Effect of Aging on the Adaptive and Proliferative Capacity of the Small Bowel
Abstracts
|
Our society is aging at a rapid rate; it is estimated that one-quarter of the US population will be >65 years old by 2050. In general, there is a decline in physiologic function with aging. Consistent with this decline, aging is associated with reduced hepatic regeneration after resection. Little is known regarding the adaptive capacity of the aged small bowel mucosa; therefore, the purpose of our study was to determine the ability of the aged small bowel mucosa to adapt following resection. Methods. The well-characterized model of intestinal hyperplasia following massive small bowel resection (SBR, a 70% proximal resection) was utilized to determine the proliferative capacity of the small bowel with aging using young (2-month-old) and aged (24-month-old; equivalent to the 8th decade of human life) F344 rats. At 7 and 14 days after operation, the distal small bowel remnant (15 cm) and corresponding sham segments were harvested, weighed and samples obtained for DNA content and histological analysis (ie, villus height). Results. Massive SBR resulted in significant adaptive hyperplasia in the remaining small bowel remnant compared with sham in both the young and aged rats at 7 and 14 days. At 7 days, the adaptive increases in weight of the small bowel remnant were similar in the young and aged rats (75% and 53% increase compared with the corresponding sham segments, respectively). At 14 days, adaptive increases in weight of the young and aged small bowel remnant were noted and, although not statistically significant, the mean weight of the small bowel in the aged rats was increased compared with the young rats (99% increase in the aged vs. 66% increase in the young rats). Similar to weight, measurement of villus height demonstrated a significant increase over sham in both the young and aged rats at 7 days. Conclusions. Our findings are the first to show that aged small bowel exhibits a proliferative and adaptive capacity in response to SBR that was equivalent to that of the young animals. Importantly, these findings demonstrate that, in contrast to the liver, the proliferative response and adaptive capacity of the small bowel is retained with aging. |
