small bowel atrophy with increased intestinal epithelial apoptosis and decreased proliferation. The authors examined these parameters after starvation in aged animals. Methods: Sixty-four 6-week-old and 26-month-old C57BL/6 mice were randomly assigned to either an ad libitum fed or fasted group. The small bowel was harvested at 12, 48, and 72 hours following starvation. Proximal gut mucosal height was measured and epithelial cells counted. Apoptosis was identified by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining. Proliferation was determined by immunohistochemical staining for proliferating cell nuclear antigen. Comparison of fed vs fasted and adults vs old groups was done by one-way ANOVA with Turkey's test and unpaired Student's t test. Significance was accepted at P < .05. Results: Aged mice had higher proximal gut weights, mucosal heights, and cell numbers at baseline compared with the adult group (P < .05). The rate of apoptosis was lower in the aged (P < .05), but proliferation was not different between groups before starvation. After starvation, proximal gut wet weight decreased only in adult mice (P < .05). Gut mucosal height and mucosal cell number decreased more in adult than in aged mice (P < .05). This was related to decreased proliferation only in the adult group (P < .05). The fold of epithelial apoptosis that increased was higher in the aged group than in the adult group after starvation (P < .05). Conclusions: Gut mucosal kinetics change with age and have lower rates of apoptosis and greater mucosal mass; the character of starvation-induced atrophy is diminished with aging. (JPEN J Parenter Enteral Nutr. 2009; 33:411-416)